LTE Mobility and Throughput - KPI
Analysis & Optimization Workshop
STUDENT BOOK
LZT1381950 R1A
LZT1381950 R1A
LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
DISCLAIMER
This book is a training document and contains simplifications.
Therefore, it must not be considered as a specification of the system.
The contents of this document are subject to revision without notice
due to ongoing progress in methodology, design and manufacturing.
Ericsson shall have no liability for any error or damage of any kind
resulting from the use of this document.
This document is not intended to replace the technical
documentation that was shipped with your system. Always refer to
that technical documentation during operation and maintenance.
© Ericsson AB 2017
This document was produced by Ericsson.
•
The book is to be used for training purposes only and it is strictly
prohibited to copy, reproduce, disclose or distribute it in any
manner without the express written consent from Ericsson.
This Student Book, LZT1381950, R1A supports course number
LZU1082504.
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Table of Contents
Table of Contents
1 LTE MOBILITY PERFORMANCE AND RELATED
PARAMETERS ............................................................................ 11
1 INTRODUCTION ............................................................................ 12
2 IDLE MODE MOBILITY MANAGEMENT ........................................ 12
2.1 PRIORITY BASED CELL RESELECTION ................................... 14
2.2 SPEED-DEPENDENT SCALING OF CELL RESELECTION ........ 16
2.3 PARAMETER RELATED TO IDLE MODE MOBILITY .................. 17
2.3.1 CASE 1: PRIORITY BASED CELL RESELECTION
EXAMPLE ............................................................................................ 18
2.3.2 CASE 2: 3CC CA EXAMPLE..................................................... 18
2.3.3 CASE 3: INITIAL TRAFFIC BALANCING .................................. 20
2.3.4 CASE 4: RESELECTION PARAMETER EXAMPLE .................. 20
2.4 STICKY CARRIER FOR IDLE MODE MOBILITY DURING
IFLB 23
3 EUTRA CONNECTED MODE MOBILITY KPI................................. 25
3.1 LTE EVENT REVIEW................................................................... 25
3.1.1 MOBILITY WITH “MOBILITY CONTROL AT POOR
COVERAGE” FEATURE ...................................................................... 27
4 MOBILITY RELATED ISSUES ANALYSIS ...................................... 28
4.1 HANDOVER FAILURE ISSUES ................................................... 29
4.2 HANDOVER PREP FAILURE- NEIGHBOR CELL LOAD
ISSUES ................................................................................................ 30
4.3 HANDOVER FAILURE, TARGET CELL LICENSE AND
ADMISSION ISSUE .............................................................................. 31
4.4 HANDOVER PREP FAILURE, OTHER CHECKS ........................ 32
5 HANDOVER EXECUTION FAILURE ISSUES AND COUNTERS ... 35
5.1 INTRA/INTER HANDOVER EXECUTION FAILURE,
POSSIBLE CAUSE .............................................................................. 35
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5.2 HANDOVER EXEC FAILURE, POOR DL SINR ISSUES
RELATED PARAMETER ...................................................................... 36
5.3 HANDOVER EXEC FAILURE, UL RSSI ISSUES RELATED
PARAMETER ....................................................................................... 36
5.4 HANDOVER EXEC FAILURE, TARGET CELL RACH ISSUE...... 37
5.5 OVERSHOOTING CELL .............................................................. 39
5.6 HANDOVER PREP/EXEC FAILURE, OTHER IMPORTANT
CHECK ................................................................................................. 39
6 IRAT HANDOVER HO OPTIMIZATION .......................................... 40
7 MCPC RELATED COUNTERS AND PARAMETERS ..................... 41
8 INTER FREQUENCY LOAD BALANCING COUNTERS AND
PARAMETERS ..................................................................................... 42
9 LTE FEATURE SUPPORTING MOBILITY KPI: .............................. 44
10 AUTOMATED MOBILITY OPTIMIZATION .................................... 45
10.1 PARAMETER RELATED TO AMO FEATURE ........................... 46
10.1.1 COUNTERS, EVENTS AND PARAMETERS AMO ................. 48
10.2 CASE STUDY 1, AMO TRIAL TEST .......................................... 49
11 MOBILITY CONTROL AT POOR COVERAGE ............................. 52
11.1 MCPC ASSOCIATED KPI AND COUNTERS ............................. 54
11.2 PARAMETERS ASSOCIATED TO MCPC FEATURE ................ 54
11.3 CASE 2, POST MCPC IMPACT ON KPIS.................................. 57
12 MULTI-LAYER SERVICE-TRIGGERED MOBILITY ...................... 59
13 SUMMARY.................................................................................... 61
2 DIFFERENT HOSR ISSUES AND IMPROVEMENT - CASE
STUDIES ..................................................................................... 63
1 COMMON FAILURE SCENARIO .................................................... 64
1.1 X2 HO PREPARATION PHASE ................................................... 64
1.2 X2 HANDOVER EXECUTION PHASE ......................................... 65
1.3 HO EXECUTION FAILURE EXAMPLE ........................................ 66
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1.4 EVENT IDENTIFICATION ............................................................ 67
2 CASE STUDIES .............................................................................. 68
2.1 CASE 1- IRAT HO, OPTIMUM PARAMETER SETTING TO
IMPROVE LTE DROP RATE ................................................................ 68
2.2 CASE 2: INTRA FREQUENCY OSCILLATING HANDOVER ....... 70
2.2.1 NETWORK ISSUE .................................................................... 70
2.2.2 CASE 2: INTRA FREQUENCY HO EVENT REVIEW ................ 71
2.2.3 PARAMETERS TUNED ............................................................ 71
2.2.4 IMPACT: KPI IMPROVEMENT ................................................. 72
2.3 CASE 3: HOSR DEGRADED WITH AMO ACTIVATION .............. 73
2.3.1 ISSUE STATEMENT ................................................................. 73
2.3.2 CIO STATISTICS OBSERVATION............................................ 73
2.3.3 CASE 3: CIO = -2 & -3 DISTRIBUTION IN DIFFERENT
CLUSTER............................................................................................. 75
2.3.4 CIO = -3 FOR FIRST TIER NEIGHBORS.................................. 75
2.3.5 POTENTIAL REASON OF UNREASONABLE CIO VALUE....... 75
2.3.6 CASE 3: TRAIL SUGGESTION ................................................. 76
2.4 CASE 4: HOSR EXECUTION IMPROVEMENT ON
DISTANCE SITE .................................................................................. 77
2.4.1 CASE 4: HOSR EXECUTION IMPROVEMENT WITH CELL
RANGE CHANGE ................................................................................ 77
2.5 CASE 5: POOR IRAT SUCCESS RATE TOWARDS POOR
WCDMA CELL FOR QCI8 .................................................................... 78
2.5.1 CASE 5: POOR IRAT PARAMETERS CHECK ......................... 79
2.5.2 CASE 5: POOR IRAT SUCCESS RATE TOWARD POOR
WCDMA CELL FOR QCI8 .................................................................... 79
2.6 POOR IRAT HOSR – OTHER REASONS & SOLUTIONS ........... 80
2.6.1 IRAT IMPROVEMENT COUNTER TO BE CHECKED .............. 80
2.6.2 CASE 6: IRAT IMPROVEMENT WITH
‘A1A2SEARCHTRESHOLDRSRP’ ....................................................... 82
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2.6.3 HIGH SAMPLES FOR
‘PMCRITICALBORDEREVALREPORT’ ............................................... 82
2.7 CASE 7: KPIS (HOSR, RET., THP.) IMPROVEMENT WITH
IFHO PARAMETER SETTING ............................................................. 83
2.8 CASE 8: COVERAGE ISSUE, CRSGAIN TUNING ...................... 86
2.9 CASE 9: HANDOVER FAILED IN PREPARATION PHASE ......... 87
2.10 CASE 10: PCI CONFUSION ...................................................... 89
2.11 CASE 11: ~100% HO EXECUTION FAILURES ......................... 90
2.11.1 CASE 11- RRC HO EXECUTION FAILURES DUE TO PCI
COLLISION .......................................................................................... 91
3 ANR: MOM – ANR CREATED ........................................................ 91
3.1 HANDOVER EVENT TRIGGERED .............................................. 92
3.2 PERIODICAL ANR (INTER-FREQUENCY AND IRAT HO) .......... 93
3.3 ANR PARAMETER EUTRAN ....................................................... 95
3.4 OBSERVABILITY ......................................................................... 98
3.5 ANR RELATED COUNTERS ....................................................... 98
3.6 SELF-ORGANIZED NETWORK & ANR FEATURES ................... 99
3.7 AUTOMATED NEIGHBOUR RELATION (PCI CONFLICT
IMPACT)............................................................................................... 99
3.8 AUTOMATED NEIGHBOUR RELATION (PCI CONFLICT
HANDLING)........................................................................................ 100
3.9 AUTOMATED NEIGHBOUR RELATION (PCI CONFLICT
DETECTION DRX) ............................................................................. 101
3.10 AUTOMATED MOBILITY OPTIMIZATION (COORDINATION
WITH ANR) ........................................................................................ 102
4 CS FALLBACK.............................................................................. 103
4.1 CSFB RELATED FEATURES .................................................... 104
4.2 CSFB CASES FOR LONG CALL SETUP TIME ......................... 105
4.3 CASE 1: CSFB CALL SETUP TIME DUE TO CORE
SIGNALING ........................................................................................ 105
4.4 CSFB FAILURE DUE TO LONG CELL RESELECTION TIME ... 106
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4.5 SIB READING DURING CELL RESELECTION ......................... 106
4.6 FAILURE DUE TO MULTIPLE RRC CONNECTION
REQUEST .......................................................................................... 107
4.7 FAILURE DUE TO MULTIPLE RRC CONNECTION
REQUEST .......................................................................................... 107
4.8 FAILURE DUE TO BAD UTRAN COVERAGE ........................... 108
4.9 CASE 2: UE FAIL TO RETURN TO LTE AFTER CSFB TO
UTRAN ............................................................................................... 109
4.9.1 CASE 2: UE FAIL TO RETURN TO LTE AFTER CSFB TO
UTRAN ............................................................................................... 109
4.9.2 CASE 2: UE FAIL TO RETURN TO LTE AFTER CSFB TO
UTRAN ............................................................................................... 110
4.10 CASE 3: UE TOOK MORE TIME WHEN RETURN BACK TO
LTE NW1 ............................................................................................ 111
5 SUMMARY ................................................................................... 113
3 LTE INTEGRITY KPIS PERFORMANCE AND RELATED
PARAMETERS .......................................................................... 115
1 INTRODUCTION .......................................................................... 116
1.1 AVERAGE UE DOWNLINK THROUGHPUT .............................. 116
1.1.1 DOWNLINK DRB TRAFFIC VOLUME..................................... 117
1.1.2 AVERAGE UE UPLINK THROUGHPUT ................................. 119
1.1.3 UPLINK DRB TRAFFIC VOLUME ........................................... 120
1.1.4 EUTRAN LATENCY KPIS ....................................................... 121
1.1.5 EUTRAN PACKET LOSS KPIS ............................................... 123
2 THROUGHPUT OPTIMIZATION STEPS ...................................... 127
2.1 DL THROUGHPUT ISSUES INVESTIGATION .......................... 127
2.2 UPLINK THROUGHPUT INVESTIGATION ................................ 128
2.3 REASONS FOR POOR DL THROUGHPUT ................................ 129
2.4 REASONS FOR POOR UL THROUGHPUT ................................ 130
2.5 THROUGHPUT TESTING INVESTIGATION ............................. 131
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3 LOW THROUGHPUT- THE COUNTERS TO BE CHECKED ........ 132
3.1 PRB UTILIZATION ..................................................................... 132
3.2 WAYS TO REDUCE PRB UTILIZATION .................................... 133
3.3 ESSENTIAL PARAMETERS ...................................................... 134
3.4 OTHER COUNTERS FOR THROUGHPUT ANALYSIS ............. 134
3.5 UL INTERFERENCE .................................................................. 135
3.6 UL RLC NACK ........................................................................... 136
3.7 POWER RESTRICTED TRANSPORT BLOCK IN UL ................ 136
3.8 CQI RANGE ............................................................................... 137
3.9 MIMO RANK DISTRIBUTION USAGE ....................................... 138
3.10 MODULATION SCHEME USAGE DL ...................................... 138
4 THROUGHPUT OPTIMIZATION- UE ESSENTIAL CHECKS ....... 139
4.1 QOS FRAMEWORK .................................................................. 140
4.2 SCHEDULING ALGORITHM SCHEDULER
CONFIGURATION ............................................................................. 142
5 FEATURE AFFECTING UL/DL THROUGHPUT ........................... 144
5.1 256 QAM DL .............................................................................. 145
5.2 64 QAM UPLINK ........................................................................ 148
5.3 64 QAM UL PARAMETERS ....................................................... 150
5.4 ERICSSON LEAN CARRIER ..................................................... 151
5.5 CARRIER AGGREGATION ....................................................... 153
5.6 POTENTIAL THROUGHPUT ..................................................... 154
5.7 UPLINK CARRIER AGGREGATION .......................................... 156
5.8 UPLINK CARRIER AGGREGATION CONFIGURATION ........... 156
5.9 ADVANCED CARRIER AGGREGATION (FAJ 801 0568).......... 158
5.9.1 INTER-ENB CARRIER AGGREGATION PERFORMANCE .... 160
5.9.2 INTER-ENB CARRIER AGGREGATION PARAMETERS ....... 161
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5.10 MULTI-CARRIER LOAD MANAGEMENT (FAJ 801 0424) ....... 162
5.11 PRESCHEDULING .................................................................. 162
5.11.1 PRESCHEDULING PARAMETERS ...................................... 164
5.12 LTE TRANSMISSION MODES DOWNLINK TRANSMISSION
MODES .............................................................................................. 165
5.12.1 WHICH MIMO MODE IS BEST? ........................................... 167
6 VOLTE IMPACT ON BB THROUGHPUT & DBS .......................... 168
7 SUMMARY ................................................................................... 170
4 ISSUE ANALYSIS, IMPROVEMENTS AND CASE-STUDIES
FOR INTEGRITY KPIS .............................................................. 171
1 CASE-1: DL THROUGHPUT IMPROVEMENT ............................. 172
2 CASE-2 UL-THROUGHPUT IMPROVEMENT .............................. 173
3 CASE-3: LTE LATENCY ISSUE.................................................... 174
3.1 CASE-3: INVESTIGATION ANALYSIS ...................................... 175
3.2 CASE-3 INVESTIGATION FOR SERVICE SPECIFIC DRX ....... 176
3.3 CASE-3 DRX PROFILE PARAMETER OPTIMIZATION ............ 176
4 CASE-STUDY 4: LOW THROUGHPUT DURING HIGH LOAD ..... 178
4.1 EXERCISE 1 – ANALYZE ROP FILES ...................................... 179
4.1.1 EXERCISE 1 – ANSWER........................................................ 180
4.2 EXERCISE 2: POSSIBLE CAUSE FOR THROUGHPUT
DEGRADATION ................................................................................. 180
4.2.1 EXERCISE 2 – ANSWER UL/DL POOR RF COUNTERS ....... 181
4.2.2 UL NOISE AND INTERFERENCE .......................................... 182
4.2.3 PDCP LAYER COUNTERS..................................................... 183
4.2.4 RLC LAYER COUNTERS ....................................................... 183
4.2.5 MAC LAYER COUNTERS....................................................... 184
4.2.6 PDCCH CONGESTION COUNTER ........................................ 185
4.2.7 UPLINK-DOWNLINK PRB UTILIZATION ................................ 185
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4.2.8 COUNTERS FOR UES SCHEDULED PER TTI: ..................... 186
4.3 EXERCISE 3: POSSIBLE ROOT CAUSE .................................. 187
4.3.1 COUNTER PMRADIORECINTERFERENCEPWR
ANALYSIS-RESULTS ........................................................................ 187
4.3.2 COUNTER PMRADIOUEREPCQIDISTR ANALYSISRESULTS ........................................................................................... 188
4.3.3 COUNTER PMRADIOUEREPCQIDISTR2 ANALYSISRESULTS ........................................................................................... 188
4.3.4 PDCP LAYER COUNTER ANALYSIS-RESULTS ................... 189
4.3.5 RLC LAYER COUNTER ANALYSIS-RESULTS ...................... 190
4.3.6 COUNTER ‘PMMACHARQ’ ANALYSIS-RESULTS FOR
UL/DL 190
4.3.7 MAC HARQ COUNTERS ANALYSIS-RESULT....................... 191
4.3.8 COUNTER PMPDCCHCCEUTIL ANALYSIS-RESULTS ......... 191
4.3.9 SE UTILIZATION ANALYSIS-RESULTS ................................. 192
4.4 EXERCISE SUMMARY .............................................................. 192
4.5 WAY FORWARD ....................................................................... 193
5 SUMMARY OF CHAPTER 4 ......................................................... 194
5 ABBREVIATIONS .......................................................................... 195
6 INDEX ............................................................................................ 207
7 TABLE OF FIGURES ..................................................................... 215
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LTE Mobility performance and related parameters
1 LTE Mobility performance and related
parameters
Objectives
After completion of this chapter the participants will be
able to:
1
Analyze LTE Mobility performance and related parameters.
1.1 Explain Parameter related to Idle mode mobility.
1.2 Describe different LTE mobility KPIs & counters for X2HO,
S1HO, IFHO, IRATHO.
1.3 Validate Mobility related parameter affecting different KPIs.
1.4 Evaluate the steps for optimization of these KPI
1.5 Analyze features with related parameters which improve LTE
Mobility KPIs
Figure 1-1: Objective of Chapter 1
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Introduction
1
This chapter introduces the LTE mobility KPIs (Key Performance Indicators)
with their associated counters, and parameters that might affect them directly. It
will also review some of the probable reasons for failure and the subsequent steps
that may be undertaken to optimize the network.
The Optimization of all the KPIs (for Accessibility, Retainability, Integrity,
Mobility) begins with the collection of network statistics. These performance
statistics are put in formulae to create meaningful Key Performance Indicators
(KPIs) and evaluated against guiding thresholds. Sometimes Performance
Recordings (i.e. Cell Trace and UE Trace) are also initiated and evaluated. In
some cases, even drive tests are performed. The data is then analyzed.
Based on this analysis the optimizer is expected to recommend on how the
performance can be further improved. After the changes have been implemented,
they are again verified with network performance data (statistics and recordings).
The whole process is repeated until the desired KPI target values are reached.
In this chapter, focus will be on Idle mode and Connected mode mobility.
Idle Mode Mobility Management
2
Idle mode mobility optimization is done to optimize cell coverage, and to
correctly define frequency layering to prioritize one cell/frequency over the other.
Idle mode optimization is based on the cell selection and cell reselection
parameters. These parameters are defined as the attributes in
‘EUtranFreqRelation’, ‘UtranFreqRelation’, ‘EUtranCellRelation’,
‘EUtranCellFDD’ and ‘EUtranCellTDD’ Managed Objects (MOs).
Although the Idle Mode Mobility does not affect the pre-defined KPIs, it is still
an important area to consider for the best performance out of a network.Figure 12 explains cell selection process and Figure 1-3 illustrates cell reselection
process.
Following are the important parameters, to be optimized for cell selection and
reselection.
‘pMax’ = 1000 { -30.33, 1000} Calculates the parameter ‘Pcompensation’
(defined in 3GPP TS 36.304), at cell reselection to an E-UTRAN Cell. Value
1000 means the parameter is not sent in the system information block. Unit dBm.
‘qOffsetFreq’ = 0 { -24, -22, -20, -18, -16, -14, -12, -10, -8, -6, -5, -4, -3, -2, -1,
0, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24} Frequency specific offset for
E-UTRAN frequencies used in connected mode. In idle mode, the negative value
of this offset is used. Specification: 3GPP TS 36.331, Unit: 1 dB.
‘qQualMin’ = 0 { -34.-3, 0} Parameter ‘Qqualmin’ in TS 36.304.
Value 0 means that it is not sent and UE applies in such case the (default) value
of negative infinity for ‘Qqualmin’. Sent in SIB3 or SIB5.
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‘qRxLevMin’ = -140 { -140, -44} The required minimum received Reference
Symbol Received Power (RSRP) level in the (E-UTRA) frequency for cell
reselection. Corresponds to parameter ‘Qrxlevmin’ in 3GPP TS 36.304. This
attribute is broadcast in SIB3 or SIB5, depending on whether the related
frequency is intra- frequency or inter-frequency. Unit: 1 dBm.
S-criterion measured RSRP
Srxlev = Qrxlevmeas – qrxLevMin + qrxLevMinOffset – Pcompensation* > 0
Squal = Qqualmeas – (qqualMin + qqualMinOffset)
Parameters
measured RSRQ
Srxlev > 0 AND Squal > 0
*Pcompensation = max(pmaxServingCell – P;0)
Parameter
UE Power: 23 dBm
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
S>0
Figure 1-2: Review: Cell Selection (S-Criterion)
0 to 24 dB
R(serving) = Qmeas(s) + qHyst
R(neighbor) = Qmeas(n) - Qoffset
R(neighbor)
Rank 2
R(neighbor)
Rank 1
R(neighbor)
Rank 3
Qoffset
qOffsetCellEUtran: Cell individual offset in the intra-frequency
and equal priority inter-frequency cell ranking criteria
qOffsetFreq: Frequency specific offset in the equal priority interfrequency cell ranking criteria
‘tReselectionEutra’
Qmeas: RSRP measurement quantity used in cell reselections
Figure 1-3: Cell Reselection (R-Criteria)
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‘qHyst(s)’ is the hysteresis value ‘qHyst’ that is read in the system information of
the serving cell. It prevents too frequent reselection back and forth between cells
of nearly equal rank. When a neighboring cell is ranked as better than the serving
cell (that is, Rn > Rs) during a time interval ‘tReselectionEutra’, the UE performs
a cell reselection to the better ranked cell.
‘Qoffset’ is an offset in the cell ranking criterion of neighbor E-UTRA cells. It
consists of a cell individual part and a frequency specific part. The frequency
specific part applies to equal priority inter-frequency cells only. According to
3GPP:
• For intra-frequency: Equals to ‘Qoffset’, if ‘Qoffset’ is valid,
otherwise this equals to zero.
•
For inter-frequency: Equals to ‘Qoffsets,n’ plus ‘Qoffsetfrequency’,
if ‘Qoffsets,n’ is valid, otherwise this equals to ‘Qoffsetfrequency’.
•
In Ericsson’s network: ‘Qoffsets,n’ = ‘qOffsetCellEUtran’ and
‘Qoffsetfrequency’ = ‘qOffsetFreq’.
By tuning ‘qHyst’, ‘qoffset’ and ‘tReselectionEutra’ parameter an operator can
optimize the cell reselection procedure as show in Figure 1-4 below.
RSRP
sIntraSearch
sNonIntraSearch
qHyst(s)
Qmeas(n)
R(n)
qoffset(s)
R(s)
Qmeas(s)
tReselectionEutra
time
Cell reselection
Figure 1-4: Cell Reselection Evaluation Process
2.1
Priority based Cell Reselection
When multiple E-UTRA and/or inter-RAT frequencies are used in a network,
priority based cell reselection should be applied.
A Network can use ‘cellreselectionPriority’ parameter to prioritize one frequency
over the other and optimize idle mode traffic as per the layering plan. The priority
based reselection can be used for IRAT frequency as well, but the equal priority
for IRAT should be avoided.
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LTE Mobility performance and related parameters
The UE only performs cell reselection evaluation for the E-UTRA and inter-RAT
frequencies that are given in system information and for which a cell reselection
priority is provided.
If the UE finds an inter-frequency carrier or an inter-RAT frequency with a cell
reselection priority higher than the frequency where the UE is camping, the UE
attempts to reselects a cell on that frequency. Cell reselection occurs if the UE
finds a cell with a ‘Srxlev’ value greater than the ‘threshXHigh’ value, or an
‘Squal’ value greater than ‘threshXHighQ’ value for that frequency. The criterion
will be used is depends on whether the parameter ‘threshServingLowQ’ is
included in SIB3.
If the UE finds an inter-frequency carrier with equal priority to the frequency
where the UE is camping, the UE performs cell reselection much in the same way
as intra-frequency cell reselection.
Cell reselection occurs if the UE finds a cell with an ‘Srxlev’ value greater than
the ‘threshXHigh’ value, or an ‘Squal value greater than the ‘threshXHighQ’
value for that frequency. Which criterion is used depends on whether the
parameter ‘threshServingLowQ’ is included in SIB3.
If the ‘Srxlev’ value of the serving cell falls below the ‘threshServingLow’ value,
inter frequency carrier or an inter-RAT frequency with cell reselection priority
lower than the frequency where the UE is camping. Cell reselection occurs if the
UE finds a cell with ‘Squal’ value of the serving cell falls below the
‘threshServingLowQ’ value, the UE attempts to reselect a cell on an inter-freq
‘rxlev’ value greater than the ‘threshXLow’ value or an ‘Squal’ value greater
than the ‘threshXLowQ’ value for that frequency. The process is explained in
Figure 1-5 below.
Neighbor cellReselectionPriority higher than for used freq
and
= Qmeas(s)
+ Qoffmbms*
Srxlev(n)R(serving)
> threshXHigh
or Squal(n)+ > threshXHighQ
trigger cell reselection to higher prio frequency (E-UTRAN or IRAT)
and
Frequency 2
Prio 2
Squal(s) < threshServingLowQ
Srxlev(s) < threshServingLow
Srxlev(n) > threshXLow
Frequency 1
Prio 1
and
or
Squal(n) > threshXLowQ
trigger cell reselection to lower prio frequency (E-UTRAN or IRAT)
›
For RSRQ based reselection threshServingLowQ is included in
SIB3 & qQualMin in SIB1
›
Configuration of equal priority IRAT frequencies should be
avoided!
Frequency 3
Prio 3
Figure 1-5: Priority Based Cell Reselection
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When the parameter ‘threshServingLowQ’ is included in SIB3, it is required that
the parameter ‘qQualMin’, the required minimum RSRQ level (dB) in the cell, is
included in SIB1.
Important Parameters that correlate to priority based reselection are as following:
‘threshXHigh’ = 4 {0, 62} The threshold used by the UE when reselecting
towards the higher priority frequency X from the current serving frequency. Each
frequency of E-UTRAN can have a specific threshold. Refer to the parameter
‘thresXHigh’ in 3GPP TS 36.304. Unit: 1 dB.
‘threshXHighQ’ = 2 {0, 31} Parameter ‘ThreshXHighQ’ is defined in TS
36.304 for the ‘EUtranFreqRelation’ that points to the intra frequency
EUtranFrequency MO class, Unit: 1 dB.
‘threshServingLowQ’ is included in systemInformationBlockType3.
When the parameter ‘threshServingLowQ’ is included in SIB3, it is required that
the parameter ‘qQualMin’, the required minimum RSRQ level (dB) in the cell, is
included in SIB1. Takes effect: Immediately
‘threshXLow’ = 0 {0...62} The threshold used in reselection towards frequency
X priority from a higher priority frequency. Each frequency of E-UTRAN can
have a specific threshold. Parameter ‘thresXlow’ is defined in 3GPP TS 36.304.
Unit: 1 dB
‘threshXLowQ’ = 0 {0...31} Parameter ‘ThreshXLowQ’ defined in TS 36.304,
for the ‘EUtranFreqRelation’ that points to the intra frequency
‘EUtranFrequency’ MO, the attribute is invalid, this attribute does not affect
SIB3. Unit: 1 dB.
2.2
Speed-Dependent Scaling of Cell Reselection
The usual ‘tReselectionEutra’ and ‘qHyst’ parameters are used in the normal
mobility state for the evaluation of the cell reselection criteria.
In the medium and high mobility states, the UE applies a scaling factor,
decreasing the value of ‘tReselectionEutra’ parameter
(‘tReselectionEutraSfMedium’ and ‘tReselectionEutraSfHigh’). In that way, the
evaluation period of cell reselection criteria is reduced.
In addition, a negative offset is added to the ‘qHyst’ hysteresis value
(‘qHystSfMedium’ and ‘qHystSfHigh’) in the cell ranking criteria. It lowers the
threshold for the reselection of intra-frequency cells.
The criteria for the UE to enter the medium and high mobility states is based on
the number of recent cell reselections performed by the UE. A sliding time
window is used. The parameter ‘tEvaluation’ determines the duration of the
sliding time window.
The parameters ‘nCellChangeMedium’ (medium mobility) and
‘nCellChangeHigh’ (high mobility) determine the number of cell reselections the
UE performs within the sliding time window. The UE applies an additional timeperiod before reentering the normal mobility state.
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The speed dependent cell reselection is illustrated in Figure 1-6.
› Three mobility states: Normal, Medium and High
› Based on the no of cell reselections made by the UE
– nCellChangeMedium
– nCellChangeHigh
– tEvaluation
Normal:
- tReselectionEutra
- qHyst
Medium:
- tReselectionEutraSfMedium
- qHystSfMedium
High:
- tReselectionEutraSfHigh
- qHystSfHigh
RSRP
RSRP
sIntra
search qHystSf
Qmeas(n) Medium /
qHyst
qHystSf
High
R(n)
qoffset(s)
R(s)
qoffset(s)
Qmeas(s)
tReselection
Eutra
sIntra
search
Qmeas(n)
R(n)
R(s)
Qmeas(s)
time
time
Cell
reselection
Cell
tReselection
reselection
EutraSfMedium /
tReselectionEutraSfHigh
Figure 1-6: Speed Dependent Scaling of Cell Reselection
2.3
Parameter related to Idle mode mobility
Some important parameters which affect idle mode mobility, is discussed below
in Figure 1-7.
pMax = 1000 { -30..33, 1000 } Calculates the parameter Pcompensation Value 1000
means the parameter is not sent in the system information block.
cellReselectionPriority = 6 { 0..7 } The absolute priority of the carrier frequency used by
the cell reselection procedure.
qOffsetFreq = 0 { -24, -22, -20, -18, -16, -14, -12, -10, -8, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4,
5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 } Frequency specific offset for E-UTRAN frequencies
used in connected mode. In idle mode, the negative value of this offset is used. Unit: 1 dB
qOffsetCellEUtran = 0 { -24, -22, -20, -18, -16, -14, -12, -10, -8, -6, -5, -4, -3, -2, -1, 0, 1,
2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 } Offset value applied to a specific cell in idle
mode mobility state
qQualMin = 0 { -34..-3, 0 }
Value 0 means that it is not sent and UE applies in such case the (default) value of
negative infinity for Qqualmin. Sent in SIB3 or SIB5.Unit: 1 dB
qRxLevMin = -140 { -140..-44 } The required minimum received Reference Symbol
Received Power (RSRP) level in the (E-UTRA) frequency for cell reselection. Unit: 1 dBm
threshXHigh = 4 { 0..62 } The threshold used by the UE when reselecting towards the
higher priority frequency X from the current serving frequency. Unit: 1 dB
threshXLow = 0 { 0..62 } The threshold used in reselection towards frequency X priority
from a higher priority frequency. Unit: 1 dB
threshServingLow = 0 { 0..62 } Specifies the threshold that the signal strength of the
serving cell must be below for cell reselection towards a lower priority Inter-Freq or IRAT
Figure 1-7: Cell selection/Reselection parameters
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2.3.1
Case 1: Priority Based Cell reselection example
This example, taken from a live network, shows values set for parameters related to
priority based cell reselection process. With the current settings, a subscriber would
reselect higher priority ‘AWS band’ 1700 MHz frequency cell (i.e. Advanced Wireless
Services. 1710 to 1755 MHz UL, and from 2110 to 2155 MHz DL band) over a low
priority 700 MHz frequency cell. If some of the values are changed, reselection process
would be impacted.
Case 1 Example is shown in Figure 1-8 below, with parameters value and
reselection criteria for 1700 and 700 frequency bands.
Case-1: MC Priority-Based Cell Reselection
Reselection Priority of AWS 1700 MHz > 700 MHz
NOTE : Considering Qrxlevminoffset =0 & Pcompensation =0 hence
Srxlev = Qrxlevmeas – Qrxlevmin
Figure 1-8: Case-1: Cell Reselection Parameter Example
2.3.2
Case 2: 3CC CA example
In this example the operator has deployed three carriers. When a network has
more than one carrier, layering is important to optimize cell reselection and
frequency prioritization. In this case the operator is using 2.6 GHz, 1.8 GHz, and
900 MHz LTE carriers and one WCDMA carrier.
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The frequency bands of 3 carriers are B3, B7 and B8, as illustrated in Figure 1-9.
Case-2: 3CC LTE-A CA : B3/B7/B8
UL + DL
DL
2.6GHz
High
Band
DL
1.8GHz
High
Band
2.6GHz
UL + DL
1.8GHz
900MHz
UL + DL
900MHz
Low Band
Figure 1-9: Parameter example Case-2
Different cell reselection criteria for a subscriber is explained in Figure 1-10 for
a subscriber moving from high to low priority and from low to high priority
frequencies. The reselection thresholds change accordingly.
Priority
LTE
WCDM
A
6
5
LTE – 2600 15M
Low to high Priority (Always measure)
RSRP L2600/L900 to High L1800 >
QrxlevminEUTRAL1800/ (-120dBm)
+ Threshxhigh (8dB) = -112dBm
7
6
LTE – 1800 15M
5
5
LTE – 900 10M
4
3
UMTS - 2100
High to low Priority to L900
RSRP L1800 < QrxlevminEUTRAL1800/2600 (120dBm) + Threshservinglow (4dB) = 116dBm
And RSRP L2600> QrxlevminEUTRAL2600 (120dBm) + ThreshxlowEUTRAN (8dB) = -112dBm
High to low Priority to L900
RSRP L1800 < QrxlevminEUTRAL1800/2600 (120dBm) + Threshservinglow (4dB) = 116dBm
And RSRP L900> QrxlevminEUTRAL900 (114dBm) + ThreshxlowEUTRAN (8dB) = -106dBm
High to low Priority to WCDMA
RSRP < QrxlevminEUTRAL1800/2600 (120dBm) + Threshservinglow (4dB) =
-116dBm
And RSCP> qRxLevMinUMTS (115dBm) + threshXLowUTRAN (6dB) = 109dBm
High to low Priority to WCDMA
RSRP < QrxlevminEUTRAL900 (114dBm) + Threshservinglow (4dB) =
-110dBm
And RSCP> qRxLevMinUMTS (115dBm) + threshXLowUTRAN (6dB) = 109dBm
Figure 1-10: Case 2: 3CC idle mode
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2.3.3
Case 3: Initial Traffic Balancing
This case is from a customer network where a second carrier was launched, but
the traffic on 2nd carrier was very low. The operator wanted to put equal traffic on
the two carriers.
CellreselectionPrio . made higher for 2C & Lower for 1C
Figure 1-11: Case 3: Initial Traffic Balance Issue & resolution on MC site
There was low/negligible traffic on the second carrier until April 21st. Faulty
hardware was suspected, health check was done – but everything looked normal.
On April 21st, ‘CellreselectionPriority’ parameter was optimized to influence the
cell reselection process for the subscribers to achieve traffic balancing. After
setting correct priorities, the second carrier started taking traffic and the two
carriers shared the load- as shown in the figure above.
The values for the parameter ‘cellReselectionPrio’ for the first and the second
carriers were set to 4 and 5 respectively to achieve the traffic balance.
2.3.4
Case 4: Reselection parameter Example
This case is another example how the idle mode mobility parameters
‘qRxLevMin’, ‘sIntraSearch’, ‘sNonIntraSearch’ could be optimized for intra and
inter frequency cell reselection.
A customer network is using parameter setting as shown in Figure 1-12. The
impacts of using the (current) settings are described in the same table. These
parameters impact cell edge coverage and intra and inter frequency search
process.
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Parameter
Current Value
Impact
qRxLevMin
-128
Too low and might impact at cell edge
coverage during call setup
sIntraSearch
62
Too early to start scanning intrafrequency-LTE, impact UE-battery-life
sNonIntraSearch
48
Too early to start scanning interfrequency-LTE/inter-RAT, impact UEbattery-life
Figure 1-12: Case 4: Key finding of improper parameter setting at one operator
With the initial settings, the UE measurement would start at -128+ 62= -66 dBm.
The proposal (after tests and field trials) was to use -124 for the ‘qRxLevMin’
and ‘sIntraSearch’ to 48 instead. This would mean the measurement would start
at -124+48= -76 dBm
If the UE is in good coverage in the first cell, there is no need to scan the other
cell too early. This would save UE battery, but slows down the cell reselection
process.
Figure 1-13: Case 4: ‘qRxlevmin’ Setting discusses the impacts.
Drive-test plot
› ‘qRxlevmin’ consideration
from operator drive-test
result
› The RSRP vs throughput
graph suggesting small
throughput at ~ -124dBm
RSRP
› Proposed ‘qRxLevMin’ = -124
› PROS: UE will be camped on 4 dB better coverage.
› CONS: User may experience service outage in case of indoor coverage
Figure 1-13: Case 4: ‘qRxlevmin’ Setting
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Figure 1-14: Case 4: Sintrasearch setting shows the results with new settings.
Drive-test plot
› ’sIntraSearch’ investigation
› From field measurement,
no better cell detected
when 1st cell better than -66
dBm (current setting)
› Proposed start intra-LTE
measurement at -76 dBm
 ‘sIntraSearch’ = 48
› Proposed ‘sIntraSearch’ = 48 together with qRxLevMin = -124
› PROS: UE save more battery in scanning other LTE cells
› CONS: slower re-selection compared to existing setting
Figure 1-14: Case 4: Sintrasearch setting
› Regarding triggering points for measurements and reselection:
– Start to measure inter-frequency/inter-RAT
– Start to re-select to inter-frequency/inter-RAT
› Big gap between two triggering point ~36dB
– Earlier the triggering, more the inter-frequency/inter-RAT
measurements
› Propose ‘sNonIntraSearch’ = 10 compared to existing 48
› PROS: UE save more battery by less scanning of inter-frequency/inter-RAT
› CONS: N/A
Figure 1-15: Case 4: Snonintrasearch setting
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The parameter changes shorten the gap between start of measurement and cell
reselection point, which in turn also saves UE battery, as shown in Figure 1-16.
RSRP/RSCP
Current
Priority: 3 RSRP (S)
qRxLevMin = -128
sIntraSearch = 62
Proposal
qRxLevMin = -124
sIntraSearch = 48
Current
qRxLevMin = -128
sNonIntraSearch = 48
RSRP/RSCP (N)
Start search intrafreq when RSRP(s)
< -66
Start search intra-freq
when RSRP(s) < -76
Start search interfreq/RAT when RSRP(s)
< -80 interStart search
freq/RAT when RSRP(s)
< -114
Priority: 2
Re-selection to inter-freq/inter-RAT, lowerpriority
RSRP(s) < -116 and RSCP(n) > -107
Closer gap between start to measure
and reselection point  save UE
battery
Figure 1-16: Case 4: Summary of change
Cell reselection and connected mode mobility process can also be optimized with
some features which define reselection and other priorities based on subscriber,
SPID, services & QCI. [These features mentioned below are discussed in detail in
the course “LTE Advanced Feature”].
Multi-Layer Service-Triggered mobility feature, FAJ 121 4124 (FDD) and FAJ
221 4124 (TDD) is an enhancement of legacy feature ‘Service Triggered
Mobility’. This feature overrides the Service Triggered Mobility feature when
both are activated. The legacy feature ‘Mobility Control at Poor Coverage’ is a
prerequisite.
Subscriber Triggered Mobility, this feature enables the Radio Resource
Management (RRM) and Mobility strategy in E-UTRAN to be based on user
specific information by the use of SPID ‘Subscriber Profile ID for RAT/
frequency priority’. It enables individual control of mobility characteristics for a
UE based on SPID.
2.4
Sticky Carrier for Idle mode mobility during IFLB
The Sticky Carrier parameter setting will allow subscriber to stay on the cell
where it has been transferred after load balancing.
Parameter ‘incrPrioServingFreqActive’ specifies whether or not the function to
set the serving frequency as sticky carrier is active in the current cell.
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When the Inter-Frequency Load Balancing feature is applied, consideration of the
UE mobility in idle mode is highly recommended. The load balancing can thus,
be improved with appropriate configuration of the UE idle mode mobility.
› When the Inter-frequency Load Balancing feature is
applied, consideration of the UE mobility in idle mode is
recommended.
› The load balancing can be improved by appropriate
configuration of the UE idle mode mobility
› Idle mode configuration
– Sticky carrier configuration
– Priority carrier configuration
Figure 1-17: Idle mode behavior with IFLB functionality
The sticky carrier method minimizes ping-pong mobility in the idle mode as
illustrated in the Figure 1-18.
› Objective: Minimize the ping-pong
mobility between idle and
connected mode due to IFLB
› Methodology: confine UE in idle
mode to the carrier frequency of
the current serving cell
› Setting: carrier frequency the UE is
camping on has higher priority than
the others
Figure 1-18: Idle mode with Sticky carrier methodology
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3
EUTRA connected mode Mobility KPI
The EUTRAN Mobility Success Rate KPI formula illustrated in Figure 1-19
below includes the Handover Preparation phase where resources are prepared in
the target cell and the Handover Execution phase where the UE moves from the
source to target cell. The KPI formula includes Intra Frequency handover where
the target and source cell are on the same frequency, Inter Frequency where they
are on different frequencies and IRAT handover where the target cell is in
another WCDMA frequency. Figure 1-19 defines mobility KPI for preparation
and execution phase.
The ability to provide the requested
service to the user with mobility.
EUTRAN Mobility Success Rate [%]:
(
=
pmHoPrepSuccLteIntraF + pmHoPrepSuccLteInterF + pmHoPrepSuccWcdma
pmHoPrepAttLteIntraF + pmHoPrepAttLteInterF + pmHoPrepAttWcdma
)
X
Equations on a
cell relation pair.
Refer to the CPI
“Key
Performance
Indicator”
Handover Preparation
(
pmHoExeSuccLteIntraF + pmHoExeSuccLteInterF + pmHoExeSuccWcdma
pmHoExeAttLteIntraF + PmHoExeAttLteInterF + pmHoExeAttWcdma
)
X 100
Handover Execution
Figure 1-19: EUTRAN Mobility KPI
3.1
LTE Event Review
Connected mode mobility is based on measurements sent by the UE. The
measurement reporting by UE can be done on an event triggered and/or on a
periodic basis.
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The LTE events are listed in Figure 1-20.
› EVENT_A1
– Serving cell becomes better than absolute threshold.
› EVENT_A2
– Serving cell becomes worse than absolute threshold.
› EVENT_A3
– Neighbor cell becomes amount of offset better than serving (Pcell).
› EVENT_A5
– Serving cell becomes worse than absolute threshold1 AND neighbor cell
becomes better than another absolute threshold2.
› EVENT_A6
– Neighbor cell becomes amount of offset better than SCell
› EVENT_B1
– IRAT neighbour becomes better than threshold
› EVENT_B2
– Serving becomes worse than threshold1 and IRAT neighbour
becomes better than threshold2
Figure 1-20: Review: LTE Events
When a UE in RRC_CONNECTED mode measures poor coverage in the current
LTE frequency, it informs the network by a measurement report for event A2
(serving cell becomes worse than threshold).
Depending on the active features and the network configuration, the UE can be
ordered to start new measurements before a handover, or a Release with Redirect
(session continuity) is triggered. In case the serving cell is fully covered by
another cell, the eNodeB can order the UE to perform a blind handover. [The
details are explained in the ‘LTE Protocols and Procedures’ and the ‘LTE Radio
Network Functionality’ courses.]
The important basic features need to be activated and optimized and which are
associated with the described mobility functionality are:
• Coverage-Triggered Inter-Frequency Session Continuity
• Coverage-Triggered GERAN Session Continuity
• Coverage-Triggered WCDMA Session Continuity
• Coverage-Triggered CDMA-eHRPD Session Continuity
• Coverage-Triggered TD-SCDMA Session Continuity
• Coverage-Triggered Inter-Frequency Handover
• Coverage-Triggered WCDMA IRAT Handover
• Intra-LTE Inter-Mode Handover
• Coverage-Triggered TD-SCDMA IRAT Handover
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A summary of coverage triggered mobility (IRAT, inter-frequency and intermode) is reviewed & illustrated in Figure 1-21 below, if MCPC feature is not
activated.
Session continuity
Blind release
with redirect (to
one of the candidate freq)
Only if QCI≠/1
FALSE
Release with
redirect (to freq
ueMeasurementActive=?
reported by A5/B2)
a5B2MobilityTimer
Bad Coverage
Event A2
Serving cell
worse than
threshold
NO
Event
A3orA5/B2
RBS determines a
set of candidate
frequenciesIs there an IF/ WCDMA/
IRAT/ Inter mode cell that
fully covers the source
cell?
YES
TRUE
Event A1
Serving worse than
threshold1 AND f2
/ IRAT/ inter mode
neighbor better
than threshold2
Good coverage
detected
covTriggeredBlindHoAllowed=true
mobilityAction=HANDOVER
coverageIndicator=covers
isHoAllowed=true
REDIRECT
mobilityAction=
?
HANDOVER
EUtranCellRelationTDD
(E)UtranCellRelation
externalUtranCellFDD
lac≠0 and lac≠-1
isHoAllowed=true
IF/IRAT/Inter mode HO
Handover
Blind
IF/IRAT/Inter mode HO
Figure 1-21: Review: Coverage triggered mobility
3.1.1
Mobility with “Mobility Control at Poor Coverage” feature
The “flow diagram” for the ‘Mobility Control at Poor Coverage’ (MCPC)
triggered functionality is shown Figure 1-22.
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Assuming that the license is installed and the feature is activated (with the
parameter ‘featureStateMobCtrlAtPoorCov’).
› Licence
– featureStateMobCtrlAtPoorCov
Session continuity
(no QCI1)
FALSE
› Redirection info
– redirect prio
(connectedModeMobilityPrio/VoicePrio or SPID)
Event
A2Critical
Blind release
with redirect (to
one of the candidate freq)
Release with
redirect (to freq
coverageIndicator=none
NO
ueMeasurementActive=?
reported by B2)
a5B2MobilityTimer
Event A2
Bad coverage
detected
RBS determines a
set of candidate
frequencies* Is there a WCDMA
TRUE
frequency cell that fully
covers the source cell?
YES
ueMeasurementActive=
ueMeasurementActiveIF,
ueMeasurementActiveUTRAN,
ueMeasurementActiveGERAN,
ueMeasurementActiveCDMA2000
Event
A3/A5/B2
covTriggeredBlindHoAllowed=true
mobilityAction=HANDOVER
coverageIndicator=covers
isHoAllowed=true
mobilityAction=
?
HANDOVER
Event A1
Good coverage
detected (both
RSRP&RSRQ)
REDIRECT
Event
A2Critical
UtranCellRelation
isHoAllowed=true
externalUtranCellFDD
lac≠0 and rac≠-1
IRAT/IF HO
Handover
Blind IRAT/IF HO
Figure 1-22: Review: “Basic” Mobility Control in Poor Coverage Operation
UEs in a cell will only make inter-frequency or IRAT measurements if the
‘ueMeasurementsActive’ parameter is set to ‘true’. The UE is allowed to make
these measurements before the timer specified by the parameter
‘a5B2MobilityTimer’ expires. If the default setting of 0 msec is used,
measurements are not made.
The decision on whether to use event A3 or A5 for other LTE frequencies
depends on the setting of the ‘interFreqMeasType’ parameter.
Mobility related issues analysis
4
When a network is to be optimized, engineers must gather information about the
problems related to KPI degradation, different cause of failures and analysis
related to these failures. This section will discuss a few issues, which generally
tend to degrade the Handover Success Rate (HOSR).
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4.1
Handover failure issues
The handover process can be divided into three phases - HO preparation, HO
execution and data forwarding/transport network. Accordingly, optimization is
based on these three issues.
Three major groups of problems:
› Handover preparation failures
› Handover execution failures
› Data forwarding failures
Reasons for poor mobility include but are not limited to
› Poor radio conditions
› Badly tuned handover parameters
Figure 1-23: Mobility Issue Analysis
The reasons for poor mobility can be poor radio (RF) conditions. Different RF
conditions can be analyzed on following basis:
LZT1381950 R1A
•
Poor RF conditions/Weak coverage: Check coverage holes,
overshooting, poor indoor planning issue.
•
Target has high uplink interference: Check performance counter
indicating the uplink signal quality. Check imbalance between UL and
DL quality/coverage.
•
Low DL quality: Check whether the transmit power of the RRU and UE
falls within link budgets.
•
ANR PCI Conflict (Collision & Confusion): With ANR this may be a
common issue, but with ANR enhancement features problematic cells
can be identified.
•
Target exceeds cell range: The target cell is more than 15km from the
UE (or the current cell range setting). In that case Ho-Exec fail occur.
Need to change cell range or ‘cellindividualoffset’ between relations (as
per required).
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•
Target is a sleeping cell: The target cell is sleeping, need to be fixed
sleeping on daily basis. Need to check the hardware and other alarms
before analyzing
Handover Failures due to Poor Radio Conditions
› Poor RF conditions/Weak coverage
› Target has high uplink interference
› Imbalance between UL and DL quality
› Low DL quality Check
› ANR PCI Conflict (Collision & Confusion)
› Target exceeds cell range
› Target is a sleeping cell
Figure 1-24: Mobility issue analysis HO Prep & Exec Failures
4.2
Handover prep failure- Neighbor Cell load issues
Handover procedure and performance can be analyzed on preparation and
execution basis. HO preparation failure can be due to neighbor cell load issue counters ‘pmHoPrepRejInHighLoad’ (MP load control),
‘pmHoPrepRejInOverload’ (procedure latency supervision) should be observed.
Figure 1-25 shows the different counters to be checked for Intra/Inter HO
Preparation failure.
Handover Preparation Failure, Check following counters?
› Handover Preparation Failure,
› pmHoPrepAttLTEIntraF
› pmHoPrepSuccLTEIntraF
› pmHoPrepAttLTEInterF
› pmHoPrepSuccLTEInterF
› Neighbor cell load issue?
› pmHoPrepRejInHighLoad (MP load control)
› pmHoPrepRejInOverload (procedure latency supervision)
Figure 1-25: Intra/Inter Handover Prep fail issue: possible cause
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LTE Mobility performance and related parameters
If above neighbor cell load counter is pegging, the following parameters,
discussed in Figure 1-26 below, in the target cell should be analyzed and
possibly tuned.
Neighbor cell load issue, tune following parameters
› tInactivityTimer , dlMaxRetxThreshold , ulMaxRetxThreshold ,
qOffsetcellEUtran , qRxLevMin
› SchedulingAlgorithm , crsGain , tPollRetransmitUl (DRB & SRB) ,
tPollRetransmitDl (DRB & SRB)
› noOfPucchCqiUsers , noOfPucchSrUsers , pdcchCfiMode
Figure 1-26: Intra/Inter Handover Prep fail issue: possible cause
If the neighbor cell load issue is found, it is recommended to reduce the number
of HO by physical optimization, or by using the relevant features (e.g. UE Level
Oscillating Handover Minimization & Automated Mobility Optimization).
Note that MP capacity of DUS/Baseband is higher than DUL- therefore,
hardware replacement might be considered.
Physical optimization like (Tilt, azimuth, height of antenna) can be used to
offload traffic from target cell.
Target cell load can be optimized by using layering strategy, optimize Idle mode
cell reselection, connected mode mobility & the load balancing parameters.
4.3
Handover failure, Target cell License and admission issue
The counters associated with HO preparation failure due to target cell license and
admission issues are discussed in Figure 1-27.
› Neighbor cell License issue
› pmHoPrepRejInLicMob
› pmHoPrepRejInLicMultiErab
› pmHoPrepRejInLicRlcUm
› pmHoPrepRejInLicConnUsers
› Admission reject
› pmHoPrepRejInBearerAdmissionRej
Figure 1-27: Intra/Inter Handover Prep fail issue: possible cause
Neighbor cell License issues can be investigated with below checks:
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4.4
•
Audit the license state, feature state, service state & other parameters
check related to Intra frequency HO feature, ‘MultiErabsPerUser’ feature
and ‘RlcUm’ feature.
•
Check the license capacity for connected users of the target cell (CUL
license), also the ‘Graceperiod’ should be noticed to exceed the licensed
capacity limits for a limited period of time, Offload traffic from the target
cell, capacity unit connected users, ‘gracePeriodTimeLeft’.
•
For admission reject issues, audit the UE admission control, the bearers
(SRB & DRB) admission control, transport network admission control &
emergency call prioritization.
•
Physical changes (Tilt, azimuth and the height of antenna) to offload
traffic from target cell. The parameters for transport network bandwidth
‘dlTransNwBandwidth’, ‘ulTransNwBandwidth’ should also be checked.
Handover Prep failure, other checks
Other issues pertaining to handover preparations failure could exist, if there is
something wrong with the target cell.
•
For the ‘Cell Down Auto’ following counters need to be checked
pmCellDowntimeAuto’ /’pmCellDownLockAuto’.
•
If eNodeB cause, for configuration issues ensure proper configuration,
especially for all new site which are integrated recently.
For the ‘Cell Down Manually’, check the counters ‘pmCellDowntimeMan’/
‘pmCellDownLockMan’, operation cause manually locked during network
configuration issues ((eg. adding/changing/removing hardware) or manually
locked during parameter change (eg. activate feature). These issues are discussed
in Figure 1-28
Other checks
› Availability Cell down:
› Cell Down Auto pmCellDowntimeAuto/pmCellDownLockAuto
› Transport Cause S1 issues pmErabRelAbnormalEnbActTnFail. Check for
alarms like Service Unavailable(S1 connection failure)
› Cell Down Manually pmCellDowntimeMan/pmCellDownLockMan
Figure 1-28: Intra/Inter Handover Prep fail issue: possible cause
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•
Auto Restart: Ensure the eNodeB structure of the restart, MP Baseband
or RRU (do complete eNB health checkup). Check RRU status, verify
SW on node, S1 links down due to faulty interface board.
•
Transport Cause S1 issues, check the counter
‘pmErabRelAbnormalEnbActTnFail’, check for the alarms like ‘Service
unavailable S1 connection failure’, hardware failure, ‘GeneralHwError’,
‘GeneralSwError’, Gigabit Ethernet Link Fault.
Common alarms to be checked incldue ‘esource configuration disable’, ‘RRU
fault’ and ‘link failure’. Check current alarms/ history of alarms and take
necessary action according to the type of alarms. If there is something wrong
with the target cell, then there may be the reasons for handover preparation fail.
MME in pool are expected to share the same IP address. If HO-Preparation fail =
100%, it might be due to MME pool is different at source and target end. The
command ‘get . termpointmme’ can be used to find out the MME pool IPs. If
different, set as per market MME pool definition.
Ensure ‘SpidHoWhiteList’ is active on the target, which has
‘primaryplmnReserved’ set to true.
•
Target cell is overloaded (High capacity): Need to offload target cell,
check IFLB, IFO, IROW feature’s parameters or increase capacity of
target cell
•
Target cell unavailable: The target cell is down / disabled; PLMN status
is true but partOfSectorPower is set to maximum value. The command
‘lgd’ can be used to check the site status.
Command ‘get . primaryplmn’ is used to find out the PLMN status and the
command ‘get . power’ is used to find out the site power status. Few ‘get’
commands printouts are shown below.
xxx_LTE> get . primaryplmn
========================================
MO
Attribute
Value
========================================
EUtranCellFDD=xxxx881
primaryPlmnAlarmSuppr false
EUtranCellFDD=xxxx881
primaryPlmnReserved false
Xxx_LTE> get . power
170512-08:06:20 10.203.41.14 16.0v
ERBS_NODE_MODEL_G_1_312_COMPLETE stopfile=/tmp/16436
============================================================
SubrackProdType=KRD901107/2_*
maxPowerDissipation 2500
……………………………………………………..
EUtranCellFDD=xxxx883
preambleInitialReceivedTargetPower -110
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EUtranCellFDD=xxxx883
prsPowerBoosting 2
EUtranCellFDD=xxxx883
rpsfPowerReduction 1000
EUtranCellFDD=xxxx883,MimoSleepFunction=1
sleepPowerControl 1 (RETAIN_SAME_POWER)
SectorCarrier=1
configuredMaxTxPower 40000
SectorCarrier=1
csiRsPowerRatio
0
……………………………………………………………………………..
txPowerPersistentLock false
SectorEquipmentFunction=S1
availableHwOutputPower 80000
SectorEquipmentFunction=S2
availableHwOutputPower 80000
SectorEquipmentFunction=S3
availableHwOutputPower 80000
=========================================================
The HO failure issues are discussed in Figure 1-29.
Other issue, typically handover preparations fail if there is
something wrong with the target cell.
› MME pool not same same. If HO-Preparation fail = 100%
› The command get . termpointmme can be used to find out the MME pool
IPs.
› SpidHoWhiteList is active on the target, which has primaryplmnReserved
set to true.
› Target cell is overloaded (High capacity).
› Target cell Unavailable : partOfSectorPower is set to maximum value.
The command lgd can be used to check the site status, get .
primaryplmn is used to find out the PLMN status and get . power is used
to find out the site power status.
Figure 1-29: Intra/Inter Handover Prep fail issue: possible cause
Check if the TAC has been defined on site according to network design. If HOPrep fail percentage is not uniform, while analyzing the cluster or the network,
AMOS command ‘get . tac’ may be used to find out TAC status. Furthermore, the
License issue/Software issues can also be checked.
Other issue:
› TAC not defined on site, as per network design.
› License issue/Software issue.
› Target cell has a fault (alarm, disabled cell, etc).
› Site Configuration issue.
Figure 1-30: Intra/Inter Handover Prep fail issue: possible cause
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LTE Mobility performance and related parameters
5
Handover Execution failure issues and counters
The Handover Execution failure counters are discussed in Figure 1-31.
› Handover Execution Failure
› pmHoExeAttLTEIntraF
› pmHoExeSuccLTEIntraF
› pmHoExeAttLTEInterF
› pmHoExeSuccLTEInterF
Figure 1-31: LTE Intra/Inter Handover Execution Failure: possible cause
5.1
Intra/Inter Handover Execution failure, possible cause
The HO execution failure can be due to coverage/indoor coverage issue or PCI
confliction or confusion, there may be some other reasons as well. Figure 1-32
shows associated counters and parameters related to handover execution and can
be tuned.
› PCI confliction or confusion
› Coverage issues
› pmBadCovEvalReport
› pmRadioTbsPwrRestricted
› pmBadCovSearchEvalReport
› Parameter to be tuned
› maximumTransmissionPower , partOfSectorPower
› confOutputPower , crsGain , pdschTypeBGain
› Indoor coverage issue (Small cell , PICO , DOT , Hetnet)
› Physical changes (Tilt , Azimuth , height of antenna)
Figure 1-32: LTE Intra/Inter Handover Execution Failure: possible cause
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5.2
Handover Exec failure, Poor DL SINR issues related
parameter
The counters and parameters related to SINR and poor coverage issues are
discussed in the Figure 1-33 below.
What are the counter and parameters related to Poor DL
SINR (CQI)?
› pmRadioUeRepCqiDistr
› pmRadioUeRepCqiDistr2
› Parameters to be tuned
› maximumTransmissionPower , partOfSectorPower
› confOutputPower , crsGain , pdschTypeBGain
› Physical optimization (Tilt , Azimuth , height of antenna).
Figure 1-33: LTE Intra/Inter Handover Execution Failure: possible cause
5.3
Handover Exec failure, UL RSSI issues related parameter
The UL RSSI related counters and the parameters are discussed in Figure 1-34
below
What are the UL RSSI related counters and other issues?
› pmRadioRecInterferencePwr
› pmRadioRecInterferencePwrPucch
› pmRadioRecInterferencePwrPrb1~100
› pmSinrPucchDistr , pmSinrPuschDistr
› Parameters to be checked
› pZeroNominalPucch, pZeroNominalPusch
› Check Power control parameters ,
› Check for Loose Connectors, faulty Antenna, VSWR alarms, faulty
TMA Connections/settings
› External interference.
Figure 1-34: LTE Intra/Inter Handover Execution Failure: possible cause
The ‘pmRadioRecInterferencePwr’ PDF counter illustrated in Figure 1-35 below
gives the measured Noise and Interference Power on the PUSCH according to
3GPP technical specification 36.214. This counter can be used to identify if a cell
has high uplink interference which can be the cause of poor Random Access. An
example of the ‘pmRadioRecInterferencePwr’ counter for a cell with high and
low uplink interference is given in Figure 1-35.
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pmRadioRecInterferencePwr:
0,139,457290,272646,84684,33072,17023,11251,8475,3359,10791,1112,146,12,0,0
pmRadioRecInterferencePwr
Low Interference
pmRadioRecInterferencePwr:
0,0,0,0,0,0,0,0,0,0,0,0,0,0,585400,314600
High Interference
The measured Noise and
Interference Power on PUSCH,
according to 36.214
PDF ranges:
[0]: N+I <= -121
[1]: -121 < N+I <= -120
[2]: -120 < N+I <= -119
[3]: -119 < N+I <= -118
[4]: -118 < N+I <= -117
[5]: -117 < N+I <= -116
[6]: -116 < N+I <= -115
[7]: -115 < N+I <= -114
[8]: -114< N+I <= -113
[9]: -113 < N+I <= -112
[10]: -112 < N+I <= -108
[11]: -108 < N+I <= -104
[12]: -104 < N+I <= -100
[13]: -100 < N+I <= -96
[14]: -96 < N+I <= -92
[15]: -92 < N+I
Unit: 1 dBm/PRB
Figure 1-35: Uplink Interference
In the case of the cell with the low uplink interference, most of the values are in
the lower ‘bins’ whereas in the cell with the high uplink interference, they are in
the higher bins. Once high uplink interference is detected on a cell, further
investigation, including a possible site visit, may be required to find the cause of
the interference. This could be due to an external source, hardware configuration
or fault on site.
5.4
Handover Exec failure, Target cell RACH issue
If Handover Failure is due to RACH failure CFRA can be used instead of CBRA.
Poor Random Access Success Rate may be due to many factors, including
overshooting cell, high uplink interference or poor RACH Root Sequence
planning. Using the same ‘rachRootSequence’ in cells in the same area can lead
to poor Random Access Success Rate as cells will be detecting RA-RNTIs from
other cells.
The ‘Automated RACH Root Sequence Allocation’ (FAJ 121 202) optional
feature sets the ‘rachRootSequence’ for each cell based on its Physical Cell
Identity (PCI) allocation, high-speed flag and cell range. Neighbor cells must
have different PCIs to avoid PCI conflicts. The result of this is that RACH root
sequence allocation based on PCI reduces root sequence overlap between cells.
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RACH issue related counters and parameters are discussed in
Figure 1-36: LTE Intra/Inter Handover Execution Failure: possible cause
Important counters and Parameters related to target cell
RACH issues,
› pmRaAttCfra ,
› pmRaSuccCfra
› Parameters to be checked
› preambleInitialReceivedTargetPower , cellrange
› powerRampingStep (Hardcoded) , preambleTransMax (Hardcoded)
› numberOfRA-Preambles (Hardcoded)
› Tune RACH related parameters.
› RF conditions (physical optimization (tilt/azimuth/antenna height)
Figure 1-36: LTE Intra/Inter Handover Execution Failure: possible cause
The equation illustrated in Figure 1-37 below can provide an approximate
indication of the Contention Based Random Access Success Rate. It should be
noted that the equation in Figure 1-37 may not be accurate since it estimates the
number of detected preambles and assumes that a detected preamble is a randomaccess attempt.
pmRaSuccCbra
pmRaAttCbra
pmRaUnassignedCfraFalse
pmRaUnassignedCfraSum
pmRaFailCbraMsg2Disc
pmRaFailCbraMsg1DiscSched
pmRaFailCbraMsg1DiscOoc
The number of successfully detected RA Msg3 for CBRA
The number of detected contention-based random access preambles
The number of detected Contention Free Random Access preambles that are
not allocated to any UE
The total number of unassigned Contention Free Random Access preambles
at each PRACH occasion during the reporting period.
The number of CBRA preambles for which no random access response (RA
Msg2) was sent due to expiration of the random
access response window.
The number of CBRA preambles that are discarded because maximum
number of RA Msg3 are already scheduled.
The number of CBRA preambles that are discarded because timing offset of
CBRA preamble corresponds to a distance greater than configured cell
range.
Figure 1-37: HO Exec Fail: Contention Based Random Access Success Rate
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5.5
Overshooting Cell
The ‘cellRange’ parameter illustrated in Figure 1-38, defines the maximum
distance from the base station where a connection to a UE can be setup and/or
maintained. The ‘Maximum Cell Range’ (FAJ 121 0869) optional feature is
required to support cell ranges >15 km, illustrated in Figure 1-38 .
ManagedElement
+-ENodeBFunction
+-EUtranCellFDD
cellRange = 15 { 1..100 }
[Unit: 1 km]
cellRange
X
pmRaFailCbraMsg1DiscOoc
Incremented for each preamble that is discarded because it
was detected from a UE outside the configured cell range.
The ‘Maximum Cell Range’ (FAJ 121 0869) optional feature is
required to support cell ranges >15 km.
Figure 1-38: HO Exec Fail: Overshooting Cell
5.6
Handover Prep/Exec failure, Other important check
The other important check related to intra/inter HO issues are listed in
Figure 1-39: Intra/Inter Frequency HO Optimization .
Intra & Inter frequency related Important parameters:
› Intra frequency LTE
› cellIndividualOffsetEUtran ; a3offset ; hysteresisA3 ; timeToTriggerA3 ,
isHoAllowed , filterCoefficientEUtraRsrp , sMeasure.
› Inter frequency LTE
› a5Threshold1RSRP ; a5Threshold2RSRP ; hysteresisA5 ;
timeToTriggerA5 , a1a2SearchThresholdRsrp ,
hysteresisA1A2SearchRsrp , searchEffortTime
› timeToTriggerA1Search , timeToTriggerA2Search ,
a2CriticalThresholdRsrp
Figure 1-39: Intra/Inter Frequency HO Optimization
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IRAT Handover HO optimization
6
The UE uses event A2 to report poor coverage to the eNodeB. The reception of
an event A2 in the eNodeB is the trigger to start the evaluation process to decide
how to move the UE to WCDMA or a second LTE frequency.
If there is a WCDMA neighbor defined with the ‘coverageIndicator’ parameter
set to ‘COVERS’ the eNodeB will use the ‘Coverage-Triggered WCDMA IRAT
Handover’ optional feature to perform a blind handover to this cell. If blind
handover is not possible the UE may be given some time to make measurements
on WCDMA. If this time expires before the UE reports event A1 or B2 or if the
UE was not given any time to measure the UE will be moved to WCDMA using
the ‘Coverage-Triggered WCDMA Session Continuity’ optional feature. This
feature uses ‘Release with Redirect’ (RwR) to move the UE to WCDMA which
will produce longer break in connection than handover.
If event A1 is reported this evaluation process is stopped and the eNodeB will
wait for another A2 event. If the UE does find a WCDMA neighbor cell and
reports event B2 the eNodeB will use ‘Coverage-Triggered WCDMA IRAT
Handover’ optional feature to perform a measurement based handover to the
reported cell or ‘Coverage-Triggered WCDMA Session Continuity’ to this cell if
handover is not allowed.
The IRAT based handover preparation phase begins when the source eNodeB
receives a measurement report with event B2 (Serving worse than threshold1 and
IRAT better than threshold2) or A2 (Serving cell worse than threshold). On
reception of this message the RBS will increment the ‘pmHoPrepAtt’ counter.
The RBS will make the handover decision based on the contents of the RRC
‘MEASUREMENT REPORT’ and the defined handover parameters. If the RBS
decides to perform the handover it will send a S1 ‘HANDOVER REQUIRED’
message containing the necessary information to prepare the handover to the
source MME e.g. target RNC Id.
The source MME identifies the target SGSN and initiates the handover resource
allocation procedure by sending ‘FORWARD RELOCATION REQUEST’
message.
Once the resources are ordered the target SGSN sends a ‘RELOCATION
REQUEST’ message to the target RNC. On reception of this message the target
RNC performs Admission Control and Radio and Iu user plane resources are
reserved for the accepted RABs. After this, the RNC acknowledge the target
SGSN sending the message ‘RELOCATION REQUEST ACKNOWLEDGE’.
On reception of this message the target SGSN will respond to the source MME
with a ‘FORWARD RELOCATION RESPONSE’ message.
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The source MME will then send a ‘S1 HANDOVER COMMAND’ message to
the source RBS. On reception of this message the source RBS will release all
resources for the UE and increment the ‘pmHoPrepSucc’ counter. Figure 1-40
below discussed different counters and parameters related to IRAT-HO.
Handover Preparation Failure?
› pmHoPrepAtt
› pmHoPrepSucc
› Possible parameters to tune?
› a1a2SearchThresholdRsrp, hysteresisA1A2SearchRsrp,
searchEffortTime, timeToTriggerA1Search ,
timeToTriggerA2Search, a2CriticalThresholdRsrp
› b2Threshold1Rsrp, b2Threshold2RscpUtra, hysteresisB2,
timeToTriggerB2, triggerQuantityB2, a5B2MobilityTimer
Figure 1-40: IRAT Handover HO optimization
7
MCPC related counters and parameters
If ‘Mobility Control at Poor Coverage’ feature is activated, ‘EUtranCell’ MO
counters that should be monitored to track the feature’s performance include
‘pmCriticalBorderEvalReport’ and ‘pmBadCovSearchEvalReport’.
Parameters to be optimized are:
ManagedElement
+-ENodeBFunction
+-EUtranCellFDD
+-UeMeasControl
+-ReportConfigSearch
a1a2SearchThresholdRsrp = -134 { -140...-44} Unit: 1 dB
a1a2SearchThresholdRsrq = -165 { -195...-30} Unit: 0.1 dB
a2CriticalThresholdRsrp = -140 { -140...-44} Unit: 1 dB
a2CriticalThresholdRsrq = -195 { -195...-30} Unit: 0.1 dB
hysteresisA1A2SearchRsrp = 20 {0...150} Unit: 0.1 dB
hysteresisA1A2SearchRsrq = 15 {0...150} Unit: 0.1 dB
hysteresisA2CriticalRsrp = 10 {0…150} Unit: 0.1 dB
hysteresisA2CriticalRsrq = 10 {0…150} Unit: 0.1 dB
timeToTriggerA1Search = 640 {0, 40, 64, 80, 100, 128, 160, 256, 320, 480, 512,
640, 1024, 1280, 2560, 5120} Unit: 1 ms
timeToTriggerA2Critical = 40 {0, 40, 64, 80, 100, 128, 160, 256, 320, 480, 512,
640, 1024, 1280, 2560, 5120} Unit: 1 ms
timeToTriggerA2Search = 40 {0, 40, 64, 80, 100, 128, 160, 256, 320, 480, 512,
640, 1024, 1280, 2560, 5120} Unit: 1 ms.
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The counters and parameters important for ‘MCPC’ based mobility are discussed
in Figure 1-41 below.
MCPC feature related counters.
› pmCriticalBorderEvalReport
› pmBadCovSearchEvalReport
› MCPC feature related parameters.
› a1a2SearchThresholdRsrp , hysteresisA1A2SearchRsrp ,
searchEffortTime
› timeToTriggerA1Search , timeToTriggerA2Search ,
a2CriticalThresholdRsrp
› hysteresisA2CriticalRsrp , timeToTriggerA2Critical ,
Figure 1-41: IRAT/Inter Frequency HO optimization
IRAT/Inter Frequency Session continuity optimization is similar to HO process.
LTE Inter Frequency Session Continuity
› pmUeCtxtRelSCEutra
Inter RAT Session continuity
› pmUeCtxtRelSCWcdma
Parameters Optimization
› Similar like Handover
Figure 1-42: IRAT/Inter Frequency Session continuity optimization
Inter frequency load balancing counters and
parameters
8
‘Subscription quanta’ is weighted based on QCI and represents a generic cost of
each bearer. The value for each QCI is configured with the parameter
‘qciSubscriptionQuanta’ (‘QciProfilePredefined’/’QciProfileOperatorDefined’).
The cell subscription capacity represents an estimate of the total cell capacity.
The value for each cell is configured with the ‘cellSubscriptionCapacity’
(‘EUtranCellFDD’/‘EUtranCellTDD’) parameter. The average subscription ratio
is observed with the counters ‘pmLbSubRatioSum’ and ‘pmLbSubRatioSamp’
(‘EUtranCellFDD’/’EUtranCellTDD’).
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Observed with the counter ‘pmLbMeasuredUe’ (‘EutranFreqRelation’), UEs are
requested to perform these measurements regardless of blind handover
possibilities. This enables the coverage conditions for load balancing to be
configured more demanding than the coverage conditions for allowing blind
handover for mobility purposes.
The A5 event represents acceptable coverage for load balancing. The A5 event is
configured with the parameters a5ThresholdRsrp and ‘hysteresisA5’
(‘ReportConfigEUtraInterFreqLb’). Observed with the counter
‘pmLbQualifiedUe’ (‘EUtranCellRelation’), reporting UEs are off-loaded until
each LBA magnitude is reached. Observed with ‘pmHoPrepAttLteInterFLb’,
‘pmHoPrepSuccLteInterFLb’, ‘pmHoExeAttLteInterFLb’,
‘pmHoExeSuccLteInterFLb’ (‘EUtranCellRelation’) counters, the off-loading is
realized by inter-frequency handover. If handover is not allowed for a certain
cell relation off-loading is inhibited. This is controlled with the (legacy)
parameter ‘isHoAllowed’ (‘EUtranCellRelation’). This means that load balancing
should not be allowed for a cell relation if handover is not defined.
The feature IFLB Activation Threshold is a licensed feature. The feature provides
an activation threshold for the Inter Frequency Load Balancing (IFLB) feature,
which can be used to reduce the number of load balancing actions taken by IFLB.
The licensing MO instance name is ‘IFLBActivationThreshold’. To optimize
IFLB below parameters can be tuned. The counters and associated parameters are
illustrated Figure 1-43 below.
› Inter-frequency load balancing
› pmHoExeAttLteInterFLb
› pmHoExeSuccLteInterFLb
› pmHoPrepAttLteInterFLb
› pmHoPrepSuccLteInterFLb
Parameter to be tuned:
› qciSubscriptionQuanta , lbThreshold , lbCeiling,
cellSubscriptionCapacity ,
› a5Threshold1Rsrp , a5Threshold2Rsrp, hysteresisA5
Figure 1-43: Inter-frequency load balancing (IFLB)
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LTE Feature supporting Mobility KPI:
9
For mobility optimization, following features can be used are listed in Figure 144 below
Figure 1-44: LTE Features for Mobility KPI
The features, affecting load based mobility are listed in Figure 1-45 below. [The
details of these features are discussed in ‘LTE Advanced Features’ training].
Figure 1-45: LTE Features affecting load based mobility(IFLB/IFO/IROW)
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10
Automated Mobility Optimization
The default mobility parameters in eNodeB are not necessarily optimized when
the operators deploy the network. The eNodeB with bad mobility parameters
suffers from Too Early Handover, Too Late Handover, Handover to Wrong Cell,
and Oscillating Handover.
Manual configuration of these thresholds is difficult and wrong settings may lead
to more drop connections and oscillating handovers. This feature automatically
configures the ‘cellIndividualOffsett’ value per cell relation in order to reduce the
number of drop connections and oscillating handovers.
The major benefits of Automated Mobility Optimization are reduced need for
manual tuning of mobility parameters and automated adjustment of cell border
when traffic changes. It may also lead to reduction in number of drops during
HO and also a reduced risk for unnecessary handovers (oscillating handovers).
Too Early Handover, HO not completed:
UE (User Equipment) experiences Handover Failure (HOF) during handover
from Cell A to Cell B, and then does RRC reestablishment in the Cell A.
According to the relation type, the counters ‘pmHoTooEarlyIntraF’ or
‘pmHoTooEarlyInterF’ are stepped on the relation from Cell A to Cell B when
Too Early Handover is detected.
Too Early Handover, HO completed:
UE experiences Radio Link Failure (RLF) after successful handover from Cell A
to Cell B, and then does RRC reestablishment in the Cell A. In this case, Cell A
forwards ‘X2AP RLF INDICATION’ signal to Cell B, then Cell B sends ‘X2AP
HANDOVER REPORT’ signal to Cell A. According to the relation type, the
counters ‘pmHoTooEarlyIntraF’ or ‘pmHoTooEarlyInterF’ are stepped on the
relation from Cell A to Cell B when Too Early Handover is detected.
Too Late Handover, HO initialized:
The UE experiences RLF in cell A and when handover is initialized from Cell A
to Cell B, and then does RRC reestablishment in the Cell B. In this case, Cell B
forwards ‘X2AP RLF INDICATION’ signal to Cell A. According to the relation
type, the counters ‘pmHoTooLateIntraF’ or ‘pmHoTooLateInterF’ are stepped on
the relation from Cell A to Cell B when Too Late Handover is detected.
Too Late Handover, HO not initialized:
The UE experiences RLF in cell A and then does RRC reestablishment in Cell B.
In this case, Cell B forwards X2AP ‘RLF INDICATION’ signal to Cell A.
According to the relation type, the counters ‘pmHoTooLateIntraF’ or
‘pmHoTooLateInterF’ are stepped on the relation from Cell A to Cell B when
Too Late Handover is detected.
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Handover to Wrong Cell, HO not completed:
UE experiences HOF or RLF during handover from Cell A to Cell B, and then
does RRC reestablishment in the Cell C. In this case, Cell C forwards X2AP
‘RLF INDICATION’ signal to Cell A. According to the relation type, the
counters ‘pmHoWrongCellIntraF’ or ‘pmHoWrongCellInterF’ will be issued on
the relation from Cell A to Cell B, and the counters
‘pmHoWrongCellReestIntraF’ or ‘pmHoWrongCellReestInterF’ are stepped on
the relation from Cell A to Cell C, when Handover to Wrong Cell is detected.
Handover to Wrong cell, HO completed:
UE experiences RLF after successful handover from Cell A to Cell B, and then
does RRC reestablishment in the Cell C. In this case, Cell C forwards X2AP
‘RLF INDICATION’ signal to Cell B, then Cell B sends X2AP ‘HANDOVER
REPORT’ signal to Cell A. According to the relation type, the counters
‘pmHoWrongCellIntraF’ or ‘pmHoWrongCellInterF’ will be issued on the
relation from Cell A to Cell B, and the counters ‘pmHoWrongCellReestIntraF’ or
‘pmHoWrongCellReestInterF’ are stepped on the relation from Cell A to Cell C,
when Handover to Wrong Cell is detected.
10.1
Parameter related to AMO feature
The parameters and counters associated to AMO feature is discussed in Figure 147, 1-48 and 1-49.
› EUtranCellRelation Managed Objects (MO) are
automatically updated:
› cellIndividualOffsetEUtran (CIO)
› qOffsetCellEUtran (qOffset)
› The operator can configure the adjustment range of the
parameters by using parameters
› cioUpperLimitAdjBySon and cioLowerLimitAdjBySon , on
MO class EUtranCellFDD or EUtranCellTDD
› hoOptStatNum, hoOptAdjThresholdAbs,
hoOptAdjThresholdPerc
Figure 1-46: Automated Mobility Optimization
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The AMO feature uses following counters to perform corrective action &
optimization, Figure 1-47 below.
› Associated Counters
pmHoTooEarlyIntraF
pmHoTooEarlyInterF
pmHoTooLateIntraF
pmHoTooLateInterF
pmHoWrongCellIntraF
Too Early Handover occurs towards intra-frequency.
Too Early Handover occurs towards an inter-frequency
Too Late Handover occurs towards an intra-frequency
Too Late Handover occurs towards an inter-freq cell
Handover to Wrong Cell towards an intra-frequency cell.
pmHoWrongCellInterF
Handover to Wrong Cell towards an inter-frequency cell.
pmHoWrongCellReestIntraF Handover to Wrong Cell with Re-estb to Intracell
pmHoWrongCellReestInterF Handover to Wrong Cell with the RRC re-estab inte cell.
pmHoOscIntraF
pmHoOscInterF
Ping-pong Handover towards intra-freq cell
Feature UE Level Oscillating Handover Minimization
Ping-pong Handover towards an inter-freq neighbor cell.
Figure 1-47: Counters, events and parameters AMO
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The ‘Automated Mobility Optimization’ feature detects these problems and then
corrects them by means of self-optimization of mobility parameters, Figure 1-48
These are the parameters for
controlling the algorithm at various
part of the evaluation :
› hoOptStatTime – defines the duration of an evaluation cycle
› hoOptStatNum – defines the minimum no. of attempts required
› hoOptAdjThresholdAbs – Weighted average quality compare
to last period in absolute terms
› hoOptAdjThresholdPerc – Weighted average quality compare
to last period in percentage terms
› cioUpperLimitAdjBySon – maximum upper range to adjust
› cioLowerLimitAdjBySon – maximum lower range to adjust
› (adjustment is in the step of 1 db)
Figure 1-48: Automated mobility optimization
10.1.1
Counters, events and parameters AMO
The Automated Mobility Optimization feature detects these problems, and then
corrects them by the means of self-optimization of mobility parameters. The
parameters associated to AMO is discussed in Figure 1-49 and Figure 1-50.
› Configurable Parameters
Parameter
MOM /
SC
Range
Unit
Defau
lt
hoOptStatTime
MOM
1..327
67
1
hour
24
The operational cycle of the handover
optimization function
hoOptStatNum
(Tho*)
MOM
1..327
67
200
The minimal number of handovers required
by the handover optimization function before
adjusting handover parameters
hoOptAdjThreshold
Abs (Tabs*)
MOM
0..327
67
5
The absolute threshold value for adjusted
handover failure rate required to adjust
handover parameters
hoOptAdjThreshold
Perc (Tperc*)
MOM
0..100
0
0.1%
50
The percentage threshold value for adjusted
handover failure rate required to adjust
handover parameters
cioUpperLimitAdjBy
Son
MOM
0..24
1 dB
4
Indicates the upper limit value of
cellIndividualOffsetEUtran range that the SON
function is allowed to adjust
cioLowerLimitAdjBy
Son
MOM
-24..0
1 dB
-3
Indicates the lower limit value of
cellIndividualOffsetEUtran range that the SON
function is allowed to adjust
Description
* Used in the previous algorithm flow
Figure 1-49: Counters, events and parameters AMO
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› Mobility parameters to be optimized by eNB
cellIndividualOffs
etEUtran
qOffsetCellEUtra
n
MOM /
SC
Range
Un
it
MOM
-24, -22, -20, -18, -16, 14, -12, -10, -8, -6, -5, 4, -3, -2, -1, 0, 1, 2, 3, 4,
5, 6, 8, 10, 12, 14, 16,
18, 20, 22, 24
1
dB
MOM
-24, -22, -20, -18, -16, 14, -12, -10, -8, -6, -5, 4, -3, -2, -1, 0, 1, 2, 3, 4,
5, 6, 8, 10, 12, 14, 16,
18, 20, 22, 24
1
dB
Defa
ult
Description
0
Offset value for the
neighbour cell.
Used when UE is in
connected mode
0
Offset value applied
to a specific cell in
idle mode mobility
state
The change of
cellIndividualOffset or qOffset
is 1db, after 6 and -6, it
becomes 2db each step
Figure 1-50: Counters, events and parameters AMO
10.2
Case Study 1, AMO trial test
An operator faced mobility issues in the network, while the subscriber was
entering in a poor coverage area followed be a late handover, because of that
other KPIs, like HOSR, accessibility, eRAB success rate, DL user throughput
was also poor and the call drop rate was also high. The operator implemented
AMO feature in the network with the parameter settings shown in the Figure 1-51
below. With the default parameter setting parameters set 1, no significant
improvements were observed, by setting parameters set 2, the mobility and other
KPIs improved. ‘hoOptStatTime’ ‘the operational cycle of the handover
optimization function’ and ‘hoOptStatNum’, ‘the minimal number of handovers
required by the handover optimization function before adjusting handover
parameters’.
› Two sets of parameters will be trialed:
Set
hoOptStatTime
hoOptStatNum
1
24 (default)
200 (default)
2
3
40
Figure 1-51: Case study 1: AMO Trial test
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Other parameters were defined as described in Figure 1-52.
› Licensing=1,OptionalFeatureLicense=AutomatedMobilityOptimization
featureState
1
› EUtranCellTDD=1
hoOptAdjThresholdAbs 5
› EUtranCellTDD=1
hoOptAdjThresholdPerc 50
› EUtranCellTDD=1
hoOptStatNum
200
› EUtranCellTDD=1
hoOptStatTime 24
› rrcConnReestActive
true
Update value:
› EUtranCellRelation=1 cellIndividualOffsetEUtran
› EUtranCellRelation=1 qOffsetCellEUtran
Figure 1-52: Case Study 1: AMO Feature parameters
The results are shown in the Figure 1-53 and Figure 1-54 below, from the first
phase trial an improvement was observed in Mobility, Retainability and
Accessibility KPI, in the test site.
Figure 1-53: Case Study 1: AMO Performance Results
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Figure 1-54: Case Study1: AMO Performance Results
While the mobility performance is improved the target of 98% handover success
is still not achieved. For that 2nd and 3rd phase of iteration with better parameter
optimization was implemented.
While the mobility performance is improved the target of 98%
handover success is still not achieved
Figure 1-55: Case Study1: AMO Performance Results
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Tried to find the other network areas to do the trail with Figure 1-56 parameters
and monitor. Since AMO work on statistics, the counters were activated to
monitor the processer load.
› From the first phase trial, it is observed an improvement in both
Mobility, Retainability and Accessibility in the test site.
› Proposal:
› Activate the counter to monitor the processer load.
› Try to find the other network area to do the trail with below parameters and
monitor.
– FeatureLicense=AutomatedMobilityOptimization featureState 1
– EUtranCellFDD hoOptStatTime 2
– EUtranCellFDD hoOptStatNum 100
– EUtranCellFDD hoOptAdjThresholdAbs 2
– EUtranCellFDD hoOptAdjThresholdPerc 20
Figure 1-56: Case Study 1: AMO Performance Results Conclusion
11
Mobility Control at Poor Coverage
The feature “Mobility Control at Poor Coverage” increases the probability that
correct mobility action is performed in some specific deployment scenarios. With
correct mobility action the outage time in case of bad coverage will be decreased
with a deployment scenario dependent.
This feature improves the Session Continuity features functionality to increase
mobility handling flexibility at poor coverage. At least one of the below features
required to start measurements in the UE, must be activated: Coverage-Triggered
WCDMA Session Continuity, Coverage-Triggered TD-SCDMA Session
Continuity, Coverage-Triggered CDMA-eHRPD Session Continuity, CoverageTriggered GERAN Session Continuity, or Coverage-Triggered Inter-Frequency
Session Continuity.
The feature “Mobility Control at Poor Coverage” uses a search zone for
interfrequency and IRAT measurements. The search zone is entered by a UE
when the A2 criteria for RSRQ and/or RSRQ are/is fulfilled (A2search). In the
search zone, the UE is configured with:
A1 (Good Coverage) measurements in order to leave the search zone.
A2 (Critical Coverage) measurements in order to trigger blind mobility actions,
handover (HO) or Release with Redirect (RwR). A1 and A2Critical use the same
trigger (RSRP or RSRQ) as for A2Search.
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A3/A5 inter-frequency and B2 IRAT measurements (Target Good Enough),
according to the configured priorities (connectedModeMobility’/’VoicePrio’) in
order to trigger possible measurement-based mobility actions, including IF/IRAT
Release with Redirect or IF/IRAT Handover.
If one of the A3/A5/B2 Target Good Enough measurement report arrives, a
Release with redirect or handover to target cell is triggered. If UE has at least one
bearer with QCI1 and handover is not possible, no blind RwR is performed and
the system continues to wait for measurement reports.
If ‘A2Critical’ is fulfilled, a blind Release with redirect or blind handover is
triggered. If UE has at least one bearer with QCI1 no blind RwR is performed
and the system continues to wait for measurement reports.
If the UE has at least one bearer with QCI1, the attribute voicePrio is used instead
of ‘ConnectedModeMobilityPrio’ to determine the priority of the frequencies. In
this case, also all frequency relation MOs which do not have this attribute will not
be measured. If the UE does not have an active voice bearer, the attribute
‘ConnectedModeMobilityPrio’ is used.
If the elapsed time since the UE entered the search zone for the first time exceeds
the value set in parameter ‘searchEffortTime’, the frequencies for which
A3/A5/B2 measurements were configured are considered to be non-feasible
targets, since no measurement report was triggered in the UE. Exclude all such
frequencies from the list, unless this action leaves the list empty, in which case
the list is left unmodified by this step.
If a bearer with QCI=1 is set up while the UE is in search zone and no "Target
Good Enough" measurements are running due to the expiry of the
‘a5B2MobilityTimer’, the ‘a5B2MobilityTimer’ and ‘Target Good Enough’
measurements are restarted! The attribute ‘voicePrio’ is used to determine the
priority of the frequencies to be measured. The trigger quantity for the A3/A5/B2
measurements is set according to the on-going A1 Search event(s). If A1 search
based on RSRP is on-going, then RSRP will be used as the trigger quantity for
A3/A5/B2 measurements. If A1 search based on RSRQ is on-going, then RSRQ
will be used as the trigger quantity for A3/A5/B2 measurements. If A1 search
based on both RSRP and RSRQ are on-going, then A3/A5/B2 measurements will
be started with both trigger quantities.
If ANR is active, it will not configure any PCI measurements in the UE while it is
in the search zone. Setting the ‘ConnectedModeMobilityPrio’ parameter to ‘-1’
excludes that frequency from mobility measurements and mobility actions.
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11.1
MCPC Associated KPI and counters
The list of the ‘EUtranCell’ MO counters and KPIs that may be used to monitor
the performance of the ‘Mobility Control at Poor Coverage’ feature is represented
in the Figure 1-57 below.
Figure 1-57: MCPC: Related Special KPI
11.2
Parameters associated to MCPC Feature
The measurement configuration is based on the parameters stated in the Figure 158 For the ‘hysteresis’ and ‘TimeToTrigger’ per event and measurement quantity
refer to CPI. Note that before L16 only one MO attribute per ‘ReportConfig’ was
used to configure the hysteresis, except for A1Search, A2Search and A2Critical
measurements, where there were different hysteresis parameters for the RSRQ
and RSRP based measurements. Since L16A there is the possibility to configure
different hysteresis values between RSRP and RSRQ for the A2, A3-IF, A5 and
‘B2 ReportConfig’. For each ‘ReportConfig’ (‘A2OuterSearch’, A5, ‘B2Utra,
B2Geran, ‘B2Cdma2000’, ‘B2Cdma20001xRtt, A3-IF).
In addition, before L16A only one MO attribute per ‘ReportConfig’ was used to
configure ‘timeToTrigger’, therefore the operator could not configure different
timeToTrigger values between RSRP and RSRQ. Since L16A there is the
possibility to configure different ‘timeToTrigger’ values between RSRP and
RSRQ for the A1, A2, A3-IF, A5, B2 ‘ReportConfig’.
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The Mobility control at poor coverage related parameters are states in Figure 158 below.
A1A2 Search Threshold
Description
The RSRP threshold for the Event A1 and Event A2 RSRP Search
a1a2SearchThresholdRsrp
measurements.
The RSRQ threshold for the Event A1 and Event A2 RSRQ Search
a1a2SearchThresholdRsrq
measurements.
The RSRP hysteresis used by the Event A1 and Event A2 RSRP Search
hysteresisA1A2SearchRsrp
measurements.
The RSRQ hysterisis used by the Event A1 and Event A2 RSRQ Search
hysteresisA1A2SearchRsrq
measurements.
The time used to determine whether the measured frequencies shall be excluded
searchEffortTime
for mobility action at critical threshold or not.
The time-to-trigger value for both the RSRP and RSRQ Event A1 Search
timeToTriggerA1Search
measurements.
The time-to-trigger value for both the RSRP and RSRQ Event A2"Search
timeToTriggerA2Search
measurements.
Critical Threshold
Description
a2CriticalThresholdRsrp
The RSRP threshold for the Event A2 RSRP Critical Coverage measurements.
a2CriticalThresholdRsrq
The RSRQ threshold for the Event A2 RSRQ Critical Coverage measurements.
The RSRP hysterisis used by the Event A2 RSRP Critical Coverage
hysteresisA2CriticalRsrp
measurements.
The RSRQ hysterisis used by the Event A2 RSRQ Critical Coverage
hysteresisA2CriticalRsrq
measurements.will be replace after this feature is Activated
Some of the A1/A2 parameters
The time-to-trigger value for both the RSRP and RSRQ Event A2 Critical
timeToTriggerA2Critical
Coverage measurements.
Figure 1-58: Mobility Control at Poor Coverage
UEs in a cell will only make inter-frequency or IRAT measurements if the
‘ueMeasurementsActive’ parameter is set to ‘true’. The time in msec the UE is
allowed to make these measurements is configured with the
‘a5B2MobilityTimer’ parameter. Using the default setting of 0 means that
measurements are not made.
The reception of A2 RSRQ triggers A5/A3/B2 with RSRQ as trigger quantity
However in some networks IRAT HO/RwR decision based on RSRQ are not
desired. The MO attribute ‘UeMeasControl::inhibitB2RsrqConfig’ can be used
to inhibit the configuration of B2-RSRQ if the event A2 Search RSRQ is
triggered when the UE enters the search zone. Since L15 it the following are
possible:
•
Inhibit of B2-RSRQ when UE enters into search zone
UEs in a cell will only make inter-frequency or IRAT measurements if the
‘ueMeasurementsActive’ parameter is set to ‘true’. The time in msec the UE is
allowed to make these measurements is configured with the
‘a5B2MobilityTimer’ parameter. Using the default setting of 0 means that
measurements are not made.
The reception of A2 RSRQ triggers A5/A3/B2 with RSRQ as trigger quantity
However in some networks IRAT HO/RwR decision based on RSRQ are not
desired. The MO attribute ‘UeMeasControl::inhibitB2RsrqConfig’ can be used to
inhibit the configuration of B2-RSRQ if the event A2 Search RSRQ is triggered
when the UE enters the search zone. Since L15 it the following are possible:
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•
Inhibit of B2-RSRQ when UE enters into search zone
•
Inhibit of B2-RSRQ when reconfiguring the “Target Good Enough”
measurements in search zone.
To activate B2-RSRQ measurement inhibition, the MO attribute
‘UeMeasControl: inhibitB2RsrqConfig’ must be set to true.
There are few enhancements in L16 and L17 for MCPC feature which can be
implemented to optimize the search zone, frequency priority, measurement
quantity, with this feature operator can define optimize UE mobility in poor
coverage and improve mobility, integrity, and retainability KPIs. Figure 1-59
illustrate the parameters.
UE Measurement Active Par.
Description
Activates or deactivates EUTRAN inter-frequency measurements for mobility
purposes when Mobility Control at Poor Coverage feature is enabled.
Activates or deactivates UTRAN measurements for mobility purposes when
ueMeasurementsActiveUTRAN
Mobility Control at Poor Coverage feature is enabled.
Activates or deactivates GERAN measurements for mobility purposes when
ueMeasurementsActiveGERAN
Mobility Control at Poor Coverage feature is enabled.
Activates or deactivates CDMA2000 measurements for mobility purposes
ueMeasurementsActiveCDMA2000
when Mobility Control at Poor Coverage feature is enabled.
Feature specific parameters
Description
Used to activate or deactivate RSRQ measurements. For more information,
EUtranCellFDD.zzzTemporary13 see Radio Network (DU-based node) or Manage Radio Network, UE
Measurement (Baseband-based node).
EUtranCellTDD.zzzTemporary13
Exists for MO classes:
ueMeasurementsActiveIF
EUtranCellFDD.zzzTemporary13
EUtranCellTDD.zzzTemporary13
Used to activate or deactivate the extended A5 "Target Good Enough"
ENodeBFunction.zzzTemporary14 check. For more information, see Radio Network (DU-based node) or
Manage Radio Network, UE Measurement (Baseband-based node).
Disables or enables configuration of B2-RSRQ if Event A2Search-RSRQ is
inhibitB2RsrqConfig
triggered when the UE enters the search zone.
Figure 1-59: Mobility Control at Poor Coverage
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11.3
Case 2, Post MCPC impact on KPIs
The impact of MCPC feature on one of the customer network mobility KPIs is
presented in Figure 1-60 below, in this example few statistics has been taken
where major changes was observed post MCPC rollout.
Figure 1-60 shows the counters values post implementation of MCPC feature, for
the ‘CriticalBorderEvalReport’, ‘BadCovSearchEvalReport’ & Bad Coverage
evaluation. ‘pmBadCovEvalReport’ counters, pegged multiple times for single
UeRef, hence reduction in counts.
Pre
Post
A1, A3, A5, B2
(WCDMA),
user-inactivity
Post Reaching
Critical Coverage
either (EUTRAN /
GERAN)
➢Introduction of new counters post the implementation of MCPC roll out :
CriticalBorderEvalReport & BadCovSearchEvalReport
➢Bad Coverage Eval Report counter pegged multiple times for Single UeRef,
hence reduction in count.
Figure 1-60: Case 2: Post MCPC evaluation L2600
Figure 1-61 shows post activation most of the ‘pmBadCovSearchEvalReport’ are
followed by an Inter-Frequency handover Execution (~75%).
Pre
Post
➢ Post Activation most of the pmBadCovSearchEvalReport are followed by an InterFrequency Execution (~75%)
Figure 1-61: Case 2: Post MCPC evaluation L2600
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Figure 1-62 below shows increase in ANR activity post implementation of
MCPC, hence an improvement in Inter Frequency HOSR(%). Number of inter
frequency relations increased.
Post
Pre
Pre
Post
➢ Increase in ANR activity post implementation of MCPC, hence an improvement in
Inter Frequency HOSR(%). Number of Inter frequency relations increased.
Figure 1-62: Case 2: Post MCPC evaluation L2600
Figure 1-63 shows that the number of eRAB Drop reduced and Minutes/Drop
increased post the implementation of MCPC feature due to improvement in the
inter frequency HOSR (%). Impact of MCPC clouded by ANR created relations.
Average Active (Min/Drop)
Post
Pre
Sum ERAB Drops Active
Post
Pre
➢Number of Erab Drop reduced and Minutes/Drop increased post the
implementation of MCPC feature due to improvement in Inter frequency HOSR(%)
E
Figure 1-63: Case 2: Post MCPC evaluation L2600
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Figure 1-64 below shows states for L1800, Improvement in inter Frequency
HOSR (%) observed post the implementation. ANR optimized for inter frequency
neighbors. UE context release to Eutra increased & to WCDMA decreased post
the rollout. the UE spends less than 4 secs in the search zone before entering the
critical coverage, a release with redirect will occur in accordance to
‘ConnectedmodeMobilityprio’ setting. i.e if Search Effort Time <4sec release
towards EUTRA and if >4 Sec release towards GERAN.
Unknown
RAT.
A2-crit
(EUTRAN)
Pre
Post
B2
(WCDMA)
➢Improvement in Inter Frequency HOSR(%) observed post the implementation on 5th Aug 2015.
ANR optimized for inter frequency neighbors post the implementation.
➢UE context release to Eutra increased & Wcdma decreased post the rollout. If the UE spends
less than 4 sec in the search zone before entering the critical coverage, a release with redirect
will occur in accordance to ConnectedmodeMobilityprioSetting . i.e Search Effort Time <4sec
release towards EUTRA, if >4 Sec release towards GERAN.
Figure 1-64: Case 2: Post MCPC evaluation L1800
12
Multi-Layer Service-Triggered Mobility
The L15B Multi-Layer Service-Triggered mobility feature, FAJ 121 4124 (FDD)
and FAJ 221 4124 (TDD) is an enhancement of legacy feature “Service
Triggered Mobility”. This feature overrides the Service Triggered Mobility
feature when both are activated. The legacy feature “Mobility Control at Poor
Coverage” is a prerequisite.
Operators today have the tendency to deploy several frequency layers in LTE as
well as in the other supported technologies, such as UTRAN, GERAN,
CDMA2000 and Cdma20001xRtt. Thus, cells in an eNodeB have mobility
relations to cells on several LTE frequencies as well as different RATs. Different
frequency layers are characterized by different coverage, and capacity, thereby
different mobility needs could be configured depending on the target frequency.
This feature can be considered as an enhancement of the “Service Triggered
Mobility” feature. The “Service Triggered Mobility” feature makes it possible to
set different thresholds per QCI for the events A2, A1, A5 and B2.
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The solution also aims to support different A5 and B2 threshold offset values per
target frequency relation or per QCI and per target frequency relation. So this
feature adds an extra level of differentiation to the service triggered mobility, as
different thresholds can be used for different frequencies. This feature overrides
the Service Triggered Mobility feature when both features are activated. To
summarize:
With the Multi-Layer Service-Triggered Mobility feature it is possible for the
operators to:
Tune different services with different A1/A2 thresholds, Tune different frequency
relations with different A5 or B2 threshold1 and threshold 2, Tune different
frequency relations and different services with different A5 or B2 threshold1 and
threshold2. With this feature the operators are also able to tune different
frequency relations as well as different services with different QoS requirements
with different mobility threshold.
The operator can set different A5-T1, A5-T2, B2-T1 and B2-T2 threshold offsets
on different QCIs and different frequency relations. Also, it can set different A1,
A2 thresholds on different QCIs in the serving cell. This means that different
QCIs could have different in/out-of poor coverage threshold (A1/A2), different
bad coverage threshold (A5-T1/B2-T1) and different good enough threshold (A5T2/B2-T2) on different target frequency relation. See Figure 1-65. Note that the
UE’s measurement threshold values are based on its QCI constellation.
The details of this feature is discussed in LTE Advance Feature Training.
A1A2Search, A5 and B2 Thresholds
for QCI
A5 and B2 Threshold per Target Frequency
Relation
Figure 1-65: Multi-Layer Service-Triggered Mobility
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13
Summary
The participants should now be able to:
1
Analyze LTE Mobility performance and related parameters.
1.1 Explain Parameter related to Idle mode mobility.
1.2 Describe different LTE mobility KPIs & counters for X2HO,
S1HO, IFHO, IRATHO.
1.3 Validate Mobility related parameter affecting different KPIs.
1.4 Evaluate the steps for optimization of these KPI
1.5 Analyze features with related parameters which improve LTE
Mobility KPIs
Figure 1-66: Summary of Chapter 1
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2 Different HOSR issues and improvement Case Studies
Objectives
After completion of this chapter the participants will be
able to:
2
2.1
2.2
2.3
2.4
Analyze KPI issues analysis, investigations and case studies for
mobility
Explain cases and investigation for different HOSR degradation
and improvements
Analyze some cases for CSFB degradation and solutions
Investigate ANR related major issues and solutions
Discuss different offline data and cases, for degradation analysis
Figure 2-1: Objective of Chapter 2
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Common Failure Scenario
1
To investigate the hand over failures, different protocol analyzers can be used,
with investigation of message flow traces at RRC protocol, S1AP or X2AP
protocols, handover failure stage can be identified. Few common failure
messages are discussed in following examples.
1.1
X2 HO Preparation Phase
If the handover is failed in preparation phase target eNodeB will not send positive
‘HandoverRequestsAcknowledge’ message, if admission failure at target end the
message will be responded ‘HandoverRequestFailure’ or no response will be
received by source cell, if there may be X2 link issue. The flow is illustrated in
Figure 2-2.
UE Src Trg CN
Target eNB
eNB eNB
|
|
MeasurementReport |==>|
|==>|
|
HandoverRequest |
HandoverRequest
pmHoPrepAttLteIntraF +
|<==|
|
HandoverRequestAcknowledge |
HandoverRequestAcknowledge
pmHoPrepSuccLteIntraF +
Source eNB
› Common failure scenario:
Target eNB responds with “Handover-Request-Failure”
› Admission failure on target enodeB
› Feature not supported in target enodeB
Target eNB does not respond to Handover Request
› Problem with X2 link
Figure 2-2: Investigation: X2 HO - Preparation
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1.2
X2 Handover Execution Phase
There can be multiple reasons for HO execution failure as, the target eNB does
not receive RRC Reconfiguration Complete command from UE, UE has moved
somewhere else, random access procedure got failed, PCI clash, UE is not located
near target eNodeB, Path switch failure etc. All scenarios will result in the expiry
of ‘tX2RelocOverall’ and ‘UeCtxtReleaseRequest’ with cause ‘tX2relocoverall’expiry.
Figure 2-3 below shows message flow for the conditions, if target eNB does not
receive RRC reconfiguration complete from UE or path switch failure.
UE Src Trg CN
eNB eNB
|
|
rrcConfigurationReconfiguration |<==|
pmHoExeAttLteIntraF +
|==>|
|
SNStatusTransfer |
|======>|
|
|
|
|==>|
|
|
|<==|
|<==|
|
UEContextRelease |
Source eNB
Target eNB
SNStatusTransfer
rrcConfigurationReconfigurationComplete
PathSwitchRequest
PathSwitchRequestAcknowledge
UEContextRelease
pmHoExeSuccLteIntraF +
|<======|
|======>|
|
|
rrcConfigurationReconfiguration
rrcConfigurationReconfigurationComplete
Common failure scenario:
› Target eNB does not receive RRC Reconfiguration Complete from UE
› UE has moved somewhere else, Random access has failed
› PCI clash – UE is not located near target enodeB
› Path switch failure
Both scenarios will result in the expiry of tX2RelocOverall, UeCtxtReleaseRequest
with cause tx2relocoverall-expiry.
Figure 2-3: Investigation: X2 HO - Execution
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1.3
HO Execution Failure Example
An example of HO execution messages is shown in Figure 2-4, which include
RRC, X2AP and S1AP messages. The handover is failed due to radio conditions
and RRC Connection Reconfiguration time out. The traces can be taken from
Layer 3 analyzer.
› Mobility Execution failure example:
› [10:59.384] /[000100]LmCellPT5(Ft_INCOMING_HANDOVER)
/vobs/erbs/node/lm/cellLmU/build/workspace/UehBearerHandlingSwU_mp750/UehBeare
rHandlingC.cpp:899 TRACE7:UE_TRACE: CellId 2, RacUeRef 20156724,
uehBearerHandlingC: received signal: timeout; port: timerRrc[0]; state: Idle; data: 0x0
› [10:59.384] /[000100]LmCellPT5(Ft_INCOMING_HANDOVER)
/vobs/erbs/node/lm/cellLmU/build/workspace/UehBearerHandlingSwU_mp750/UehBeare
rHandlingC.cpp:708 TRACE2:UE_TRACE: CellId 2, RacUeRef 20156724, RRC
Connection Reconfiguration timeout
Figure 2-4: Investigation: X2 HO - Execution
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1.4
Event Identification
When Handover is being analyzed, event identification is an important step to
detect RRC message ‘measurement report’, sent by the UE to the eNodeB. The
report has a ‘measId’ field, to know ‘measId’ field,
‘rrcConnectionReconfiguration’ message should be analyzed, the message
contains the event information, measured quantity and measured frequency.
example is illustrated in Figure 2-5.
› All mobility is triggered by an event. This event is reported by the UE in
the measurement report.
› To understand what “measID:1” means, look at the
rrcConnectionReconfiguration msg
These message can be taken from TEMS or any other protocol analyzer
Figure 2-5: Identifying Events – example
›
criticalExtensions c1 :
rrcConnectionReconfiguration-r8 : {
›
measConfig {
›
measObjectToAddModList {
›
{
›
measObjectId 1,
›
measObject measObjectEUTRA : {
›
carrierFreq 50,
›
allowedMeasBandwidth mbw6,
›
presenceAntennaPort1 TRUE,
›
neighCellConfig '10'B
›
}
› ……
› reportConfigToAddModList {
›
{
›
reportConfigId 1,
›
reportConfig reportConfigEUTRA : {
›
triggerType event : {
›
eventId eventA3 : {
›
a3-Offset 6,
›
reportOnLeave FALSE
› …..
› measIdToAddModList {
›
{
›
measId 1,
›
measObjectId 1,
›
reportConfigId 1
›
},
Refers to the
carrierFreq 50
(earfcndl = 50,
Band 2100)
Refers to
EUTRA
eventA3
Definition of measId 1
Figure 2-6: Identifying Events - example
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In ‘rrcConnectionReconfiguration’ message EnodeB sends the measurement
configuration command to inform the UE about event and measured frequency
relation. Figure 2-6 shows about ‘reportConfigid’ and ‘measObjectid’ which
refer about event and ‘earfcndl’.
Case Studies
2
This Section presents some case studies, most of which are taken from real
network setup and the parameters optimized for mobility KPI. Some of these
parameter changes shall demonstrate some positive results and few negative
impacts as well, these cases are being discussed here to understand and analyze
the impact of different parameter optimization and the results shows in these case
studies may vary network to network, based on other conditions. The main idea is
to understand how different parameters may affect mobility KPIs.
2.1
Case 1- IRAT HO, optimum parameter setting to improve
LTE drop rate
Degradation in eRAB was observed for the one site in one of the customer
network. The site was having retainability(mobility) failures & all 3 cells
observed in worst offenders, site was located at border. From cell trace analysis
of RSRP Vs distance graphs (approximate data), as shown in Figure 2-7, it looks
like drops were due to poor coverage. Previous IRAT triggering point was ‘-117
dBm’, ‘A2thresholdRSRPPrim’ (-116), ‘HysteresisA2Prim’ (10),
‘B2threshold1RSRP’ (-116). ‘B2thresholdRSCPUtra’ (-115) dBm and MCPC
feature was not activated.
› Degradation in ERAB is observed for one Site, to one of the customer.
› The site having retainability(mobility) issue & all 3 cells observed in
worst offenders. Site is located at border,
› From Celltrace analysis of RSRP Vs distance graphs (approximate
data), It looks like drops were due to Poor Coverage,
› Previous IRAT Triggering point : -117 dBm A2thresholdRSRPPrim (116), HysteresisA2Prim (10), B2threshold1RSRP(-116).
› B2thresholdRSCPUtra = -115 dBm.
› MCPC feature is not activated.
› Note Please refer to IRAT triggering mechanism as per S/W version deployed in N/W,
Figure 2-7: Case 1- IRAT HO, optimum parameter setting to improve LTE drop
rate
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RSRP Vs Distance chart is shown below in Figure 2-8, showing most of the
samples in poor coverage <-116.
› RSRP Vs Distance chart
› Showing most of samples in poor coverage (< -116 dBm), Those calls
should be redirected to UMTS before it drops in LTE.
Figure 2-8: Case 1- IRAT HO, optimum parameter setting to improve LTE drop
rate
It was better to try with optimum IRAT settings, previous IRAT triggering point
was -117 dBm ‘A2thresholdRSRPPrim’ (-116), ‘HysteresisA2Prim’ (10),
‘B2threshold1RSRP’ (-116). Recommended IRAT triggering point: ………….
(Measurement basis) & ……... (Release with Redirect) by settings IRAT
parameters so UE will be redirect to UMTS before drops in LTE, With MCPC
feature mobility of LTE subscriber in poor coverage can be optimized, A2 and
‘A2Critical’ search zone parameters can be optimized. The parameter for MCPC
are already discussed in chapter 1.
› Previous IRAT Triggering point : -117 dBm A2thresholdRSRPPrim (116), HysteresisA2Prim (10), B2threshold1RSRP(-116)
› What should be new recommended IRAT Trigger point
› -113 (Measurement basis) & -119 (Release with Redirect) by settings
below IRAT parameters so UE will be redirect to UMTS before drops in
LTE
Figure 2-9: Case 1- IRATHO, Parameter setting to improve LTE drop rate
This case is an example of how mobility parameters are impacting mobility and
retainability KPIs.
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By optimizing the parameters, improvements were seen as shown in Figure 2-10
› Pre-Post Retainability trend, Drops rate improved while
there was no degradation in UMTS KPIs.
Figure 2-10: Case 1- IRAT HO optimum parameter setting to improve LTE drop
rate
2.2
Case 2: Intra frequency Oscillating Handover
2.2.1
Network issue
In an operator network HO oscillation rate was high for intra frequency (ping
pong handover) in a cell relation, the counter checked ‘PmHoOscIntraF’, was
pegging high. Parameter optimization need to be done to improve handover
success rate and to reduce HO oscillation rate, as stated in
Figure 2-11: Case 2: Oscillating Handover..
› In a Network intra frequency HO oscillation rate (ping pong
handover) for an area was high.
› Optimization need to be done to Improve Handover
success rate and to reduce Ho oscillation rate
› Counter Checked:
› ‘PmHoOscIntraF’
› Execution Selection Criteria : All site
Figure 2-11: Case 2: Oscillating Handover
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2.2.2
Case 2: Intra frequency HO Event review
Figure 2-12 is a review for A3 event and associated parameters.
neighbour becomes amount offset better than serving
To activate the function
bestCellReleaseActive = TRUE
RSRP
UE measure neighbouring cells
measurement reports include
RSRP and RSRQ
Serving
LTE Cell
S
E
S
E
sMeasure
A3offset
S
E
HysteresisA3
Enter
Event A3
Start measuring
neighbors
End measuring
neighbors
Leave
Event A3
Measurement Reports
reportIntervalA3
timeToTriggerA3
reportAmountA3
(0 = continual during event)
Neighbour
LTE Cell
Example:
•A3offset: 3dBm
•HysteresisA3: 1dBm
•reportIntervalA3: 2s
•timeToTriggerA3: 320ms
•sMeasure: 0 - Disabled
Time
In connected mode, eNB determines when the
handover occurs based on the UE reports
Figure 2-12: Case 2: Intra frequency HO
2.2.3
Parameters Tuned
To check the sustainability of A3, event trigger time is increased with parameter
‘TimeToTriggerA3’ from 40 to …....
› Action Taken:
› Increased timer event A3
› Parameter Changing
For HO Oscillation AMO feature or UE Level Oscillating
Handover Minimization feature can be used.
Figure 2-13: Case 2: Oscillating Handover
The ‘TimeToTriggerA3’ parameter provide additional time to UE to check
sustainability of received signals before triggering the event. Automated mobility
optimization feature’s parameters setting can also be used to optimize oscillating
HO, too early, too late and HO to wrong cell.
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2.2.4
Impact: KPI improvement
After changing the ‘timetotriggerA3’ parameter, HO oscillation improved with
good margin, intra frequency HO also improved as shown in the
Figure 2-14: Case 2: Performance result and
Figure 2-15: Case 2: Performance result.
Result:
HO oscillation rate improved from 22.24% to 14.57%
Figure 2-14: Case 2: Performance result
Intra frequency success rate improved from 98.6% to 99%
Figure 2-15: Case 2: Performance result
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2.3
Case 3: HOSR degraded with AMO activation
2.3.1
Issue statement
An Operator has observed, that the HOSR has been degraded after AMO feature
is activated in a cluster.
Since AMO feature is used to improve HOSR, this degradation indicates to a
wrong parameter setting, which needs to be analyzed.
› HOSR degraded after activating AMO function in the cluster.
› Following is the HOSR trend in the network
› What may be the reason of HOSR degradation?
Figure 2-16: Case 3: With AMO HOSR degraded
2.3.2
CIO statistics observation
When the issue observed, first point of check was AMO basic functionality.
AMO changes CIO value on the basis of different HO statistics, after HOSR
degradation CIO values were observed which was changed by AMO feature.
CIO values indicate that there have been, many too early handovers in the
network. The reasonable results of CIO should have almost the same percentage
for negative and positive values.
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The CIO values are analyzed as given in Figure 2-17.
› CIO collected: CIO statistics based on kget files:
CIO
-6
-3
-2
-1
0
1
2
3
4
Count of cellIndividualOffsetEUtran
2
20053
16105
23201
239647
2646
584
212
154
Percentate
0.00066093
6.6268126
5.322137183
7.667116099
79.19492142
0.87441012
0.1929915
0.070058558
0.050891594
› What you observe from above figure?
› Negative
CIOstatistics
value of
isthe
much
more than the positive CIO value that
Figure 2-17:
Case 3: CIO
network
means there are many too early handover in the network.
Next step is to check which neighbour relations are impacting with these CIO
› The reasonable result of CIO value should be that negative and
settings, it was observed that negative CIO was defined on the relations less than
positive
havewealmost
the the
same
percentage.
2 KM. And
if CIO isCIO
negative,
can analyze
impact
on handover. Figure 218 indicates distance in KM versus CIO counts. With negative CIO, handover
become …………. and downlink interference increase.
› Pick up the relations with different CIO value and calculate
the distance between relations:
CIO=-3
CIO=-2
CIO=-1
Distance(km) Count of Distance Distance(km) Count of Distance Distance(km) Count of Distance
[0,1)
11131
[0,1)
7658
[0,1)
8267
[1,2)
6300
[1,2)
5547
[1,2)
8568
[2,3)
1790
[2,3)
1939
[2,3)
4163
[3,4)
466
[3,4)
627
[3,4)
1515
[4,5)
95
[4,5)
120
[4,5)
344
[5,6)
31
[5,6)
51
[5,6)
145
[6
31
[6
55
[6
124
› Here most of the negative CIO value showing impact on the
relations less than 2km.
› It will make handover harder especially when CIO=-3, and cause
Figure 2-18: Case 3: CIO & distance analysis
high downlink interference.
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2.3.3
Case 3: CIO = -2 & -3 distribution in different cluster
› Following is the statistics of CIO=-2 & -3 distributed in cluster
Figure 2-19: Case 3: CIO=-2 & -3 distribution In the cluster
2.3.4
CIO = -3 for first tier neighbors
After analyzing, it was found that many first round neighbour relations was
having CIO = -3, which makes handover harder to prime neighbours. As shown
in Figure 2-20.
› It is unreasonable that source cell 4G18_4413416E_4 has many first round neighbor
relation with CIO= -3. The cell marked with red circle is neighbor relation with CIO= -3 of cell
4G18_4413416E_4
Figure 2-20: Case 3: Example of unreasonable CIO value
2.3.5
Potential reason of unreasonable CIO value
AMO might set higher CIO value if handover fails due to some reasons other
than RF condition, then to return to positive CIO value is difficult as discussed in
Figure 2-21. ‘TimeToTriggerA3’ is an important parameter to minimize
oscillating HO.
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AMO re-corrective CIO mechanism is illustrated in Figure 2-21 below
› Mechanism of AMO re-corrective CIO
› If target cell get transmission alarms during handover process and cause
handover failure, AMO feature will interpret, it caused by radio conditions and
adjust CIO value to -3. Once adjusting CIO to -3 dB in cell relation, it is very
hard to trigger re-adjustment of CIO since target cell RSRP level should be
7dB(A3offset: 3dBm HysteresisA3: 1dBm) larger than the source cell and
need handover attempt larger than 200 (‘hoOptStatNum’=200).
› At this situation, target cell becomes a high DL interference cell to the source
cell and will impact source cell handover to other cells. If ‘hoOptStatNum’ can
be adjusted to 100 for example at second time, CIO value may can readjust to -1 or 0.
› TimeToTriggerA3:
› At current configuration, ‘timeToTriggerA3’=40ms, which is very short and will
cause early handover. Once CIO sets to -3, it is very hard to re-adjust to 0.
Larger setting of timeToTriggerA3 (eg. 320ms or 480ms) is recommended to
avoid action of corrective CIO.
Figure 2-21: Case 3: Potential reason of unreasonable CIO value
2.3.6
Case 3: Trail Suggestion
If AMO has bad impact on HOSR ‘cioUpperLimitAdjBySon’ and
‘cioLowerLimitAdjBySon’ parameters can be adjusted. The AMO feature gives
good results if the AMO parameters are correctly tuned.
› Once setting CIO=-3, it is very hard to adjust CIO to -1 or 0
by AMO function itself. CIO need be set to 0 periodically
especially in network which have large quantity of
transmission related alarms.
› ‘timeToTriggerA3’ need be set to 320 or 480ms, which is the
reasonable setting to avoid early handover.
› If AMO has a bad impact on HOSR, we can degrade the
consequence by adjusting ‘cioUpperLimitAdjBySon’ and
‘cioLowerLimitAdjBySon’.
› For a cluster the trail can be done with different set of
parameter values.
Figure 2-22: Case 3: Trail suggestion
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2.4
Case 4: HOSR Execution Improvement On Distance Site
CIO values indicate that there have been, many too early handovers in a network.
The reasonable results of CIO should have almost the same percentage for
negative and positive values.
Major HO failures observed between 2 cells, Distance between
two neighbors was higher but those are 1st tier neighbors.
Issue was RACH success rate. During HO execution.
Suggest some optimization steps.
Figure 2-23: Case 4: HOSR Execution Improvement On Distance Site
2.4.1
Case 4: HOSR Execution improvement with cell range
change
The measures taken in the cell are shown in Figure 2-24 below.
› Trial done to increase ‘cellrange’ from 14 To 23 Km on target
cell *2090_7A to improve RACH success rate.
› ‘MaximumCellRange’ feature should be activated &
PreableFormate should be 1.
› Huge improvement observed in HOSR between this relation.
› Need to monitor. Other KPIs where cellrange changed(Peak
UL throughput might be reduced because Preamble format 1-2
consumes more UL PRBs (Time division).
› The Maximum Cell Range feature is activated by setting the
“featureStateMaximumCellRange” (MO: MaximumCellRange)
to 1 (ACTIVATED).
Figure 2-24: Case 4: HOSR Execution improvement with cell range change
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HOSR execution improvement is shown in Figure 2-25 below
Figure 2-25: Case 4: HOSR Execution improvement with cell range changes
2.5
Case 5: Poor IRAT success rate towards poor WCDMA cell
for QCI8
In an operator network IRAT Handover success rate towards WCDMA was poor,
handover execution was failing. When observed the WCDMA RSCP was poor
during Handover. The cells having poor UMTS coverage being selected for
measurement based IRAT and eventually dropping the call. Figure 2-26 below
shows the issue statement.
› IRAT Handover success rate was observed towards
WCDMA, handover execution was failing.
› When observed the WCDMA RSCP was poor during
Handover.
› Cells having poor UMTS coverage being selected for
measurement based IRAT and eventually dropping the
call.
› Which parameter to be Tuned?
Figure 2-26: Case 5: Poor IRAT success rate to poor WCDMA Cell for QCI8
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2.5.1
Case 5: Poor IRAT parameters check
‘B2Threshold2RscpUtra’ Parameter defines the threshold which UMTS cell must
meet by hysteresis for a period of ‘TimeToTriggerB2’ in order to being reported
by the UE provided LTE Cell is worse than ‘B2Threshold1Rsrp’+Hysteresis for a
period of ‘TimeToTriggeB2’.
Default value for ‘B2Threshold2RscpUtra’ is set to -115 dBm resulting in cells
having poor UMTS coverage being selected for measurement based IRAT and
eventually dropping the call. Changing this parameter would affect LTE as well.
If the IRAT HO need to be optimized only for QCI8, QCI specific offset
‘B2Threshold2RscpUtraoffset’, a site level parameter can be optimized, so
changes were made to QCI=8. Figure 2-27.
› ‘B2Threshold2RscpUtra’ Parameter defines the threshold which
UMTS cell must meet by hysteresis for a period of ‘timetotrigger’ in
order to being reported by the UE provided LTE Cell is worse than
‘B2Threshold1Rsrp’+Hysteresis for a period of ‘timetotrigger’.
› Default value for ‘B2Threshold2RscpUtra’ is set to -115 dBm resulting
in cells having poor UMTS coverage being selected for measurement
based IRAT and eventually dropping the call. Changing this parameter
would affect LTE as well .
› ‘B2Threshold2RscpUtraoffset’ is QCI specific offset site level
parameter, so changes were made to QCI=8
Figure 2-27: Case 5: Poor IRAT success rate to poor WCDMA Cell for QCI8
› B2Threshold2RscpUtraoffset was changed from 0 to 10 effectively
reducing B2Threshold2RscpUtra to -105dBm
2.5.2
Case 5: Poor IRAT success rate toward poor WCDMA cell
for QCI8
Figure 2-28 below shows the result after ‘B2Threshold2RscpUtraoffset’ was
changed from 0 to 10, effectively reducing ‘B2Threshold2RscpUtra’ to -105dBm,
IRAT HO toward poor WCDMA cell reduced. Since the setting can be done per
QCI basis operator can optimize these parameters on QCI level.
Figure 2-28: Case 5: Poor IRAT success rate to poor WCDMA Cell for QCI8
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2.6
Poor IRAT HOSR – Other reasons & solutions
Major reasons / causes behind poor IRAT handover success rate is discussed in
Figure 2-29, coverage gap between LTE & 3G/Other Technology, Improper
parameter settings (‘a1a2SearchThresholdRsrp’, ‘a2CriticalThresholdRSRP’,
‘b2ThresholdRscpUtra’).
The Best way to optimize IRAT is by doing physical optimization. Antenna tilt
can be checked through the command ‘get . electrical’. Antenna model number
can be checked through the command ‘get . antenna’.
Major reasons / causes behind poor IRAT handover success rate are as follows
✓ Coverage gap between LTE & 3G/Other Technology.
✓ Improper parameter setting (a1a2SearchThresholdRsrp,
a2CriticalThresholdRSRP, b2ThresholdRscpUtra).
The Best way to optimize IRAT is doing physical optimization. We can measure
antenna tilt and adjust the EDT.
› Antenna tilt can be checked through the command: get . electrical
› Antenna model no. can be checked through the command get . antenna
Figure 2-29: Poor IRAT HOSR – Other reasons & solutions
2.6.1
IRAT improvement Counter to be checked
Following counters can be observed in order to perform IRAT analysis,
‘pmBadCovSearchEvalReport’, ‘pmCriticalBorderEvalReport’. If more samples
are pegged under ‘pmBadCovSearchEvalReport’, it reflects that more subscribers
have gone to the bad coverage area, consider the need to optimize MCPC feature,
‘A2 search’ and ‘A2critical’ event parameters.
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One can follow the procedure as shown in Figure 2-30 below.
Process to fetch the counters
STEP 1:
Check following two counters to
perform IRAT analysis
✓pmBadCovSearchEvalReport
✓pmCriticalBorderEvalReport
STEP 2: Use OSS RC and
ENIQ tool to fetch these
counters, Select NodeB and
MO Class EUtranCellFDD, to
get counter of the MO
STEP 3: Select the above
mentioned counters.
Figure 2-30: IRAT improvement Solution Procedure Contd…
A case is discussed in Figure 2-31 below, where more samples were found for the
‘pmBadCovSearchEvalReport’ counter.
If more samples are found under pmBadCovSearchEvalReport.
In a Network, found that in WCL01558, the gamma sector has high IRAT
and also found very high samples under pmBadCovSearchEvalReport.
Which Parameters to be fixed?
Figure 2-31: Case 6: IRAT improvement Solution Procedure Contd…
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2.6.2
Case 6: IRAT improvement with ‘a1a2SearchTresholdRsrp’
The network optimization team changed the values of the parameters
‘a1a2SearchThresholdRsrp’, ‘b2Threshold2RscpUtra’. The parameter optimized
‘a1a2SearchThresholdRsrp’ from -110 dBm to ……. dBm and
‘b2Threshold2RscpUtra’ from -115 dBm to ……... dBm on 20/04 and found
good improvement in IRAT.
› Change the values of the parameters
› a1a2SearchThresholdRsrp, b2Threshold2RscpUtra.
› Parameter optimized
› a1a2SearchThresholdRsrp from -110 dBm to -112 dBm and
b2Threshold2RscpUtra from -115 dBm to -105 dBm
› Found good improvement in IRAT.
Figure 2-32: Case 6: IRAT improvement Solution Procedure Contd…
2.6.3
High Samples for ‘pmCriticalBorderEvalReport’
High samples have been observed for the counter ‘pmCriticalBorderEvalReport’,
IRAT cases also seem to be high. One sector is having high IRAT handover and
high ‘pmCriticalBorderEvalReport’. Figure 2-33 shows the counter samples in
the sector.
If more samples are found under pmCriticalBorderEvalReport.
Found SCL00197 Gamma sector has high IRAT and also found very
high samples under pmCriticalBorderEvalReport.
Which Parameter to be fixed?
Figure 2-33: Case 6: IRAT improvement Solution Procedure Contd…
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Parameters can be changed ‘a2CriticalThresholdRsrp’. The value of
‘a2CriticalThresholdRsrp’ was changed from -122 dBm to ……dBm and found
good improvement in IRAT as shown in Figure 2-34 below.
› We can change the value of the parameter –
a2CriticalThresholdRsrp.
Parameter changed:
› The value of a2CriticalThresholdRsrp from -122 dBm to 124dBm
› Found good improvement in IRAT.
Figure 2-34: Case 6: IRAT improvement Solution Procedure Contd…
2.7
Case 7: KPIs (HOSR, Ret., Thp.) Improvement with IFHO
parameter setting
In a city submarket, a tunnel site has been launched with a single carrier on 1900
Band. The operator has had 2C & 3C launches on 1900 Band. Further
investigation reveals, there are nearby DAS sites which are on 700 Band, and
there has been no HO from 700 to 1900.
› In a city submarket, Tunnel site launched with single Carrier on 1900
Band
› The operator having 2C & 3C launches on 1900 Band
› Issue observed, It has near by DAS sites working on 700 Band, there
was no HO from 700 to 1900 band
✓ MAP view for tunnel site
Figure 2-35: Case 7: KPIs Improvement with IFHO parameter setting
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This case is an example of an optimized parameter setting for a network having
frequency layering and when subscriber is to be moved from low priority to high
priority, the search parameters for Idle mode and connected mode can create
impact on all KPIs. Figure 2-36 shows the parameter changed for optimization.
Figure 2-37, Figure 2-38 and Figure 2-39 showing KPIs improvement after
parameters optimization in the network.
› Team proposed operator to changes IFHO setting &
Defined these both way, resulted in all KPI Improvement
› KPI Trend given in Next Slide, ( good improvement in
drops rate)
Figure 2-36: Case 7: KPIs (HOSR,Ret.,Thp.) Improvement with ifho parameter
setting
Accessibility KPI with IFHO parameter setting
➢
KPI Trend Accessibility
Figure 2-37: Case 7: KPIs Improvement with IFHO parameter setting
Retainability KPI improvement after IFHO parameter setting.
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➢
KPI Trend Retainability
Figure 2-38: Case 7: KPIs Improvement with IFHO parameter setting
PDCP Throughput improvement.
➢
KPI Trend Throughput
Figure 2-39: Case 7: KPIs Improvement with IFHO parameter setting
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2.8
Case 8: Coverage issue, crsGain Tuning
A Network trend shows poor coverage area, there are few areas where RSRP was
poorer than -105 dBm, as shown in Figure 2-40. Suggested solution was to adjust
‘CrsGain’, ‘CrsGain’ power of the resource element containing reference
symbols. If the symbols contain data, then the parameter ‘pdschTypeBGain’
should be used. If we adjust the ‘CrsGain’ we should move the mobility borders
according to the parameter changed, ie if ‘CrsGain’ is lowered by 3dB then the
mobility thresholds should be lowered by 3dB. To optimize the network, the first
step was to find the area with poor RSRP, with TEMS or any other tool the area
was identified with poor coverage. as shown in Figure 2-40.
Area Selection For Review: Area coverage can be plotted with TEMS tool
Poor Coverage
Area (RSRP ≤ 105dBm)
Figure 2-40: Case 8: Coverage issue, crsGain Tuning
Cell Selection Steps: Select area: RSRP < -105dBm which is consider as poor
coverage area. Serving cell closes to the poor coverage area are selected to
increased CRS Gain, Figure 2-41shows that area.
Cell Selection Steps:
1. Select area: RSRP < -105dBm which is consider as poor coverage area.
2. Serving cell closes to the poor coverage area are selected to increased CRS
Gain
Figure 2-41: Case 8: Cell Selection to Increase crsGain
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crsGain = 0 { -300, -200, -100, 0, 177, 300, 477, 600} sets the DL power of the
cell specific reference signal (CRS) relatively a reference level defined by the
power of the PDSCH type-A resource elements. If ‘crsGain’ is +3dB, the CRS
power is 3dB higher than a PDSCH type A resource element. PDSCH type A
resource elements are located in symbols that do not contain CRS. By Increasing
CRS power coverage increased in poor coverage area. Also reduce Type-B
PDSCH power accordingly. New proposed values are shown in Figure 2-42
› What is crsGain parameter and relation between CRS gain and
pdschTypeBGain ?
› Increasing CRS power to improve coverage in poor coverage area.
› Reduce type-B PDSCH power accordingly.
Parameter:
MO Class Name
EUtranCellFDD
Parameter Name
crsGain
Current Network
0
New Proposed
300
ENodeBFunction
pdschTypeBGain
0
1
Figure 2-42: Case 8: Coverage issue, crsGain Tuning Example
Expected coverage to be improved slightly upon increased CRS power gain in
poor coverage area. Some KPIs such as user throughput, RRC Connection drop
could be affected due to coverage improve meaning more users are able to keep
in the network.
Expected coverage to be improve slightly upon increased CRS power
gain in poor coverage area.
Some KPIs such as user throughput, RRC Connection drop could be
affected due to coverage improve meaning more users are able to
keep in the network.
Figure 2-43: Case 8: Coverage issue, crsGain Tuning
2.9
Case 9: Handover failed in preparation phase
There may be different reasons of handover failure in preparation phase.
Handover failed due to RRC setup failures in target cells. HO rejected from target
cell as load is high or license issues. The case is discussed in Figure 2-44 below.
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› KPI Impact: Handover failed in target phase.
› Root Cause: Handover failed due to RRC setup failures in
target cells. HO rejected from Target cell.
› Lets discuss few reasons of RRC failed in target cell?
Figure 2-44: Case 9: Handover failed during RRC setup
There may be different reason of RRC fail in target cell: CU license congestion,
PUCCH resource congestion etc. Solution is CU license expansion, PUCCH
parameter modification. After changes in ‘noOfPucchSrUsers’ &
‘noOfPucchCqiUsers’ from 160 to 320, RRC setup SR become normal and then
handover recover as well. The counter to be checked in target cell are
‘pmPucchSrCqiResCongCqi’ & ‘pmPucchSrCqiResCongSr’. As shown in
Figure 2-45, both parameters depend on PUCCH utilization in uplink.
› There may be different reason of RRC fail in target cell: CU license
congestion, PUCCH resource congestion, etc.
› Solution: CU License expansion, PUCCH parameter modification.
› After change noOfPucchSrUsers & noOfPucchCqiUsers from 160 to
320, RRC setup SR is normal and then handover recover as well.
Figure 2-45: Case 9: Handover failed in preparation phase
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2.10
Case 10: PCI Confusion
A network cell reported worst Intra LTE HO Execution, after analysis it was
found due to PCI confusion between 51011-430052-6 & 51011-420211-6 cell.
The relation was deleted toward 51011-430052-6. The case-10 is illustrated in
Figure 2-46 below.
› JK4G18_MC4424219E_6 is the
worst Intra LTE HO Execution due
to PCI confusion between 51011430052-6 & 51011-420211-6. Delete
relation toward 51011-430052-6 has
been done.
Figure 2-46: Case 10: PCI Confusion
The relation was again created by ANR, Relation from 4G18_MC4424219E_6 to
51011-430052-6 come again on 2016-10-26 07:08:46 created by X2. To avoid
PCI conflict, the network team block the relation on 2016-10-26 10:47: 25,
Figure 2-47 shows the block relation print.
› Relation from 4G18_MC4424219E_6 to 51011-430052-6 come again
on 2016-10-26 07:08:46 created by X2  block relation done on 201610-26 10:47:25 (UTC)
Figure 2-47: Case 10: PCI Confusion
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2.11
Case 11: ~100% HO Execution failures
In a network cell Intra frequency HO KPI shows nearly ~ 100% failure rate,
mainly towards one PCI. If so many HO fails toward one relation, one reason of
failure can be PCI conflict. By checking KPI it was found HO preparation
success is 100% while maximum HO execution is failing. As shown in Figure 248.
KPI shows nearly ~ 100% failure rate of Intra frequency HO, mainly
towards one PCI.
By checking KPI it is found HO preparation Success is 100% while
maximum HO execution is failing.
Figure 2-48: Case 11: ~100% HO Execution failures
When checked target eNB it was found that, it has same PCIs as another eNB
much closer to the source. If there isn’t another eNb closer to the source, then this
could indicate that the target eNb is an over shooter. In this case solution was to
down tilt the target.
By analyzing, Target eNB has same PCIs as another eNB much closer to
the source. If there isn’t another eNb closer to the source, then this could
indicate that the target eNb is an over shooter. You will then have to down
tilt the target.
Figure 2-49: Case 11- RRC HO Execution failures due to PCI Collision
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2.11.1
Case 11- RRC HO Execution failures due to PCI Collision
Following measures can be taken for PCI collision cases, as shown in Figure 2-50
below.
› To resolve ANR-PCI clashes. Delete
externalenodebfunction, externaleutrancellfdd, termpttoenb
and eutrancellrelation
› ANR added cells from the closer eNB as neighbors in
every case, resulting in a substantial increase in Handover
Success Rate
› Recommended to review PCI plan if two neighbor sites
having same PCI value
› In Below case 02215 & 02697 had same PCI, So HO
failures observed in near by area.
Figure 2-50: Case 11- RRC HO Execution failures due to PCI Collision
3
ANR: MOM – ANR Created
ANR creates the neighboring cell relations that are needed for providing full
mobility in LTE and from LTE to other technologies (WCDMA and GSM). It
creates the necessary relationships between cells to succeed with handover when
the user is moving in the network. The relationship is setup in time for when the
handover is needed. Meaning that ANR creates the neighboring cell relation
when the UE reports a new cell as best serving.
ANR automatically cleans-up not used neighbors in the neighboring cell list. It
means that the neighboring cell list will always be optimal.
The support for ANR contains control via policies. All policies comes with
default settings allowing simple activation of ANR. All changes made by ANR
are displayed in OSS-RC, such as outputted in Bulk CM export.
ANR shows very promising results where we believe that it will both contribute
to reducing OpEx and improving network performance at the same time.
The goal of ANR is to set up cellRelations to neighboring cells. To do that, ANR
will create CellRelation, ExtEnb, ExtCell and TermPointToEnb. However,
Frequency and FreqRelation objects are created by the operator. ANR will only
search for neighboring cells on operator defined frequencies.
It is bad for the UE that request a lot of measurements when you are on the cell
edge.
May be with many measurements dropped calls increase, because we configure
measurement gaps. – That is time-gaps during which the cell will not
communicate with the UE, because the UE will search for other cells.
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There are many other measurements that we want to configure. Load Balancing,
Carrier Aggregation.
Neighbor Cell Relations are defined using following MOs:
• ‘EutranFreqRelation’ for Intra LTE Neighbors
• ‘GERANFreqGroupRelation’ for GSM neighbors
• ‘UTRANFreqRelation’ for WCDMA neighbors
• ‘CDMA2000FreqBandRelation’ for CDMA2000 neighbors
EnbFunction
EUtranCellFDD/TDD
EUtraNetwork
EUtran
FreqRelation
EUtran
CellRelation
EUtran
Frequency
reference
External
EnbFunction
External
EUtranCellFDD/TDD
TermPoint
ToEnb (X2)
Pre-configured MOs
ANR created MOs
Figure 2-51: ANR: MOM – ANR Created
3.1
Handover event triggered
ANR trigger point, ANR specific thresholds should be set earlier than ordinary
HO thresholds, used for increasing probability for handover over X2, used for a
portion of the UEs (the rest use HO event trigger).
If a surrounding cell is ranked better cell than the S-eNodeB cell (UE reports in
A3 (or A5) (neighbor becomes amount of offset better than serving) for the best
PCIs) but its PCI does not correspond to any of the S-eNodeB’s defined
neighboring cells, the ANR function is “activated”. S-eNodeB orders the UE to
retrieve the Cell Global Identity (CGI) of the best ranked surrounding cell (from
now on called target eNodeB Cell, or T-eNodeB cell). The UE can only do the
CGI measurement in long DRX mode (i.e. when it is inactive). The measurement
can take up to 260ms hence this first handover may fail.
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ANR then creates a neighbor cell relationship between the S-eNodeB cell and the
T-eNodeB cell. S-eNodeB establishes SCTP with the T-eNodeB. Successful
SCTP establishment confirms that the signaling transport is working.
S-eNodeB requests X2 setup by sending, for each own cell, the PCI, LCI, TAC,
PLMN-id and frequency. The T-eNodeB adds all S-eNodeB’s cells to its
neighbor list and sends the PCI, LCI, TAC, PLMN-id and frequency of all its
own cells to the S-eNodeB, which in turn add all cells to its neighbor list.
Successful establishment of X2 application layer confirms that the application
layer is working. The X2 interface is now established, the neighbor lists are in
place and the neighbor cell relation is in place. Figure 2-52 shows the process.
The S-eNodeB sends a handover request over X2 to the T-eNodeB, which in
turns performs Admission Control, allocates resources and acknowledges back to
S-eNodeB (with Handover Command), and S-eNodeB in turns starts handover
execution by sending ‘RRC Connection Reconfiguration’ command to the UE. At
the same time S-eNodeB starts Data Forwarding of unacknowledged and unsent
data packets over the X2 interface to the T-eNodeB. The handover execution
ends when the UE successfully accesses the T-eNodeB and sends a Handover
Confirm message. The T-eNodeB notifies the MME and S-GW that the handover
is completed, the bearer is switched from S-eNodeB to the T-eNodeB and the
resources are release in S-eNodeB.
1. RSRP (or RSRQ) of the serving cell is below
RSRP or RSRQ
sMeasure
2. UE starts measuring DL RSRP (or RSRQ)
3. UE reports in A3 (neighbor becomes amount of
UE starts measuring
offset better than serving) for the best PCIs
Serving
cell
4. If the best PCI is not in the neighbor cell list the
UE reports Ncell for HO (HO triggered)
UE is ordered to measure and report CGI for sMeasure
it
5. The UE is set for long DRX to be able to read CGI
Target cell
6. UE measures and reports CGI
7. Serving eNodeB exchange cell data with target
A3
eNodeB Two methods can be used to obtain the
IP address:
Distance from
1. over S1: eNodeBConfigTransfer and
eNodeB
MMEConfigTransfer (L11B and onwards)
Target eNodeB
2. DNS lookup to retrieve the T-eNodeB IP
address (fallback option) (L11A)
Serving eNodeB
8. Serving eNodeB creates cell relationship to Target
cell
9. Handover can now be executed over S1
10. X2 is setup between the eNodeBs (i.e. setup of
X2
SCTP)
ANR specific actions
11. Handover can be executed over X2
UENormal HO actions
12. OSS-RC is updated
Figure 2-52: Handover event triggered
3.2
Periodical ANR (Inter-frequency and IRAT HO)
The feature can be used together with manual optimization of neighbor lists, and
is also able to remove neighbor LTE cell relations which have not been used
within a particular time period (‘removeNrelTime’).
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For target cell, number of measurement reports is controlled for each RAT by a
number of parameters e.g. ‘anrUtranMeasReportMax’,
‘anrGeranMeasReportMax’, ‘anrUtranMeasReportDecr’ ,
‘anrGeranMeasReportDecr’, ‘anrUtranMeasReportIncr’,
‘anrGeranMeasReportIncr’, ‘anrUtranMeasReportMin’,
‘anrGeranMeasReportMin’.
1. A limited set of active UEs in cells are configured to measure and report
ANR A3 event (neighbor becomes offset better than serving) with an
ANR threshold
2. UE reports PCIs that fulfills ANR A3 threshold
3. Same procedure as for handover event triggered ANR
RSRP or RSRQ
UE starts measuring
UE reports target cell to ANR (event triggered)
Serving cell
UE reports target cell for HO (HO triggered)
sMeasure
Target cell
ANR A3
A3
Gained time
ANR specific actions
Normal HO actions
Figure 2-53: ANR event triggered
The measurement configuration sent to the UE depends on the corresponding
mobility measurement configuration and are delta in relation to that. The delta
values broaden the cell border and provide the Automated Neighbor Relations
feature with information on new cells before they are needed for handover,
providing more time to perform CGI readingAs a consequence of having smaller
“A3offset” (“A3offset-a3offsetAneDelta”) the ANR A3event will happen before
real A3 event creating the time to create a neighbor relation and X2 interface in
time for real handover.
Similar to A3, the event A5 is associated with different thresholds when it is
configured for ANR, then in the handover measurement case. Notice that this is
valid for FDD only. The equation for calculating the RSRP or RSRQ threshold1
and threshold 2 values for the ANR feature are listed here,
RSRP:
a5Threshold1Rsrp + a5Threshold1RsrpAnrDelta
a5Threshold2Rsrp - a5Threshold2RsrpAnrDelta
RSRQ:
a5Threshold1Rsrq + a5Threshold1RsrqAnrDelta
a5Threshold2Rsrq - a5Threshold2RsrqAnrDelta
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After providing the eNodeB with either a specific number of reports
‘maxNoPciReportsEvent’ or a specific time ‘maxTimeEventBasedPciConf’, a
UE selected for these types of measurements is then relieved from sending any
more ANR-specific PCI reports during the time it is connected to the eNodeB.
Figure 2-52 shows the ANR process.
›
›
›
›
›
›
›
A limited set of connected UEs are ordered to perform periodic ANR
measurement (ReportStrongestCellsForSON)
UEs measure and report the strongest PCI
ANR assesses if reported PCIs are valid neighbors
If the PCI is not in the neighbor cell list the UE is ordered to measure and
report CGI for it. UEs are at the same time set in long DRX mode
Neighboring cell relation is created
OSS-RC is updated
The updated list is used at next handover
LTE
WCDMA/GSM/(CDMA)
ANR specific actions
Normal HO actions
Figure 2-54: Periodical ANR (Inter-frequency and IRAT HO)
3.3
ANR Parameter EUTRAN
The minimum number of UEs that are used for NR reporting is controlled by the
‘anrUesEUtraIntraFMin’ and ‘anrUesThreshInterFMin’ parameters for intra and
inter frequency neighbors respectively.
Every time a neighbor cell report for handover is received with unknown
neighbor cells the number of ANR reporting UEs is increased by the setting of
the ‘anrUesEUtraIntraFIncrHo’ for intra frequency neighbors and
‘anrUesThreshInterFIncrHo’ for inter frequency neighbors. The maximum
number ANR reporting UEs is set with the ‘anrUesEUtraIntraFMax’ and
‘anrUesThreshInterFMax’ for intra and inter frequency neighbors respectively.
Every time a neighbor cell report is received with only known neighbor cells the
number of ANR reporting UEs is decreased by ‘anrUesEUtraIntraFDecr’ for intra
frequency neighbors and ‘anrUesThreshInterFDecr’. Figure 2-55 illustrate the
important parameters which can be tuned for ANR,
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›
PCI Reporting
cellAddRsrpOffsetEutran
cellAddRsrqOffsetEutran
cellAddRankLimitEutran
Ncell min. power offset
Ncell min. quality offset
Ncell highest rank
anrUesEUtraIntraFMax
anrUesEUtraIntraFMin
anrUesEUtraIntraFDecr
anrUesEUtraIntraFIncrAnr
anrUesEUtraIntraFIncrHo
Max. UEs with ANR thresh.
Min. UEs with ANR thresh.
UE decr. for report with no new PCI
UE incr. for ANR report with new PCI
UE incr. for HO report with new PCI
› CGI Reporting
cellAddRsrpThresholdEutran
cellAddRsrqThresholdEutran
Ncell min. received power in ANR report
Ncell min. received qual. in ANR report
Figure 2-55: Parameters EUTRAN 1(3)
X2BlackList and X2WhiteList should be updated to set list of eNB for X2
update.
› X2 Establishment
x2retryTimerStart = 30s
x2retryTimerMaxAuto = 1440min
Start value for X2 setup retry timer
Max value for X2 setup retry timer
› X2 white/black listing
x2BlackList
x2WhiteList
cannot setup X2 to listed eNB
cannot remove X2 to listed eNB
› HO Permission
hoAllowedEutranPolicy = true
If ANR shall set isHoAllowed=true or
false to new Ncells
Figure 2-56: Parameters 2(3)
‘removeNrelTime’, specifies how long neighbor relations without any
communication to the neighbor cell must remain in the RBS. 1000 means that
automatic removal is not performed. If set to 0, the MO is removed within five
minutes
‘removeNcellTime’, specifies how long neighbor cells without any neighbor
relations must remain in the RBS. 1000 means that automatic removal is not
performed. If set to 0, the MO is removed within five minutes.
‘removeNenbTime’, specifies how long neighbor RBSs without any neighbor
cells must remain in the RBS. 1000 means that automatic removal is not
performed. If set to 0, the MO is removed within five minutes.
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‘isRemoveAllowed’, indicates whether the ANR function is allowed to remove
this MO. It does not restrict operator removal of the MO. MOs created by ANR
have this parameter set to TRUE initially. Figure 2-57 below shows some of
these parameters.
›
›
Removal of Neighbor Objects
removeNrelTime = 30days
›
removeNcellTime = 30days
›
removeNenbTime = 7days
›
isRemoveAllowed = true
EUtranCellRelation
ExternalEUtranCellFDD
› ctrlMode = auto
ExternalENbFunction
Time of inactivity before auto.
Removal
Time with no Nrel before auto.
Removal
Time with no Ncell before auto.
Removal
Auto removal barring
Control state for ANR
ExternalEUtranCellFDD
EUtranCellRelation
TermPointToEnb (X2)
Figure 2-57: Parameters 3(3)
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3.4
Observability
For ANR observability OSS logs, eNodeB logs, ANR related counters and
internal events can be used
› OSS Log
– All changes to objects made by ANR
(creation/deletion/attribute settings)
› Counters
– pmAnrNeighbrelAdd (not active in default scanner)
– pmAnrNeighbrelRem (not active in default scanner)
› Events
– INTERNAL_EVENT_UE_ANR_CONFIG_PCI
– INTERNAL_EVENT_UE_ANR_PCI_REPORT
– INTERNAL_PROC_ANR_CGI_REPORT
– INTERNAL_PROC_X2_CONN_SETUP
– INTERNAL_EVENT_X2_CONN_RELEASE
– INTERNAL_EVENT_NEIGHBENB_CHANGE
– INTERNAL_EVENT_NEIGHBCELL_CHANGE
– INTERNAL_EVENT_NEIGHBREL_ADD
– INTERNAL_EVENT_NEIGHBREL_REMOVE
Figure 2-58: Observability
3.5
ANR Related Counters
When a neighbor relation for a cell is added by the ANR function the
‘pmAnrNeighbrelAdd’ counter is incremented, the ‘pmAnrNeighbrelRem’
isincremented for all neighbor relations removed by the ANR function.
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Following are the ANR related important counters which can be observed for
ANR optimization. As shown in Figure 2-59.
Counter
pmAnrNeighbrelAdd
Description
Number of neighbour relations added by the ANR
function.
Number of neighbour relations removed by the ANR
function.
The counter counts the number of successfully
added EUtran neighbors by the ANR function.
ANR function has added a neighbor Geran cell
relation. The counter is created in OSS from the
event INTERNAL_EVENT_NEIGHBREL_ADD cause
value Geran.
ANR function has added a neighbor Utran cell
relation. The counter is created in OSS from the
event INTERNAL_EVENT_NEIGHBREL_ADD cause
value Utran.
ANR function has deleted a neighbor GERAN cell
relation. The counter is created in OSS from the
event INTERNAL_EVENT_ NEIGHBREL_REMOVE.
ANR function has deleted a neighbor Utran cell
relation. The counter is created in OSS from the
event INTERNAL_EVENT_ NEIGHBREL_REMOVE.
pmAnrNeighbrelRem
pmAnrNeighbrelAddEUtran
pmAnrNeighbrelAddGeran
pmAnrNeighbrelAddUtran
pmAnrNeighbrelDelGeran
pmAnrNeighbrelDelUtran
Figure 2-59: ANR Related Counters
3.6
Self-Organized Network & ANR Features
Important SON/ANR features which can be used for Mobility KPI optimization
are mentioned in Figure 2-60 below
Included Functions:
› Automated Neighbor Relations (Enhanced in L17.Q1)
› Automated Mobility Optimization (Enhanced in L17.Q1)
› Automated RACH Root Sequence Allocation
› Overlaid Cell Detection
› PCI Conflict Reporting
› UE Level Oscillating Handover Minimization
Figure 2-60: Self-Organizing Networks (FAJ 801 0435)
3.7
Automated Neighbour Relation (PCI Conflict Impact)
PCI conflicts can exist in LTE Networks due to the dense deployment of cells
and the limited number of PCI values. While PCI conflicts produce poor
handover performance they also affect the performance of the Automatic
Neighbour Relation (ANR) feature. Figure 2-61 shows an example.
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In this example, there is a PCI conflict between Cell B and Cell C as both are
using PCI 7 on the same frequency.
Cell A has Cell B in the neighbour relations list but not Cell C.
Measurement reports for PCI 7 sent by UEs in Cell A will be assumed to be for
cell B even if it was cell C detected by the UE. This will produce handover
failures for the cell relation between cell A and cell B since cell B will always be
the target cell even when cell C may have been more suitable. Furthermore, the
ANR feature will not be able to add neighbour relation between cell A and cell C
as is it is not using an unknown PCI.
If the ANR problematic cell Policy functionality is enabled, that is the
'problematicCellPolicy' parameter is set to 'AUTO_DETECT' or
'AUTO_DETECT_AND_BAR' the 'hoSuccLevel' read only parameter will show
a 'LOW' or 'MEDIUM' value in the case of PCI conflict.
ManagedElement
+-ENodeBFunction
+-EUtranCellFDD/TDD
+-EUtranFreqRelation
+-EUtranCellRelation = ECGI B
hoSuccLevel = LOW or MEDIUM
+-EUtranCellRelation = ECGI C
+-AnrFunction
pciConflictDetectionEcgiMeas = true
problematicCellPolicy = 1 or 2
1= AUTO_DETECT
2= AUTO_DETECT_AND_BAR
pciConflictMobilityEcgiMeas = true
Neighbour
Relation
eNodeB
Cell A
PCI 9
ECGI A
Cell B
PCI 7
ECGI B eNodeB
PCI Conflict
Cell C
PCI 7
ECGI C
PCI 7
eNodeB
Measurement Report is always assumed to be for Cell B
even if Cell C was detected.
=> Handover failures for Cell A to B relation
=> ANR cannot add cell relation from Cell A to C
Figure 2-61: Automated Neighbour Relation (PCI Conflict Impact)
3.8
Automated Neighbour Relation (PCI Conflict Handling)
The ANR function is enhanced in L17.Q1 to allow it to detect and handle PCI
conflicts. Figure 2-62 shows the example.
To enable ANR to detect PCI conflicts the new 'pciConflictDetectionEcgiMeas'
parameter must be set to 'true' and the existing 'problematicCellPolicy' parameter
set to 'AUTO_DETECT' or 'AUTO_DETECT_AND_BAR'.
With these parameter settings the ANR function will request extra E-UTRAN
Cell Global Identifier (ECGI) measurements for any neighbour relation where the
'hoSuccLevel' read-only parameter is showing 'LOW' or 'MEDIUM'. In this
example we would get a 'LOW' or 'MEDIUM' handover success level for the
EUtranCellRelation from Cell A to B because of the PCI conflict with cell C.
This will mean that extra ECGI measurements will be requested whenever PCI 7
is reported.
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By sending the ECGI the eNodeB will be made aware of the PCI conflict and will
add neighbour relation for the conflicting cell. In this example the UE reports the
ECGI of Cell C and cell relation is added. Since we have two neighbours in cell
A using the same PCI and frequency we now have PCI confusion. Handover
performance will be poor now for both cell relations as UEs will still only report
the PCI.
The 'pciConflictMobilityEcgiMeas' parameter is introduced in L17.Q1 to allow
the Operator to control if ECGI measurements are requested prior to handover, in
case a PCI conflict is detected. In this example setting it to true will mean that
ECGI measurements will be used to support handover between Cell A and B and
Cell A and C even though there is PCI confusion.
ManagedElement
+-ENodeBFunction
+-EUtranCellFDD/TDD
+-EUtranFreqRelation
+-EUtranCellRelation = ECGI B
hoSuccLevel = LOW or MEDIUM
Added
+-EUtranCellRelation = ECGI C
+-AnrFunction
pciConflictDetectionEcgiMeas = true
New
problematicCellPolicy = 1 or 2
1= AUTO_DETECT
2= AUTO_DETECT_AND_BAR
pciConflictMobilityEcgiMeas = true
Neighbour
Relation
eNodeB
Cell A
PCI 9
ECGI A
Cell B
PCI 7
ECGI B eNodeB
PCI Conflict
Cell C
PCI 7
ECGI C
ECGI C
New
eNodeB
Extra ECGI measurements requested for any neighbour relations
where ‘hoSuccLevel’ = ‘LOW’ or ‘MEDIUM’
=> Allows ANR to add neighbour relation
ECGI measurements used to support handover with confusion
Figure 2-62: Automated Neighbour Relation (PCI Conflict Handling)
3.9
Automated Neighbour Relation (PCI Conflict Detection
DRX)
The new ‘AnrPciConflictDrxProfile’ Managed Object Class is introduced in
L17.Q1 to allow the Operator to configure the DRX profile used by UEs to read
the ECGI for ANR PCI conflict detection.
The ‘anrPciConflictDrxInactivityTimer’ parameter sets the number of
consecutive PDCCH subframes after successfully decoding a PDCCH that
indicates an initial UL or DL user data transmission for this UE.
The ‘anrPciConflictLongDrxCycle’ parameter indicates the duration of the long
DRX cycle in subframes and the ‘anrPciConflictOnDurationTimer’ parameter
sets the number of consecutive PDCCH subframes at DRX Cycle initialization.
UEs requested to make ECGI measurements for ANR PCI Conflict Detection
will follow this DRX profile.Figure 2-63 shows the example of ANR PCI conflict
detection DRX.
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ManagedElement
+-ENodeBFunction
+-AnrPciConflictDrxProfile New MO
anrPciConflictDrxInactivityTimer = PSF2
anrPciConflictLongDrxCycle = SF320
anrPciConflictOnDurationTimer = PSF1
eNodeB
1, 2, 3, 4, 5, 6, 8, 10, 20, 30, 40, 50, 60, 80, 100, 200, 300,
500, 750, 1280, 1920, 2560 or 0 PDCCH Sub-Frames
Default = PSF2 (2 PDCCH Sub-Frames)
10, 20, 32, 40, 64, 80, 128, 160, 256, 320, 512,
640, 1024, 1280, 2048 or 2560 Sub-Frames.
Default = SF320 (320 Sub-Frames)
1, 2, 3, 4, 5, 6, 8, 10, 20, 30, 40, 50, 60, 80, 100
or 200 PDCCH Sub-Frames
Default = PSF1 (1 PDCCH Sub-Frame)
anrPciConflictDrxInactivityTimer
Receiver ON
anrPciConflictLongDrxCycle
ECGI
Receiver OFF
anrPciConflictOnDurationTime
r
anrPciConflictOnDurationTimer
Figure 2-63: Automated Neighbour Relation (PCI Conflict Detection DRX)
3.10
Automated Mobility Optimization (Coordination with ANR)
The Automated Neighbour Relation (ANR) function removes neighbour relations where
no reports have been received for the time specified by the 'removeNrelTime' parameter.
By changing the cell individual offset the Automated Mobility Optimization (AMO)
function will impact when and if a UE moves to that cell. This can lead to the cell being
no longer reported resulting in removal of the cell relation by the ANR function. Once
the neighbour relation is removed the AMO function will reset the cell individual offsets
for the cell and UEs will start to report it again. Once enough reports are received the
neighbour relation will be created again by ANR. This creates the cycle of adding,
optimizing and then later removing the relation illustrated here.
Coordination between the AMO and ANR functions is introduced in L17.Q1 to
avoid this cycle.
If no reports are received for a neighbour relation in the time specified by the
'removeNrelTime' parameter, the AMO function is operable and a cell individual
offset less than 0 is used the AMO function will reduce the absolute value of the
cell individual offset by 1. This should make it more likely that UEs will report
the cell and avoid the neighbour relation being removed by the ANR function.
In L17.Q1 if the AMO function is 'OPERABLE' and the 'amoState' read-only
parameter is set to 'ENABLED' the AMO function can prevent the ANR function
from moving a 'EUtranCellRelation' Managed Object to the candidate cell
relations or deleting a 'EUtranCellRelation' Managed Object when certain
conditions are fulfilled. When the legacy conditions are fulfilled for moving a
'EUtranCellRelation' Managed Object to a candidate cell relation the L17.Q1
enhancement will prevent it from being moved if the cell individual offset is not
equal to 0. Also when the legacy conditions are fulfilled for deleting a
'EUtranCellRelation' Managed Object the L17.Q1 enhancement will prevent it
from being deleted if the cell individual offset is less than 0. This will give the
AMO function more time to work on these neighbour relations. Figure 2-64.
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After L17.Q1
ANR
removes
relation
Neighbo
r with
no
reports
Bad
Neighbor
Cell
With bad
HO stat
AMO
adjusts
Cell
Individual
Offset
Cycle of adding, optimizing and then
later removing neighbour relation
Candidate list (256)
ANR
creates
Relation
Legacy conditions fulfilled for
moving to Candidate list
EXCEPT where Cell
Individual Offset ≠ 0
When AMO function is
OPERABLE and
‘amoState’ =
‘ENABLED’
Coordination between AMO
and ANR avoids cycle
Legacy conditions
fulfilled for moving to
EUtranCellRelation
Delete EUtranCellRelation (128)
Before L17.Q1
ANR
creates
Relation
If Cell
Individual
Offset < 0
reduce
absolute
value by 1
Legacy conditions
fulfilled for deletion
EXCEPT where Cell
Individual Offset < 0
Neighbo
r with no
reports
Bad
Neighbor
Cell
With bad
HO stat
AMO
adjusts
Cell
Individual
Offset
Figure 2-64: Automated Mobility Optimization (Coordination with ANR)
4
CS FALLBACK
CS Fallback function in EPS enables the provisioning of the CS services when
the UE is served by E-UTRAN. A CS Fallback enabled terminal connected to EUTRAN can use GERAN or UTRAN to connect to the CS domain. There is also
CS Fallback to CDMA2000.
The parameters ‘csFallbackPrio’ for UTRAn, GERAN and CDMA2000 provide
the priority for a GERAN/UTRAN/CDMA2000 frequency group at CS fallback
of an emergency call. Priority levels -1 to 7 are defined where 7 is the highest
priority
The parameters ‘csFallbackPrioEc’ for UTRAn, GERAN and CDMA2000
provide the priority for a GERAN/UTRAN/CDMA2000 frequency group at CS
fallback of an emergency call. Priority levels -1 to 7 are defined where 7 is the
highest priority. The value -1 means the the frequency is excluded.
The parameters ‘altCsfbTargetPrioEc’ in ‘GeranFreqGroupRelation’ MO and in
‘UtranFreqRelation’ MO provide the GERAN/UTRAN frequency group for
emergency calls among all frequencies related to the cell for UEs in connected
mode.
Figure 2-65 shows important MO class and parameters to be tuned, for CSFB.
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Lte
CSFB TO WCDMA
WCDMA
MO Class Name
UtranFreqRelation
UtranFreqRelation
MO_Value
10713
10713
UtranFreqRelation
mobilityActionCsfb
CsfbToGeranUtr
an
featureState
rimCapable
OptionalFeatureLicense
ExternalUtranCellFDD
Parameter Name
csFallbackPrio
csFallbackPrioEC
Recommendation
4
4
1
(RELEASE_WITH_REDIRECT_N
ACC)
1 (ACTIVATED)
0 (RIM_CAPABLE)
Figure 2-65: CSFB
4.1
CSFB Related Features
The important CSFB related features are mentioned in Figure 2-66.
Feature
Number
Feature Name
FAJ 121 0856
CS Fallback for GSM and WCDMA
LTE
FAJ 121 0921
Emergency Call Handling for CS Fallback
LTE
FAJ 121 0876
Redirect with System Information
LTE
FAJ 121 0495
GERAN Session continuity, covered triggered
LTE
FAJ 121 0493
WCDMA Session continuity, covered triggered
LTE
FAJ 121 1474
LTE Cell Reselection
WCDMA
FAJ 121 1610 R1
CS Fallback from LTE
WCDMA
FAJ 121 1610 R2
CS Fallback from LTE – DMCR
WCDMA
FAJ 121 2179
RIM Support for System Information transfer to LTE
WCDMA
FAJ 121 2174
Release With Redirect to LTE
WCDMA
FAJ 121 155
GSM-LTE Cell Reselection
GSM
FAJ 121 1872
LTE to GSM NACC
GSM
FAJ 121 1873
Fast return to LTE after call release
GSM
Optional
Figure 2-66: CSFB – Radio feature list
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Important CSFB related KPIs are shown in Figure 2-67. An example from a
network shows the values of the KPIs.
CSFB call setup success rate=received Alerting times/ sponsored extended
service request times*100
CSFB Call setup time: Extended service request->Alerting
Reselection time back to LTE: Disconnect->Tracking area update request.
Related KPI in a Project:
› CSFB call setup success rate=received Alerting times/ sponsored
Extended service request times*100
› CSFB Call setup time: Extended service request->Alerting
› Reselection time back to LTE: Disconnect->Tracking area update
request.
Figure 2-67: KPI Definition Example
4.2
CSFB Cases for long CALL SETUP TIME
Below Figure 2-68 shows 4 cases for longer setup time because of different
reasons and CSFB failure in a project (CSFB call setup time>9.5s).
Below are 4 cases for longer setup time because of different
reasons and CSFB failure in Project( CSFB call setup
time>9.5s):
1. Core network respond with long time
2. Cell reselection
3. Multi RRC Request
4. RSCP and Ec/No continual bad due to long distance from
server site
Figure 2-68: CSFB Cases for long CALL SETUP TIME
4.3
Case 1: CSFB CALL SETUP TIME due to Core Signaling
According to the signaling shown in Figure 2-69, it takes about 9.8 seconds
waiting for CN to response. The core network time is more than expected.
Recommend to investigate Core Network side.
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According to the signaling it takes about 9.8 seconds waiting for CN
to response. Recommend to investigate Core Network side.
Figure 2-69: CSFB Case 1: Longer setup time due to Core Network signaling
4.4
CSFB failure due to long Cell reselection time
According to the signaling, Figure 2-70, it takes about 5.5 seconds waiting for
CN to respond. Recommend to investigate Core Network side. CSFB call setup
failure due to cell reselection, which consumes nearly 7.3 seconds to get access to
3G and call proceeding, need to check reselection criteria, reselection CSFB
priorities and WCDMA dominance cell in the area.
According to the signaling it takes about 5.5 seconds waiting for CN to respond.
Recommend to investigate Core Network side.
CSFB call setup failure due to cell reselection, which consumes nearly 7.3
seconds to get access to 3G and call proceeding
Start -- 11:26:22.866
7.3seconds
Proceeding – 11:26:30:171
5.5 seconds
CN Responding – 11:26:35:677
Figure 2-70: CSFB Case 1: CSFB failure due to long Cell reselection time
4.5
SIB reading during Cell reselection
UE took 5.7 to read SIB due to cell reselection. Normally reading SIB time is
0.1-0.3s, Figure 2-71 shows the traces.
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Start -- 11:26:23.171
5.7seconds to Read SIB
End – 11:26:28:872
› UE took 5.7 to read SIB
due to cell reselection.
Normally reading SIB
time is 0.1-0.3s
Figure 2-71: CSFB Case 1: SIB reading during Cell reselection
4.6
Failure due to Multiple RRC connection Request
CSFB call setup failure due to Multi RRC Request, which consumes nearly 6.2
seconds to get access to 3G and call proceeding, authentication in WCDMA
network is also happening during CSFB process. Figure 2-72 shows the time
taken.
CSFB call setup failure due to Multi RRC Request, which consumes
nearly 6.2 seconds to get access to 3G and call proceeding
Figure 2-72: CSFB Case 1: Failure due to Multiple RRC connection Request
4.7
Failure due to Multiple RRC connection Request
UE sent 3 times RRC Connection Request. This process took long time as shown
in Figure 2-73.
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First RRC -- 12:20:18.047
2.1seconds
Second RRC – 12:20:20:155
2.0seconds
Third RRC –
12:20:22:154
0.4seconds
RRC Completed –
12:20:22:552
› UE sent 3 times RRC
CONNECTION REQUEST.
This process took long time
Figure 2-73: CSFB Case 1: Failure due to Multiple RRC connection Request
4.8
Failure due to Bad UTRAN Coverage
It takes about 7.3s from Extend service request to call proceeding, from the
message view, Ec/No continual bad due to long distance from server site. It takes
about 4.1s for CN respond, recommended to investigate CN side, detail shown in
CSFB Call setup time（Top 4）
Figure 2-74.
1. It takes about 7.3s from Extend service request to call proceeding
2. From the message view, Ec/No continual bad due to long distance
from server site.
3. It takes about 4.1s for CN respond, recommend to investigate CN side.
Start
13.3s
Waiting
CN
4.1s
End
Call#
EXTENDED_SERVICE_REQUEST->CM
Service Request
CM_Service_RequestSETUP>SETUP
>Call_PROCEEDING
Call_PROCEEDING>ALERTING
Total
0:00:04.1
17.899
4
0:00:01.5
0:00:11.5
0:00:00.3
Figure 2-74: CSFB Case 1: Failure due to Bad UTRAN Coverage
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4.9
Case 2: UE Fail to Return to LTE After CSFB to UTRAN
Problem: A customer reports that the UE fail’ to return to LTE after CSFB to
UTRAN customer provide TEMS log to show that UE remained camped in
UTRAN cell. Figure 2-75 shows the traces. Need to interpret the logs, inorder to
analyze the issue.
› Problem: customer reports that UE fail to return to LTE after CSFB to UTRAN
› Customer provide TEMs log to show that UE remained camped in UTRAN cell
Figure 2-75: Case 2: UE Fail to Return to LTE After CSFB to UTRAN
4.9.1
Case 2: UE Fail to Return to LTE After CSFB to UTRAN
› Facts:
– Successful CSFB to UTRAN Cell
– Need to check if eUTRAN Cell prior is higher than UTRAN Cell
OFFLINE_L1M_0655> get . cellReselectionPriority
========================================================================================================
=========
MO
Attribute
Value
========================================================================================================
=========
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10838_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655A, EUtranFreqRelation=1691
cellReselectionPriority 6
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10588
cellReselectioPriority 4
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10563
cellReselectionPriority 4
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10813_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10788_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655A, UtranFreqRelation=3011_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10838_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, EUtranFreqRelation=1691
cellReselectionPriority 6
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10588
cellReselectionPriority 4
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10563
cellReselectionPriority 4
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10813_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10788_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, UtranFreqRelation=3011_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, EUtranFreqRelation=1691
cellReselectionPriority 6
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10838_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10588
cellReselectionPriority 4
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10563
cellReselectionPriority 4
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10813_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10788_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, UtranFreqRelation=3011_TME
cellReselectionPriority 2
Figure 2-76: Case 2: UE Fail to Return to LTE After CSFB to UTRAN
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The UE did successful CSFB to UTRAN Cell, but fails to return back to LTE,
Need to check if eUTRAN Cell priority is higher than UTRAN Cell, LTE priority
should be higher than WCDMA. Figure 2-76 shows ’get’ command printout for
cellreselection priority.
4.9.2
Case 2: UE Fail to Return to LTE After CSFB to UTRAN
Investigation need to be performed OSS reports, UE specific trace, eNB cell
trace, check configuration. Adjust eUTRAN cell priority to be higher than
UTRAN cell priority. It is discussed in Figure 2-77.
› Investigation: OSS reports, UE specific trace, eNB cell trace, Check Configuration
› Adjust eUTRAN Cell Priority to be Higher than UTRAN Cell Priority
OFFLINE_L1M_0655> get . cellReselectionPriority
==================================================================================================
===============
MO
Attribute
Value
==================================================================================================
===============
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10838_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655A, EUtranFreqRelation=1691
cellReselectionPriority 6
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10588
cellReselectionPriority 4
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10563
cellReselectionPriority 4
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10813_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655A, UtranFreqRelation=10788_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655A, UtranFreqRelation=3011_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10838_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, EUtranFreqRelation=1691
cellReselectionPriority 6
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10588
cellReselectionPriority 4
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10563
cellReselectionPriority 4
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10813_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, UtranFreqRelation=10788_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655B, UtranFreqRelation=3011_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, EUtranFreqRelation=1691
cellReselectionPriority 6
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10838_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10588
cellReselectionPriority 4
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10563
cellReselectionPriority 4
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10813_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, UtranFreqRelation=10788_TME
cellReselectionPriority 2
EUtranCellFDD=L1M_0655C, UtranFreqRelation=3011_TME
cellReselectionPriority 2
Figure 2-77: Case 2: UE Fail to Return to LTE After CSFB to UTRAN Answer
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4.10
Case 3: UE took more time when return back to LTE NW1
In some networks the return time to LTE after a CS call finished in WCDMA was
analyzed, the KPI was not meeting, when compared with other networks. The
UE took more time to return to LTE in the network 1 than the other two
networks, the message trace for 3 networks is shown in Figure 2-78, Figure 2-79
& Figure 2-80 respectably. UE took more time in first network ‘NW1’ as shown
in Figure 2-78 compared with other 2 networks ‘NW2’ and ‘NW3’ shown in later
figures. This is an exercise for participants to see 3 traces and find the difference
in message trace in the figures.
Figure 2-78: Case 3: UE took more time when return back to LTE NW1
Figure 2-79: Case 3: UE took more time when return back to LTE NW2
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UE took less time in network-3, Figure 2-80 below, as compare to network-1.
Let’s analyze the trace.
Figure 2-80: Case 3: UE took more time when return back to LTE NW3
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5
Summary
The participants should now be able to:
2
2.1
2.2
2.3
2.4
Analyze KPI issues analysis, investigations and case studies for
mobility
Explain cases and investigation for different HOSR degradation
and improvements
Analyze some cases for CSFB degradation and solutions
Investigate ANR related major issues and solutions
Discuss different offline data and cases, for degradation
analysis
Figure 2-81: Summary of Chapter 2
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LTE Integrity KPIs Performance and related Parameters
3 LTE Integrity KPIs Performance and related
Parameters
Objectives
After completion of this chapter the participants will be
able to:
3
3.1
3.2
3.3
3.4
3.5
3.6
Explain LTE Integrity KPIs performance and related parameters.
Describe different LTE integrity KPIs & counters related to
Throughput, Latency
Explain associated parameters related to different Integrity KPIs
Relate QOS and Scheduling profile for integrity optimization
Analyze steps to effectible troubleshoot throughput issues
Explore related features and associated parameters for
throughput enhancement
Measure VOLTE effect on throughput and data services KPIs
Figure 3-1: Objective of Chapter 3
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Introduction
1
EUTRAN Integrity is a measure of the Network’s ability to provide wireless enduser services with end-user performance quality that meets expectations. This
Integrity performance can be divided into the three parts listed below:
•
EUTRAN Throughput:
The speed at which packets can be transferred once the first
packet has been scheduled on the air interface.
•
EUTRAN Latency:
The time it takes to schedule the first packet on the air
interface, determined from the time it was received in RBS.
•
EUTRAN Packet Loss:
The ratio of lost and transferred packets.
This chapter starts with a review on integrity KPIs, their formulas and associated
counters will be discussed first, post which, the main focus is intended to be on
optimization steps, associated parameters and features, which are important for
integrity, mainly throughput KPI will be discussed.
1.1
Average UE Downlink Throughput
The average UE downlink throughput KPI formula is illustrated in Figure 3-2
below.
The speed at which packets can be
transferred once the first packet has
been scheduled on the air interface.
Average UE DL Throughput [kbps]:
=
pmPdcpVolDlDrb + pmPdcpVolDlDrbTransUm – S Qci pmPdcpVolDlDrbLastTTIQci
pmUeThpTimeDl/1000
Figure 3-2: Review: EUTRAN Throughput KPIs
The average UE downlink throughput per QCI for unacknowledged mode RLC
and Acknowledged mode RLC KPI is illustrated in Figure 3-3.
For cases where ‘pmUeThpTimeDl’ is small and / or where ‘pmPdcpVolDlDrb’
is similar magnitude to ‘pmPdcpVolDlDrbLastTti’ (causing a small numerator
from two large values).
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Total DL PDCP UE Throughput shown in Figure 3-3.
The speed at which packets can be
transferred once the first packet has
been scheduled on the air interface.
Average UE DL Throughput per Qci (unacknowledged mode RLC) [kbps]:
=
pmPdcpVolDlDrbTransQci – pmPdcpVolDlDrbLastTTIQci
pmDrbThpTimeDlQci/1000
Average UE DL Throughput per Qci (acknowledged mode RLC) [kbps]:
=
pmPdcpVolDlDrbQci – pmPdcpVolDlDrbLastTTIQci
pmDrbThpTimeDlQci/1000
Figure 3-3: Review: EUTRAN Throughput KPIs
1.1.1
Downlink DRB Traffic Volume
The counters used to measure the downlink DRB throughput are illustrated in
Figure 3-4 below.
The last TTI with
data is removed
since coding may
be based on size
rather than radio
conditions and
hence does not
impact the end
user.
Traffic Volume Measured by:
pmPdcpVolDlDrbLastTTI
Traffic Volume Measured by:
pmPdcpVolDlDrbTransUm
Traffic Volume Measured by:
pmPdcpVolDlDrb
DL Transport Time measured by:
pmUeThpTimeDl
Data arrives to
empty DL buffer
First data is
transmitted to the UE
No transmission, buffer not empty
(e.g. due to contention)
Failed transmission
(Block Error)
Successful transmission by AM
RLC, buffer not empty
Transmission by UM RLC
Time (ms)
Successful
transmission
by AM RLC,
buffer empty
Figure 3-4: Review: DL DRB Traffic Volume Measurement
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The total DRB traffic volume carried by Acknowledged Mode (AM) RLC that
has been transferred and acknowledged by the UE in the downlink direction is
measured at the PDCP layer using the ‘pmPdcpVolDlDrb’ ACC counter. The
‘pmPdcpVolDlDrbTransUm’ ACC counter measures the DRB traffic transmitted
by the RBS using Unacknowledged Mode (UM) RLC.
The downlink DRB traffic volume in the last Transmission Time Interval (TTI)
of each packet session is also measured with the ‘pmPdcpVolDlDrbLastTTI’
counter as illustrated in Figure 3-4. This extra measurement is necessary since
the coding in the last TTI when the buffer is being emptied may be selected based
on size and not the radio conditions, hence the throughput in this last TTI will not
impact the end user.
The DL Transport Time is measured by the ‘pmUeThpTimeDl’ ACC counter
comprises those periods from when the first part of the PDCP SDU of the DL
buffer was transmitted on Uu until the buffer is emptied, excluding the TTI
emptying the buffer.
The details of the downlink DRB throughput counters are given in Figure 3-5
below.
Counter Name
pmPdcpVolDlDrb
pmPdcpVolDlDrbLastTTIQci
pmPdcpVolDlDrbTransUm
pmUeThpTimeDl
Managed
Object
Description
Counter
Type
EutranCellFDD
The total volume (PDCP SDU) on Data Radio Bearers that has been
transferred (acknowledged by the UE) in the downlink direction.
Continuous measurement for DRBs aggregated to cell level.
Unit: kilobit (1 000 bits)
ACC
EutranCellFDD
The total transmitted DL PDCP SDU volume per QCI that are
included in the last data transmission in a data burst which is large
enough to be transmitted across several TTIs.
The bin accumulates the transmitted DL PDCP SDU volume per QCI
that are included in the last data transmission in a data burst which is
large enough to be transmitted across several TTIs.
PDF
EutranCellFDD
The total volume (PDCP SDU) on Data Radio Bearers for RLC UM
that has been transmitted in the downlink direction in the PDCP layer.
This is a continuous measurement after Robust Header Compression ACC
for DRBs aggregated to cell level
Unit: kilobit (1 000 bits)
EutranCellFDD
The effective DL transport time comprises those periods from when
the first part of the PDCP SDU of the DL buffer was transmitted on
Uu until the buffer is emptied, excluding the TTI emptying the buffer
This is a continuous measurement for UEs aggregated to cell level.
Unit: ms
ACC
Figure 3-5: Review: DL DRB Traffic Volume Counters
Note: Also valid for EutranCellTDD
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The counters illustrated in Figure 3-5 are reset at the end of each ROP and
collected by the Primary scanner on the RBS. Further counters used by DRB
Throughput are described in Figure 3-6.
Counter Name
Managed
Object
Description
Counter
Type
pmPdcpVolDlDrbTransQci
EutranCellFDD
The total volume (PDCP SDU) on Data Radio Bearers that has been
transmitted in the downlink direction in the PDCP layer per QCI.
Continuous measurement after Robust Header Compression for
DRBs aggregated to cell level.
PDF
pmPdcpVolDlDrbQci
EutranCellFDD
The total volume (PDCP SDU) that has been transferred
(acknowledged by the UE) on Data Radio Bearers in the downlink
direction per QCI.
The counter accumulates acknowledged DL PDCP volume per QCI.
PDF
EutranCellFDD
The DL transmission time used for DL DRB Throughput per QCI. It
comprises of time periods from when the first piece of data in a data
burst is transmitted until the second last piece of data in the data burst
PDF
is transmitted.
The bin accumulates the DL transmission time per QCI for each large
data burst that needs to be transmitted across multiple TTIs.
pmDrbThpTimeDlQci
Figure 3-6: Review: DL DRB Traffic Volume Counters
1.1.2
Average
UEforUplink
Throughput
Note: Also valid
EutranCellTDD
The Average UE Uplink Throughput KPI formula is illustrated in Figure 3-7.
The speed at which packets can be
transferred once the first packet has
been scheduled on the air interface.
Average UE UL Throughput [kbps]:
=
pmUeThpVolUl
pmUeThpTimeUl/1000
Average UE UL Throughput per LCG [kbps]:
=
pmLcgThpVolUlLcg
pmLcgThpTimeUlLcg/1000
Figure 3-7: Review: EUTRAN Throughput KPIs
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1.1.3
Uplink DRB Traffic Volume
The counters used to measure the uplink DRB throughput are illustrated in Figure
3-8 below.
Traffic Volume Measured by:
pmUeThpVolUl
Contributions
from the first 4
and last TTI
removed
UL Transport Time measured by:
pmUeThpTimeUl
Data arrives to
empty UL buffer
Grants sent
to the UE
Secheduling request sent to RBS
Time (ms)
First data sent to RBS
Send buffer is empty again
No receptions, buffer not empty
(e.g. due to contention)
Failed receptions
(Block Error)
Successful receptions, buffer not
empty
Receptions excluded from
throughput measurement
Successful
reception,
buffer empty
Figure 3-8: Review: UL DRB Traffic Volume Measurement
Due to the time difference in the scheduling decision by RBS and the
transmission time by the UE the first four receptions are excluded from the DRB
traffic volume measurement. The contribution from the last TTI is also removed
since the coding when the buffer is being emptied may be selected based on size
and not the radio conditions, hence the throughput in this last TTI will not impact
the end user. The details of the uplink DRB throughput counters are given in
Figure 3-9 below.
Counter Name
pmUeThpVolUl
pmUeThpTimeUl
pmLcgThpVolUlLcg
pmLcgThpTimeUlLcg
Managed
Object
Description
Counter
Type
EutranCellFDD
The UL volume used for UL UE Throughput. It comprises of the
MAC SDU volume received on Uu, excluding the volume received in
the first 4 data receptions of an UL buffer transfer and the TTI
ACC
emptying the UL buffer.
This is a continuous measurement for UEs aggregated to cell level.
Unit: kilobit (1 000 bits)
EutranCellFDD
The effective UL transport time comprises those periods from when
the first part of the PDCP SDU of the UL buffer was received on Uu
until the buffer is emptied, excluding the TTI emptying the buffer.
This is a continuous measurement for UEs aggregated to cell level.
Unit: ms
ACC
EutranCellFDD
The UL volume used for UL DRB Throughput per LCG. It comprises
of the MAC SDU volume received on Uu per LCG, excluding the
volume received in the first 4 data transmissions and the data
transmission emptying the UL buffer.
The bin accumulates the UL volume per LCG for large data bursts
that needs to be transmitted across multiple TTIs
PDF
EutranCellFDD
The UL transmission time used for UL DRB Throughput per LCG. It
comprises of time periods from when the 5th data transmission is
received on Uu until the second last data transmission is received.
The bin accumulates the UL transmission time per LCG for large
data bursts that need to be transmitted across multiple TTIs.
PDF
Note: Also valid for EutranCellTDD
Figure 3-9: Review: UL DRB Traffic Volume Counters
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The counters illustrated in Figure 3-9 are reset at the end of each ROP and
collected by the Primary scanner on the RBS.
1.1.4
EUTRAN Latency KPIs
The EUTRAN Latency KPIs formulas are illustrated in Figure 3-10 below.
The time it takes to schedule the first
packet on the air interface, determined
from the time it was received in RBS.
Downlink Average Latency [ms]:
=
pmPdcpLatTimeDl
pmPdcpLatPktTransDl
Downlink Average Latency per QCI [ms]:
=
pmPdcpLatTimeDlQci
pmPdcpLatPktTransDlQci
Uplink Latency not measured
Figure 3-10: Review: EUTRAN Latency KPIs
As illustrated in Figure 3-10 above, there is a KPI formula for overall average
downlink latency and one to measure the average latency for each QCI value.
The Uplink DRB Latency is not measured in LTE RAN.
The ‘pmPdcpLatPktTransDl’ and ‘pmPdcpLatPktTransDlQci’ counters count the
number of packets that are used for downlink latency measurement. The latency
is measured in msec by the ‘pmPdcpLatTimeDl’ and ‘pmPdcpLatTimeDlQci’
counters as illustrated in Figure 3-11.
Packet forwarding during handover may mean that the target cell has to buffer
data before it is possible to schedule the UE. For this reason, samples during
handover are excluded from the latency counters as this would give a distorted
interpretation of the actual latency experienced by the end user, which is not
affected by packet forwarding.
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The latency Example is illustrated in Figure 3-11
PDCP SDU arrival
Samples
during
Handover
excluded
No
Buffer empty?
No receptions, buffer not empty
(e.g. due to contention)
Successful receptions, buffer not
empty
Yes
Note: Corresponding counter per QCI:
pmPdcpLatPktTransDlQci+
t=t0
pmPdcpLatPktTransDl +
No
Packet sent on
Uu?
Yes
Data arrives to
empty DL buffer
First data is
transmitted to the UE
t=t1
t1 – t0
pmPdcpLatTimeDl +
aggregated t = (t1 – t0)
Note: Corresponding counter per QCI:
pmPdcpLatTimeDlQci+
End
Figure 3-11: Review: Downlink Latency Measurement
The details of the downlink latency counters are given in Figure 3-12 below.
Counter Name
pmPdcpLatTimeDl
pmPdcpLatPktTransDl
pmPdcpLatTimeDlQci
pmPdcpLatPktTransDlQci
Managed Object
Description
Counter
Type
EutranCellFDD
Aggregated DL Latency for a measurement period. The effective
DL Latency time comprises the time from PDCP SDU entering
the buffer until the first data has been transmitted to the UE.
This measurement for UEs aggregated to cell level and only
PDCP SDUs that enter an empty buffer are measured.
Unit: msec
ACC
EutranCellFDD
Number of packets for downlink Latency measurements during
measurement period.
This measurement for UEs aggregated to cell level and only
PDCP SDUs that enter an empty buffer are measured.
PEG
EutranCellFDD
Aggregated DL Latency for a measurement period per QCI.
The effective DL Latency time comprises the time from PDCP
SDU entering the buffer until the first data has been transmitted to
the UE. Only latency for PDCP SDUs that enters an empty buffer
is measured.
Unit: msec
PDF
EutranCellFDD
Number of samples for DL Latency measurements during
measurement period per QCI.
This counter registers the number of samples for DL Latency
measurements during measurement period per QCI.
PDF
Figure 3-12: Downlink Latency Counters
The counters illustrated in Figure 3-12 above are reset at the end of each ROP
but only the ‘pmPdcpLatTimeDl’ and ‘pmPdcpLatPktTransDl’ counters are
collected by the Primary scanner on the RBS.
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1.1.5
EUTRAN Packet Loss KPIs
The EUTRAN Packet Loss KPI formulas are illustrated in Figure 3-13 below.
EUTRAN Packet Loss KPIs
The ratio of lost and transferred packets.
Downlink Packet Error Loss Rate [%]:
=
pmPdcpPktDiscDlPelr + pmPdcpPktDiscDlPelrUu + pmPdcpPktDiscDlHo + A
pmPdcpPktReceivedDl – pmPdcpPktFwdDl + A
Where A = (pmPdcpPktDiscDlEth + pmPdcpPktDiscDlNoUeCtxt) x
X100
pmPdcpPktReceivedDl
∑ pmPdcpPktReceivedDl
RBS
Uplink Packet Loss Rate [%]:
pmPdcpPktLostUl
=
pmPdcpPktLostUl + pmPdcpPktReceivedUl
X100
Figure 3-13: EUTRAN Packet Loss KPIs
Total number of packets (PDCP SDUs) received in PDCP buffer in the RBS from
the SGW is counted by the ‘pmPdcpPktReceivedDl’ counter. The number of
these for which no part has been transmitted over the air interface in the downlink
direction that are discarded in the PDCP layer due to reasons other than handover
is counted with the ‘pmPdcpPktDiscDlPelr’ counter. Those which at least a part
has been transmitted over the air interface in the downlink direction but not
positively acknowledged, and it was decided that no more transmission attempts
will be done, due to reasons other than handover is counted with the
‘pmPdcpPktDiscDlPelrUu’ counter. Those lost due to Handover are counted
with the ‘pmPdcpPktDiscDlHo’ counter.
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The Downlink Packet Error Loss Rate per QCI and the Uplink Packet Loss Rate
are illustrated in Figure 3-14.
EUTRAN Packet Loss KPIs
The ratio of lost and transferred packets.
Downlink Packet Error Loss Rate per Qci [%]:
=
pmPdcpPktDiscDlPelrQci + pmPdcpPktDiscDlPelrUuQci + pmPdcpPktDiscDlHoQci + B
X100
pmPdcpPktDiscDlPelrQci + pmPdcpPktDiscDlPelrUuQci + pmPdcpPktDiscDlHoQci + B + pmPdcpPktTransDlQci
B= [pmPdcpPktDiscDlEth + pmPdcpPktDiscDlNoUeCtxt] X
pmPdcpPktReceivedDlQci
∑ pmPdcpPktReceivedDlQci
RBS
Uplink Packet Loss Rate per Qci [%]:
pmPdcpPktLostUlQci
=
pmPdcpPktLostUlQci + pmPdcpPktReceivedUlQci
X100
Figure 3-14: EUTRAN Packet Loss KPIs
The total number of DRB packets (PDCP SDUs) forwarded to target cell at
handover for downlink sessions is counted with the ‘pmPdcpPktFwdDl’.
Total number of downlink DRB packets (PDCP SDUs) discarded in the Ethernet
part of the RBS are counted with the ‘pmPdcpPktDiscDlEth’ counter. It should
be noted that this is a baseband processor resource level counter unlike almost all
others that are cell level.
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The counters used to measure downlink packet loss are illustrated in Figure 3-15.
Only partially transmitted over air
interface due to reasons other than HO:
pmPdcpPktDiscDlPelrUu
No part transmitted over air interface
due to reasons other than HO:
pmPdcpPktDiscDlPelr
Total packets (PDCP SDUs) received
in the PDCP layer in the RBS:
pmPdcpPktReceivedDl
SGW
Lost due to HO:
pmPdcpPktDiscDlHo
Discarded in Ethernet part of RBS:
pmPdcpPktDiscDlEth
(NOTE baseband processor level
counter)
Forwarded to target cell at HO:
pmPdcpPktFwdDl
Figure 3-15: Downlink Packet Loss Measurement
Total packets received in the UL:
pmPdcpPktReceivedUl
Total packets lost in the UL:
pmPdcpPktLostUl
Figure 3-16: Uplink Packet Loss Measurement
The total number of packets lost in the uplink direction is counted with the
‘pmPdcpPktLostUl’ counter and the total number successfully received packets
with the ‘pmPdcpPktReceivedUl’ counter as illustrated in Figure 3-16 above.
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The details of the counters used in the Packet Loss KPI formulas are given in
Figure 3-17 below.
Counter Name
Managed Object
Description
Counter
Type
pmPdcpPktReceivedDl
EutranCellFDD
Total number of packets (PDCP SDUs) received in PDCP in the
RBS in the downlink direction.
ACC
pmPdcpPktDiscDlPelr
EutranCellFDD
Total number of DRB packets (PDCP SDUs) for which no part has
been transmitted over the air in the downlink that are discarded due
to reasons other than handover or active queue management.
ACC
pmPdcpPktDiscDlPelrUu EutranCellFDD
Total number of packets (PDCP SDUs) for which at least a part has
been transmitted over the air in the downlink direction but not
positively acknowledged, and it was decided that no more
transmission attempts will be done, due to reasons other than
handover. Only applicable to DRB packets.
ACC
pmPdcpPktFwdDl
EutranCellFDD
Total number of DRB packets (PDCP SDUs) forwarded to target
cell at handover for downlink sessions.
Packet forwarding is started when the source cell transmits the
RRCConnectionReconfiguration message and ends when it
receives the end marker or UE Context Release from the target cell.
ACC
pmPdcpPktDiscDlEth
BbProcessingResource
Total number of downlink DRB packets (PDCP SDUs) discarded in
ACC
the Ethernet part of the RBS.
pmPdcpPktReceivedUl
EutranCellFDD
Total number of packets (PDCP SDUs) received in the uplink
direction.
ACC
pmPdcpPktLostUl
EutranCellFDD
Total number of packets (PDCP SDUs) lost in the uplink direction.
ACC
Figure 3-17: Packet Loss Counters
The counters illustrated in Figure 3-17 above are reset at the end of each ROP
and all but the ‘pmPdcpPktFwdDl’ counter is collected by the Primary scanner on
the RBS.
Counter Name
Managed Object
Description
Counter
Type
pmPdcpPktDiscDlPelrQci
EutranCellFDD
Total number of DL packets (PDCP SDUs) per QCI that are
discarded in the PDCP layer due to reasons other than
handover or active queue management. No part of these
packets has been transmitted over the air.
PDF
pmPdcpPktDiscPelrUuQci
EutranCellFDD
Total number of DL packets (PDCP SDUs) per QCI for which
at least a part has been transmitted over the air but not
positively acknowledged due to reasons other than handover,
and it was decided that no more transmission attempts will be
done.
PDF
pmPdcpPktDiscDlHoQci
EutranCellFDD
Total number of DL packets (PDCP SDUs) discarded due to
HO per QCI.
PDF
pmPdcpPktTransDlQci
EutranCellFDD
Total number of DL packets (PDCP SDUs) transmitted
successfully per QCI.
PDF
PmPdcpPktDiscDlNoUeCtxt
BbProcessingResource
Number of DRB packets (PDCP SDUs) discarded in
downlink due to that the specific Tunnel Endpoint Identifier
(TEID) is not mapped to any UE context
ACC
Figure 3-18: Packet Loss Counters
Note: Also valid for EutranCellTDD
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Further counters used in packet loss KPIs are described in Figure 3-18 and Figure
3-19.
Counter Name
Managed
Object
Description
Counter
Type
pmPdcpPktReceivedDlQci
EutranCellFDD
Total number of DL packets (PDCP SDUs) received in PDCP in the
RBS per QCI.
PDF
pmPdcpPktLostUlQci
EutranCellFDD
Total number of UL packets (PDCP SDUs) lost per QCI.
PDF
pmPdcpPktReceivedUlQci
EutranCellFDD
Total number of UL packets (PDCP SDUs) received per QCI.
PDF
Figure 3-19: Packet Loss Counters
2
Throughput Optimization Steps
The LTE end user quality of service is impacted by the cumulative effect of
various nodes & interfaces. Figure 3-20 below shows the contributing factors to
the end user throughput.
• HO
Mobility
Ping pong
• Packet
forwarding
eNodeB
features
• MIMO 2x2 4x4
• HARQ
eNodeB setup
Params
Audit
• Rec. values
Radio Environment
• C/I, SINR
• Link Adaptation
• MCS allocated
Peak
performance
Session
Establishment
Times
Core network /
PDN performance
• IP delays
• Router / #of hops
• Packet losses
• Session
Performance
End to End
Performance,
Core network delays
Delay of cell
transition
BLER at Air I/F:
Retransmission
rate
End server /
UE laptop
• TCP/IP
settings
• MTU size
E2E Dimensioning
• Number of active
users/cell
• RB allocated
• Backhaul
TCP/IP issues
Available
bandwidth
per user
End user throughput
Figure 3-20: Throughput Optimization
2.1
DL Throughput Issues Investigation
It is recommended to consider the Accessibility, Mobility and Retainability KPI.
Dl Throughput would reduce with increase in number of connected users
’pmRrcConnMax’. Average CQI, % of 64QAM samples and RI indicates DL
SINR status. Average CQI should be high (>10%), % of 64QAM sample should
be high (>10%), High PRB and PDCCH utilization would impact the DL
Throughput ‘pmPrbUtilDl / pmPrbUtilUl’.
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High value of DL latency(>9ms) and RLC retransmission (> 1%) would impact
DL throughput. High occurrence of ‘pmRadioTbsPwrRestricted’ and
‘pmBadCovEvalReport’ indicates poor DL coverage. DL throughput related
issues and investigation is discussed in Figure 3-21 below.
Total
performance
Check all important Accessibly, Mobility and Retainability KPI.
RRC connected
users
Dl Throughput would reduce with increase in number of
connected users (pmRrcConnMax).
CQI ,64/16QAM,TM
modes
Average CQI should be high (>10%), % of 64QAM sample should be high (>10%),
PRB(DL) and
PDCCH utilization
High PRB and PDCCH utilization would impact the DL
Throughput (pmPrbUtilDl / pmPrbUtilUl).
DL Latency and
RLC retransmission
High value of DL latency(>9ms) and RLC retransmission(> 1%)
would impact DL throughput.
Power limited UE
and No of A2
Search
High occurrence of pmRadioTbsPwrRestricted and
pmBadCovEvalReport indicates poor DL coverage.
Holistic overview of performance makes analysis simpler
Av CQI, % 64QAM samples and RI indicates DL SINR status
Basic health check up and baseline parameter/feature Audit along with all checks
Figure 3-21: Analysis Flow for Dl Throughput Investigation
2.2
Uplink Throughput Investigation
To investigate uplink throughput related issues, re-consider the important
Accessibly, Mobility and Retainability KPI. Make the baseline Audit for
parameters and features.
The uplink RSSI may impact the throughput, check the interference counters
‘pmRadioRecInterferencePwrPUCCH’ / ‘pmRadioRecInterferencePwr’. Poor UL
SINR conditions would impact UL throughput. Poor UL SINR conditions would
impact UL throughput, check the counters ‘pmsinrpucchdistr’ &
‘pmsinrpuschdistr’. High number of power limited UE indicates poor uplink
coverage, check the ‘pmRadioTbsPwrRestricted’,
‘pmRadioTbsPwrUNRestricted’ counters.
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The investigation areas for low UL throughput are illustrated in Figure 3-22.
Total
performance
Alarm & Parameter/
Feature Check
RSSI
Check all important Accessibly, Mobility and Retainability KPI.
Holistic overview of performance makes analysis simpler
Make Baseline Audit for Parameter and feature
High uplink RSSI would impact the throughput
(pmRadioRecInterferencePwrPUCCH / pmRadioRecInterferencePwr)
% of 16 QAM
samples
Low usage of 16 QAM modulations scheme in UL would impact
the UL throughput
PUCCH & PUSCH
SINR
Poor UL SINR conditions would impact UL throughput
Power limited UE
(pmsinrpucchdistr & pmsinrpuschdistr )
High number of power limited UE indicates poor uplink coverage
(pmRadioTbsPwrRestricted ,pmRadioTbsPwrUNRestricted)
Figure 3-22: Analysis Flow for UL throughput Investigation
2.3
Reasons for poor DL Throughput
The general optimization strategy to analyze DL throughput issues is described in
Figure 3-23 below, it covers the reasons for poor DL throughput.
Figure 3-23: Downlink Throughput Optimization
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To analyze throughput issues, it should be determined, if the reasons of low
throughput in the network is one of the following shown in Figure 3-24 below or
a combination of them.
› BLER (bad coverage)
› Downlink Interference (Bad CQI)
› MIMO Parameters
› Scheduling algorithm
› Low Demand
› CQI reporting frequency
› Other (VSWR, Backhaul capacity)
Figure 3-24: Downlink Throughput Optimization (contd..)
2.4
Reasons for poor UL Throughput
The general optimization strategy to analyze the UL throughput issues is
described in Figure 3-25 below, it covers reasons for the poor UL throughput.
› The general optimization strategy and bad throughput reasons
Figure 3-25: Uplink Throughput Optimization
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To analyze the UL throughput issues, it should be determined if the reasons for
low throughput in the network is one of the following given in Figure 3-26 below
or a combination of more than one issue.
› BLER (bad coverage)
› Uplink Interference (high RSSI)
› Low Power headroom
› Scheduling algorithm
› Low Demand
› Other (VSWR, Backhaul capacity)
Figure 3-26: Uplink Throughput Optimization (contd..)
2.5
Throughput Testing Investigation
While investigating the throughput issues in the network, the first consideration
must be to check the following licenses are applied/enabled/operable and
associated parameters are preferably set to optimum values. The licenses for
Downlink/Uplink baseband capacity, channel bandwidth in uplink and downlink,
256- QAM, 64-QAM in DL / 16-QAM UL, Dual/Quad Antenna Performance
Package for MIMO, Carrier aggregation features should be operable,
› The following licenses are applied/enabled/operable.
Parameters are set to optimum.
› Downlink/Uplink Baseband Capacity
› Channel Bandwidth
› 256- QAM, 64-QAM DL / 16-QAM UL
› Dual/Quad Antenna DL Performance Package
› Carrier Aggregation features
Figure 3-27: Throughput Testing: Checks
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3
Low Throughput- The Counters to be checked
3.1
PRB Utilization
The utilization of downlink Physical Resource Blocks (PRBs) in each eNodeB,
relative downlink Physical Resource Block (PRB) pair utilization (total number
of used PRB pairs by available PRB pairs) on the Physical Downlink Shared
Channel (PDSCH) are collected with the ‘pmPrbUtilDl’ PDF counter, as
illustrated in Figure 3-28.
The utilization of uplink Physical Resource Blocks (PRBs) in each eNodeB,
relative uplink Physical Resource Block (PRB) pair utilization (total number of
used PRB pairs by available PRB pairs) on the Physical Uplink Shared Channel
(PUSCH) collected with the ‘pmPrbUtilUl’ PDF counter.
For Good UL and DL throughput, UL and DL PRB utilization should be low
respectively (<80%).
› Counters pmPrbUtilUl and pmPrbUtilDl are the PDF counters with 10
ranges each
› Concept of weighted average is used to calculate average PRB
utilization. Weight of each range (for PDF range[0] from 0 to 10 it has
taken as 5) is multiplied by sample in that range and sum of it is divided
by total number of samples(in one ROP of 15 minutes it is always going
to be 15)
Figure 3-28: PRB Utilization
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‘pmPrbUtilDL’ and ‘pmPRBUtilUL’ is illustrated in Figure 3-29 below..
PRB Utilization in UL:
PRB Utilization in Dl :
pmPrbUtilUl
pmPrbUtilDl
A distribution that shows the downlink Physical
Resource Blocks (PRB) utilization (total number
of used PRB by available PRB) on the Physical
Downlink Shared Channel (PDSCH).
A distribution that shows the Physical Resource Blocks
(PRB) utilization (total number of used PRB by
available PRB) on the Physical Uplink Shared Channel
(PUSCH).
PDF ranges:
[0]: 0 % <= Utilization < 10 %
[1]: 10 % <= Utilization < 20 %
[2]: 20 % <= Utilization < 30 %
[3]: 30 % <= Utilization < 40 %
[4]: 40 % <= Utilization < 50 %
[5]: 50 % <= Utilization < 60 %
[6]: 60 % <= Utilization < 70 %
[7]: 70 % <= Utilization < 80 %
[8]: 80 % <= Utilization < 90 %
[9]: 90 % <= Utilization
Unit: -
PDF ranges:
[0]: 0 % <= Utilization < 10 %
[1]: 10 % <= Utilization < 20 %
[2]: 20 % <= Utilization < 30 %
[3]: 30 % <= Utilization < 40 %
[4]: 40 % <= Utilization < 50 %
[5]: 50 % <= Utilization < 60 %
[6]: 60 % <= Utilization < 70 %
[7]: 70 % <= Utilization < 80 %
[8]: 80 % <= Utilization < 90 %
[9]: 90 % <= Utilization
Unit: -
Condition: One sample should be the utilization
during the sample gathering period.
Condition: One sample should be the
utilization during the sample gathering
period.
For Good UL and DL throughput- UL and DL PRB utilization should be low
respectively ( <80%)
Figure 3-29: PRB Utilization
3.2
Ways to reduce PRB utilization
There are very limited means to reduce the PRB utilization. However, some of
these methods can be tried on the case by case basis, Traffic offloading to less
utilized neighboring cells, with IFLB/IFO features. Reduce the control channel
resources (Before that check PDCCH utilization). Add Bandwidth (if system is
operating < 20Mhz), bandwidth increase would increase number of PRBs,
Channel should be equal to licensed bandwidth. Reduce inactivity timer
(‘tInactivityTimer’) value so that inactive user can be released early. Some other
features like MIMO, CA, 256QAM, 64 QAM, 16QAM, IRC, UL/DL FSS can
also be used to reduce PRB utilization, as illustrated in Figure 3-30.
› There are very limited means of reducing of PRB utilization .How ever
some of these methods can be tried on case by case basis
› Traffic offload to less utilized neighboring cells, IFLB, IFO
› Reduce control channel resources(Before that check PDCCH
utilization)
› Add Bandwidth (if system is operating < 20Mhz) as Bandwidth
increase would increase number of PRB, Channel should be equal to
licensed bandwidth
› Reduce inactivity timer (tInactivityTimer) value so that inactive user
can be released early
› MIMO, CA, 256QAM, 64 QAM, 16QAM, IRC, UL/DL FSS
Figure 3-30: Ways to reduce PRB utilization
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Essential Parameters
The essential parameters affecting PRB utilization and throughput need to be
optimized are discussed in Figure 3-31 below.
› Radio Network MO parameters:
EUtranCellFDD
› dlChannelBandwidth / ulChannelBandwidth=should be equal to
license bandwidth
noOfTxAntennas for MIMO= 2
noOfRxAntennas for MIMO= 2
› transmission Mode default is 3, TxDiv and Open Loop Spatial
Multiplexing (2x2 MIMO)
› pdcchCfiMode (number of OFDM symbols used for PDCCH, 1->3)
› maximumTransmissionPower = 460 (for 40 watt site)
› partOfSectorPower (for a sector)= 100
› pZeroNominalPucch  some UEs need this to be increased or
ACK/NACKs are not received successfully on PUCCH.
› pZeroNominalPusch  some UEs need this to be increased from
default or lots of errors seen on PUSCH.
– SectorEquipmentFunction
› confOutputPower = license power (20/40/60 Watt)
Figure 3-31: Essential Parameters
3.4
Other Counters for Throughput Analysis
Few more important counters that can be considered for throughput analysis are
shown in Figure 3-32 below.
› UL Interference on PUCCH / PUSCH:
‘pmRadioRecInterferencePwrPUCCH’ / ‘pmRadioRecInterferencePwr’
› SINR of PUCCH / PUSCH:
‘pmSinrPucchDistr’ / ‘pmSinrPuschDistr’
› RLC ACK/NACK:
‘pmRlcArqUlack’ / ‘pmRlcArqUlNack’
› Transport block PWR restricted:
‘pmRadioTbsPwrRestricted’ / ‘pmRadioTbsPwrUNRestricted’
› Scheduling activity per cell in UL and DL:
‘pmSchedActivityCellDl’ /’pmSchedActivityUeDl’
› Rank distribution MIMO/ SIMO:
‘pmRadioTxRankDistr’
› Number of A2 events(UE in poor coverage) :
‘pmBadCovEvalReport’
Figure 3-32: Counters for throughput analysis
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3.5
UL Interference
To observe UL interference on PUCCH / PUSCH, counters in Figure 3-33.
‘pmRadioRecInterferencePwrPUCCH’ / ‘pmRadioRecInterferencePwr’ should
be observed and for SINR of PUCCH / PUSCH counters ‘pmSinrPucchDistr’ /
‘pmSinrPuschDistr’ shown in Figure 3-34 should be observed, for good
throughput in UL, UL- RSSI value should be low (< -105 dBm), and few samples
should be in poor SINR range.
UL Interference on PUCCH* :
UL interference on PUSCH :
pmRadioRecInterferencePwrPUCCH pmRadioRecInterferencePwr
The measured Noise and Interference Power on
PUCCH
PDF ranges:
[0]: N+I <= -121
[1]: -121 < N+I <= -120
[2]: -120 < N+I <= -119
[3]: -119 < N+I <= -118
[4]: -118 < N+I <= -117
[5]: -117 < N+I <= -116
[6]: -116 < N+I <= -115
[7]: -115 < N+I <= -114
[8]: -114< N+I <= -113
[9]: -113 < N+I <= -112
[10]: -112 < N+I <= -108
[11]: -108 < N+I <= -104
[12]: -104 < N+I <= -100
[13]: -100 < N+I <= -96
[14]: -96 < N+I <= -92
[15]: -92 < N+I
Unit: dBm/PRB
The measured Noise and Interference Power on
PUSCH
PDF ranges:
[0]: N+I <= -121
[1]: -121 < N+I <= -120
[2]: -120 < N+I <= -119
[3]: -119 < N+I <= -118
[4]: -118 < N+I <= -117
[5]: -117 < N+I <= -116
[6]: -116 < N+I <= -115
[7]: -115 < N+I <= -114
[8]: -114< N+I <= -113
[9]: -113 < N+I <= -112
[10]: -112 < N+I <= -108
[11]: -108 < N+I <= -104
[12]: -104 < N+I <= -100
[13]: -100 < N+I <= -96
[14]: -96 < N+I <= -92
[15]: -92 < N+I
Unit: dBm/PRB
Figure 3-33: RSSI
SINR of PUCCH:
SINR for PUSCH:
pmSinrPucchDistr
pmSinrPuschDistr
Distribution of the SINR values calculated for PUCCH .
Distribution of the SINR values calculated for PUSCH .
› PDF ranges:
› [0]: SINR <= -15
› [1]: -15 < SINR <= -12
› [2]: -12 < SINR <= -9
› [3]: -9 < SINR <= -6
› [4]: -6 < SINR <= -3
› [5]: -3 < SINR <= 0
› [6]: 0 < SINR <= 3
› [7]: 3 < SINR
› Unit: dB
Condition: Each SINR value for PUCCH per UE calculated
on a TTI basis yields one sample in the distribution.
› PDF ranges:
› [0]: SINR <= -5
› [1]: -5 < SINR <= -2
› [2]: -2 < SINR <= 2
› [3]: 2 < SINR <= 6
› [4]: 6 < SINR <= 10
› [5]: 10 < SINR <= 14
› [6]: 14 < SINR <= 17
› [7]: 17 < SINR
› Unit: dB
Condition: Each SINR value for PUSCH per UE calculated
on a TTI basis yields one sample in the distribution.
For good throughput in UL - FEW Samples in poor SINR ranges
Figure 3-34: UL SINR
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3.6
UL RLC NACK
The total number of successful RLC PDU transmissions (ACKs) in the uplink
direction is observed with ‘pmRlcArqUlack’. The counter does continuous
measurement for Radio Bearers aggregated to cell level.
The total number of unsuccessful RLC PDU and RLC PDU segment
transmissions (NACKs) in the uplink direction can be observed with counter
‘pmRlcArqUlNack’. For good throughput in UL, UL RLC NACK ratio should be
low. And below Figure 3-35 illustrated the counters.
RLC ACK:
pmRlcArqUlack
RLC NACK:
pmRlcArqUlNack
› The total number of successful
RLC PDU transmissions (ACKs)
in the uplink direction.
› Condition: Continuous
measurement for Radio Bearers
aggregated to cell level..
› The total number of unsuccessful
RLC PDU and RLC PDU
segment transmissions (NACKs)
in the uplink direction.
› Condition: Continuous
measurement for Radio Bearers
aggregated to cell level.
For good throughput in UL –UL RLC NACK RATIO should be low
Figure 3-35: UL RLC NACK
3.7
Power restricted transport block in UL
The number of Transport Blocks on MAC level scheduled in uplink where the
UE was considered to be power limited. A Transport Block is considered to be
power limited when the estimated required transmit power is higher than the UE
maximum transmit power, counter is ‘pmRadioTbsPwrRestricted’. The scanner
not included in any predefined scanner.
‘pmRadioTbsPwrUNRestricted’ are the number of Transport Blocks on MAC
level scheduled in uplink where the UE was NOT considered to be power limited.
A Transport Block is considered to be power limited when the estimated required
transmit power is higher than the UE maximum transmit power. Figure 3-36
shows these counters.
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Ratio of power limited blocks to non-power limited blocks should be low for
good throughput in UL, ratio should be < 50%.
Transport block PWR restricted:
pmRadioTbsPwrRestricted
› The number of Transport Blocks on MAC
level scheduled in uplink where the UE was
considered to be power limited.
› Unit: › Condition: A Transport Block is considered
to be power limited when the estimated
required transmit power is higher than the
UE maximum transmit power.
› Counter type: PEG
› Scanner: Not included in any predefined
scanner
Transport block PWR restricted:
pmRadioTbsPwrUNRestricted
› The number of Transport Blocks on MAC level
scheduled in uplink where the UE was NOT
considered to be power limited.
› Unit: › Condition: A Transport Block is considered to
be power limited when the estimated required
transmit power is higher than the UE maximum
transmit power.
› Counter type: PEG
› Scanner: Not included in any predefined
scanner
Ratio of power limited to non power limited blocks should be low
For Good throughput in UL- Ratio should be low(< 50%)
Figure 3-36: Power restricted transport block-UL
3.8
CQI Range
As shown in Figure 3-37 the counter ‘pmRadioUeRepCqiDistr’ gives CQI
distribution in DL and the counter ‘pmRadioUeRepCqiDistr; is a PDF counter
and it gives value range from 0 to 15. For good throughput in DL- average CQI
should be high (>10).
CQI is a feedback mechanism from UE to eNB for downlink
› pmRadioUeRepCqiDistr gives CQI distribution in DL
› pmRadioUeRepCqiDistr is a PDF counter and it gives
value in range from 0 to 15
› CQI 1-6 map to QPSK
› CQI 7-9 map to 16QAM
› CQI 10-15 map to 64QAM
For good throughput in DL- Average CQI should be high (>10)
Figure 3-37: CQI
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3.9
MIMO RANK distribution usage
Rank distribution MIMO counter is ‘pmRadioTxRankDistr’, discussed in Figure
3-38. The transmission mode / rank distributions give more detailed information
on how much each transmission mode and rank is used. For good throughput in
DL high samples of MIMO Rank 2 should be observed.
Rank distribution MIMO/ SIMO : pmRadioTxRankDistr
The transmission mode / rank distributions gives more detailed information on how much each
transmission mode and rank is used.
PDF ranges:
[0]: Transmit diversity  same information both branches
[1]: Open Loop SM Rank 1 SIMO
[2]: Open Loop SM Rank 2  MIMO
[3]: Closed Loop SM rank 1
[4]: Closed Loop SM rank 2
Unit: Counter type: PDF
Scanner: Not included in any predefined scanner
SM stands for Spatial Multiplexing
For Good throughput in DL- High samples of MIMO Rank 2
Figure 3-38: MIMO RANK distribution usage
3.10
Modulation Scheme usage DL
Different modulation scheme samples can be observed with the counters
discussed in Figure 3-39 for DL and in Figure 3-40 for uplink. The percentage of
QPSK Samples, 16 QAM Samples, 64QAM Samples & 256QAM samples (if
HOM implemented) can be calculated and for good DL throughput, high usage of
256 QAM, 64 QAM and 16 QAM scheme in DL should be observed.
› QPSK Samples (%) = 100 * (pmMacHarqDlAckQpsk/
(pmMacHarqDlAckQpsk + pmMacHarqDlAck16qam +
pmMacHarqDlAck64qam))
› 16 QAM Samples (%) = 100 * (pmMacHarqDlAck16qam /
(pmMacHarqDlAckQpsk + pmMacHarqDlAck16qam +
pmMacHarqDlAck64qam))
› 64QAM Samples(%) = 100 * (pmMacHarqDlAck64qam/
(pmMacHarqDlAckQpsk + pmMacHarqDlAck16qam +
pmMacHarqDlAck64qam))
For good DL throughput- High usage of 256 QAM, 64 QAM and 16 QAM
scheme in DL
Figure 3-39: Modulation scheme usage DL
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Modulation scheme used in UL is illustrated in Figure 3-40
QPSK Samples (%) = 100 * ((pmMacHarqUlSuccQpsk/
(pmMacHarqUlSuccQpsk+ PmMacHarqUlSucc16qam ))
16 QAM Samples (%) =100 * ((pmMacHarqUlSucc16qam/
(pmMacHarqUlSuccQpsk+ PmMacHarqUlSucc16qam ))
For good UL throughput - High usage of 64/16 QAM scheme in UL
Figure 3-40: Modulation scheme usage UL
4
Throughput Optimization- UE essential checks
UE Subscriber profile also play an important role in high throughput, subscribed
charging characteristics, Aggregate Maximum Bit Rate (AMBR), Max requested
bandwidth in Downlink, Max requested bandwidth in Uplink, RAT frequency
selection priority, APN configuration profile, default Context Identifier (default
APN for the EPS User), APN Configuration (every APN associated to the EPS
Users), QOS parameter setting, transport Network characteristics. These profiles
are important for throughput optimization, Figure 3-41.
UE Subscriber profile (End User (EPS User) subscription data is stored
in the HSS)
› Subscribed Charging Characteristics
› Aggregate Maximum Bit Rate (AMBR)
Max requested bandwidth in Downlink
Max requested bandwidth in Uplink
› RAT frequency selection priority
› APN configuration profile:
Default Context Identifier (default APN for the EPS User)
APN Configuration (every APN associated to the EPS User)
› QOS Parameter setting
› Transport Network issue
Figure 3-41: Throughput Optimization-essential checks
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4.1
QOS Framework
The LTE Quality of Service (QoS) Handling coordinates and assigns the
appropriate QoS to other functions in LTE RAN. The RBS maps QCIs (Quality
of Service Class Identifiers) to priorities for different Data Radio Bearers (DRBs)
in the LTE radio interface and different data flows in the transport network.
The LTE QoS Handling complies with the 3GPP QoS concept. It provides
service differentiation per UE by support of multiple parallel bearers. To provide
service differentiation in the uplink, traffic separation must be ensured between
the different data flows within the UE. This is done by offering an operatorconfigurable mapping between QCIs and LCGs (Logical Channel Groups, also
sometimes referred to as radio bearer groups).
Signaling Radio Bearers (SRBs) are assigned higher priority than Data Radio
Bearers (DRBs). SRB1 has higher priority than SRB2.
For the UL, the transport network benefits from QoS by mapping QCI to
DiffServ Code Point (DSCP) in the RBS. This enables the transport network to
prioritize between its different data flows over the S1 interface in the uplink and
over the X2 interface for the downlink data in case of Packet Forwarding.
For the DL, a similar mapping is performed in the S-GW for the S1 DL data.
If a user has multiple bearers with different QCI, these users will be separated in
the radio network into different bearers. This separation will achieve benefits for
the end-user QoS as it removes the risk that one service such as file download
would block the traffic for a voice call.
QoS Handling is based on mapping QCIs received from the core network to
RBS-specific parameters. This makes it possible to have different priorities and
DSCP values.
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The LTE QoS Handling is realized by a central function in the RBS, which
directly influences the radio and transport network performance. The QOS
process is illustrated in Figure 3-42 below.
DSCP: DiffServ Code Point
OSS: Operations Support
System
QoS: Quality of Service
QCI: QoS Class Indentifier
RC: Radio and Core
Core Network
- absPrioOverride
- priority
resourceType logicalChannelGroupRef
QCI Table,
Example of
population
Standardized
QCIs
OSS-RC
QoS parameters
QCI Table
QCI
RT
Prio
LCG
DSCP
1
GBR
2
2
46
2
GBR
4
1
36
:
:
:
:
:
9
Non-GBR
9
3
12
10
3
0
10-255
parameters
QCI, ARP
paArpOverride
Scheduler
QCI table
•QoS configuration
QoS
translation
Priorities
LCGs
QoS Handling
DL Packet
Forwarding
(X2)
UL/DL
(Radio Interface)
Radio Network
UL
(S1)
Transport Network
UE
Figure 3-42: QoS Framework
In uplink, the distribution of the granted resources is done per logical channel
internally within the UE using the rate control function. The RBS maps the QCI
to LCG and informs the UE about the association of a logical channel to a LCG
and the logical channel priority for each logical channel.
The reason for using LCGs is that the Buffer Status Report (BSR) is sent per
LCG and not per logical channel. This reduces the uplink signaling load.
Standardized QCIs (1-9) are used, according to 3GPP TS 23.203.
Non-standardized QCIs (10-256) are all given the same priority, which shall be
lower compared to priorities for the standardized QCIs. For the uplink, the
priorities are translated to logical channel priorities and sent to the UE, which
may differentiate/prioritize between its logical channels.
Mapping QCIs to Logical Channel Groups (LCGs) can be configured in OSS-RC
and enables traffic separation in the uplink. There are three LCGs (1-3) available.
By default, LCG 1 is assigned to all QCIs. The UE performs prioritization
between its own logical channels. This is referred to as UE rate control.
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The QOS based scheduling example is discussed in Figure 3-43.
Prio
LCG
Abs Prio Override
QCI 1
2
1
HI_PRIO_OVERRIDE
QCI 2
3
1
NO_OVERRIDE
QCI 3
4
2
NO_OVERRIDE
Scheduled before all other QCIs*
Scheduled according
to scheduling
algorithms **
RF, PF
UE
Rate
Control
*In UL, the established bearer
with highest prio represents the
abs prio for the LCG
**In UL, the established bearer
with highest prio represents the
scheduling algorithm for the
LCG
Figure 3-43: QoS Aware Scheduler – Absolute priority example
4.2
Scheduling Algorithm Scheduler Configuration
The two main scheduling algorithms are ‘Resource Fair’ and ‘Minimum Rate
Proportional Fair’. The later one works together with the QoS Aware Scheduler
feature. This scheduling algorithm is based on channel quality information and
scheduled data rates. It allows better sharing of RAN, RBS and baseband
resources between different radio bearers, thus providing a trade-off between user
demands and system performance.
Considering the fact, in a mobile network environment, different users will
experience different radio conditions at a certain time; this scheduling algorithm
prioritizes users experiencing good radio quality, thus leading to a higher
throughput when compared to the basic scheduling method (Resource Fair).
However, to avoid some users being allocated too few or no resources due to
poor channel quality, fairness is provided also by taking into account the average
rate in scheduler prioritization. The scheduler needs as an input the channel
quality of the users in the cell and the average rates of their flows. Therefore, it
monitors the Channel State Information (CSI) from the UE and measurements
performed in the RBS. The average rate is calculated based on previous
transmissions for the flows. When resources are divided among users the
prioritization is based on a weighted measure of the channel quality and average
rate.
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In many scenarios, cell capacity can be increased by using the low fairness
versions of the proportional fair scheduling algorithms. These algorithms increase
the share of the resources given to users with good channel conditions. This leads
to an overall increase in capacity. Different scheduling algorithm are illustrated in
Figure 3-44.
› Proportional Fair Scheduling algorithms
parameter: QciProfilePredefined.schedulingAlgorithm
› Equal Rate
› Proportional Fair High
› Proportional Fair Medium
› Proportional Fair Low
› Max C/I
› Min rate in UL/DL. Parameters:
– QciProfilePredefined.ulMinBitRate
– QciProfilePredefined.dlMinBitRate
Figure 3-44: Scheduler Configuration
The feature also helps in giving a consistent cell edge throughput with the
minimum rate Quality of Service (QoS) characteristic. The basic concept is that
flows experiencing a bit rate lower than their configured minimum bit rate will be
prioritized before flows that have a bit rate above their configured minimum rate.
As mentioned above, Proportional Fair scheduling feature takes into account both
scheduled data rate and radio channel quality. The tradeoff between user fairness
and the system performance can be tuned by Channel Quality Fraction (CQF).
The CQF controls how big portion of channel quality should contribute to a user's
priority. With increasing fairness, the scheduler will try to bring all the users to
the same received data rate range. On the other hand, system performance could
degrade, as more resources need to be allocated to users in bad channel
conditions to give them as high data rate as users in good channel conditions. In
the most unfair setting (Max C/I), then resources are spent on good channel users
yielding a high system throughput. However, cell edge users are disfavored.
To control the CQF’s impact on the scheduler, five different scheduling
algorithms can be configured, see Figure 3-44 above.
These 5 different types of configuration profiles will allow the operator to set the
network behavior to a scenario that varies from providing higher fairness to the
users (equal rate) to a higher capacity (Max C/I), which provides a higher
throughput.
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This is detailed in the charts of the below Figure 3-45.
Opportunistic scheduling enables increased capacity and
increased cell edge throughput in higher load scenarios
User Throughput
Higher fairness
Higher capacity
Average Cell Throughput
Higher fairness
Higher capacity
Figure 3-45: Proportional Fair Scheduling Benefits
Feature affecting UL/DL Throughput
5
Important LTE features affecting UL/DL throughput is shown in Figure 3-46
below.
Figure 3-46: LTE Features enhancing UL/DL Throughput
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5.1
256 QAM DL
The feature provides support of 256 QAM in DL. This allows much higher data
rate for 256-QAM capable UEs when their DL link quality is very good.
Compared to 64 QAM, this feature increases the DL user peak rate (MAC layer)
from 150 Mbps to about 195 Mbps with 20 MHz bandwidth and 2-layer MIMO.
With 3-carrier carrier aggregation, the DL user peak rate can reach about 587
Mbps.
In L16A, 256 QAM is supported in transmission mode 1, 2, 3 and 4, while the
highest rank is limited to 2.
To support the feature, UE must support 256 QAM as specified in 3GPP Release
12: This includes reporting 256 QAM capability, can be configured to use CQI
table for 256 QAM and can demodulate and decode transport blocks using 256
QAM.
256 QAM is supported only with rank of 1 and 2. If 4x4 MIMO license is
enabled/activated and a UE is capable of 4x4 MIMO, 256 QAM is not supported
for the UE.
In case of cross-DU CA, the UE peak rate of 587 Mbps can’t be supported if the
CA capable UE has PCell on one DU and two SCells on the other DU.
The license MO instance name is ‘Dl256Qam’. To activate the feature, one needs
to enable and activate the feature license. The attribute ‘dl256QamEnabled’
should be set to TRUE. This attribute is used to enable or disable the feature on
cell level.
Since low transmit EVM (error vector magnitude) is needed to achieve good 256
QAM performance, the attribute ‘radioTransmitPerformanceMode’ is used to
configure the desired radio performance mode. This attribute sets the desired
mode, not the actual mode. Whether the radio can operate at the desired mode
also depends on the configured carrier powers for all carriers transmitted from the
radio.
If supported, radios can be configured to work in one of the four radio transmit
performance modes:
DEFAULT: Legacy, radio shall behave the same as in L15B. Performance for 64
QAM may not be optimal for some radios.
‘QAM_64_BOOST’: The requested power headroom is for 64-QAM
performance.
‘QAM_256_BOOST’: The requested power headroom is for 256-QAM
performance, which is more than that for 64-QAM.
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MAX_POWER_CLASS: The requested power headroom is the maximum the
radio can provide. This could provide good 256-QAM performance, but the radio
will not be power efficient. In addition, too much headroom will cause
performance issues as the radio transmit signal will not be operating within its
optimal dynamic range.
The attribute ‘dl256QamStatus’ indicates whether radio has enough power
headroom for 256 QAM. If ‘dl256QamStatus’ = SUPPORTED, it means radio
has enough power headroom for 256 QAM. If ‘dl256QamStatus’ =
DEGRADED, it means 256 QAM can be supported, but the radio power
headroom may not be enough to achieve 256 QAM peak rate. If
‘dl256QamStatus’ = NOT_SUPPORTED, it means radio doesn’t have enough
power headroom to support 256 QAM, or the 256 QAM license is not enabled, or
the ‘dl256QamEnabled’ is not set to TRUE. As describer earlier, the lack of radio
power headroom can be due to carrier power configuration or other factors like
temperature.
In order to achieve 256 QAM peak rate, please ensure that the total configured
carrier power is less than the max radio transmit power and the value of
‘dl256QamStatus’ is SUPPORTED.
ManagedElement
+-ENodeBFunction
+-SectorCarrier
radioTransmitPerformanceMode
(DEFAULT, QAM_64_BOOST, QAM_256_BOOST,
MAX_POWER_CLASS)
A desired radio transmit operating mode, which is tailored to
achieve good throughput performance for a given highest
modulation in downlink.
+-EUtranCellFDD / EUtranCellTDD
dl256QamEnabled {True, False}
Enable or disable 256 QAM support in DL
dl256QamStatus (Read Only)
{NOT_SUPPORTED, DEGRADED, SUPPORTED}
Indicate whether 256 QAM can be supported and whether
radio has enough power headroom
Figure 3-47: 256 QAM DL Parameters
The target EVM for 256-QAM is 2%. The requested power headrooms are stored
in radio data base, and are used to set the radio according to the configured radio
performance mode. In 16A, the power headroom stored in radio data base may
not map to the target EVM for some radios or for some configurations (like
narrow bandwidth).
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Although the radio performance mode is per sector-carrier, the support of 256
QAM is on the cell level. In case of combined cell with multiple radios, if any
radio can’t support radio performance mode, 256 QAM is not supported by the
cell. Similarly, if all radios support radio performance mode but one radio doesn’t
have enough power headroom for 256 QAM, then 256 QAM is not supported by
the cell.
The feature can be supported in mixed mode where one radio transmits and
receives signals for LTE and other technologies. However, LTE throughput
degradation may be observed in some cases.
The attribute ‘radioTransmitPerformanceMode’ is per sector-carrier. If multiple
sector-carriers are supported by a single radio, the same
‘radioTransmitPerformanceMode’ should be configured. If different radio
performance modes are configured for different sector-carriers in this case, the
highest mode is used by the radio (the order of the modes from high to low is:
MAX_POWER_CLASS, QAM_256_BOOST, QAM_64_BOOST, and
DEFAULT). For example, sector-carrier1 and sector-carrier2 are supported by
the same radio, while the ‘radioTransmitPerformanceMode’ is configured as
“DEFAULT” for sector-carrier1 and ‘QAM_256_BOOST’ for sector-carrier2. In
this case, the radio will use ‘QAM_256_BOOST’ mode. However, the
performance mode displayed on the user interface for sector-carrier1 is still
“DEFAULT”.
The feature supports two modulation modes: the legacy mode in which the
highest modulation is 64 QAM, and the higher order modulation (HOM) mode in
which the highest modulation is 256 QAM. In HOM mode, 256 QAM can be
selected whenever link quality permits. The dynamic mode switch between the
two modes is supported.
When a 256 QAM capable UE is in legacy mode, it can use any transmission
mode that is supported in our product so far.
For a 256 QAM capable UE, if it is in legacy mode and is in any of the four Tx
modes listed above, it can be switched to HOM mode when the DL link quality is
good enough. If it is in legacy mode and is in a Tx mode other than the four
modes listed above, switching to HOM mode is not allowed. If any UE is in
HOM mode and is in a Tx mode other than the four modes listed above, the UE
will be put into legacy mode.
If 4x4 MIMO license is enabled and a UE is 4x4 MIMO capable, the UE will not
be put in HOM mode. This is mainly due to development cost and uncertainty
about UE support. If 4x4 MIMO license is disabled and a UE is capable of 4x4
MIMO and 256 QAM, we will limit the UE’s reported rank to 2.
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The tables shown in Figure 3-48 for MCS index to transport block size index is
defined to be used in HOM mode. Here we see that the modulation order steps up
to 8 bits per symbol for the higher MCS indexes.
MCS Index
Modulation Order
TBS Index
I MCS
Qm
I TBS
0
2
0
1
1
2
2
2
2
2
4
2
3
3
2
6
4
2
4
4
2
8
5
2
5
5
4
10
6
2
6
6
4
11
7
2
7
7
4
12
8
2
8
8
4
13
9
2
9
9
4
14
10
4
9
10
4
15
11
4
10
11
6
16
12
4
11
12
6
17
13
4
12
13
6
18
14
4
13
14
6
19
15
4
14
15
6
20
16
4
15
16
6
21
17
6
15
17
6
22
18
6
16
18
6
23
19
6
17
19
6
24
18
20
8
8
25
MCS Index
I MCS
Modulation Order
TBS Index
Qm
I TBS
0
2
0
1
2
2
2
3
20
6
21
6
19
21
22
6
20
22
8
28
23
6
21
23
8
29
24
6
22
24
8
30
25
6
23
25
8
31
26
6
24
26
8
32
8
33
27
6
25
27
28
6
26
28
2
29
4
30
6
31
8
29
2
30
4
31
6
reserv ed
27
reserv ed
Figure 3-48: Link Adaptation Tables
5.2
64 QAM Uplink
64-QAM Uplink is an optional feature that enables higher order modulation on
the PUSCH. Enabling the feature increases the number of bits per symbol used in
LTE physical layer resources and thus improves throughput.
Support of 64QAM in PUSCH by Category 5 UEs is defined in 3GPP since
Release 8. Support of 64QAM in PUSCH by UL Category 5 and 13 UEs is
defined in 3GPP Release 12.
UL MU-MIMO, UL Carrier Aggregation and Clustered PUSCH will work
together with 64-QAM Uplink.
There should be no limitation on the number of 64QAM users that this feature
should support. MCS with 64QAM modulation will only be scheduled for UEs
that support it. Furthermore, a power offset to ‘p0_NominalPusch’ can be used
for 64QAM capable UEs in order to have a higher target SINR for selecting the
most efficient MCS.
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64QAM is selected based on estimated uplink channel quality. Since UE is power
limited, 64QAM may be applied in good radio conditions with the knowledge of
UE’s power headroom. The overall uplink cell throughput and spectral efficiency
is expected to increase, however the amount of the increase depends on the ratio
of 64QAM users and their channel characteristics. Ideally it allows for single user
uplink peak rate and spectral efficiency as below:
•
~75 Mbps in 20 MHz FDD, while ~55 Mbps in case of 16QAM
•
3.75 bits/s/Hz, while 2.75 bits/s/Hz in case of 16QAM
– More information transferred in each UL
radio symbol (total 6 bit)
› 50% more compared to 16-QAM
– Higher peak bit rate in good radio
conditions
64-QAM
› Operator benefit
– Improved cell capacity
– Improved peak rates
6 bits/symbol
50% higher UL peak rates and increased cell capacity
Figure 3-49: 64-QAM Uplink (FDD/TDD)
› 64QAM modulation increases the number of bits that can be
transmitted per symbol.
› Allows uplink peak rate of up to 70 Mbps* for 64 QAM capable
UEs in FDD 20 MHz bandwidth.
› Allows uplink peak rate of up to 13.77 Mbps* for 64QAM capable
UEs in TDD 20 MHz bandwidth with UL/DL configuration 2.
› Increases uplink throughput for 64 QAM capable UEs in good
coverage areas.
Bits per symbol vs modulation
*Note : This is based on that the configuration is 96 SBs in TTI
without PRACH, and 90 SBs in TTI
with PRACH, with SRS disabled
Number of bits per symbol
7
6
5
4
3
2
1
0
QPSK
16QAM
64QAM
Modulation
Figure 3-50: 64 QAM UL Benefits
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5.3
64 QAM UL Parameters
New MOM attribute ‘puschPwrOffset64qam’ is introduced considering that the
majority of the UEs are not capable of 64 QAM in Uplink. With this in mind it is
desired to keep ‘pZeroNominalPusch’ unchanged. The ‘puschPwrOffset64qam’
is used to control the received SINR target and enable maximum throughput for
64QAM, which in some configurations is not possible otherwise.
The ‘puschPwrOffset64qam’ is an offset to ‘pZeroNominalPusch’ in close-loop
power control. For 64QAM capable UEs (regardless of the actual modulation),
the PUSCH Tx power per resource element is calculated by
(‘pZeroNominalPusch’ + ‘puschPwrOffset64qam’).
When setting ‘puschPwrOffset64qam’, the following need to be considered:
setting of ‘pZeroNominalPusch’, number of RX antennas, and the desired
performance for 64QAM capable UEs.
For 2 Rx, ‘pZeroNominalPusch’ + ‘puschPwrOffset64qam’ needs to be -100
dBm or higher to achieve maximum throughput. For more than 2 Rx, this needs
to be adjusted considering the diversity gain, in ideal case 3 dB and in reality the
gain should be less than 3 dB.
If UL MU-MIMO is enabled in the eNB, ‘puschPwrOffset64qam’ should be set
to 0 to avoid extra interference when pairing UEs w/wo 64QAM capability.
When this feature is enabled and the ‘puschPwrOffset64qam’ > 0 dB, 64QAM
capable UEs will generate more interference within the cell and towards
neighboring cells. The throughput of UEs without 64QAM capability will be
impacted. This behavior is expected due to two reasons:
• Higher PUSCH power for 64QAM users will generate more interference to the
other users.
• The higher PUSCH power also gives better SINR thus 64QAM users have
advantage in frequency selective scheduling.
The attribute ‘ul64qamEnabled’ should be set to TRUE. This attribute is used to
enable or disable the feature on cell level.
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New counters and performance indicators are introduced by this feature in order
to monitor the performance of 64QAM in PUSCH. It also changes the calculation
of existing performance indicators.
+- EUtranCellFDD/EUtranCellTDD
puschPwrOffset64Qam {0..8} Unit: 1 dB def.: 0 dB
Power offset to the target received PUSCH Power Spectral Density
(PSD) for 64-QAM-capable UEs. Used to control the received SINR
target.
It is used to enable maximum throughput for 64QAM, which in some
configurations is not possible.
For 2Rx, pZeroNominalPusch + puschPwrOffset64qam needs to be 100 dBm or higher to achieve maximum throughput.
+-EUtranCellFDD/EUtranCellTDD
ul64qamEnabled {True, False} def.: True
Enable or disable 64 QAM support in UL
Figure 3-51: 64 QAM UL Parameters
5.4
Ericsson Lean Carrier
The cell specific reference signals (CRS) are UE known symbols that are inserted
within the OFDM time and frequency grid. The reference symbols are used by
the UE for intra and inter frequency mobility measurements, downlink channel
estimation, Automatic Gain Control and Automatic Frequency Control.
In 3GPP, the Cell specific Reference Signals (CRSs) are specified to always be
transmitted. The CRSs contribute to severe inter-cell interference towards
neighboring cells. Specifically, in low load conditions, the CRS induced
interference is often the dominating factor that limits DL throughput
performance.
The Ericsson Lean Carrier feature addresses this problem by only sending CRSs
when and where they are needed to support the traffic, while minimizing the
harmful interference.
Transmissions of reference signals are limited to a bare minimum without
negative impact of network KPI e.g. mobility and call setup success rate. The
overall reduction of CRS transmissions depends on cell load. Up to 80%
reduction in emitted reference signal power can be achieved.
LTE devices requires reference signals to function. Today, excessive LTE
reference signaling causes interference between cells limiting network
performance. Continuous reference signal transmission is done across all
subframes and PRBs at all times.
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In contrast, Ericsson Lean Carrier adapts 5G lean concepts to reduce LTE
reference signaling and the associated inter cell interference, improving the
mobile experience. Ericsson Lean Carrier Transmits Reference Signals in
subframes and in PRBs only when required.
Ericsson Lean Carrier:
Ericsson Lean Carrier:
Current LTE reference signaling
User Data
causes interference between cells Throughput
Ericsson Lean Carrier
dynamically reduces reference
signaling by up to 80%, reducing
inter-cell interference
Interference
Interference
USER
DATA
USER
DATA
User Data
Throughput
Figure 3-52: Ericsson Lean Carrier Applying 5G concepts to today’s 4G LTE
Reference signals are muted all times except for the following:
• Reference signals are always transmitted on the 6 center PRB. This
ensures that devices can evaluate the cell for cell selection purposes.
• Reference signals are always transmitted over the full bandwidth at the
following occasions:
- SIB sub-frames
- Paging sub-frames
- During connection set up until DRX configuration is sent to UE.
All devices are configured with DRX.
- When a UE is scheduled
- During “on-duration” in DRX cycle, since this is the time when the
UE is monitoring the PDCCH.
- Configurable to enable more sub-frames with full reference signal
bandwidth pre and post “on-duration”
With the Ericsson Lean Carrier function, the CRS are muted in subframes where
they are not expected by the UEs. This reduces the overall inter cell interference
and improves downlink user bit rates. It should be noted that CRS are not muted
in the six center sub-carriers.
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5.5
Carrier Aggregation
The 'Carrier Aggregation' Value Package contains 7 functions, Figure 3-53.
The 'DL 4CC Carrier Aggregation' function is new in L17.Q1.
The optional feature 4CC DL Carrier Aggregation Extension enables carrier
aggregation of up to four DL component carriers.
With Carrier Aggregation a UE may use resources from multiple cells. With 4CC
DL Carrier Aggregation Extension, the UE may use up to 4 DL CCs and 1 UL
CC at the same time.
The main benefits of 4CC DL Carrier Aggregation Extension are as follows:
• Enables bandwidth aggregation of three FDD carriers in DL, up to 60
MHz aggregated BW.
• More efficient use of scattered spectrum.
• Further increased UE downlink bitrate.
For VoLTE Interaction:
• If Enhanced PDCCH Link Adaption (PDCCH LA) is enabled and a
VoLTE bearer is configured, no data (VoLTE or other) will be scheduled
on SCells. This may give a throughput degradation for CA capable UEs
during VoLTE calls
• If Enhanced PDCCH LA is not enabled, there is no special handling of
VoLTE, and VoLTE traffic can be scheduled either on the PCell or an
activated SCell.
A UE configured with a SCell consumes more resources, one for the PCell and one
for each configured SCell, than a UE that only has a PCell, yet it is still counted as
one connected UE from the connected UE license perspective. As the 4CC DL
Carrier Aggregation Extension feature allows up to 3 configured SCells per UE,
the loading limit can be reached by fewer UEs than was previously possible.
Existing mechanisms with the right configuration ensure that SCell configuration
is stopped before the loading limit is reached and therefore prevents carrier
aggregation UEs from blocking the attachment of new UEs to the system.
The PUCCH resource dimensioning must be considered.
UE may use up to 4 downlink + 1 uplink CA supported only for FDD at the same
time. As result of the feature implementation further increased UE peak rates are
expected. However, the benefit decreases as the number of users with traffic
activity increases.
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The UL UE peak throughput is reduced in good radio conditions because of extra
HARQ ACK/NACK for the downlink transmission for the SCells to be sent
through PUSCH when the UE is configured with multiple SCells.
Ericsson Lean Carrier:
Ericsson Lean Carrier:
Current LTE reference signaling
User Data
causes interference between cells Throughput
Ericsson Lean Carrier
dynamically reduces reference
signaling by up to 80%, reducing
inter-cell interference
Interference
Interference
USER
DATA
USER
DATA
User Data
Throughput
Figure 3-53: Ericsson Lean Carrier Applying 5G concepts to today’s 4G LTE
5.6
Potential throughput
Calculated based on bandwidth, number of codewords and channel
condition (only used for deactivation decision as CQI is only reported
for activated SCells).
3CC DL Carrier Aggregation Extension L16B Enhancement
The largest Transport Block Size (TBS) that can be carried with 100 PRBs and
256QAM is 97896 bits according to 3GPP TS 36.213. Since the Transmission
Time Interval (TTI) is 1 msec this equates to a bit rate of 97.896 Mbps. Based on
this TBS the peak throughput of one 20 MHz Cell Carrier (CC) is 97.896 X 2 =
195.792 Mbps assuming 2X2 MIMO and 97.896 X 4 = 391.584 Mbps, assuming
4X4 MIMO.
In L16A the ‘3CC DL Carrier Aggregation Extension’ (FAJ 121 3084) optional
feature supports a maximum of two layers per carrier and the ‘4×4 Quad Antenna
Downlink Performance Package’ (FAJ 121 3076) does not support 4X4 MIMO
with carrier aggregation and the ‘256 QAM Downlink’ (FAJ 121 4422) does not
support more than two layers.
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The peak downlink throughput using 3 CC carrier aggregation is 3 X 195.792 =
587.376 Mbps as illustrated in Figure 3-54.
Largest TBS for 100 PRBs is
97896 bits
97896 bits in 1 msec
= 97.896 Mbps
2X2 MIMO:
97.896 X 2 = 195.792 Mbps
4X4 MIMO:
97.896 X 4 = 391.584 Mbps
L17A
*UE limited to 10 layers
L16B
20 MHz +
20 MHz +
256
QAM +
256
QAM +
MIMO:
= 195.792
= 391.584
MIMO:
256
20 MHz +
QAM +
= 195.792
20 MHz +
256
QAM +
= 195.792
20 MHz +
256
QAM +
= 195.792
20 MHz +
256
QAM +
CAT
16
978.96 Mbps
20 MHz +
256
QAM +
= 391.584
Figure 3-54: 4CC DL Carrier Aggregation Extension
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5.7
Uplink Carrier Aggregation
If we assume 6 out of the 100 uplink PRBs in a 20 MHz Cell carrier (CC) are
allocated for PUCCH the largest Transport Block Size (TBS) that can be carried
with the remaining 94 PRBs using 64 QAM is 68808 bits according to 3GPP TS
36.213. Since the Transmission Time Interval (TTI) is 1 msec this equates to a
bit rate of 68.808 Mbps. Based on this TBS the peak uplink throughput of one 20
MHz Cell Carrier (CC) is 68.808 Mbps.
3GPP TS 36.213 V13.1.1 (2016-03) Table 7.1.7.2.1-1
Assuming 6 PRBs in 20
MHz Cell Carrier are
reserved for PUCCH
the largest TBS carried
by remaining 94 PRBs
= 68808 bits
68808 bits in 1 msec
= 68.808 Mbps
Carrier 1
Band A
Carrier 2
Band B
Carrier 1 Carrier 2
64
68.808 Mbps
QAM
Inter-Band
20 MHz +
or
or
Intra-Band
137.616 Mbps
Band C
20 MHz +
Same
Digital Unit
Radio Node
(DUS31/41)
64
68.808 Mbps
QAM
Baseband
Radio Node
(5216/5212)
Figure 3-55: Uplink Carrier Aggregation
The ‘Uplink Carrier Aggregation’ (FAJ 121 4425) L16B optional feature
introduces support for uplink carrier aggregation of two inter-band noncontiguous or intra-band contiguous Cell Carrier combinations as specified in
latest 3GPP 36.101. This means that the peak uplink throughput using carrier
aggregation of two 20 MHz carriers assuming 64 QAM is used is 137.616 Mbps
(68.808 X 2) as illustrated in Figure 3-55.
Uplink Carrier Aggregation is not supported for intra-band non-contiguous
carriers, inter-band 3 CC DL + 2 CC UL combinations that use two bands or
FDD and TDD uplink combinations. UEs capable of 3 CC DL + 2 CC UL and 2
CC DL + 2 CC UL as well as UEs capable of just 2 CC DL + 2 CC UL are
supported. The aggregated Cell Carriers must also belong to the same DUS31,
DUS41, Baseband 5212 or Baseband 5216.
5.8
Uplink Carrier Aggregation Configuration
Uplink Carrier Aggregation can only operate in conjunction with downlink
carrier aggregation. The number of configured uplink aggregated carriers will
always be equal to or less than the number of configured downlink aggregated
carriers.
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The UE will have one uplink Primary Cell (PCell) and at most one secondary cell
(SCell) and will transmit the PUCCH in PCell only. SCells are first configured
with an RRC Connection Reconfiguration message and then activated with a
MAC Control Element. The total UE transmit power remains unchanged (23
dBm) independent of the number of UL component carriers. The UE receives
UL grants per activated cell, and the HARQ feedback is transmitted in the same
cell as where the grant was received. The UE controls on which component
carrier the UL data is transmitted if it receives more than one grant in one TTI.
eNodeB
ManagedElement
+-ENodeBFunction
+-EUtranCellFDD/TDD
networkSignallingValueCa = CA_NS_31
Enables additional spectrum emission requirements for CA according to 3GPP
TS 36.101, table 6.2.4A-1.
+-EUtranFreqRelation
+-EUtranCellRelation
sCellCandidate = ALLOWED
The cell indicated by the value of parameter cellrelation can be used as an
SCell CC for UEs that use this cell as their PCell CC for both UL and DL.
+-CarrierAggregationFunction
sCellActDeactUlDataThresh = 100 { 0..5000 }
If the minimum time needed to transmit all bits in all priority queues in UL of a
UE is higher than sCellActDeactUlDataThresh, activation of one or more
secondary cells is considered.
Unit: 0.1 Number of UL subframes
sCellActDeactUlDataThreshHyst = 90 { 0..5000 }
If minimum time needed to transmit all bits in all priority queues in UL of a UE
is less than sCellActDeactUlDataThresh minus
sCellActDeactUlDataThreshHyst, deactivation of one CC is considered.
Unit: 0.1 Number of UL subframes
Figure 3-56: Uplink Carrier Aggregation Parameters
By setting the ‘sCellCandidate’ parameter illustrated in Figure 3-56 above to
‘ALLOWED’ the cell relation may be used as a SCell for both uplink and
downlink Carrier Aggregation. As Multiple-Timing Alignment is not supported
the distance between the antenna of the PCell and the antenna of the SCell must
be less than 300m. In cases where the distance between the antenna of the PCell
and the antenna of the SCell is greater than 300m the ‘sCellCandidate’ parameter
should be set to ‘ONLY_ALLOWED_FOR_DL’ to allow downlink Carrier
Aggregation only. The ‘NOT_ALLOWED’ and ‘AUTO’ settings for the
‘sCellCandidate’ parameter have the same effect of excluding the cell relation as
a candidate for SCell for UEs using this cell as their primary component carrier
(PCell). A UE is evaluated for Carrier Aggregation by checking its CA band and
bandwidth combination support at initial attach, RRC connection reestablishment or incoming handover.
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An uplink CA Scell is selected from one of the downlink SCells so long as it is
uplink Carrier Aggregation capable and its frequency is supported by the UE. If
the minimum time needed to transmit all bits in all priority queues in UL of a UE
is higher than the setting of the ‘sCellActDeactUlDataThresh’ parameter
activation of a secondary cell is considered. The SCell is activated if either
uplink or downlink activation criteria are met. The UE is first scheduled on the
activated cell where it has the highest SINR. If it has enough power and buffer
contents left after scheduling on the first cell it will be scheduled on the second
cell as well.
If minimum time needed to transmit all bits in all priority queues in UL of a UE
is less than the value of the ‘sCellActDeactUlDataThresh’ parameter minus the
‘sCellActDeactUlDataThreshHyst’ parameter deactivation of the UL SCell is
considered. The SCell is deactivated if both uplink and downlink deactivation
criteria are met.
The new ‘networkSignallingValueCa’ parameter illustrated in Figure 3-56
enables additional spectrum emission requirements for Carrier Aggregation
according to 3GPP TS 36.101, table 6.2.4A-1 to be sent to the UE in the
additionalSpectrumEmissionSCell-r10 Information Element. The default setting
of ‘CA_NS_31’ according to 3GPP TS 36.101, table 6.2.4A-1 corresponds to no
additional spectrum emission requirements.
The ‘Carrier Aggregation’ (FAJ 121 3046/1) optional feature is a prerequisite for
Uplink Carrier Aggregation and will enable a static 2 CC DL + 2 CC UL
configuration. To support 3 CC DL CA + 2 CC UL CA the ‘3CC DL Carrier
Aggregation Extension’ (FAJ 121 3084) and ‘Dynamic SCell Selection for
Carrier Aggregation’ (FAJ 121 3063) optional features must be active.
5.9
Advanced Carrier Aggregation (FAJ 801 0568)
The ‘Advanced Carrier Aggregation’ Value Package contains 3 functions. The
‘Inter-eNB Carrier Aggregation’ and ‘Carrier Aggregation-Aware Inter
Frequency Load Balancing’ functions are enhanced in L17.Q1.
Included Functions:
› Inter-eNB Carrier Aggregation (Enhanced in L17.Q1)
› Carrier Aggregation-Aware IFLB (Enhanced in L17.Q1)
› Configurable SCell Priority
Figure 3-57: Advanced Carrier Aggregation (FAJ 801 0568)
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The ‘Inter-eNB Carrier Aggregation’ (FAJ 121 4469) optional feature makes it
possible for Rel-10 Carrier Aggregation capable UEs to receive data from cells
belonging to different eNodeBs. The eNodeB that has the serving cell (Master
eNB) will forward user-data over the X2 interface to the external eNB that has
the Scell (EScell). This feature makes it possible to use carrier aggregation in
scenarios where the carriers are not deployed on the same eNodeB. The term
‘External Secondary Cell’ (ESCell) illustrated in Figure 3-58 below is used to
denote a secondary cell that belongs to an external eNodeB.
The greater flexibility in selection of secondary cells for carrier aggregation
possible with the ‘Inter-eNB Carrier Aggregation’ optional feature allows the UE
to use a nearly optimal set of cells for Carrier Aggregation thus improving end
user experience in many scenarios. It also makes it easier to take advantage of
under-utilized eNodeBs by making it easier for them to be used in carrier
Aggregation scenarios.
The Nodes involved in inter eNodeB Carrier Aggregation must be time and phase
synchronized. This feature is only supported for FDD networks and only on the
DUS31/41 hardware.
The X2 one-way latency between master and external eNodeB must be lower
than 9 ms, and for best performance 5 ms or less is preferred. This delay is
constantly monitored by the ‘Inter-eNB Carrier Aggregation’ optional feature and
when the maximum delay exceeds 9 ms, or the link quality is poor the inter
eNodeB Carrier Aggregation activity is stopped between the affected eNodeB
pair. The link will be periodically tested and Carrier Aggregation resumed
between the pair when appropriate.
Carrier
Aggregation
possible in
scenarios
where the
carriers are not
deployed on the
same eNodeB
External eNodeB
Support in 52 series
hardware added in L17.Q1
FDD PCell + TDD SCell
supported in L17.Q1
52xx
52xx
Master
Master eNodeB
eNB
X2
S
1
Small eNodeB
52xx
52xx
Macro eNodeB
X2
UEs in coverage
area of Small cell
can now perform
Carrier
Aggregation with
Macro cell
Figure 3-58: Inter-eNB Carrier Aggregation
Another typical use-case illustrated in Figure 3-58 above is where a small cell is
deployed in the coverage area of a macro but supporting fewer frequencies than
the macro. Without this feature UEs in the coverage area of the small cell could
not perform carrier aggregation with the frequencies of the macro cell however
with this feature it is now possible.
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5.9.1
Inter-eNB Carrier Aggregation Performance
The inter-eNodeB Carrier Aggregation performance is dependent on the X2 and
processing delays. In the illustration here we can see how these delays affect the
standard 8 TTI HARQ loop meaning that the UE cannot be scheduled every TTI.
•
To prevent control channel scheduling conflict with local UEs the
Modulation Coding Scheme is limited to 27 for inter eNodeB traffic.
This means that inter-eNodeB Carrier Aggregation cannot achieve the
same peak bit rates as intra-EnodeB or Elastic RAN Carrier Aggregation.
•
The graph shown here illustrates the peak throughput Efficiency Fraction
for an External SCell with 20 MHz Bandwidth for X2 latencies between
1 and 9 msec.
Scheduling
at eNodeB
Retransmission in response to 1N (NACK)
Non-ESCell-UE HARQ
response timing loop
UE ACK (A) or NACK (N)
UE cannot be scheduled every TTI in ESCell
Scheduling
at eNodeB
ESCell-UE HARQ
response timing loop
3GPP TS 36.213 V13.1.1 Table 7.1.7.2.1-1
To prevent control
channel scheduling
conflict with local
UEs the Modulation
Coding Scheme is
limited to 27 for inter
eNodeB traffic.
20 MHz Bandwidth ESCell
Efficiency Fraction
UE ACK (A) or NACK (N)
X2 Latency (msec)
Figure 3-59: Inter-eNB Carrier Aggregation Performance
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5.9.2
Inter-eNB Carrier Aggregation Parameters
The configuration process for inter eNodeB Carrier Aggregation is very similar to
legacy Carrier Aggregation and makes it possible to set the ‘sCellCandidate’
parameter to ‘ALLOWED’ or ‘ONLY_ALLOWED_FOR_DL’ for up to 12
‘ExternalEUtranCellFDD’ MOs as illustrated in Figure 3-60 below. External
cells will automatically be excluded by the ‘Uplink Carrier Aggregation’ optional
feature so setting the ‘sCellCandidate’ parameter to ‘ALLOWED’ or
‘ONLY_ALLOWED_FOR_DL’ is effectively the same.
eNodeB
ManagedElement
+-ENodeBFunction
+-EUtranCellFDD
+-EUtranFreqRelation
+-EUtranCellRelation
EUtranCellRelationId = ExternalEUtranCellFDDId
sCellCandidate = ALLOWED or ONLY_ALLOWED_FOR_DL
esCellCaConfigurationAvail = ENABLED
If indicated cell is currently able to serve as ESCell. New read-only parameter
+-EUtraNetwork
+-ExternalENodeBFunction
+-TermPointToENB
New read-only parameter
interEnbSwCompatibilityState = COMPATIBLE
Reflects whether the eNodeBs designated in the endpoints
between eNodeBs have inter-eNodeB-compatible capabilities.
+-TermPointToLbm New MO
operationalState
TermPointToLbmId
+-ExternalEUtranCellFDD
New read-only parameter
remoteCellState = ENABLED
Reflects whether the indicated cell is currently able to serve as an SCell.
Figure 3-60: Inter-eNB Carrier Aggregation Parameters
The new 'termPointToLbm' MO class illustrated in Figure 3-60 above, is created
by the system when an eNB establishes communication between its own and a
partner's LBM (LTE baseband modules) for the purposes of Inter-eNB Carrier
Aggregation. The need for Inter-eNB Carrier Aggregation configuration is
triggered when the 'sCellCandidate' parameter is set to 'ALLOWED' or
'ONLY_ALLOWED_FOR_DL' and the referenced SCell is external.
The ‘esCellCaConfigurationAvail’, ‘interEnbSwCompatibilityState’ and
‘remoteCellState’ read-only parameters illustrated in Figure 3-60 above are also
introduced with the ‘Inter eNodeB Carrier Aggregation’ optional feature.
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5.10
Multi-carrier Load Management (FAJ 801 0424)
The 'Multi-carrier Load Management' Value Package contains 6 functions. The
'Inter-Frequency Load Balancing' and 'UE Throughput-Aware IFLB' functions
are enhanced in L17.Q1.
Included Functions:
› Best Neighbor Relations for Intra-LTE Load Management
› Coverage-Adapted Load Management
› IFLB Activation Threshold
› Inter-Frequency Load Balancing (Enhanced in L17.Q1)
› Limited Uplink-Aware IFLB
› UE Throughput-Aware IFLB (Enhanced in L17.Q1)
Figure 3-61: Multi-carrier Load Management (FAJ 801 0424)
5.11
Prescheduling
Prescheduling is a feature that minimizes the uplink round trip time by blindly
giving PUSCH grants to UE in advance. This is achieved by sending UL
scheduling grants without explicit scheduling request from the UE side.
Prescheduling grants are only sent in low load.
› Prescheduling is a method to minimize UL delay (and
hence round trip time) by means of blindly giving PUSCH
grants to a UE in advance, without receiving buffer status
information (SR, BSR).
Scheduling request is
no longer mandatory
to get UL grant
SR
Grant
Figure 3-62: Prescheduling
Prescheduling is used to improve user plane and initial control plane latency
which leads to the following enhanced areas:
• Reduced download time, especially for complex web pages where the
improvement is significant.
• Clear improvement of the so-called speed-tests (pingtests). Different versions
of speed-test are commonly used by smart phones users to measure bandwidth
quality.
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• Faster connection set-up times.
The Operator benefits are:
• Reduced End-user latency
• Low latency is important for small data transmission and is typically
measured by broadband network test applications
Pre-scheduling is persistently allocating UL transmission resources to the device,
therefore User plane latency is reduced due to less signaling.
Pre-scheduling allocates transmission opportunities in the uplink even if no
scheduling request has been received from the device. The device has to respond
even if there is no data to send.
An example of a Round Trip Delay measurement with prescheduling OFF is
illustrated in Figure 3-63 below.
Delay Breakdown
PING 0
SR encod. and alignment
5
5
SR
1
PING
15
20
PING
eNB processing
3
Grant
1
10
3GPP specified delay
4
1
PING
PING
1
3
PING
Core network delay
2
1
Time [ms]
1
23 ms Total round trip delay *
*Note: Numbers are example only
Figure 3-63: Prescheduling OFF
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An example of a Round Trip Delay measurement with prescheduling ON is
illustrated in Figure 3-64 below.
Delay Breakdown
PING 0
Grant
PING
5
10
PING
3GPP specified delay
4
1
PING
PING
1
3
PING
Core network delay
2
1
1
15
20
Time [ms]
13 ms Total round trip delay *
*Note: Numbers are example only
Figure 3-64: Prescheduling ON
5.11.1
Prescheduling Parameters
The parameters that control the Prescheduling feature are illustrated in Figure 365 below.
ManagedElement
+-ENodeBFunction
initPreschedulingEnable
Indicates that prescheduling is enabled during connection setup
phase
+-PredchedulingProfile
preschedulingDataSize
Granted data size during prescheduling period.
preschedulingDuration
Prescheduling is stopped if there are no UL
transmissions during this time.
preschedulingPeriod
Period in ms lapsed between granted prescheduling
instances
Figure 3-65: Prescheduling Parameters
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5.12
LTE transmission modes Downlink transmission modes
The LTE transmission modes for downlink is shown in Figure 3-66. The 4x4
Quad Antenna DL Performance Package provides support for up to rank 4 DL
transmission for UEs that support it (UE Category 5). This enables 4-way to
transmit diversity and 4-way spatial multiplexing. It also results in improvements
to downlink coverage and capacity, especially in high-quality channel conditions.
This gives twice the peak rate compared to rank 2.
TM3 (open loop spatial multiplexing) as well as TM4 (closed loop spatial
multiplexing) is supported for both FDD and TDD.
With this feature operator will be able to configure the 4TX cells with either TM3
or TM4 for both TDD and FDD. Dynamic switching between the modes may be
implemented later.
For TDD, it will support TDD ul-dl subframe configuration 2, and special
subframe configurations 6 and 7. Supported 4-layer capable UE category is 5.
This feature uses existing Key Performance Indicators (KPIs) for system
performance evaluation and monitoring. Significant DL throughput gain is
expected with this feature compared to 4x2 MIMO.
It is preferable to measure the PM counters in the network having high traffic
activity, and compare calculated DL cell throughput to the performance achieved
by 4X2 MIMO under the same conditions. Other DL throughput related KPIs
such as DL PDCP UE throughput can also be used to measure DL throughput
gain. There should be significant improvement on other KPIs as well compared to
4x2 MIMO.
The feature is license controlled. The licensing MO instance name is
‘QuadAntDlPerfPkg4x4’. As a prerequisite, the following feature shall be
enabled:
• 4x2 Quad Antenna Downlink Performance Package, FAJ 221 3041.
For TDD, it will support TDD ul-dl subframe configuration 2, and special
subframe configurations 6 and 7.
In both FDD and TDD, this feature requires the following RAN features to be
active:
• Dual-Antenna Downlink Performance Package
• 4x2 Quad Antenna Downlink Performance Package
This feature cannot be enabled if the following feature is active:
• TM9 8x2 Octal Antenna Downlink Performance Package
• Combined Cell
• Octal Antenna Uplink Performance Package
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The recommended antenna configuration depends on the extent that 4x4 MIMO
capable UEs are deployed in the network compared to 4x2 MIMO only capable
UEs.
• When there are relatively few 4x4 MIMO capable UE’s in the cell, two
columns of closely spaced cross-polarized antenna elements are
recommended in order to maximize beam forming gain.
• When there are relatively many 4x4 MIMO capable UE’s in the cell,
two spatially separated columns of cross-polarized antenna elements are
recommended in order to maximize the rank of the RF channel.
There is a fundamental trade-off between maximizing beamforming gain versus
maximizing the rank of the RF channel. The former improves cell edge
performance for 4x2 MIMO capable UEs. The latter improves peak throughput
for 4x4 MIMO capable UEs only.
When switching from 2TX to 4TX deployment:
• It is necessary to re-tune the ‘cfiMode’, CRS scaling, HO thresholds
(‘qRxLevMin’, A2/A5/B2 thresholds) settings that may have been
optimized for 2TX but are not necessarily optimum for 4TX.
• For the same cell power and CRS scaling, the measured RSRP at a
given location in the cell configured will be lower by 3dB going from
2TX to 4TX. This is due to the way RSRP is defined by 3GPP standard.
The change in RSRP levels is what necessitates re-tuning of HO
thresholds.
• Consider setting ‘cfiMode’ to 4 or 5. This helps mitigate the fact that
there are fewer CCEs for PDCCH with 4TX compared to 2TX since the
introduction of 2 additional CRS comes at the expense of REs available
for PDCCH and PDSCH.
The Adjustable CRS Power feature sets default values for two parameters,
‘crsGaincrsGain’ and ‘pdschTypeBGain’. However, these default values are not
always suitable for 4TX MIMO cells of large size. In large cells, these default
values must be tuned to maximize the performance for feature ‘4×4 Quad
Antenna Downlink Performance Package’. If the cell is coverage-limited, the
parameters are tuned based on network deployment density. If the cell is
interference-limited, the parameters are tuned based on network load.
In release 11, enhanced support for ‘CoMP’ (Co-ordinated Multipoint
Transmission/reception) with transmission mode 10 is introduced.
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Different MIMO related features are discussed in ‘LTE L17 Advanced Radio
Network Features’ course.
Rel-8
Rel-9
› TM1 “Single-antenna port”
› TM2 “Transmit diversity”
› TM3 “Open-loop spatial multiplexing”
› TM4 “Closed-loop spatial multiplexing”
› TM5 “Codebook based MU-MIMO”
› TM6 “Rank-1 closed-loop spatial multiplexing”
› TM7 “Single layer transmission”
› TM8 “Dual-layer transmission”
1, 2 or 4 antenna ports
with cell-specific
reference signals (CRS)
UE-specific reference signals for
demodulation (DM-RS)
Rel-10 › TM9 “Up-to-8 layer transmission”
+ 1 CSI-RS resource for
enhanced feedback
Rel-11 › TM10 “TM9 + CoMP support”
+ multiple CSI-RS resources,
CSI-IM – new interference measurements,
antenna port co-location, PDSCH mapping
flexible configurability of RS sequences
Figure 3-66: LTE transmission modes Downlink transmission modes
5.12.1
Which MIMO Mode is Best?
The best transmission mode to use will depend on the antenna configuration as
summarized in Figure 3-67.
› 2TX (Crosspol):
– Best mode is TM3 (OLSM)
– There is little or no benefit in running TM4 (CLSM) for 2TX.
› 4TX (Dual crosspol):
– Best mode for 4TX radio is TM4 (CLSM) (4x4,4x2).
› 8TX
– TM8 is today most efficient. However TM8 was introduced in Rel-9,
thus not all terminals supports TM8. Then TM7 or TM3 will be used
– TM8 is as TM7 only supported in TDD
– TM9 offers higher capacity and cell edge bit rates
– TM9 will be applicable for both FDD and TDD
– In order to run 8 layers spatial multiplexing TM9 is needed
Figure 3-67: Which MIMO Mode is Best?
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VOLTE Impact on BB Throughput & DBS
6
The VoIP co-exist together with Packet Switched (PS) data in a network. PDCCH
can be the limiting resource when VoIP traffic is present in the system. This is
not normally the case for other PS services. If there are large numbers of VoIP
users, other PS services are blocked and capacity is not fully used. PS throughput
will be zero when the system reaches the PDCCH limitation. VoIP is a GBR
service, which means that it has priority in the scheduler before other PS services
like mobile broadband. VoIP is given QCI = 1 marking it as GBR.
The introduction of DBS and SABE is expected to increase the capacity in mixed
scenarios:
•
Increased throughput for PS users for the same amount of VoIP users in a
cell
•
Increased number of VoIP users per cell for the same PS throughput
The Delay-Based Scheduling and Grant Estimation feature provides improved
average Uplink (UL) and Downlink (DL) throughput for Mobile Broadband
(MBB) services in a mixed scenario with both Voice over IP (VoIP) and MBB
services while not reducing the VoIP capacity, specifically when a large number
of VoIP users are active in the cell.
It is also possible to increase the VoIP capacity instead of improving the average
UL and DL throughput for MBB services.
› RR: Round Robin
Scheduler with QoS
aware scheduling, VoIP
users will always have
higher priority than Data
Users.
› DBS: Delay based
Scheduling and Grant
Estimation used.
Delay based scheduling gains seen in at high VoIP load, where the scheduling capacity is limited
Figure 3-68: VOLTE Impact on BB Throughput & DBS
By applying an age-dependent weight to VoIP packets, scheduling resources are
only used for VoIP services when this is required to avoid exceeding the ‘Packet
Delay Budget (PDB)’. This results in the scheduling of several VoIP packets
during a scheduling instance and efficient use of the RBS resources. Figure 3-68
and Figure 3-69 present the simulation results with the feature Delay Based
Scheduling on and without the feature (Round Robin used instead).
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Figure 3-69: VOLTE Impact on BB Throughput & DBS
When the ‘schedulingAlgorithm’ parameter for a particular QCI is set to
‘DELAY_BASED’ as illustrated in the Figure 3-70 for QCI 1, the scheduler will
give it a small scheduling weight before what is known as the ‘bundling time’.
This weight will slowly increase as the age of the oldest packet in the buffer
increases. Once the age of the oldest packet reaches the ‘bundling time’ the
scheduling weight will be sharply increased. Although this will not guarantee
that the data is scheduled it will greatly improve its chances. At low load the data
could be scheduled before bundling time but at high load it may be scheduled
after the ‘bundling’ time. The ‘bundling time’ is hardcoded to 40 msec.
Scheduling
weight
Larger Weight after bundling time,
but not guaranteed scheduling
eNodeB
ManagedElement
+-ENodeBFunction
+-QciTable
+-QciProfilePredefined=qci1
schedulingAlgorithm = DELAY_BASED
Small weight increase
before reaching the
bundling time
Bundling Time
(Hard coded to 40 msec)
Age of oldest
packet
Figure 3-70: VOLTE Impact on BB Throughput & DBS
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Summary
7
The participants should now be able to:
3
Explain LTE Integrity KPIs performance and related parameters
3.1 Describe different LTE integrity KPIs & counters related to Throughput,
Latency
3.2 Explain associated parameters related to different Integrity KPIs
3.3 Relate QOS and Scheduling profile for integrity optimization
3.4 Analyze steps to effectible troubleshoot throughput issues
3.5 Explore related features and associated parameters for throughput
enhancement
3.6 Measure VOLTE effect on throughput and data services KPIs
Figure 3-71: Summary of Chapter 3
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Issue Analysis, Improvements and Case-Studies for Integrity KPIs
4 Issue Analysis, Improvements and CaseStudies for Integrity KPIs
Objectives
After completion of this chapter the participants will be
able to:
4
4.1
4.2
4.3
4.4
Classify the issues, analyze them for improvements and discuss
few case studies for Integrity KPIs.
Identify steps for UL/DL Throughput investigation & essential
check
Describe DL & UL throughput optimization strategy
Discuss different cases of throughput & Latency degradation
Analyze cases based on low throughput high latency exercises
and provable solutions
Figure 4-1: Objective of Chapter 4
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Case-1: DL Throughput improvement
1
A Network has been observed to have low downlink average throughput, but
while changing the scheduling algorithm from proportional fair high to
proportional fair low, the average cell throughput has improved by around 30%.
Cell capacity also shows significant improvement, but the algorithm has reduced
cell edge user throughput. Hence, for throughput KPI optimization the correct
scheduling algorithm does play an important role.
In many scenarios, cell capacity can be increased by using the low fairness
versions of the proportional fair scheduling algorithms. These algorithms increase
the share of the resources given to users with good channel conditions. This leads
to an overall increase in capacity.
The minimum rate feature helps in giving a consistent cell edge throughput with
the minimum rate Quality of Service characteristic. The basic concept is that
flows experiencing a bit rate lower than their configured minimum bit rate will be
prioritized before flows that have a bit rate above their configured minimum rate.
As mentioned above, Proportional Fair scheduling feature takes into account both
scheduled data rate and radio channel quality. The tradeoff between user fairness
and the system performance can be tuned by Channel Quality Fraction (CQF).
The CQF controls how big portion of channel quality should contribute to a user's
priority.
OBJECTIVE: To check Impact on Dl Avg Sector Throughput by changing
Scheduling Algorithm.
Proportional Fair(High) to Proportional Fair Low.
1.Proportional Fair High(2): Pros and Cons?
Pros- Each user Treat Equally.
Cons- User which is in Good RF Condition not get RB as per
Desired.Finally Overall Average Sector/UE Throughput Dip .
2. Proportional Fair Low(0): Pros and Cons?
Pros- Avg sector/UE Throughput improved (30-40)% Theoretically while at
the same time cell edge user get at least Minimum bit rate. Capacity
improved.
Cons- Less fair towards Cell edge user.
Figure 4-2: CASE 1: DL Throughput
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2
Case-2 UL-Throughput improvement
An Operator has observed a low UL throughput; further observations also
indicates towards a poor throughput in few cells in some areas of the network.
The throughput plot shows the low throughput cells and areas, as shown in Figure
4-3.
After checking the QOS parameters and some other investigations the
optimization team has suggested the following parameter changes.
‘pZeroNominalPucch’: From -117 to -103
‘pZeroNominalPusch’: From -106 to -96.
P0_PUSCH is the target PSDrx, for each resource block, set according to the
parameter ‘pZeroNominalPusch’. It is common for all UEs in the cell
‘P0_PUCCH’ is the target PSDrx, corresponding to ‘P0_PUCCH’ from PUSCH.
It is set according to the parameter ‘pZeroNominalPucch’ and signaled separately
on BCCH System Information Blocks (SIBs)
Increasing the values of the ‘pZeroNominalPusch’ and ‘pZeroNominalPucch’
parameters result in higher signal power, but will also result in increased intercell interference, which may affect cell edge UE. Decreasing the values of the
parameters will have the opposite effect.
With parameter change ‘pZeroNominalPucch’ from -117 to -103 and
‘pZeroNominalPusch’ from -106 to -96 gave good improvement for UL
throughput, the UL-throughput plot is shown in Figure 4-3 below.
An Operator complain about low UL throughput, stats shows the
low throughput in some cells.
Changed the parameter and get good improvement in UL
throughput.
pZeroNominalPucch: From -117 to -103
pZeroNominalPusch: From -106 to -96.
What may be negative effect of this?
Post
Pre
Figure 4-3: CASE 2: UL Throughput Improvement
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With fractional path-loss power control, an operator configurable cell specific
pathloss compensation factor (α) is introduced. Alpha < 1.0, allows users to be
received with variable PSD depending on their path loss i.e. the user with small
path loss will be received with high PSD. This parameter is broadcast in the cell
in SIB2. The broadcast alpha is used for Semi Persistent Scheduling and dynamic
scheduling, while ‘alpha’ = 1 is used for RA response.
With fractional path-loss power control, it is easier to set power control
parameters that will enable UL peak rate in the cell without sacrificing cell edge
performance too much. Besides, trade-off will be possible between average and
cell edge throughput.
The benefit of the features can be observed via the uplink user throughput
distribution taken over a sufficiently long period of time. With fractional pathloss power control, the trade-off between peak, average and cell-edge throughput
levels should be achieved with a combined setting of the parameters,
‘pZeroNominalPusch’ and ‘alpha’.
By varying the value of alpha for a given ‘pZeroNominalPusch’ (P0) value.
Uplink received power and user throughput is reduced when lowering alpha,
given the interference level is constant. Thus, a lower ‘alpha’ should be
accompanied by a higher P0 to maintain throughput at the cell edge
Case-3: LTE Latency Issue
3
For a Network the overall latency degraded. Overall downlink latency and
latency per QCI in Figure 4-4 below shows, the latency of QCI1 degraded most.
The overall latency degraded and the latency of QCI1 degraded most
Figure 4-4: Case 3: LTE Latency issue
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3.1
Case-3: Investigation analysis
Parameter audit and the investigation of recent network changes, followed by the
configuration logs were checked for the said duration, while during the
degradation. Configuration Log investigation shows the major reason is that the
feature ‘SS DRX’ was activated during the time, Figure 4-5.
› The degradation occurred around 17th Feb to 23rd Feb
› Configuration Log investigation shows the major reason is feature SS
DRX
Before
After
2 questions were submitted:
1. Why did SS DRX impact the Latency ?
2. Why was QCI1 impacted most ?
Figure 4-5: Case 3: Investigation Analysis
‘Service-specific DRX’ feature allows the operator to configure, default
connected-mode DRX parameters and service-specific connected mode DRX
parameters.
Service specific connected mode DRX parameters refer to DRX settings that
change depending on the services that are established. This is based on the QCI
values of the bearers. The connected mode DRX parameters can be adjusted
based on the services that are currently in use by the UE.
Service Specific DRX Introduction
SS DRX Overview:
Service-specific DRX allows the operator to configure the following:
• Default connected-mode DRX parameters
• Service-specific connected mode DRX parameters
SS DRX Benefit:
The connected mode DRX parameters can be adjusted based on the
services that are currently in use by the UE.
• This feature allows a mobile broadband connected mode DRX
configuration to be used by default, but to switch to a VoLTE-specific
DRX value when a VoLTE call is established.
• Significant Improvement to Battery Saving during a Voice Call.
Figure 4-6: Case 3: Investigation Analysis
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Service-specific connected mode DRX parameters can be considered to be redefined. Instead of having one setting for all the services, a set of DRX settings
can be configured by operator, providing the “best fit” DRX settings for certain
services. DRX configuration is chosen based on current UE’s primary service
configured by the operator.
Each QCI associates one DRX profile, based on its services characteristics. The
same DRX profiles can be set to multiple QCIs. Each QCI has ‘drxPriority’, a
higher value indicates a higher priority for the associated DRX profile if multiple
QoS are serving a UE. Among QCIs, ‘drxPriority’ should be set with a unique
value unless the same DRX Profile is associated for those QCIs. If two QCIs are
configured with the same ‘drxPriority’ values but different ‘drxProfiles’, eNB
could randomly pick one of the profiles for DRX settings. DRX configuration for
ANR CGI measurement takes a higher priority than QCI based DRX
configurations
3.2
Case-3 Investigation for Service Specific DRX
The service specific DRX allowed the oprator to set short DRX cycle and long
DRX cycle. A packet can arrive at the eNB when the UE is in SLEEP mode This
means that the packet will be stored in the eNB buffer until the UE is in WAKE
mode and this causes Extra Latency. DRX is a balance between latency and
battery saving. Figure 4-7 below illustrate the function of SS DRX.
Why SS DRX impact the Latency
› A packet can arrive at the eNB when the UE is in SLEEP mode
› This means that the packet will be stored in the eNB buffer until the UE is in WAKE
mode
› This causes Extra Latency
› DRX is a balance between latency and battery saving
Extra latency time
eNB receives packet for UE,
but stores it in the buffer until UE had finished DRX cycle
SLEEP
longDRX-Cycle
CycleStartO
ffse
UE monitors the PDCCH
One successful decoding of PDCCH frame
Short DRX is only for one cycle before
Starts the inactivity time
going to long DRX shortDrxCycleTimer =1
over the air
Ue Mode DurationTimer = 10ms
WAKE
Packet transmitted
Packet held in buffer
eNB Buffer
drx-inactivity timer
shortDRX-
longDRX-Cycle
UE monitors the PDCCH
UE monitors the PDCCH Cycle
UE monitors the PDCCH
Figure 4-7: Case 3: Investigation Analysis
3.3
Case-3 DRX Profile Parameter Optimization
The UE specific DRX and the ‘ServiceSpecificDrx’ are optional features, with
both the feature licenses, the operator is able to configure an extended DRX
profiles table and can map a DRX profile to QCI and set DRX priority.
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Up to 19 DRX profiles can be configured by operator, each profile contains two
DRX configurations for UEs supporting or not supporting short DRX
respectively. Under the same DRX profile, ‘longDrxCycleOnly’ does not have to
be the same as ‘longDrxCycle’, so advantage of UE’s capability on supporting
shortDrxCycle can be well taken.
‘QciProfileOperatorDefined’ (or Predefined) ‘drxPriority’, the relative priority
among the DRX profiles, i.e. if the bearer that is setup with this QCI has a higher
DRX priority than any of the existing bearers, the DRX configuration will be set
to those selected by the ‘drxProfileId’ for this QCI. The ‘drxPriority’ has to be
unique across all the configured ‘QciProfilePredefined’ and
‘QciProfileOperatorDefined’ MOC instances except for instances where the
drxProfileId is the same. That is, instances that share the same ‘drxProfileId’ may
have the same ‘drxPriority’ value. Also note that larger drxPriority values
indicate higher relative priority. Change takes effect: Object unlocked. Range: 0
to 100, Default=0
In this case QCI 1 has highest ‘drxPriority’= ‘10’ and the other parameters set for
QCI 1 is not correctly optimized. Let’s analyze the set parameters for QCI1
shown in Figure 4-8.
The value of ‘longDrxCycle’ is in number of sub-frames. If ‘shortDrxCycle’ is
configured, the value of ‘longDrxCycle’ shall be a multiple of the
‘shortDrxCycle’ value. The ‘longDrxCycleOnly’ value is used as ‘longDrxCycle’
when the UE does not support ‘shortDrxCycle’. The value of
‘longDrxCycleOnly’ is in number of sub-frames.
Why QCI1 was impacted most
Current setting
› The QCI 1 DRX profile need to be optimized.
Figure 4-8: Case 3: Investigation Analysis
The parameters can be understood below as:
• ‘DrxProfile’-‘drxRetransmissionTimer’: Specifies the maximum
number of consecutive PDCCH-subframe(s) as soon as a DL
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retransmission is expected by the UE. TS36.331 Ch. 6.3.2, RRC
parameter ‘drx-RetransmissionTimer’.
Change takes effect: Object unlocked, Default=PSF2, Range: 0,1,2,3,4,5,6,7
• ‘DrxProfile’-‘shortDrxCycle’: Specifies the consecutive subframes
between on-duration phases, i.e. the period of re-occuring onduration phases. The parameter is applied when the UE follows the
short DRX cycle. The parameter is ignored if ‘shortDrxCycleTimer’
= 0. In that case ‘longDrxCycle’ is applied and the UE follows the
long DRX cycle only. Corresponds to 3GPP information element
‘shortDRX-Cycle’.
Dependencies: The use of ‘shortDrxCycles’ is disabled if the
attribute shortDrxCycleTimer = 0.
Change takes effect: Object unlocked, Default=SF40, Range: 0,1,2,3,4,5, 6…,15
• DrxProfile-‘shortDrxCycleTimer-long’: Specifies the number of
consecutive subframes the UE must follow the short DRX cycle after
the DRX Inactivity Timer has expired. Value in multiples of
shortDRX-Cycles. A value of 1 corresponds to 1 * ‘shortDRXCycle’, a value of 2 corresponds to 2 * ‘shortDRX-Cycle’ and so on.
Corresponds to 3GPP timer drxShortCycleTimer. The value 0 means
that short DRX cycles are not used.
Change takes effect: Object unlocked, Range: 0 to 16, Default=4
Case-Study 4: Low throughput during High Load
4
The customer has reported that on 5 Mhz sites which cover special events, the
users have no significant throughput when there are high number of RRC
connected users in the cell.
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The Scheduling algorithm is set to Proportional Fair Low. This feature makes it
possible to benefit from the fact that different users experience different radio
conditions at a certain time. By prioritizing users experiencing good channel
quality, a higher throughput can be achieved, compared to the Resource Fair
algorithm. However, to avoid some users being allocated too few or no resources
due to poor channel quality, fairness is provided by also considering the average
rate in scheduler prioritization.
› Case Details:
Special event sites with 5 MHz
Scheduling algorithm is set to Proportional Fair Low
› Proportional Fair Low:
– Benefit from the fact that different users experience different radio conditions at
a certain time.
– A higher throughput can be achieved when compared to Resource Fair
algorithm
– It prioritizes users experiencing good channel quality
– To avoid some users being allocated too few or no resources due to poor
channel quality, fairness is provided by taking into account the average rate in
scheduler prioritization
Figure 4-9: Case-Study 4: Reported issue
4.1
Exercise 1 – Analyze ROP files
Collected counters (ROP file excel format) are provided by instructor and kept at
\Exercises\ROP_files\
Exercise 1: Analyze the ROP files in order to determine why low throughput is
experienced when a high number of users are connected to the cell. Analyze the
ROP files in excel format given by instructor, in order to find the cell and time
period where low downlink throughput is observed.
Hints: Use the KPI files (given excel files) to get an overview of the downlink
throughput.
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Figure 4-10 is a brief introduction for exercise 1.
› Collected data:
ROP files: \Exercises\ILL00081_ropfiles\ILL00081_ropfiles
› Analyze the ROP files in order to determine why low
throughput is experienced when a high number of users are
connected to the cell.
› Use the ROP files (excel) in order to find the cell and time
period where low downlink throughput is observed.
› Hints:
–
Use the chart option in the provided KPI excel to get an overview of
the downlink throughput.
Figure 4-10: Exercise 1 – Analyze ROP files
4.1.1
Exercise 1 – Answer
A Cell ILL00081_7A_1 starts to experience roughly no throughput at 10-28
16:30 PM and lasts tills 10-28 20:15 PM which is roughly 4 hours’ duration.
› Cell ILL00081_7A_1 starts to experience roughly no
throughput at 28 Oct 16:30 and lasts tills 28 Oct 20:15 which is
roughly 4 hours.
Figure 4-11: Exercise 1 - Answer
4.2
Exercise 2: Possible cause for throughput degradation
Once you have identified the cell and time-period when the problem starts to
occur then we can move onto determining the possible causes for throughput
degradation.
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The next step is to list counters which can indicate possible bottlenecks to
validate.
Hints: In order to have good throughput; the RF environment needs to be good as
well. List counters which can be used to validate the RF environment
› Once you have identified the cell and time period when the
problem starts to occur then we can move onto determining
the possible causes for throughput degradation.
› The next step is to List counters which can indicate
possible bottlenecks to validate.
› Hints: In order to have good throughput then the RF
environment needs to be good as well. List counters which
can be used to validate the RF environment?
Figure 4-12: Exercise 2:
4.2.1
Exercise 2 – Answer UL/DL poor RF counters
Name some counters related to UL and DL interference in Figure 4-13
› UL Interference:
pmRadioRecInterferencePwr : The measured Noise and
Interference Power on PUSCH,
› DL Interference:
pmRadioUeRepCQIDistr: Rank 1 (TX Diversity)
pmRadioUeRepCQIDistr2: Rank 2 (MIMO)
Figure 4-13: Exercise 2 - Answer
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4.2.2
UL Noise and Interference
The Power on PUSCH can be observed with pmRadioRecInterferencePwr’ which
gives the measured noise and interference power on PUSCH, according to
36.214.
› UL Interference:
pmRadioRecInterferencePwr : The measured Noise and Interference
Power on PUSCH, according to 36.214.
PDF ranges:
[0]: N+I <= -121
[1]: -121 < N+I <= -120
[2]: -120 < N+I <= -119
[3]: -119 < N+I <= -118
[4]: -118 < N+I <= -117
[5]: -117 < N+I <= -116
[6]: -116 < N+I <= -115
[7]: -115 < N+I <= -114
[8]: -114< N+I <= -113
[9]: -113 < N+I <= -112
[10]: -112 < N+I <= -108
[11]: -108 < N+I <= -104
[12]: -104 < N+I <= -100
[13]: -100 < N+I <= -96
[14]: -96 < N+I <= -92
[15]: -92 < N+I
Figure 4-14: Exercise 2 – Answer
DL Interference can be measured with ‘pmRadioUeRepCQIDistr’: Rank 1 (TX
Diversity) ‘pmRadioUeRepCQIDistr2’: Rank 2 (MIMO), PDF counters, Figure
4-15.
› DL Interference:
pmRadioUeRepCQIDistr: Rank 1 (TX Diversity)
pmRadioUeRepCQIDistr2: Rank 2 (MIMO)
PDF ranges:
[0]: CQI = 0
[1]: CQI = 1
[2]: CQI = 2
[3]: CQI = 3
[4]: CQI = 4
[5]: CQI = 5
[6]: CQI = 6
[7]: CQI = 7
[8]: CQI = 8
[9]: CQI = 9
[10]: CQI = 10
[11]: CQI = 11
[12]: CQI = 12
[13]: CQI = 13
[14]: CQI = 14
[15]: CQI = 15
Figure 4-15: Exercise 2 – Answer cont’d
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4.2.3
PDCP Layer counters
Name some counters, provide the number of packets received, transmitted, and
discarded at the PDCP layer. Write down the answers in Figure 4-16 below.
➢PDCP Layer counters: The following counters will provide
the number of packets received, transmitted, and discarded
at the PDCP layer
pmPdcpPktTransDl
pmPdcpPktReceivedDl
Figure 4-16: Exercise 2 – Answer cont’d
pmPdcpPktDiscDlPelr
pmPdcpPktDiscDlPelrUu
4.2.4
RLC Layer counters
The counters below provide an indication for the total number of successful and
unsuccessful transmissions at the RLC layer. ‘pmRlcArqDlAck’,
‘pmRlcArqDlNack’, ‘pmRlcArqUlAck’, ‘ pmRlcArqUlNack’, Figure 4-17.
Following formulas can be used to determine the success rate at
RLC.RLC UL success rate % = pmRlcArqUlAck/( pmRlcArqUlAck +
pmRlcArqUlNack) * 100%
RLC DL success rate % = pmRlcArqDlAck/(pmRlcArqDlAck
+pmRlcArqDlNack) * 100%
➢RLC Layer counters: The counters provide an indication for the total
number of successful and unsuccessful transmissions at the RLC layer.
pmRlcArqDlAck
pmRlcArqDlNack
pmRlcArqUlAck
pmRlcArqUlNack
➢The following formulas can be used to determine the success rate at RLC.
RLC UL success rate % = pmRlcArqUlAck/( pmRlcArqUlAck+
pmRlcArqUlNack) * 100%
RLC DL success rate % = pmRlcArqDlAck/( pmRlcArqDlAck+
pmRlcArqDlNack) * 100%
Figure 4-17: Exercise 2 – Answer Cont’d
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4.2.5
MAC Layer counters
The counters being used during HARQ transmission, are distributed per
modulation scheme. ‘pmMacHarqDlAckQpsk’, ‘pmMacHarqDlNackQpsk’,
‘pmMacHarqDlDtxQpsk’, ‘pmMacHarqDlAck16qam’,
‘pmMacHarqDlNack16qam’, ‘pmMacHarqDlDtx16qam’,
‘pmMacHarqDlAck64qam’, ‘pmMacHarqDlNack64qam’,
‘pmMacHarqDlDtx64qam’, ‘pmMacHarqUlSuccQpsk’,
‘pmMacHarqUlFailQpsk’, ‘pmMacHarqUlDtxQpsk’,
‘pmMacHarqUlFail16qam’, ‘pmMacHarqUlSucc16qam’,
‘pmMacHarqUlDtx16qam’. These counters should be monitor for MAC layer
retransmission per modulation scheme, Figure 4-18.
› MAC Layer counters: The counters are distributed per modulation
scheme being used during HARQ transmission.
› pmMacHarqDlAckQpsk, pmMacHarqDlNackQpsk,
pmMacHarqDlDtxQpsk
› pmMacHarqDlAck16qam, pmMacHarqDlNack16qam,
› pmMacHarqDlDtx16qam, pmMacHarqDlAck64qam,
pmMacHarqDlNack64qam, pmMacHarqDlDtx64qam
› pmMacHarqUlSuccQpsk, pmMacHarqUlFailQpsk,
pmMacHarqUlDtxQpsk
› pmMacHarqUlFail16qam. pmMacHarqUlSucc16qam,
pmMacHarqUlDtx16qam
Figure 4-18: Exercise 2 – Answer Cont’d
The formula, in Figure 4-19, can be used to determine the BLER % for each type
of modulation scheme. Use the respective counters for the modulation scheme
that is of interest.
› The following formula can be used to determine the BLER % for each type of
modulation scheme. Use the respective counters for the modulation scheme
that is of interest.
› HARQ DL ACK Success Rate= pmMacHarqDlAck / (pmMacHarqDlAck +
pmMacHarqDlNack)
› HARQ UL ACK Success Rate= pmMacHarqUlSucc / (pmMacHarqUlSucc +
pmMacHarqUlFail)
› Example: Acknowledgement success rate for DL 16QAM.
› HARQ DL ACK Success Rate 16QAM =
pmMacHarqDlAck16qam/(pmMacHarqDlAck16qam+
pmMacHarqDlNack16qam) * 100%
› Note: The eNodeB is designed to function at 10% BLER. The ack success rate
is to be 90% or greater.
Figure 4-19: Exercise 2 – Answer Cont’d
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4.2.6
PDCCH Congestion Counter
Counter ‘pmPdcchCceUtil[0-19]’ is shown in Figure 4-20, ‘pmPdcchCceUtil’ is
PDF counter of % of CCEs utilized compared with total CCEs available (at the
maximum CFI permitted by ‘pdcchCfiMode’) each sub frame, considering
bandwidth and antenna configuration.
› PDCCH Congestion:
› Counter pmPdcchCceUtil[0-19]
pmPdcchCceUtil: PDF of % of CCEs utilized compared with total CCEs available (at the
maximum CFI permitted by pdcchCfiMode) each sub frame, considering bandwidth and
antenna configuration.
[0]: utilization <= 5%
[1]: 5% < utilization <= 10%
[2]: 10% < utilization <= 15%
[3]: 15% < utilization <= 20%
[4]: 20% < utilization <= 25%
[5]: 25% < utilization <= 30%
[6]: 30% < utilization <= 35%
[7]: 35% < utilization <= 40%
[8]: 40% < utilization <= 45%
[9]: 45% < utilization <= 50%
[10]: 50% < utilization <= 55%
[11]: 55% < utilization <= 60%
[12]: 60% < utilization <= 65%
[13]: 65% < utilization <= 70%
[14]: 70% < utilization <= 75%
[15]: 75% < utilization <= 80%
[16]: 80% < utilization <= 85%
[17]: 85% < utilization <= 90%
[18]: 90% < utilization <= 95%
[19]: 95% < utilization <= 100%
Figure 4-20: Exercise 2 – Answer Cont’d
4.2.7
Uplink-Downlink PRB Utilization
The Counter ‘pmPrbUtilDl[0-9],’ is a distribution that shows the downlink
Physical Resource Blocks (PRB) utilization (total number of used PRB by
available PRB on the Physical Downlink Shared Channel (PDSCH).
‘pmPrbUtilUl[0-9]’ is a distribution that shows the Physical Resource Blocks
(PRB) utilization (total number of used PRB by available PRB) on the Physical
Uplink Shared Channel (PUSCH).
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below Figure 4-21 illustrate the PRB utilization counter.
› Downlink PRB Utilization:
pmPrbUtilDl[0-9]
A distribution that shows the downlink Physical Resource Blocks (PRB)
utilization (total number of used PRB by available PRB on the Physical Downlink
Shared Channel (PDSCH).
› Uplink PRB Utilization:
pmPrbUtilUl[0-9]
A distribution that shows the Physical Resource Blocks (PRB) utilization (total number of
used PRB by available PRB) on the Physical Uplink Shared Channel (PUSCH).
PDF ranges:
[0]: 0 % <= Utilization < 10 %
[1]: 10 % <= Utilization < 20 %
[2]: 20 % <= Utilization < 30 %
[3]: 30 % <= Utilization < 40 %
[4]: 40 % <= Utilization < 50 %
[5]: 50 % <= Utilization < 60 %
[6]: 60 % <= Utilization < 70 %
[7]: 70 % <= Utilization < 80 %
[8]: 80 % <= Utilization < 90 %
[9]: 90 % <= Utilization
Figure 4-21: Exercis 2 – Answer Cont’d
4.2.8
Counters for UEs scheduled per TTI:
Internal check can be done to validate the number of users which are being
scheduled per TTI, following formula can be used:
‘ulSesPerTti’=’pmSchedActivityUeUl’/’pmSchedActivityCellUl’
‘dlSesPerTti’=’pmSchedActivityUeDl’/’pmSchedActivityCellDl’
Figure 4-22 illustrate the counters for scheduled number of UEs per TTI.
› UEs scheduled per TTI:
› Internal check can be done to validate the number of users which are being
scheduled per TTI
› The following formula can be used:
– ulSesPerTti=pmSchedActivityUeUl/pmSchedActivityCellUl
– dlSesPerTti=pmSchedActivityUeDl/pmSchedActivityCellDl
Figure 4-22: Exercise 2 – Answer Cont’d
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4.3
Exercise 3: possible root cause
Analyze the counters found in step 2 to determine the possible root causes for the
low downlink throughput.
Hint: Focus only on the cell and time line found in exercise 1 to see performance
degradations.
› Analyze the counters found in step 2 to determine the possible
root causes for the low downlink throughput.
› Hint: Focus only on the cell and time line found in exercise 1 to
see performance degradations.
Figure 4-23: Exercise 3:
4.3.1
Counter pmRadioRecInterferencePwr analysis-results
The counter ‘pmRadioRecInterferencePwr’ has high number of pegs in bins 10
and 11 which represents the measured noise and interference is in the range of 112 to -104. Figure 4-25 and Figure 4-24 is kept blank as participants are
expected to find the counter values and graph from excel sheets. And write down
on blank space.
› Counter pmRadioRecInterferencePwr: shows high number of
pegs in bins 10 and 11 which represents the measured noise
and interference is in the range of -112 to -104.
Figure 4-24: Exercise 3 – Answer Cont’d
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4.3.2
Counter pmRadioUeRepCQIDistr analysis-results
The Counter ‘pmRadioUeRepCQIDistr’ shows the majority of the UEs using
Rank Indicator 1 are reporting CQI values of 4 and 5. Figure 4-25 is kept blank
participants are expected to find the counter values and graph from excel sheets.
› Counter pmRadioUeRepCQIDistr shows the majority of the
UEs using Rank Indicator 1 are reporting CQI values of 4 and
5.
Figure 4-25: Exercise 3 – Answer Cont’d
4.3.3
Counter pmRadioUeRepCQIDistr2 analysis-results
The counter ‘pmRadioUeRepCQIDistr2’ shows the majority of the UEs using
Rank Indicator 2 are reporting CQI values from 2 to 5. The results are shown in
Figure 4-26.
› Counter pmRadioUeRepCQIDistr2 shows the majority of the
UEs using Rank Indicator 2 are reporting CQI values from 2 to
5.
Figure 4-26: Exercise 3 – Answer Cont’d
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4.3.4
PDCP layer counter analysis-results
PDCP layer counter analysis shows no issues at the PDCP layer as the number of
received packets ‘pmPdcpPktReceivedDl’ is equivalent to the number of
transferred packets ‘pmPdcpFwdDl’. If there would have been issues, then the
number of PDCP discards ‘pmPdcpDisc’ would have high counts.
› PDCP layer counter analysis shows no issues at the PDCP layer as the
number of received packets (pmPdcpPktReceivedDl) is equivalent to the
number of transferred packets (pmPdcpFwdDl). If there would have been
issues then the number of PDCP discards (pmPdcpDisc) would have high
counts.
Figure 4-27: Exercise 3 – Answer Cont’d
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4.3.5
RLC layer counter analysis-results
The success rate at RLC layer should be well above 90%. You will see from the
RLC counters that in RLC UL direction there are many NACKs. If you were to
compute the RLC ACK rate in both directions, you will notice that on RLC
Uplink the success rate is below 90% while on downlink it’s close to 99%. This
gives an indication that there is an issue on uplink. Figure 4-28.
› The success rate at RLC layer should be well above 90%. You will see
from the RLC counters that in RLC UL direction there are many NACKs. If
you were to compute the RLC ACK rate in both directions you will notice
that on RLC Uplink the success rate is below 90% while on downlink its
close to 99%. This gives an indication that there is an issue on uplink.
Figure 4-28: Exercise 3 – Answer Cont’d
4.3.6
Counter ‘pmMacHarq’ analysis-results for UL/DL
› Counters pmMacHarq for uplink and downlink gives an indication of the
modulation scheme being used. The eNodeB is designed to function at
10% BLER. From the counters we can see that most of the UEs are using
QPSK modulation in downlink and uplink. You can calculate the BLER by
looking at the success rate and we would like to see 90% or greater.
Figure 4-29: Exercise 3 – Answer Cont’d
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4.3.7
MAC HARQ Counters analysis-result
The blank Part in Figure 4-30 below, is an exercise for participants to find the
results.
› If you take a closer look at the success rate in uplink by using
the raw counters you will see that in uplink for QPSK we are
below the 90% target and in some of the ROPs we are below
80%.
Figure 4-30: Exercise 3 – Answer Cont’d
4.3.8
Counter pmPdcchCceUtil analysis-results
The analysis for the counter ‘pmPdcchCceUtil’ shows high levels (~80%) of
PDCCH congestion is observed during high load., The blank Part in Figure 4-31
below, is an exercise for participants to find the results.
➢The analysis for the counter pmPdcchCceUtil shows high levels (~80%) of
PDCCH congestion is observed during high load.
Figure 4-31: Exercise 3 – Answer Cont’d
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4.3.9
SE utilization analysis-results
Number of SEs per TTI shows that when low downlink throughput occurs, the
scheduler is prioritizing UEs in uplink rather than downlink. Poor UL
performance using proportional fair scheduling algorithm is causing the scheduler
to prioritize UEs which don`t exceed the UL average bit rate, Figure 4-32 below
shows the results.
› Number of SEs per TTI shows that when low downlink throughput occurs,
the scheduler is prioritizing UEs in uplink rather than downlink. Poor UL
performance using proportional fair scheduling algorithm is causing the
scheduler to prioritize UEs which don`t exceed the UL average bit rate
causing
the UL to starve downlink.
3.5
3
2.5
dlSesPerTtti
ulSesPerTti
sumofSesPerTti
2
1.5
1
0.5
45
30
19
:
15
18
:
00
17
:
45
16
:
30
14
:
15
13
:
00
5
9:
4
12
:
0
8:
3
11
:
5
7:
1
0
Figure 4-32: Exercise 3 – Answer Cont’d
4.4
Exercise Summary
With the above analysis and KPI results, it can be safely deduced that the
throughput was degraded because of High Uplink Interference and Poor channel
quality which leads to higher CCE aggregation causing PDCCH congestion.
Scheduling algorithm set to proportional fair low causes additional problems by
scheduling users on Uplink which don’t meet average bit rate throughput (lower
than ‘ulMinBitRate’) so these users will be given priority by the scheduler. This
causes the uplink to starve the downlink as well as UEs in poor RF are given
priority over UEs in good RF. The results are discussed in Figure 4-33 below.
› High Uplink Interference
› Poor channel quality which leads to higher CCE aggregation causing
PDCCH congestion
› Scheduling algorithm set to proportional fair low causes additional
problems.
Figure 4-33: Exercise Summary
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4.5
WAY FORWARD
The following recommendations, as discussed in Figure 4-34, were geared
towards reducing number of retransmissions and PDCCH congestion in order to
achieve higher cell downlink throughput when a high number of RRC connected
users is reached in the cell.
When sending an RLC PDU the UE/eNodeB may poll the eNOdeB/UE to send a
STATUS report and starts the poll retransmit timer. If a timeout occurs, then the
RLC PDU is retransmitted. By extending the time for polling allows additional
time for the PDCCH to be used for scheduling of other UEs. This change is
intended to reduce the PDCCH congestion (ie. Counter ‘pmPdcchCceUtil’) and
serve other UEs. Parameters ‘tPollRetransmitUl’ and ‘tPollRetransmitDl’
Retransmissions have the highest priority within the scheduler. In highly loaded
sites whereby there is high uplink interference and UEs at the cell border which
are in poor cell coverage, reducing the number of RLC retransmissions for
Signaling Radio Bearer and Data Radio Bearer to 8 allows UEs which require a
high number of retransmissions to be dropped giving other UEs an opportunity to
be scheduled. The change can cause a retainability degradation due to the
reduction in the number of retransmissions. This change is intended to reduce the
PDCCH congestion (ie. Counter ‘pmPdcchCceUtil’). Parameters
‘dlMaxRetxThreshold’ and ‘ulMaxRetxThreshold’
The following recommendations were geared towards reducing number
of retransmissions and PDCCH congestion
› By extending the time for polling allows additional time for the PDCCH
to be used for scheduling of other UEs. This change is intended to
reduce the PDCCH congestion (ie. Counter pmPdcchCceUtil) and
serve other UEs. Parameters tPollRetransmitUl and tPollRetransmitDl
› RLC retransmissions for SRB and to 8 Parameters
dlMaxRetxThreshold and ulMaxRetxThreshold
› PDCCH congestion (ie. Counter pmPdcchCceUtil). can be alleviated by
› feature Enhanced PDCCH Link Adaptation & PDCCH Power Boost
feature.
› Change scheduling algorithm from proportional fair scheduling to
resource fair.
Figure 4-34: WAY FORWARD
To reduce the CFI (Control Format Indicator) and number of CCEs (Control
Channel Elements) utilization for the UE, in order to alleviate some of the
PDCCH congestion. We can use few feature (ie. Counter ‘pmPdcchCceUtil’).
Following features can be used ‘Enhanced PDCCH Link Adaptation’ & ‘PDCCH
Power Boost feature’. PDCCH CFI mode can be defined Auto maximum.
LZT1381950 R1A
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
When proportional fair scheduling is used as scheduling algorithm, UEs must
meet a minimum bit rate (1 Kb/s). UEs which don’t meet a minimum bit rate will
be given higher priority to be scheduled which causes other UEs in good radio
condition to be starved. There were UEs which wouldn’t meet the minimum bit
rate (1 Kb/s) on the uplink which was causing the scheduler to prioritize these
users and starving UEs with downlink data. Change scheduling algorithm from
proportional fair scheduling to resource fair.
Summary of Chapter 4
5
The participants should now be able to:
4
4.1
4.2
4.3
4.4
Classify the issues, analyze them for improvements and
discuss few case studies for Integrity KPIs.
Identify steps for UL/DL Throughput investigation & essential
check
Describe DL & UL throughput optimization strategy
Discuss different cases of throughput & Latency degradation
Analyze cases based on low throughput high latency exercises
and provable solutions
Figure 4-35: Summary of Chapter 4
- 194 -
© Ericsson AB 2017
LZT1381950 R1A
Abbreviations
5 Abbreviations
1XRTT
3GPP
3PP
AAA
ACIR
ACK
ACLR
ACM
ACP
ACS
AES
AGW
AIF
AIR
AISG
AKA
AM
AMBR
A-MPR
AMR
ANM
ANR
AP
APAC
API
APN
A-RACF
ARP
ARPU
ARQ
ARW
AS
A-SBG
ASC
ASD
ASSL
ASSR
AuC
LZT1381950 R1A
operating mode of CDMA2000. 1x (the number of 1.25MHz channels)
Radio Transmission Technology
3rd Generation Partnership Project
3rd Party Product
Authentication, Authorization and Accounting
Adjacent Channel Interference Ratio
Acknowledgement
Adjacent Channel Leakage Ratio
Address Complete Message (ISUP Message)
Automatic Cell Planning
Adjacent Channel Selectivity
Advanced Encryption Standard
Access Gateway
Auto-Integration Function
Automated Integration of RBS
Antenna Interface Standards Group
Authentication and Key Agreement
Acknowledged Mode
Aggregate Maximum Bit Rate
Additional Maximum Power Reduction
Adaptive Multi-Rate
Answer Message (ISUP Message)
Automated Neighbor Relation
Aggregation Proxy
Asia Pacific
Application Programming Interface
Access Point Name
Access-Resource Admission Control Function
Allocation and Retention Priority
Average Revenue Per User
Automatic Repeat Request
Add RBS Wizard
Access Stratum
Access SBG
Antenna System Controller
Automatic SW Download
Adjacent Subcarrier Set Leakage
Adjacent Subcarrier Set Rejection
Authentication Centre
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
AV
B2B UA
BB
BCCH
BCE
BCH
BE-DB
BEM
BFCP
BGCF
BGF
BM-SC
BS
BSR
BW
C/I
CA
CAI
CAPEX
CAPEX
CAS
CAZAC
C-BGF
CCCH
CCE
CFR
CFRA
CIC
CM
CMC
CMDB
CN
CO
CoH
COMINF
Authentication Vector
Back To Back User Agent
Broadband
Broadcast Control Channel
Business Communication Enabler
Broadcast Channel
Back End Database
Block Edge Masks
Binary Floor Control Protocol
Breakout Gateway Control Function
Border Gateway Function
Broadcast-Multicast Service Center
Base Station
Buffer Status Report
Bandwidth
Carrier-to-Interference Power Ratio
Certificate Authority
Customer Administration Interface
Capital Expenditure
Capital Expenditure
Customer Administration System
Constant Amplitude Zero Auto-Correlation
Core Border Gateway Function
Common Control Channel
Control Channel Elements
Counter Cipher Mode with Block Chaining Message Authentication
Code Protocol
Cyclic Delay Diversity
Cumulative Distribution Function
Call Diversion
Code Division Multiple Access
Carrier Ethernet
The European Conference of Postal and Telecommunications
Administrations
Channel Feedback Report
Contention Free Random Access
Carrier Identification Code
Configuration Management
Connection Mobility Control
Configuration Management Data Base
Core Network
Conference Owner
Conference Handler
Common O&M Infrastructure
CO-OP
Cooperative Open-OSS Project (interface also called Itf-P2P)
CORBA
CoSe
CP
CPC
C-plane
CPM
CQI
CRC
Common Object Request Broker Architecture
IMS Communication Services
Control Plane
Continous Packet Connectivity
Control Plane
Converged IP Messaging
Channel Quality Indicator
Cyclic Redundancy Check
CCMP
CDD
CDF
CDIV
CDMA
CE
CEPT
- 196 -
© Ericsson AB 2017
LZT1381950 R1A
Abbreviations
C-RNTI
Cell RNTI
CS
Circuit Switched
CSCF
Call Session Control Function
CSFB
Circuit Switched FallBack
CSV
Comma-Separated Values
CTR
Cell TRace
CUDB
Centralized User Database
CW
Codeword
CX-AS
Capability Exchange Application System
DBL
Dynamic Black List
DBS/SABE Delay Based Scheduling/Service Aware Buffer Estimation
DCCH
Dedicated Control Channel
DCH
Dedicated Channel
DCI
Downlink Control Information
DCN
Data Communication Network
DECT
Digital Enhanced Cordless Telecommunications
DFT
Discrete Fourier Transform
DFT-SDFT Spread OFDM
OFDM
DHCP
Dynamic Host Configuration Protocol
DHCP
Dynamic Host Configuration Protocol
Diameter represents the next generation of authentication,
Diameter authorization, and accounting (AAA) controls for network access,
optimized for mobile access and advanced services
DL
Downlink
DL-SCH
Downlink Shared Channel
Domain Name System (Defined in STD 13, RFC 1034, RFC 1035 and
DNS
a number of following RFCs.)
DNS
Domain Name Service
DRB
Data Radio Bearer
DRX
Discontinuous Reception
DSCP
Differentiated Services Code Point
DSL
Digital Subscriber Line
DTCH
Dedicated Traffic Channel
DTX
Discontinuous Transmission
DwPTS
Downlink Pilot Time Slot
International Public Telecommunication Numbering Plan as describe in
E.164
the ITU-T Recommendation E.164.
EBS
Ericsson Blade System
ECC
Electronic Communications Committee
ECGI
E-UTRAN Cell Global Identifier
ECM
EPS Connection Management
E-CSCF
Emergency-CSCF
E-DCH
Enhanced DCH
eDNS
External DNS
e-GEM
e-GEM 2
EHPLMN
EMA
EMEA
EMM
eNB
ENM
LZT1381950 R1A
Enhanced Generic Ericsson Magazine
Enhanced Generic Ericsson Magazine 2:nd version
Equivalent Home PLMN
Ericsson Multi-Activation
Europe, Middle East and Africa
EPS Mobility Management
E-UTRAN NodeB
Ericsson Network Manager
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
eNode B
ENUM
EPC
EPS
E-RAB
ESM
ETSI
ETWS
E-UTRA
E-UTRAN
EV-DO
EVM
EXB
FCC
FDD
FDM
FDMA
FEC
FFS
FFT
FM
FMC
FMX
FQDN
FS
FTP
FW
GBR
GCL
GE
GERAN
GGSN
GIBA
GINR
GMPLS
GNSS
GP
GPRS
GSM
GSMA
GSTN
GTP
GTP-C
GTP-U
GUI
GUTI
GW
HA-CS
HARQ
HD
HDVC
HLR
- 198 -
E-UTRAN NodeB
A working group within IETF that produced a standard for E.164
number and DNS. Defined in IETF RFC 2916.
Ericsson Policy Control
Evolved Packet System
E-UTRAN Radio Access Bearer
EPS Subscriber Module
European Telecommunications Standards Institute
Earth Quake and Tsunami Warning System
Evolved UTRA
Evolved UTRAN, used as synonym for LTE in the document.
Evolution - Data Optimized
Error Vector Magnitude
Extension Blade
Federal Communications Commission
Frequency Division Duplex
Frequency Division Multiplexing
Frequency Division Multiple Access
Forward Error Correction
For Further Study
Fast Fourier Transform
Fault Management
Fixed-Mobile Convergence
Fault Management Expert
Fully Qualified Domain Name
Frame Structure
File Transfer Protocol
Fire Wall
Guaranteed Bit Rate
Generalized Chirp Like
Gigabit Ethernet
GSM EDGE Radio Access Network
Gateway GPRS Support Node
GPRS IMS Bundled Authentication
Gain to Interference and Noise Ratio
Generalized Multi-Protocol Label Switching
Global Navigation Satellite System
Guard Period
General Packet Radio Service
Global System for Mobile communication
GSM Association
General Switched Telephone Network (PSTN + PLMN)
GPRS Tunneling Protocol
GTP Control
GTP User Data Tunneling
Graphical user Interface
Globally Unique Temporary Identifier
Gateway
High Availability Cluster Solution
Hybrid ARQ
High Definition
High Quality Video Conferencing
Home Location Register
© Ericsson AB 2017
LZT1381950 R1A
Abbreviations
HO
HOM
HP
HPLMN
HRPD
HSDPA
HS-DSCH
HSPA
HSS
HSS-FE
HSUPA
HTTP
HTTP
HTTPS
HW
HW
IASA
IBCF
I-BGF
ICB
ICIC
ICS
I-CSCF
ID
iDNS
IEEE
IETF
IFFT
IM
IMEI
IMPI
IMS
IMSI
IMSI
IMS-M
IMT
IP
IPSec
IPTV
Ipv4
Ipv6
IPW
IRAT
IRAT
IS
ISC
ISDN
ISER
ISI
ISIM
ISM
ISUP
ITU
LZT1381950 R1A
Handover
Higher Order Modulation
Hewlett Packard
Home PLMN
High Rate Packet Data
High Speed Downlink Packet Access
High Speed Downlink Shared Channel
High Speed Packet Access
Home Subscriber Server
HSS Front End
High Speed Uplink Packet Access
Hypertext Transfer Protocol
Hypertext Transfer Protocol
Hypertext Transfer Protocol over Secure Socket Layer
Hardware
Hardware
Inter-Access Anchor
Interconnection Border Control Function
Interconnection Border Gateway Function
Incoming Call Barring
Inter-Cell Interference Coordination
IMS Centralized Services
Interrogating CSCF
Identifier
Internal DNS
Institute of Electrical and Electronics Engineers
Internet Engineering Task Force
Inverse FFT
Instant Messaging
International Mobile Equipment Identity
IP Multimedia Private Identity
IP Multimedia subsystem
International Mobile Subscriber Identity
Individual Mobile Subscriber Identity
IMS Messaging
IMS Multimedia Telephony
Internet Protocol
IP Security
Internet Protocol Television (Television over IP)
Internet Protocol version 4. (Defined in IETF STD 5 and RFC 791).
Internet Protocol version 6.(Defined in IETF RFC 2460)
IPWorks
Inter Radio Access Technology
Inter Radio Access Technology
Integrated Site
IMS Service Control interface. (Defined in 3GPP TS 23.228)
Integrated Services Digital Network
Integrated Site Edge Router
Inter Symbol Interference
IMS SIM
IMS Subscriber Module
ISDN User Part
International Telecommunications Union
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
ITU-R
ITU Radio Communication Sector
Telecommunication Standardization Sector of the International
ITU-T
Telecommunications Union
IWF
Interworking function
IWS
CDMA200 InterWorking Solution
JCP
Java Community Process
JSR
Java Specification Request
KPI
Key Performance Indicator
LAN
Local Area Network
LB
Load Balancing
LCID
Logical Channel ID
LCR
Low Chip Rate
LCR-TDD Low Chip Rate TDD
LDAP
Lightweight Directory Access Protocol. (Defined in IETF RFC 1777)
LDC
Linear Dispersion Code
LDPC
Low-Density Parity-check Code
LED
Light Emitting Diode
LTE
Long Term Evolution
M3UA
MTP Level 3 (MTP3) User Adaptation Layer
MAC
Medium Access Control
MAP
Mobile Application Part
MAR/MAA Multimedia Authentication Request/Answer (Diameter Message)
MBA
Management Based Activation
MBMS
Multimedia Broadcast Multicast Service
MBR
Maximum Bit Rate
MBSFN
Multicast Broadcast Single Frequency Network
MCCH
Multicast Control Channel
MCE
Multi-cell/multicast Coordination Entity
MCH
Multicast Channel
MCID
Malicious Communication Identification
MCR
Malicious Communication Rejection
MCS
Modulation and Coding Scheme
MEF
Mobile Entertainment Forum
MeGaCo
Media Gateway Control Protocol (also referred to as H.248)
MGC
Media Gateway Controller
MGCF
Media Gateway Controller Function
MGW
Media Gateway
MIB
Management Information Base
MIMO
Multiple Input Multiple Output
MiO
Messaging in One
ML-PPP
Multilink point to point protocol
MM
Mobility Management
MME
Mobility Management Entity
M-MGw
Mobile Media Gateway
MMS
Multimedia Messaging Service Managed Objects interface (MOCI)
MMTel
Multi Media Telephony
MNP
Mobile Number Portability
MOCI
Managed Object Configuration Interface
MOP
Maximum Output Power
MOS
Mean Opinion Score
MP
Media Proxy
MPLS
Multiple Protocol Label Switching
MPR
Maximum Power Reduction
- 200 -
© Ericsson AB 2017
LZT1381950 R1A
Abbreviations
MRFC
MRFP
MRS
MS
MSAP
MSC
MSISDN
MSP
MSS
MTAS
MTCH
MU-MIMO
mUPE
MXB
NAB
NACK
NAI
NAS
NASS
NAT
NB
NBA
NCC
NCL
NCLI
NCS
NE
NEM
NENA
NGMN
NGSA
NH
NM
NMS
NMX
NNI
NOC
NR
NRT
N-SBG
NSP
NW
O&M
OAM
OCB
OFDM
OFDMA
OMA
OMC
OOB
OPEX
OSS
OSS-RC
LZT1381950 R1A
Media Resource Function Controller
Media Resource Function Processor
Media Resource System
Management Services
MCH Subframe Allocation Pattern
Mobile Switching Center
Mobile Subscriber Integrated Services Digital Network-Number
Multi Service Proxy
Mobile Softswitch Solution
Multimedia Telephony Application Server
Multicast Traffic Channel
Multiple User-MIMO
MBMS UPE
Main Switching Blade
Name and Address Book
Negative Acknowledgement
Network Access Identifier
Non-Access Stratum
Network Attachment Subsystem
Network Address Translation
Narrowband
NASS Bundled Authentication
Network Color Code
Neighbour Cell List
Node Command Line Interface
Neighbouring Cell Support
Network Element
Network Element Manager
National Emergency Number Association
Next Generation Mobile Networks
Next Generation Service Assurance
Next Hop Key
Network Management
Network Management System
Network level deployment of expert rules
Network – Network Interface
Network Operations Center
Neighbor cell Relation
Non Real Time
Network SBG
Network Server Platform
Network
Operation and Maintenance
Operations Administration and Management
Outgoing Call barring
Orthogonal Frequency Division Multiplexing
Orthogonal Frequency Division Multiple Access
Open Mobile Alliance
Operation and Maintenance Center
Out of Band
Operating Expenditures
Operation and Support System
Operation and Support System Radio and Core
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
OTN
P(N)CCH
P2P
PA
PANI
PAPR
PAR
PARC
PBBTE
PBC
PBCH
PBN
PBR
PC
PCC
PCCH
PCEF
PCFICH
PCH
PCI
PCM
PCO
PCRF
P-CSCF
PDB
PDCCH
PDCP
PDN
PDN-GW
PDP
PDSCH
PDSN
PDU
PGM
P-GW
PHICH
PHR
PHS
PHY
PLMN
PM
PMCH
PMI
PMIP
PnP
PoP
PRACH
PRB
PRD
P-RNTI
PS
PSC
- 202 -
Operator Terminal Network
Paging (and Notification) Control Channel
Peer-to-Peer
Power Amplifier
P-Access-Network-Info (SIP Header)
Peak to Average Power Ratio
Peak to Average Ratio
Per Antenna Rate Control
Provider Backbone Bridge Traffic Engineering
Power and Battery Cabinet
Physical Broadcast Channel
Packet Backbone Network
Prioritized Bit Rate
Personal Computer
Policy and Charging Control
Paging Control Channel
Policy Charging Enforcement Function
Physical Control Format Indicator Channel
Paging Channel
Physical Cell ID
Pulse Code Modulation
Protocol Configuration Option
Policy and Charging Rules Function
Proxy - Call Session Control Function
Packet Delay Budget
Physical Downlink Control Channel
Packet Data Convergence Protocol
Packet Data Network
Packet Data Network Gateway
Packet Data Protocol
Physical Downlink Shared Channel
Packet Data Serving Node is a component of a CDMA2000 mobile
network
Protocol Data Unit
Presence Group and Data Management
PDN Gateway
Physical Hybrid ARQ Indicator Channel
Power Headroom Report
Personal Handy-phone System
Physical layer
Public Land Mobile Network
Performance Management
Physical Multicast Channel
Precoding Matrix Indicator
Proxy Mobile IP
Plug and Play
Point of Presence
Physical Random Access Channel
Physical Resource Block
Permanent Reference Document (by GSMA)
Paging RNTI
Packet Switched
Packet Scheduling
© Ericsson AB 2017
LZT1381950 R1A
Abbreviations
P-SCH
PSD
PSK
PSTN
PTT
PUCCH
PUI
PUSCH
QAM
QCI
QoS
QPP
QPSK
RA
RA
RAC
RACH
RADIUS
RAN
RAN
RANAP
RA-RNTI
RAT
RB
RBC
RBG
RBS
RCS
RCS-e
RET
RF
RFC
RI
RLC
RM
RNC
RNL
RNTI
RoHC
ROP
RPLMN
RRC
RRM
RRU
RS
RSN
RT
RTCP
RTP
RTSP
RU
RX
LZT1381950 R1A
Primary Synchronization Channel
Power Spectrum Density
Pre-Shared Keys
Public Switched Telephone Network
Push To Talk
Physical Uplink Control Channel
Public User Identity
Physical Uplink Shared Channel
Quadrature Amplitude Modulation
QoS Class Identifier
Quality of Service
Quadrature Permutation Polynomial
Quadrature Phase Shift Keying
Random Access
Registration Authority
Radio Admission Control
Random Access Channel
Remote Authentication Dial In User Service (Defined in RFC 2865,
RFC 2866 and RFC 2869)
Radio Access Network
Radio Access Network
RAN Application Part
Random Access RNTI
Radio Access Technology
Radio Bearer
Radio Bearer Control
Radio Bearer Group
Radio Base Station
Rich Communication Suite
Rich Communication Suite-enhanced
Remote Electrical Tilt
Radio Frequency
Request for Comment
Rank Indicator
Radio Link Control
Rate Matching
Radio Network Controller
Radio Network Layer
Radio Network Temporary Identifier
Robust Header Compression
Recording Output Periods
Registered PLMN
Radio Resource Control
Radio Resource Management
Radio Remote Unit
Reference Signal
Retransmission SN
Real Time
RTP Control Protocol
Real Time Protocol
Real Time Streaming Protocol
Resource Unit
Receiver
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
S1-MME
S1-U
SAE
SAP
SAPC
SAR/SAA
SB
SBC
SBG
SCC-AS
SCCH
SCCP
SCEP
SC-FDMA
SCH
S-CSCF
SCTP
SDES
SDF
SDH
SDMA
SDP
SDU
SeGW
SEM
SFN
SFP
SFTP
S-FTP
SGC
SGSN
S-GW
SI
SIB
SID
SIM
SINR
SIP
SI-RNTI
SIS
SISO
SLA
SLF
SLO
SM
SMO
SMRS
SMS
SMS
SN
SNF
SNR
SOAP
- 204 -
S1 for the control plane
S1 for the user plane
System Architecture Evolution
Service Access Point
Service Aware Policy Controller
Server Assignment Request/Answer (Diameter Message)
Scheduling Block
Session Border Controller
Session Border Gateway
Service Centralization and Continuity Application Server
Shared Control Channel
Signaling Connection Control Part
Simple Certificate Enrolment Protocol
Single Carrier – Frequency Division Multiple Access
Synchronization Channel
Serving CSCF
Stream Control Transmission Protocol
Session Description Protocol Security Descriptions
Service Data Flow
Synchronous Digital Hierarchy
Spatial Division Multiple Access
Session Description Protocol
Service Data Unit
Security Gateway
Spectrum Emission Mask
System Frame Number
Small Form factor Pluggable
Secure File Transfer Protocol
Secure File transfer protocol
Session Gateway Controller
Serving GPRS Support Node
Serving Gateway
System Information
System Information Block
Silence Insertion Descriptor
Subscriber Identity Module
Signal to Interference and Noise Ratio
Session Initiation Protocol
System Info RNTI
Site Infrastructure Support
Single Input Single Output
Service Level Agreement
Subscriber Location Function
Service Level Objectives
Session Management
Software Manager Organizer
Software Management Repository
Short Message Service
Short Message Service
Sequence Number
Service Network Framework
Signal to Noise Ratio
Simple Object Access Protocol
© Ericsson AB 2017
LZT1381950 R1A
Abbreviations
SON
SOX
S-PARC
SPDF
SPID
SQL
SR
SRB
SRTP
SRVCC
SS7
S-SCH
SSH
SSL
SSLIOP
SSO
SSP
SU
SU-MIMO
SW
SW
TA
T-ADS
TAS
TAU
TB
TBD
TCP
TDD
TDM
TF
TFCI
TFP
TFT
TISPAN
TLA
TLP
TLS
TM
TMA
TMO
TNL
TPC
TSP
TTI
TTM
TX
UA
UAC
UCI
UE
UETR
LZT1381950 R1A
Self-Organizing Networks
Simple Outline XML
Selective PARC
Session Policy Decision Function
Subscriber Profile ID for RAT/Frequency Priority
Structured Query Language
Scheduling Request
Signaling Radio Bearer
Secure Real-Time Protocol
Single Radio Voice Call Continuity
Signaling System, No 7
Secondary Synchronization Channel
Secure Shell
Secure Sockets Layer
IIOP over SSL
Single Sign On
Self-Service Portal
Scheduling Unit
Single-User MIMO
Software
Soft Ware
Tracking Area
Terminating-Access Domain Selection
Telephony Application Server
Tracking Area Update
Transport Block
To Be Decided
Transmission Control Protocol
Time Division Duplex
Time-Division Multiplexing
Transport Format
Transport Format Combination Indicator
Traffic Forwarding Policy
Traffic Flow Template
Telecoms & Internet converged Services & Protocols for Advanced
Networks
Three Letter Acronym
TEMS LinkPlanner
Transport Layer Security
Transparent Mode
Tower Mounted Amplifier
T-Mobile International AG
Transport Network Layer
Transmit Power Control
Ericsson Telecom Server Platform
Transmission Time Interval
Time To Market
Transmitter
User Agent. An endpoint in a SIP based network.
User Agent Client
Uplink Control Information
User Equipment
UE Trace
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
UL
UL-SCH
UM
UMTS
UNI
UP
UPE
U-plane
UpPTS
URA
URI
URL
USIM
UTRA
UTRAN
VAD
VoHSPA
VoIP
VoLTE
VPLMN
VRB
WAP
WAPECS
WCDMA
WCG
WDM
WiMAX
WUIGM
X2-C
X2-U
XCAP
XDMS
XML
XML
- 206 -
Uplink
Uplink Shared Channel
Unacknowledged Mode
Universal Mobile Telecommunication System
User-to-Network Interface
User Plane
User Plane Entity
User plane
Uplink Pilot Time Slot
UTRAN Routing Area
Uniform Resource Identifier. (Defined in RFC 2396)
Uniform Resource Locator. The address of a file (resource) accessible
on the Internet. (Defined in RFC 2396)
Universal SIM (3G SIM)
UMTS Terrestrial Radio Access
UMTS Terrestrial Radio Access Network
Voice Activity Detector
Voice over HSPA
Voice over IP
Voice over LTE
Visited PLMN
Virtual Resource Block
Wireless Access Protocol
Wireless Access Policy for Electronic Communications Services
Wideband Code Division Multiple Access
Web Communication Gateway
Wavelength Division Multiplexing
Worldwide Interoperability for Microwave Access
Web User Interface for Group and Data Management
X2-Control plane
X2-User plane
XML Configuration Access Protocol
XML Document Management Server
extensible Markup Language
Extensible Markup Language
© Ericsson AB 2017
LZT1381950 R1A
Index
6 Index
3rd Generation Partnership Project, 12, 13,
14, 16, 36, 140, 141, 145, 148, 151, 154,
156, 158, 166, 178, 195, 199
3rd Party Product, 195
A working group within IETF that produced a
standard for E.164 number and DNS.
Defined in IETF RFC 2916., 198
Access Gateway, 195
Access Point Name, 139, 195
Access SBG, 195
Access Stratum, 195
Access-Resource Admission Control
Function, 195
Acknowledged Mode, 118, 195
Acknowledgement, 154, 190, 195
Adaptive Multi-Rate, 195
Add RBS Wizard, 195
Additional Maximum Power Reduction, 195
Address Complete Message (ISUP
Message), 195
Adjacent Channel Interference Ratio, 195
Adjacent Channel Leakage Ratio, 195
Adjacent Channel Selectivity, 195
Adjacent Subcarrier Set Leakage, 195
Adjacent Subcarrier Set Rejection, 195
Advanced Encryption Standard, 195
Aggregate Maximum Bit Rate, 139, 195
Aggregation Proxy, 195
Allocation and Retention Priority, 195
Answer Message (ISUP Message), 195
Antenna Interface Standards Group, 195
Antenna System Controller, 195
Application Programming Interface, 195
Asia Pacific, 195
Authentication and Key Agreement, 195
Authentication Centre, 195
Authentication Vector, 196
LZT1381950 R1A
Authentication, Authorization and Accounting,
195, 197
Auto-Integration Function, 195
Automated Integration of RBS, 195
Automated Neighbor Relation, 29, 53, 58, 59,
89, 91, 92, 93, 94, 95, 97, 98, 99, 100, 101,
102, 103, 176, 195
Automatic Cell Planning, 195
Automatic Repeat Request, 195, 198, 202
Automatic SW Download, 195
Average Revenue Per User, 195
Back End Database, 196
Back To Back User Agent, 196
Bandwidth, 153, 196
Base Station, 196
Binary Floor Control Protocol, 196
Block Edge Masks, 196
Border Gateway Function, 196
Breakout Gateway Control Function, 196
Broadband, 168, 169, 196
Broadcast Channel, 196
Broadcast Control Channel, 173, 196
Broadcast-Multicast Service Center, 196
Buffer Status Report, 141, 196
Business Communication Enabler, 196
C/I, 143
Call Diversion, 196
Call Session Control Function, 197, 199, 204
Capability Exchange Application System, 197
Capital Expenditure, 196
Carrier Ethernet, 196
Carrier Identification Code, 196
Carrier-to-Interference Power Ratio, 143, 196
CDMA200 InterWorking Solution, 200
Cell RNTI, 197
Cell TRace, 197
Centralized User Database, 197
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
Certificate Authority, 18, 133, 145, 153, 157,
158, 196
Channel Feedback Report, 196
Channel Quality Indicator, 127, 137, 145,
154, 188, 196
Circuit Switched, 103, 111, 197
Circuit Switched FallBack, 103, 104, 105,
106, 107, 108, 109, 110, 197
Code Division Multiple Access, 26, 52, 196
Codeword, 197
Comma-Separated Values, 197
Common Control Channel, 196
Common O&M Infrastructure, 196
Common Object Request Broker
Architecture, 196
Conference Handler, 196
Conference Owner, 196
Configuration Management, 91, 196
Configuration Management Data Base, 196
Connection Mobility Control, 196
Constant Amplitude Zero Auto-Correlation,
196
Contention Free Random Access, 37, 196
Continous Packet Connectivity, 196
Control Channel Elements, 192, 196
Control Plane, 196
Converged IP Messaging, 196
Cooperative Open-OSS Project (interface
also called Itf-P2P), 196
Core Border Gateway Function, 196
Core Network, 105, 106, 108, 196
Counter Cipher Mode with Block Chaining
Message Authentication Code Protocol,
196
CRS, 166
Cumulative Distribution Function, 196
Customer Administration Interface, 196
Customer Administration System, 196
Cyclic Delay Diversity, 196
Cyclic Redundancy Check, 196
Data Communication Network, 197
Data Radio Bearer, 32, 117, 118, 119, 120,
121, 124, 197
Dedicated Channel, 197
Dedicated Control Channel, 197
Dedicated Traffic Channel, 197
Delay Based Scheduling/Service Aware
Buffer Estimation, 197
DFT Spread OFDM, 197
Diameter represents the next generation of
authentication, authorization, and
accounting (AAA) controls for network
- 208 -
access, optimized for mobile access and
advanced services, 197, 200, 204
Differentiated Services Code Point, 140, 197
Digital Enhanced Cordless
Telecommunications, 197
Digital Subscriber Line, 197
Discontinuous Reception, 92, 101, 102, 152,
175, 176, 177, 178, 197
Discontinuous Transmission, 197
Discrete Fourier Transform, 197
Domain Name Service, 197, 198, 199
Domain Name System (Defined in STD 13,
RFC 1034, RFC 1035 and a number of
following RFCs.), 197, 198, 199
Downlink, 18, 29, 36, 49, 87, 101, 117, 118,
119, 127, 128, 129, 131, 132, 133, 137,
138, 140, 144, 145, 146, 147, 151, 153,
154, 155, 156, 157, 158, 161, 165, 168,
172, 177, 181, 182, 183, 190, 197
Downlink Control Information, 197
Downlink Pilot Time Slot, 197
Downlink Shared Channel, 197
Dynamic Black List, 197
Dynamic Host Configuration Protocol, 197
Earth Quake and Tsunami Warning System,
198
Electronic Communications Committee, 197
Emergency-CSCF, 197
Enhanced DCH, 197
Enhanced Generic Ericsson Magazine, 197
Enhanced Generic Ericsson Magazine 2
nd version, 197
EPS Connection Management, 197
EPS Mobility Management, 197
EPS Subscriber Module, 198
Equivalent Home PLMN, 197
Ericsson Blade System, 197
Ericsson Multi-Activation, 197
Ericsson Network Manager, 197
Ericsson Policy Control, 198
Ericsson Telecom Server Platform, 205
Error Vector Magnitude, 145, 146, 198
Europe, Middle East and Africa, 197
European Telecommunications Standards
Institute, 198
E-UTRAN Cell Global Identifier, 100, 101,
197
E-UTRAN NodeB, 33, 65, 90, 96, 110, 150,
158, 159, 160, 161, 176, 197, 198
E-UTRAN Radio Access Bearer, 198
Evolution - Data Optimized, 198
Evolved Packet System, 103, 139, 197, 198
© Ericsson AB 2017
LZT1381950 R1A
Index
Evolved UTRA, 12, 13, 14, 15, 16, 23, 100,
103, 197, 198
Evolved UTRAN, used as synonym for LTE in
the document., 12, 16, 23, 100, 103, 197,
198
extensible Markup Language, 205, 206
Extensible Markup Language, 205, 206
Extension Blade, 198
External DNS, 197
Fast Fourier Transform, 198, 199
Fault Management, 198
Fault Management Expert, 198
Federal Communications Commission, 198
File Transfer Protocol, 198
Fire Wall, 198
Fixed-Mobile Convergence, 198
For Further Study, 198
Forward Error Correction, 198
Frame Structure, 198
Frequency Division Duplex, 23, 59, 94, 149,
153, 156, 159, 165, 198
Frequency Division Multiple Access, 198
Frequency Division Multiplexing, 198
Fully Qualified Domain Name, 198
Gain to Interference and Noise Ratio, 198
Gateway, 198
Gateway GPRS Support Node, 198
General Packet Radio Service, 198, 204
General Switched Telephone Network (PSTN
+ PLMN), 198
Generalized Chirp Like, 198
Generalized Multi-Protocol Label Switching,
198
Gigabit Ethernet, 198
Global Navigation Satellite System, 198
Global System for Mobile communication, 91,
92, 198
Globally Unique Temporary Identifier, 198
GPRS IMS Bundled Authentication, 198
GPRS Tunneling Protocol, 198
Graphical user Interface, 198
GSM Association, 198, 202
GSM EDGE Radio Access Network, 26, 52,
59, 103, 198
GTP Control, 198
GTP User Data Tunneling, 198
Guaranteed Bit Rate, 168, 198
Guard Period, 198
Handover, 29, 30, 31, 32, 33, 34, 35, 38, 39,
40, 41, 42, 45, 46, 52, 55, 64, 65, 66, 68,
LZT1381950 R1A
69, 70, 71, 72, 73, 75, 79, 83, 87, 89, 90,
91, 92, 93, 95, 166, 199
Hardware, 199
Hewlett Packard, 199
High Availability Cluster Solution, 198
High Definition, 198
High Quality Video Conferencing, 198
High Rate Packet Data, 199
High Speed Downlink Packet Access, 199
High Speed Downlink Shared Channel, 199
High Speed Packet Access, 199, 206
High Speed Uplink Packet Access, 199
Higher Order Modulation, 138, 147, 148, 199
Home Location Register, 198
Home PLMN, 199
Home Subscriber Server, 199
HSS Front End, 199
Hybrid ARQ, 154, 157, 160, 184, 191, 198
Hypertext Transfer Protocol, 199
Hypertext Transfer Protocol over Secure
Socket Layer, 199
Identifier, 23, 199, 200, 202, 205
IIOP over SSL, 205
IMS Centralized Services, 199
IMS Communication Services, 196
IMS Messaging, 199
IMS Multimedia Telephony, 199
IMS Service Control interface. (Defined in
3GPP TS 23.228), 199
IMS SIM, 199
IMS Subscriber Module, 199
Incoming Call Barring, 199
Individual Mobile Subscriber Identity, 199
Instant Messaging, 199
Institute of Electrical and Electronics
Engineers, 199
Integrated Services Digital Network, 199
Integrated Site, 199
Integrated Site Edge Router, 199
Inter Radio Access Technology, 14, 25, 26,
27, 28, 40, 41, 42, 52, 53, 55, 68, 69, 70,
78, 79, 80, 81, 82, 83, 93, 95, 199
Inter Symbol Interference, 199
Inter-Access Anchor, 199
Inter-Cell Interference Coordination, 199
Interconnection Border Control Function, 199
Interconnection Border Gateway Function,
199
Internal DNS, 199
International Mobile Equipment Identity, 199
International Mobile Subscriber Identity, 199
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
International Public Telecommunication
Numbering Plan as describe in the ITU-T
Recommendation E.164., 197, 198
International Telecommunications Union,
197, 199, 200
Internet Engineering Task Force, 198, 199,
200
Internet Protocol, 33, 168, 196, 199, 202, 206
Internet Protocol Television (Television over
IP), 199
Internet Protocol version 4. (Defined in IETF
STD 5 and RFC 791)., 199
Internet Protocol version 6.(Defined in IETF
RFC 2460), 199
Interrogating CSCF, 199
Interworking function, 200
Inverse FFT, 199
IP Multimedia Private Identity, 199
IP Multimedia subsystem, 196, 198, 199
IP Security, 199
IPWorks, 199
ISDN User Part, 195, 199
ITU Radio Communication Sector, 200
Java Community Process, 200
Java Specification Request, 200
Key Performance Indicator, 12, 25, 28, 44,
50, 54, 68, 72, 84, 90, 99, 105, 111, 116,
119, 121, 123, 126, 127, 128, 151, 172,
179, 192, 200
Light Emitting Diode, 200
Lightweight Directory Access Protocol.
(Defined in IETF RFC 1777), 200
Linear Dispersion Code, 200
Load Balancing, 200
Local Area Network, 200
Logical Channel ID, 200
Long Term Evolution, 11, 12, 18, 23, 25, 26,
28, 33, 35, 36, 38, 40, 44, 59, 60, 68, 69,
70, 79, 80, 89, 91, 92, 93, 99, 105, 109,
110, 111, 112, 115, 121, 127, 140, 141,
144, 147, 148, 151, 152, 154, 161, 165,
167, 174, 198, 200, 206
Low Chip Rate, 200
Low Chip Rate TDD, 200
Low-Density Parity-check Code, 200
Main Switching Blade, 201
Malicious Communication Identification, 200
Malicious Communication Rejection, 200
Managed Object Configuration Interface, 200
Management Based Activation, 200
Management Information Base, 200
Management Services, 201
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Maximum Bit Rate, 200
Maximum Output Power, 200
Maximum Power Reduction, 200
MBMS UPE, 201
MCH Subframe Allocation Pattern, 201
Mean Opinion Score, 200
Media Gateway, 200
Media Gateway Control Protocol (also
referred to as H.248), 200
Media Gateway Controller, 200
Media Gateway Controller Function, 200
Media Proxy, 30, 31, 33, 200
Media Resource Function Controller, 201
Media Resource Function Processor, 201
Media Resource System, 201
Medium Access Control, 136, 145, 157, 184,
191, 200
Messaging in One, 200
MIMO, 166
Mobile Application Part, 200
Mobile Entertainment Forum, 200
Mobile Media Gateway, 200
Mobile Number Portability, 200
Mobile Softswitch Solution, 201
Mobile Subscriber Integrated Services Digital
Network-Number, 201
Mobile Switching Center, 201
Mobility Management, 200
Mobility Management Entity, 33, 40, 41, 93,
200
Modulation and Coding Scheme, 148, 200
MTP Level 3 (MTP3) User Adaptation Layer,
200
Multi Media Telephony, 200
Multi Service Proxy, 201
Multicast Broadcast Single Frequency
Network, 200
Multicast Channel, 200, 201
Multicast Control Channel, 200
Multicast Traffic Channel, 201
Multi-cell/multicast Coordination Entity, 200
Multilink point to point protocol, 200
Multimedia Authentication Request/Answer
(Diameter Message), 200
Multimedia Broadcast Multicast Service, 200,
201
Multimedia Messaging Service Managed
Objects interface (MOCI), 200
Multimedia Telephony Application Server,
201
© Ericsson AB 2017
LZT1381950 R1A
Index
Multiple Input Multiple Output, 131, 133, 138,
145, 147, 154, 165, 166, 167, 182, 200,
201, 205
Multiple Protocol Label Switching, 200
Multiple User-MIMO, 148, 150, 201
Name and Address Book, 201
Narrowband, 201
NASS Bundled Authentication, 201
National Emergency Number Association,
201
Negative Acknowledgement, 136, 154, 201
Neighbor cell Relation, 95, 201
Neighbour Cell List, 201
Neighbouring Cell Support, 201
Network, 201
Network – Network Interface, 201
Network Access Identifier, 201
Network Address Translation, 201
Network Attachment Subsystem, 201
Network Color Code, 201
Network Element, 201
Network Element Manager, 201
Network level deployment of expert rules,
201
Network Management, 201
Network Management System, 201
Network Operations Center, 201
Network SBG, 201
Network Server Platform, 201
Next Generation Mobile Networks, 201
Next Generation Service Assurance, 201
Next Hop Key, 201
Node Command Line Interface, 201
Non Real Time, 201
Non-Access Stratum, 201
Open Mobile Alliance, 201
Operating Expenditures, 201
operating mode of CDMA2000. 1x (the
number of 1.25MHz channels) Radio
Transmission Technology, 195
Operation and Maintenance, 196, 201
Operation and Maintenance Center, 201
Operation and Support System, 91, 98, 110,
141, 196, 201
Operation and Support System Radio and
Core, 91, 141, 201
Operations Administration and Management,
201
Operator Terminal Network, 202
Orthogonal Frequency Division Multiple
Access, 201
LZT1381950 R1A
Orthogonal Frequency Division Multiplexing,
151, 197, 201
Out of Band, 201
Outgoing Call barring, 201
P-Access-Network-Info (SIP Header), 202
Packet Backbone Network, 202
Packet Data Convergence Protocol, 85, 117,
118, 123, 124, 165, 183, 189, 202
Packet Data Network, 202
Packet Data Network Gateway, 202
Packet Data Protocol, 202
Packet Data Serving Node is a component of
a CDMA2000 mobile network, 202
Packet Delay Budget, 168, 202
Packet Scheduling, 202
Packet Switched, 168, 202
Paging (and Notification) Control Channel,
202
Paging Channel, 202
Paging Control Channel, 202
Paging RNTI, 202
PDN Gateway, 202
Peak to Average Power Ratio, 202
Peak to Average Ratio, 202
Peer-to-Peer, 196, 202
Per Antenna Rate Control, 202, 205
Performance Management, 165, 180, 202
Permanent Reference Document (by GSMA),
202
Personal Computer, 202
Personal Handy-phone System, 202
Physical Broadcast Channel, 202
Physical Cell ID, 29, 35, 37, 53, 65, 89, 90,
91, 92, 93, 95, 99, 100, 101, 102, 202
Physical Control Format Indicator Channel,
202
Physical Downlink Control Channel, 101,
127, 133, 152, 153, 166, 168, 177, 185,
191, 192, 193, 202
Physical Downlink Shared Channel, 87, 132,
166, 185, 202
Physical Hybrid ARQ Indicator Channel, 202
Physical layer, 202
Physical Multicast Channel, 202
Physical Random Access Channel, 202
Physical Resource Block, 127, 132, 133, 134,
151, 152, 154, 156, 185, 186, 202
Physical Uplink Control Channel, 88, 135,
153, 156, 157, 173, 203
© Ericsson AB 2017
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Physical Uplink Shared Channel, 36, 132,
135, 148, 150, 151, 154, 162, 173, 182,
185, 203
Plug and Play, 202
Point of Presence, 202
Policy and Charging Control, 202
Policy and Charging Rules Function, 202
Policy Charging Enforcement Function, 202
Power Amplifier, 202
Power and Battery Cabinet, 202
Power Headroom Report, 202
Power Spectrum Density, 174, 203
Precoding Matrix Indicator, 202
Presence Group and Data Management, 202
Pre-Shared Keys, 203
Primary Synchronization Channel, 203
Prioritized Bit Rate, 202
Protocol Configuration Option, 202
Protocol Data Unit, 136, 193, 202
Provider Backbone Bridge Traffic
Engineering, 202
Proxy - Call Session Control Function, 202
Proxy Mobile IP, 202
Public Land Mobile Network, 33, 93, 197,
198, 199, 202, 203, 206
Public Switched Telephone Network, 198,
203
Public User Identity, 203
Pulse Code Modulation, 202
Push To Talk, 203
QoS, 143
QoS Class Identifier, 23, 42, 53, 59, 60, 79,
116, 121, 124, 140, 141, 168, 169, 174,
175, 176, 177, 203
Quadrature Amplitude Modulation, 131, 133,
138, 145, 146, 147, 148, 149, 150, 151,
154, 156, 203
Quadrature Permutation Polynomial, 203
Quadrature Phase Shift Keying, 138, 203
Quality of Service, 60, 140, 141, 142, 143,
176, 203
Radio Access Network, 121, 140, 142, 160,
165, 203
Radio Access Technology, 14, 15, 23, 94,
139, 203, 205
Radio Admission Control, 203
Radio Base Station, 40, 41, 96, 116, 118,
119, 120, 121, 122, 123, 124, 126, 140,
141, 142, 168, 195, 203
Radio Bearer, 203
Radio Bearer Control, 203
Radio Bearer Group, 203
- 212 -
Radio Frequency, 29, 75, 166, 181, 192, 203
Radio Link Control, 116, 118, 128, 136, 183,
190, 193, 203
Radio Network Controller, 40, 203
Radio Network Layer, 203
Radio Network Temporary Identifier, 197,
202, 203, 204
Radio Remote Unit, 29, 33, 203
Radio Resource Control, 26, 40, 45, 46, 64,
65, 66, 67, 87, 88, 90, 91, 93, 107, 108,
157, 178, 193, 203
Radio Resource Management, 23, 203
RAN Application Part, 203
Random Access, 37, 174, 203
Random Access Channel, 37, 38, 203
Random Access RNTI, 37, 203
Rank Indicator, 127, 203
Rate Matching, 203
Real Time, 203
Real Time Protocol, 203
Real Time Streaming Protocol, 203
Receiver, 150, 203
Recording Output Periods, 119, 121, 122,
126, 179, 180, 203
Reference Signal, 203
Registered PLMN, 203
Registration Authority, 37, 174, 203
Remote Authentication Dial In User Service
(Defined in RFC 2865, RFC 2866 and RFC
2869), 203
Remote Electrical Tilt, 203
Request for Comment, 197, 198, 199, 200,
203, 206
Resource Unit, 203
Retransmission SN, 203
Rich Communication Suite, 203
Rich Communication Suite-enhanced, 203
Robust Header Compression, 203
RTP Control Protocol, 203
S1 for the control plane, 204
S1 for the user plane, 204
Scheduling Block, 204
Scheduling Request, 88, 205
Scheduling Unit, 205
Secondary Synchronization Channel, 205
Secure File transfer protocol, 204
Secure File Transfer Protocol, 204
Secure Real-Time Protocol, 205
Secure Shell, 205
Secure Sockets Layer, 205
Security Gateway, 204
Selective PARC, 205
© Ericsson AB 2017
LZT1381950 R1A
Index
Self-Organizing Networks, 99, 205
Self-Service Portal, 205
Sequence Number, 203, 204
Server Assignment Request/Answer
(Diameter Message), 204
Service Access Point, 204
Service Aware Policy Controller, 204
Service Centralization and Continuity
Application Server, 204
Service Data Flow, 204
Service Data Unit, 118, 204
Service Level Agreement, 204
Service Level Objectives, 204
Service Network Framework, 204
Serving CSCF, 204
Serving Gateway, 93, 140, 204
Serving GPRS Support Node, 40, 204
Session Border Controller, 204
Session Border Gateway, 195, 201, 204
Session Description Protocol, 204
Session Description Protocol Security
Descriptions, 204
Session Gateway Controller, 204
Session Initiation Protocol, 202, 204, 205
Session Management, 204
Session Policy Decision Function, 205
Shared Control Channel, 204
Short Message Service, 204
Signal to Interference and Noise Ratio, 36,
127, 128, 135, 148, 150, 158, 204
Signal to Noise Ratio, 204
Signaling Connection Control Part, 204
Signaling Radio Bearer, 32, 205
Signaling System, No 7, 205
Silence Insertion Descriptor, 204
Simple Certificate Enrolment Protocol, 204
Simple Object Access Protocol, 204
Simple Outline XML, 205
Single Carrier – Frequency Division Multiple
Access, 204
Single Input Single Output, 204
Single Radio Voice Call Continuity, 205
Single Sign On, 205
Single-User MIMO, 205
Site Infrastructure Support, 204
Small Form factor Pluggable, 204
Soft Ware, 33, 195, 205
Software, 33, 195, 205
Software Management Repository, 204
Software Manager Organizer, 204
Spatial Division Multiple Access, 204
LZT1381950 R1A
Spectrum Emission Mask, 204
Stream Control Transmission Protocol, 93,
204
Structured Query Language, 205
Subscriber Identity Module, 199, 204, 206
Subscriber Location Function, 204
Subscriber Profile ID for RAT/Frequency
Priority, 23, 205
Synchronization Channel, 204
Synchronous Digital Hierarchy, 204
System Architecture Evolution, 204
System Frame Number, 204
System Info RNTI, 204
System Information, 204
System Information Block, 106, 107, 152, 204
Telecommunication Standardization Sector of
the International Telecommunications
Union, 197, 200
Telecoms & Internet converged Services &
Protocols for Advanced Networks, 205
Telephony Application Server, 205
TEMS LinkPlanner, 205
Terminating-Access Domain Selection, 205
The European Conference of Postal and
Telecommunications Administrations, 196
Three Letter Acronym, 205
Time Division Duplex, 23, 59, 149, 156, 165,
200, 205
Time To Market, 205
Time-Division Multiplexing, 205
T-Mobile International AG, 205
To Be Decided, 205
Tower Mounted Amplifier, 205
Tracking Area, 205
Tracking Area Update, 205
Traffic Flow Template, 205
Traffic Forwarding Policy, 205
Transmission Control Protocol, 205
Transmission Time Interval, 118, 120, 154,
156, 157, 160, 186, 192, 205
Transmit Power Control, 205
Transmitter, 182, 205
Transparent Mode, 205
Transport Block, 205
Transport Format, 205
Transport Format Combination Indicator, 205
Transport Layer Security, 205
Transport Network Layer, 205
UE Trace, 205
UMTS Terrestrial Radio Access, 198, 206
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
UMTS Terrestrial Radio Access Network, 12,
16, 59, 103, 108, 109, 110, 198, 206
Unacknowledged Mode, 118, 206
Uniform Resource Identifier. (Defined in RFC
2396), 206
Uniform Resource Locator. The address of a
file (resource) accessible on the Internet.
(Defined in RFC 2396), 206
Universal Mobile Telecommunication System,
69, 78, 79, 206
Universal SIM (3G SIM), 206
Uplink, 18, 29, 36, 101, 120, 128, 129, 130,
131, 132, 133, 135, 136, 137, 139, 140,
144, 148, 149, 150, 151, 153, 154, 156,
157, 158, 162, 163, 168, 173, 174, 181,
182, 183, 190, 192, 206
Uplink Control Information, 205
Uplink Pilot Time Slot, 206
Uplink Shared Channel, 206
User Agent Client, 205
User Agent. An endpoint in a SIP based
network., 205
User Equipment, 12, 14, 15, 16, 21, 23, 24,
25, 26, 28, 29, 31, 32, 39, 40, 41, 45, 46,
52, 53, 55, 56, 59, 60, 65, 67, 68, 69, 71,
79, 91, 92, 93, 94, 95, 100, 101, 102, 103,
106, 107, 109, 110, 111, 112, 116, 117,
118, 119, 120, 121, 128, 136, 139, 140,
141, 142, 145,147, 149, 151, 152, 153,
- 214 -
154, 157, 158, 159, 160, 162, 165, 166,
173, 175, 176, 177, 178, 193, 205
User plane, 206
User Plane, 206
User Plane Entity, 201, 206
User-to-Network Interface, 206
UTRAN Routing Area, 206
Virtual Resource Block, 206
Visited PLMN, 206
Voice Activity Detector, 206
Voice over HSPA, 206
Voice over IP, 168, 206
Voice over LTE, 153, 206
Wavelength Division Multiplexing, 206
Web Communication Gateway, 206
Web User Interface for Group and Data
Management, 206
Wideband Code Division Multiple Access, 18,
25, 26, 40, 52, 59, 78, 79, 91, 92, 106, 107,
110, 111, 206
Wireless Access Policy for Electronic
Communications Services, 206
Wireless Access Protocol, 206
Worldwide Interoperability for Microwave
Access, 206
X2-Control plane, 206
X2-User plane, 206
XML Configuration Access Protocol, 206
XML Document Management Server, 206
© Ericsson AB 2017
LZT1381950 R1A
Table of Figure
7 Table of Figures
Figure 1-1: Objective of Chapter 1 ................................................................................................ 11
Figure 1-2: Review: Cell Selection (S-Criterion) ............................................................................ 13
Figure 1-3: Cell Reselection (R-Criteria) ....................................................................................... 13
Figure 1-4: Cell Reselection Evaluation Process ........................................................................... 14
Figure 1-5: Priority Based Cell Reselection ................................................................................... 15
Figure 1-6: Speed Dependent Scaling of Cell Reselection ............................................................ 17
Figure 1-7: Cell selection/Reselection parameters ........................................................................ 17
Figure 1-8: Case-1: Cell Reselection Parameter Example ........................................................... 18
Figure 1-9: Parameter example Case-2 ........................................................................................ 19
Figure 1-10: Case 2: 3CC idle mode ............................................................................................. 19
Figure 1-11: Case 3: Initial Traffic Balance Issue & resolution on MC site ..................................... 20
Figure 1-12: Case 4: Key finding of improper parameter setting at one operator ........................... 21
Figure 1-13: Case 4: ‘qRxlevmin’ Setting ...................................................................................... 21
Figure 1-14: Case 4: Sintrasearch setting ..................................................................................... 22
Figure 1-15: Case 4: Snonintrasearch setting ............................................................................... 22
Figure 1-16: Case 4: Summary of change ..................................................................................... 23
Figure 1-17: Idle mode behavior with IFLB functionality ................................................................ 24
Figure 1-18: Idle mode with Sticky carrier methodology ................................................................ 24
Figure 1-19: EUTRAN Mobility KPI ............................................................................................... 25
Figure 1-20: Review: LTE Events .................................................................................................. 26
Figure 1-21: Review: Coverage triggered mobility ......................................................................... 27
Figure 1-22: Review: “Basic” Mobility Control in Poor Coverage Operation ................................... 28
Figure 1-23: Mobility Issue Analysis .............................................................................................. 29
Figure 1-24: Mobility issue analysis HO Prep & Exec Failures ..................................................... 30
Figure 1-25: Intra/Inter Handover Prep fail issue: possible cause.................................................. 30
Figure 1-26: Intra/Inter Handover Prep fail issue: possible cause.................................................. 31
Figure 1-27: Intra/Inter Handover Prep fail issue: possible cause.................................................. 31
Figure 1-28: Intra/Inter Handover Prep fail issue: possible cause.................................................. 32
Figure 1-29: Intra/Inter Handover Prep fail issue: possible cause.................................................. 34
Figure 1-30: Intra/Inter Handover Prep fail issue: possible cause.................................................. 34
Figure 1-31: LTE Intra/Inter Handover Execution Failure: possible cause ..................................... 35
Figure 1-32: LTE Intra/Inter Handover Execution Failure: possible cause ..................................... 35
Figure 1-33: LTE Intra/Inter Handover Execution Failure: possible cause ..................................... 36
Figure 1-34: LTE Intra/Inter Handover Execution Failure: possible cause ..................................... 36
Figure 1-35: Uplink Interference .................................................................................................... 37
Figure 1-36: LTE Intra/Inter Handover Execution Failure: possible cause ..................................... 38
Figure 1-37: HO Exec Fail: Contention Based Random Access Success Rate ............................. 38
Figure 1-38: HO Exec Fail: Overshooting Cell ............................................................................... 39
LZT1381950 R1A
© Ericsson AB 2017
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LTE Mobility and Throughput - KPI Analysis & Optimization Workshop
Figure 1-39: Intra/Inter Frequency HO Optimization ...................................................................... 39
Figure 1-40: IRAT Handover HO optimization ............................................................................... 41
Figure 1-41: IRAT/Inter Frequency HO optimization ...................................................................... 42
Figure 1-42: IRAT/Inter Frequency Session continuity optimization .............................................. 42
Figure 1-43: Inter-frequency load balancing (IFLB) ....................................................................... 43
Figure 1-44: LTE Features for Mobility KPI ................................................................................... 44
Figure 1-45: LTE Features affecting load based mobility(IFLB/IFO/IROW) ................................... 44
Figure 1-46: Automated Mobility Optimization ............................................................................... 46
Figure 1-47: Counters, events and parameters AMO .................................................................... 47
Figure 1-48: Automated mobility optimization................................................................................ 48
Figure 1-49: Counters, events and parameters AMO .................................................................... 48
Figure 1-50: Counters, events and parameters AMO .................................................................... 49
Figure 1-51: Case study 1: AMO Trial test .................................................................................... 49
Figure 1-52: Case Study 1: AMO Feature parameters .................................................................. 50
Figure 1-53: Case Study 1: AMO Performance Results ................................................................ 50
Figure 1-54: Case Study1: AMO Performance Results ................................................................. 51
Figure 1-55: Case Study1: AMO Performance Results ................................................................. 51
Figure 1-56: Case Study 1: AMO Performance Results Conclusion .............................................. 52
Figure 1-57: MCPC: Related Special KPI ...................................................................................... 54
Figure 1-58: Mobility Control at Poor Coverage ............................................................................ 55
Figure 1-59: Mobility Control at Poor Coverage ............................................................................ 56
Figure 1-60: Case 2: Post MCPC evaluation L2600 ...................................................................... 57
Figure 1-61: Case 2: Post MCPC evaluation L2600 ...................................................................... 57
Figure 1-62: Case 2: Post MCPC evaluation L2600 ...................................................................... 58
Figure 1-63: Case 2: Post MCPC evaluation L2600 ...................................................................... 58
Figure 1-64: Case 2: Post MCPC evaluation L1800 ...................................................................... 59
Figure 1-65: Multi-Layer Service-Triggered Mobility ...................................................................... 60
Figure 1-66: Summary of Chapter 1 .............................................................................................. 61
Figure 2-1: Objective of Chapter 2 ................................................................................................ 63
Figure 2-2: Investigation: X2 HO - Preparation.............................................................................. 64
Figure 2-3: Investigation: X2 HO - Execution ................................................................................ 65
Figure 2-4: Investigation: X2 HO - Execution ................................................................................ 66
Figure 2-5: Identifying Events – example ...................................................................................... 67
Figure 2-6: Identifying Events - example ....................................................................................... 67
Figure 2-7: Case 1- IRAT HO, optimum parameter setting to improve LTE drop rate .................... 68
Figure 2-8: Case 1- IRAT HO, optimum parameter setting to improve LTE drop rate .................... 69
Figure 2-9: Case 1- IRATHO, Parameter setting to improve LTE drop rate ................................... 69
Figure 2-10: Case 1- IRAT HO optimum parameter setting to improve LTE drop rate ................... 70
Figure 2-11: Case 2: Oscillating Handover .................................................................................... 70
Figure 2-12: Case 2: Intra frequency HO ...................................................................................... 71
Figure 2-13: Case 2: Oscillating Handover .................................................................................... 71
Figure 2-14: Case 2: Performance result ...................................................................................... 72
Figure 2-15: Case 2: Performance result ...................................................................................... 72
Figure 2-16: Case 3: With AMO HOSR degraded ......................................................................... 73
Figure 2-17: Case 3: CIO statistics of the network ........................................................................ 74
Figure 2-18: Case 3: CIO & distance analysis ............................................................................... 74
Figure 2-19: Case 3: CIO=-2 & -3 distribution In the cluster .......................................................... 75
Figure 2-20: Case 3: Example of unreasonable CIO value............................................................ 75
Figure 2-21: Case 3: Potential reason of unreasonable CIO value ................................................ 76
Figure 2-22: Case 3: Trail suggestion ........................................................................................... 76
Figure 2-23: Case 4: HOSR Execution Improvement On Distance Site......................................... 77
Figure 2-24: Case 4: HOSR Execution improvement with cell range change ................................ 77
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Figure 2-25: Case 4: HOSR Execution improvement with cell range changes .............................. 78
Figure 2-26: Case 5: Poor IRAT success rate to poor WCDMA Cell for QCI8 ............................... 78
Figure 2-27: Case 5: Poor IRAT success rate to poor WCDMA Cell for QCI8 ............................... 79
Figure 2-28: Case 5: Poor IRAT success rate to poor WCDMA Cell for QCI8 ............................... 79
Figure 2-29: Poor IRAT HOSR – Other reasons & solutions ......................................................... 80
Figure 2-30: IRAT improvement Solution Procedure Contd… ....................................................... 81
Figure 2-31: Case 6: IRAT improvement Solution Procedure Contd… .......................................... 81
Figure 2-32: Case 6: IRAT improvement Solution Procedure Contd… .......................................... 82
Figure 2-33: Case 6: IRAT improvement Solution Procedure Contd… .......................................... 82
Figure 2-34: Case 6: IRAT improvement Solution Procedure Contd… .......................................... 83
Figure 2-35: Case 7: KPIs Improvement with IFHO parameter setting .......................................... 83
Figure 2-36: Case 7: KPIs (HOSR,Ret.,Thp.) Improvement with ifho parameter setting ................ 84
Figure 2-37: Case 7: KPIs Improvement with IFHO parameter setting .......................................... 84
Figure 2-38: Case 7: KPIs Improvement with IFHO parameter setting .......................................... 85
Figure 2-39: Case 7: KPIs Improvement with IFHO parameter setting .......................................... 85
Figure 2-40: Case 8: Coverage issue, crsGain Tuning .................................................................. 86
Figure 2-41: Case 8: Cell Selection to Increase crsGain ............................................................... 86
Figure 2-42: Case 8: Coverage issue, crsGain Tuning Example ................................................... 87
Figure 2-43: Case 8: Coverage issue, crsGain Tuning .................................................................. 87
Figure 2-44: Case 9: Handover failed during RRC setup............................................................... 88
Figure 2-45: Case 9: Handover failed in preparation phase .......................................................... 88
Figure 2-46: Case 10: PCI Confusion............................................................................................ 89
Figure 2-47: Case 10: PCI Confusion............................................................................................ 89
Figure 2-48: Case 11: ~100% HO Execution failures .................................................................... 90
Figure 2-49: Case 11- RRC HO Execution failures due to PCI Collision ....................................... 90
Figure 2-50: Case 11- RRC HO Execution failures due to PCI Collision ...................................... 91
Figure 2-51: ANR: MOM – ANR Created ...................................................................................... 92
Figure 2-52: Handover event triggered.......................................................................................... 93
Figure 2-53: ANR event triggered ................................................................................................. 94
Figure 2-54: Periodical ANR (Inter-frequency and IRAT HO) ........................................................ 95
Figure 2-55: Parameters EUTRAN 1(3) ........................................................................................ 96
Figure 2-56: Parameters 2(3) ........................................................................................................ 96
Figure 2-57: Parameters 3(3) ........................................................................................................ 97
Figure 2-58: Observability ............................................................................................................. 98
Figure 2-59: ANR Related Counters.............................................................................................. 99
Figure 2-60: Self-Organizing Networks (FAJ 801 0435) ................................................................ 99
Figure 2-61: Automated Neighbour Relation (PCI Conflict Impact) .............................................. 100
Figure 2-62: Automated Neighbour Relation (PCI Conflict Handling) .......................................... 101
Figure 2-63: Automated Neighbour Relation (PCI Conflict Detection DRX) ................................. 102
Figure 2-64: Automated Mobility Optimization (Coordination with ANR) ...................................... 103
Figure 2-65: CSFB ...................................................................................................................... 104
Figure 2-66: CSFB – Radio feature list........................................................................................ 104
Figure 2-67: KPI Definition Example ........................................................................................... 105
Figure 2-68: CSFB Cases for long CALL SETUP TIME .............................................................. 105
Figure 2-69: CSFB Case 1: Longer setup time due to Core Network signaling ........................... 106
Figure 2-70: CSFB Case 1: CSFB failure due to long Cell reselection time ................................. 106
Figure 2-71: CSFB Case 1: SIB reading during Cell reselection.................................................. 107
Figure 2-72: CSFB Case 1: Failure due to Multiple RRC connection Request ............................ 107
Figure 2-73: CSFB Case 1: Failure due to Multiple RRC connection Request ............................ 108
Figure 2-74: CSFB Case 1: Failure due to Bad UTRAN Coverage.............................................. 108
Figure 2-75: Case 2: UE Fail to Return to LTE After CSFB to UTRAN ........................................ 109
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Figure 2-76: Case 2: UE Fail to Return to LTE After CSFB to UTRAN ........................................ 109
Figure 2-77: Case 2: UE Fail to Return to LTE After CSFB to UTRAN Answer ........................... 110
Figure 2-78: Case 3: UE took more time when return back to LTE NW1 ..................................... 111
Figure 2-79: Case 3: UE took more time when return back to LTE NW2 ..................................... 111
Figure 2-80: Case 3: UE took more time when return back to LTE NW3 ..................................... 112
Figure 2-81: Summary of Chapter 2 ............................................................................................ 113
Figure 3-1: Objective of Chapter 3 .............................................................................................. 115
Figure 3-2: Review: EUTRAN Throughput KPIs .......................................................................... 116
Figure 3-3: Review: EUTRAN Throughput KPIs .......................................................................... 117
Figure 3-4: Review: DL DRB Traffic Volume Measurement ......................................................... 117
Figure 3-5: Review: DL DRB Traffic Volume Counters ................................................................ 118
Figure 3-6: Review: DL DRB Traffic Volume Counters ................................................................ 119
Figure 3-7: Review: EUTRAN Throughput KPIs .......................................................................... 119
Figure 3-8: Review: UL DRB Traffic Volume Measurement ......................................................... 120
Figure 3-9: Review: UL DRB Traffic Volume Counters ................................................................ 120
Figure 3-10: Review: EUTRAN Latency KPIs.............................................................................. 121
Figure 3-11: Review: Downlink Latency Measurement ................................................................ 122
Figure 3-12: Downlink Latency Counters .................................................................................... 122
Figure 3-13: EUTRAN Packet Loss KPIs .................................................................................... 123
Figure 3-14: EUTRAN Packet Loss KPIs .................................................................................... 124
Figure 3-15: Downlink Packet Loss Measurement ...................................................................... 125
Figure 3-16: Uplink Packet Loss Measurement ........................................................................... 125
Figure 3-17: Packet Loss Counters ............................................................................................. 126
Figure 3-18: Packet Loss Counters ............................................................................................. 126
Figure 3-19: Packet Loss Counters ............................................................................................. 127
Figure 3-20: Throughput Optimization ......................................................................................... 127
Figure 3-21: Analysis Flow for Dl Throughput Investigation ......................................................... 128
Figure 3-22: Analysis Flow for UL throughput Investigation ......................................................... 129
Figure 3-23: Downlink Throughput Optimization ......................................................................... 129
Figure 3-24: Downlink Throughput Optimization (contd..)............................................................ 130
Figure 3-25: Uplink Throughput Optimization .............................................................................. 130
Figure 3-26: Uplink Throughput Optimization (contd..) ................................................................ 131
Figure 3-27: Throughput Testing: Checks ................................................................................... 131
Figure 3-28: PRB Utilization ....................................................................................................... 132
Figure 3-29: PRB Utilization ........................................................................................................ 133
Figure 3-30: Ways to reduce PRB utilization ............................................................................... 133
Figure 3-31: Essential Parameters .............................................................................................. 134
Figure 3-32: Counters for throughput analysis ............................................................................ 134
Figure 3-33: RSSI ....................................................................................................................... 135
Figure 3-34: UL SINR ................................................................................................................. 135
Figure 3-35: UL RLC NACK ........................................................................................................ 136
Figure 3-36: Power restricted transport block-UL ........................................................................ 137
Figure 3-37: CQI ......................................................................................................................... 137
Figure 3-38: MIMO RANK distribution usage .............................................................................. 138
Figure 3-39: Modulation scheme usage DL ................................................................................. 138
Figure 3-40: Modulation scheme usage UL ................................................................................. 139
Figure 3-41: Throughput Optimization-essential checks .............................................................. 139
Figure 3-42: QoS Framework ...................................................................................................... 141
Figure 3-43: QoS Aware Scheduler – Absolute priority example ................................................. 142
Figure 3-44: Scheduler Configuration.......................................................................................... 143
Figure 3-45: Proportional Fair Scheduling Benefits ..................................................................... 144
Figure 3-46: LTE Features enhancing UL/DL Throughput ........................................................... 144
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Figure 3-47: 256 QAM DL Parameters ........................................................................................ 146
Figure 3-48: Link Adaptation Tables............................................................................................ 148
Figure 3-49: 64-QAM Uplink (FDD/TDD) ..................................................................................... 149
Figure 3-50: 64 QAM UL Benefits ............................................................................................... 149
Figure 3-51: 64 QAM UL Parameters .......................................................................................... 151
Figure 3-52: Ericsson Lean Carrier Applying 5G concepts to today’s 4G LTE ........................... 152
Figure 3-53: Ericsson Lean Carrier Applying 5G concepts to today’s 4G LTE ........................... 154
Figure 3-54: 4CC DL Carrier Aggregation Extension ................................................................... 155
Figure 3-55: Uplink Carrier Aggregation ...................................................................................... 156
Figure 3-56: Uplink Carrier Aggregation Parameters ................................................................... 157
Figure 3-57: Advanced Carrier Aggregation (FAJ 801 0568) ....................................................... 158
Figure 3-58: Inter-eNB Carrier Aggregation................................................................................. 159
Figure 3-59: Inter-eNB Carrier Aggregation Performance ........................................................... 160
Figure 3-60: Inter-eNB Carrier Aggregation Parameters ............................................................. 161
Figure 3-61: Multi-carrier Load Management (FAJ 801 0424) ..................................................... 162
Figure 3-62: Prescheduling ......................................................................................................... 162
Figure 3-63: Prescheduling OFF ................................................................................................. 163
Figure 3-64: Prescheduling ON ................................................................................................... 164
Figure 3-65: Prescheduling Parameters ...................................................................................... 164
Figure 3-66: LTE transmission modes Downlink transmission modes ......................................... 167
Figure 3-67: Which MIMO Mode is Best? .................................................................................... 167
Figure 3-68: VOLTE Impact on BB Throughput & DBS ............................................................... 168
Figure 3-69: VOLTE Impact on BB Throughput & DBS ............................................................... 169
Figure 3-70: VOLTE Impact on BB Throughput & DBS ............................................................... 169
Figure 3-71: Summary of Chapter 3 ............................................................................................ 170
Figure 4-1: Objective of Chapter 4 .............................................................................................. 171
Figure 4-2: CASE 1: DL Throughput ........................................................................................... 172
Figure 4-3: CASE 2: UL Throughput Improvement ...................................................................... 173
Figure 4-4: Case 3: LTE Latency issue ....................................................................................... 174
Figure 4-5: Case 3: Investigation Analysis .................................................................................. 175
Figure 4-6: Case 3: Investigation Analysis .................................................................................. 175
Figure 4-7: Case 3: Investigation Analysis .................................................................................. 176
Figure 4-8: Case 3: Investigation Analysis .................................................................................. 177
Figure 4-9: Case-Study 4: Reported issue .................................................................................. 179
Figure 4-10: Exercise 1 – Analyze ROP files............................................................................... 180
Figure 4-11: Exercise 1 - Answer ................................................................................................ 180
Figure 4-12: Exercise 2: .............................................................................................................. 181
Figure 4-13: Exercise 2 - Answer ................................................................................................ 181
Figure 4-14: Exercise 2 – Answer ............................................................................................... 182
Figure 4-15: Exercise 2 – Answer cont’d ..................................................................................... 182
Figure 4-16: Exercise 2 – Answer cont’d ..................................................................................... 183
Figure 4-17: Exercise 2 – Answer Cont’d .................................................................................... 183
Figure 4-18: Exercise 2 – Answer Cont’d .................................................................................... 184
Figure 4-19: Exercise 2 – Answer Cont’d .................................................................................... 184
Figure 4-20: Exercise 2 – Answer Cont’d .................................................................................... 185
Figure 4-21: Exercis 2 – Answer Cont’d ...................................................................................... 186
Figure 4-22: Exercise 2 – Answer Cont’d .................................................................................... 186
Figure 4-23: Exercise 3: .............................................................................................................. 187
Figure 4-24: Exercise 3 – Answer Cont’d .................................................................................... 187
Figure 4-25: Exercise 3 – Answer Cont’d .................................................................................... 188
Figure 4-26: Exercise 3 – Answer Cont’d .................................................................................... 188
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Figure 4-27: Exercise 3 – Answer Cont’d .................................................................................... 189
Figure 4-28: Exercise 3 – Answer Cont’d .................................................................................... 190
Figure 4-29: Exercise 3 – Answer Cont’d .................................................................................... 190
Figure 4-30: Exercise 3 – Answer Cont’d .................................................................................... 191
Figure 4-31: Exercise 3 – Answer Cont’d .................................................................................... 191
Figure 4-32: Exercise 3 – Answer Cont’d .................................................................................... 192
Figure 4-33: Exercise Summary .................................................................................................. 192
Figure 4-34: WAY FORWARD .................................................................................................... 193
Figure 4-35: Summary of Chapter 4 ............................................................................................ 194
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