4G Paging Performance
Monitoring Guidelines
Paging Description (4G)
› Paging messages are transmitted in all cells within the affected tracking area by the RBS on the Physical Downlink Shared Channel (PDSCH).
The Paging Radio Network Temporary Identity (P-RNTI) is broadcast on PDCCH where the information about the modulation and coding
scheme of the PDSCH data containing the RRC Paging message, is found.
› The information in PDCCH is transmitted with a Cyclic Redundancy Check (CRC), which is scrambled with the P-RNTI. This notifies the UEs about
the presence of a Paging message within in the same subframe.
› When a UE detects a P-RNTI on the PDCCH, it demodulates and decodes the Paging message, contained in the PDSCH, and forwards it over the
Paging Channel (PCH) to the Medium Access Control (MAC) layer.
Ericsson Internal | 2018-02-21
Paging Description (4G)
o
Paging message may be triggered either by MME in core network or eNB in Radio Access Network
o
UEs in idle mode monitor the PDCCH channel for P-RNTI used for paging to receive paging message from eNB. The UE needs to monitor the
PDCCH only at certain UE specific paging occasion, i.e. only at specific subframe in specific radio frame. At other times the UE may go for sleep
mode to save battery power.
o
Paging Frame (PF): One Paging Frame (PF) is one Radio Frame in which the UE is looking for paging message. One Paging Frame may contain
one or multiple Paging Occasion(s).
o
Paging Occasion (PO): It is a subframe where there may be P-RNTI transmitted on PDCCH addressing the paging message for the UE. There is
always only one paging occasion for each UE in a DRX cycle.
Ericsson Internal | 2018-02-21
Paging Dimensioning Calculation
— Paging capacity in LTE:
— Paging Capacity in MME
— Paging Capacity in RBS
— SGSN-MME paging capacity depends on the number of SCTP/S1 boards in the SGSN-MME and the hardware type.
For MkVI hardware type, the recommendation is to not exceed 2000 outgoing pages/s per SCTP board andfor MkVIII
hardware type the recommendation is not to exceed 6000 outgoing pages/s per SCTP board.
— As an example, for an SGSN-MME configured with 5 SCTP boards of MkVI hardware type it is not recommended to
exceed 2000 x 5 = 10000 outgoing pages/s.
— The total RBS paging capacity is given as the minimum of the four capacity below:
—
—
—
—
CPU load
PDSCH load
Blocking
PDCCH load
— The paging capacity related to CPU load is expressed as:
General rule: the paging intensity should <90% cpu load capacity
Ericsson Internal | 2018-02-21
Paging Dimensioning Calculation
— Paging capacity related to PDSCH load:
— Using the cost for conveying one paging message, the PDSCH paging load is expressed as a function of the
paging intensity:
Where:
—
—
is the paging intensity, that is, the average number of incoming pages to the RBS per second
where:
—
— To calculate the paging capacity for PDSCH load, the following expression is used:
where
is the tolerable PDSCH load due to paging
(general guideline: it should not exceed 5%)
Ericsson Internal | 2018-02-21
Paging Dimensioning Calculation
— Paging capacity related to Blocking:
— The following expression gives paging capacity in relation to blocking, in pages per seconds:
—
is paging capacity in relation to blocking expressed as pages per PO
—
is the number of POs per radio frame
— The following figure that shows paging capacity per PO versus blocking probability and value of
maxNoOfPagingRecords
›
Ericsson Internal | 2018-02-21
As general rule, the blocking probability should not exceed 2%.
Paging Dimensioning Calculation
— Paging capacity related to PDCCH load:
— PDCCH paging capacity is written as:
— Number of CCE per radio frame:
— As general rules, maximum
tolerable PDCCH load is 5%
— Paging capacity vs PDCCH load:
Ericsson Internal | 2018-02-21
Paging Dimensioning Calculation Summary
CPU Load (90%) Paging Capacity
Per HW Type
Baseband Type
DUL20
DUS31/DUS41/
BB5212/BB5216
microRBS
picoRBS
Blocking 2% and Load 5% Paging Capacity
Per LTE BW without ELC
LTE BW
maxNoOf
PagingRe
cords
1250
5 MHz
380
200
~90% Paging Capacity
(pages/sec)
900
*Current typical HW used in the Network is
BB5216
nB
Blocking
(2%)
PDCCH
Load
(5%)
PDSCH
Load
(5%)
Paging
Capacity
(Pages/s)
Paging
Capacity
(Pages/hour)
7
T
330
-
380
330
1,188,000
10 MHz
16
T
970
-
770
770
2,772,000
15 MHz
16
T
970
-
1140
970
3,492,000
20 MHz
16
T
970
-
1640
970
3,492,000
Blocking 2% and Load 5% Paging Capacity
Per LTE BW with ELC Active and nB parameter is set to T/4
The total RBS paging capacity is
given as the minimum of
capacity:
✓
✓
✓
✓
HW Type
Blocking
PDCCH load
PDSCH load
Ericsson Internal | 2018-02-21
LTE BW
maxNoOf
PagingRe
cords
nB
Blocking
(2%)
PDCCH
Load
(5%)
PDSCH
Load
(5%)
Paging
Capacity
(Pages/s)
Paging
Capacity
(Pages/hour)
5 MHz
7
T/4
85
-
380
85
306,000
10 MHz
16
T/4
240
-
770
240
864,000
15 MHz
16
T/4
240
-
1140
240
864,000
20 MHz
16
T/4
240
-
1640
240
864,000
TA Dimensioning
Briefly, the purpose of Tracking area dimensioning exercise is to determine the number of RBSs that can be accommodated
in one Tracking Area list where a page is sent by an MME. This number is calculated both from MME perspective as well as
from RBS perspective and the minimum of the two is taken as the limiting factor.
Ericsson Internal | 2018-02-21
TA Dimensioning | NumberSiteperTAC
Number Site Simulation per TAC are by assuming using below parameter :
—
—
—
—
—
—
Average LTE configuration is 10 MHz or more
nB and maxNoOfPagingRecords settings are T and 16
Average Subs per Cell are 450 Subs/Cell
Average Paging Request per Subs in Busy Hour are 5 Paging_Request/Subs/Busy_Hour
Average Cell per Site is 3 Cells
GoS 2%, Occupancy 75%
Without ELC
Number_of_eNodeB_per_TAC
With ELC (50% of Cells Active)
Number_of_eNodeB_per_TAC
Ericsson Internal | 2018-02-21
= 75% * ( 2,772,000 ) / ( 3 x 5 x 450 )
= 308 Site
= 75% * ( (2,772,000 + 864,000) / 2 ) / (3 x 5 x 450)
= 202 Site
Paging Related Parameters and Recommended Values
MO
Class
Name
Paging
Paging
Parameter Name
Parameter Description
The maximum allowed number of paging records included
in one Radio Resource Control (RRC) paging message. It is
maxNoOfPagingRecords
the allowed maximum number of UE that can be paged per
paging occasion.
defaultPagingCycle
Paging
nB
Paging
pagingDiscardTimer
Ericsson Internal | 2018-02-21
Range and
Values
1..16
The paging cycle (also referred to as T) used by the RBS
and broadcast in system information type 2. If the UEspecific Discontinuous Reception (DRX) cycle is provided
32,64,128,256
in S1AP paging and has a smaller value than
defaultPagingCycle, the UE-specific DRX cycle overrides
defaultPagingCycle.
Used to calculate the number and position of Paging
Occasions (PO) and Paging Frames
The numerical value of nB depends on the value of the
defaultPagingCycle (T) and can be set to one of the
following values: 4T, 2T, T, 1/2T,1/4T, 1/8T, 1/16T, 1/32T
When nB is set to T, 2T or 4T, it determines the number of
T4, T2,T, T1_2,
POs per PF, and the PO position in PF.
T1_4, T1_8,
When nB is set to a value smaller than T, it affects the
T1_16, T1_32
System Frame Number of the PF, the position of PO in the
PF, and also distribution of UE into groups with the same
PF.
When nB is set to a smaller value, the groups are fewer but
larger, or more but smaller.
The length of time a received paging is retained or queued
in the RBS before it is discarded. The timer should be set to
the same (or smaller) value as the paging resend timer in
1..15
MME (T3413). This setting prevents the RBS from retaining
or sending an old paging after the re-sent copy is received
from the MME.
Default
Value
Recommended
Value
3
7 (5MHz)
16 (>=10MHz)
128
128
Comment
By increasing this
parameter, paging
capacity related to
blocking will be
increased.
1.28 seconds. Can be
decreased to reduce
setup time with
drawback of increased
battery consumption in
UEs
T
T (non ELC)
T/4 (ELC)
The setting of this
parameter will mainly
impact to PDCCH load
capacity.
By increasing this
parameter, the paging
capacity related to
blocking will be
increase, but it will
potentially limit paging
related to PDCCH load
capacity.
3
3
This is equal to T3413
(default value)
RAN Counter & KPI for Paging Performance Monitoring
o Counters which need to be monitored
related to Paging performance:
o pmPagS1Received
o pmPagS1Discarded
o pmPagReceived
o pmPagDiscarded
o The discarded paging should be at the
lower value compare to expected blocking
probability, i.e. 2% as general rule.
o Paging success rate per Cell: 100*
(pmPagReceived-pmPagDiscarded )/
pmPagReceived
o Paging optimization is required if the
discarded paging is higher than expected
blocking probability.
Ericsson Internal | 2018-02-21
Paging Performance Monitoring | AnalysisFlow
Note: further assessment is
needed to define the threshold
after parameter standardization
Start
Paging discard
> 1%
Is
pmPagS1Dis
carded
Pegged?
No
Yes
Is #page/s >
90% CPU
load capacity
Is paging
intensity > xx
pages/sec
No
Yes
Is there
alarm/hw
problem?
Yes
No
HW problem / alarm
solving or identify and
solve other issue
No
Yes
CPU Load Evaluation /
hw problem
check/solving
No
Is paging
parameters
optimized?
Yes
Is paging
discard >
1%
Yes
Parameter
Optimization
Ericsson Internal | 2018-02-21
TA Splitting
End
No
Optimization Acitivities
Tuning/optimization of paging performance from radio side is mainly related to paging capacity to ensure
there is enough paging capacity in order to prevent paging discards while keeping the paging load on PDCCH
and PDSCH channels along wtih RBS and MME CPU loads.
Key Activities:
— Parameter tuning mainly maxNoOfPagingRecords and nB.
— tInactivityTimer can be tuned as well, but it need to put more attention to other capacity and performance.
— TA Splitting
— Some key rules for TA planning:
— TAs and TA lists should be planned so that areas with frequent TA update signaling are located in low traffic areas
— TAs and TA lists should be planned so that the need for TA updates is minimized. This is accomplished by
considering how users travel within the network. Busy roads, railways, and so on, should cross as few TA list borders
as possible.
— To minimize CS call setup delay when using CS Fallback the coverage of the TA list should be within the coverage
of one and only one LA of GSM/WCDMA.
— Potential features:
— MME Configurable and Adaptive Paging
Ericsson Internal | 2018-02-21
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