Mobility in LTE
Radio Network Design for Roll-Outs (RNDR)
Connected Mode Mobility
Idle Mode Mobility
Soc Classification level
1
© Nokia Siemens Networks
Presentation / Author / Date
Connected Mode Mobility
Soc Classification level
2
© Nokia Siemens Networks
Presentation / Author / Date
Connected Mode Mobility
• Overview
– Mobility supported in different releases
– Mobility triggers
– Mobility Thresholds
• Connected Mode Mobility types
– Intra and Inter-frequency Handovers
– S1 Handover
– IRAT Handover to WCDMA
– eNACC to GSM
– RRC Connection Release with Redirect
– CS Fallback
Soc Classification level
3
© Nokia Siemens Networks
Presentation / Author / Date
Overview
• Procedures supported:
– Handover: Transfer of an ongoing call/data session from a cell to another
without call interruption. Handovers in LTE are:
o Network controlled
o UE assisted
o Hard handovers: Only a connection exist to one cell at a time
– Redirection: Similar to handover, but requires connection release prior to the
transfer the ongoing call
– Cell change: procedure dedicated for call transfer from LTE to GSM; it requires
connection release
Licensing:
• All IRAT HO, inter-frequency HO, CSFB to UTRAN/GERAN via redirect and S1
handovers are optional features:
• When enabled they are activated for the whole eNodeB
• If deactivated the eNB does not configure UE to measure other technologies/
frequencies so handover is not triggered
Soc Classification level
4
© Nokia Siemens Networks
Presentation / Author / Date
Mobility supported in different Releases
FDD:
RL10
RL20
RL30
Intra eNB Handover
Inter Frequency HO (intra
eNB and via X2)
IRAT Handover: LTE to
WCDMA
Inter eNB HO via X2 interface
S1 based HO
eNACC from LTE to GSM
RRC connection Release with
Redirect
CSFB to UTRAN or GSM
via Redirect
TDD:
RL15TD
RL25TD
Intra eNodeB Handover
IRAT Handover: LTE to WCDMA
Inter eNodeB Handover via X2
eNACC from LTE to GSM
Inter frequency handover (intra eNodeB and via X2)
CSFB to UTRAN or GSM via
Redirect
RRC connection Release with Redirect
Inter eNodeB Handover via S1
Soc Classification level
5
© Nokia Siemens Networks
Presentation / Author / Date
Mobility Triggers (1/3)
• Mobility is handled via events triggering. 3GPP defines following events:
Event A1 Serving becomes better than
threshold
Event A2 Serving becomes worse than
threshold
Events A4 and B1
are not supported
in RL30
Event A3 Neighbour becomes offset better
than serving
Event A4 Neighbour becomes better than
threshold
Event A5 Serving becomes worse than
threshold1 and neighbour
becomes better than threshold2
Event B1 Inter RAT neighbour becomes
better than threshold
Event B2 Serving becomes worse than
threshold1 and inter RAT
neighbour becomes better than
threshold2
Soc Classification level
6
© Nokia Siemens Networks
Presentation / Author / Date
Mobility Triggers (2/3)
• Event A2/A1: RSRP of serving cell is down/up-crossing certain RSRP threshold
(threshold2a/ threshold1)
• Event A3 (better cell HO): RSRP of neighbour cell is a predefined offset better
than RSRP of serving (for intra and inter frequency HOs)
• Event A5 (coverage HO): RSRP of serving cell is down-crossing certain
threshold, while RSRP of neighbour cell is up-crossing an other threshold (for intra
and inter frequency HOs)
threshold3a
threshold3
neighbour
Soc Classification level
7
© Nokia Siemens Networks
Mobility Triggers (3/3)
Inter-RAT measurements (GERAN or UMTS supported in RL30)
• Event B2: Serving cells RSRP down-crossing threshold1, while neighbour cell
RSSI or CPICH RSCP or CPICH Ec/No up-crossing threshold2
• Triggers for Inter-RAT reports are:
– RSSI in case of GERAN
– CPICH RSCP or CPICH EC/N0 in case of UMTS
Signal
Level
B2 trigger
B2 thold 2
Inter-RAT
Neighbour cell
signal
B2 thold 1
RSRP serving
move direction
Soc Classification level
8
© Nokia Siemens Networks
Handover Thresholds
Measurement Activations
• Threshold 1 (Th1): UE does not perform measurements of neighbour cells when
the serving cell RSRP is above Threshold1 (Th1)
• Thresholds 2 (Th2_interfreq/Th2_WCDMA/Th2_GSM):UE starts performing
measurement gaps when one of the Th2 events is reported to the eNodeB in a
measurement report. Event A2
• Threshold2a (Th2a): Measurement gaps are cancelled if serving cell RSRP rises
above Th2a. Event A1
• Threshold 4 (Th4):RRC Connection Release with redirection is triggered if no
suitable intra or inter frequency/IRAT cells are found. Event A2
threshold2InterFreq
Event A2
Intra –LTE + Inter
Freq measurements
Intra –LTE
measurements
No measurements
except serving cell
Intra –LTE + Inter
Freq + WCDMA +
GSM
measurements
RRC
Intra –LTE + Inter
Connection
Freq + WCDMA
Release and
measurements
re-direction
RSRP (dBm)
Th1
Soc Classification level
9
© Nokia Siemens Networks
Threshold1
S-measure
EventA2/A1
Th2a
Th2_InterFreq
Threshold2a
a1-threshold
Event A1
Th2_WCDMA
Th2_GSM
Th4
threshold2WCDMA threshold2GERAN
Event A2
Event A2
threshold4
Event A2
Intra- and Inter-frequency Handover Thresholds
Serving cell (not including neighbour cell thresholds)
• Example values:
Soc Classification level
10
© Nokia Siemens Networks
Presentation / Author / Date
Mobility thresholds comments
RRC_connected mode
• LTE thresholds are relative to -140 dBm. This means if for example threshold3 is
set to 21, the RSRP value is (-140+21=) -119dBm
• The following restrictions need to be fulfilled:
– Threshold4 < Threshold3 < Threshold2_xxxx <= Threshold2a < Threshold1
– Threshold3 < Threshold3a
– Threshold3InterFreq < Threshold3aInterFreq
• The higher the threshold the better the RSRP signal
Soc Classification level
11
© Nokia Siemens Networks
IRAT (WCDMA) handover thresholds
Serving cell
Threshold2InterFreq
Threshold3
When RSRP is below
Threshold2InterFreq, UE starts
measurements on other
frequencies.
When RSRP is below
Threshold3, UE will
perform HO to neighbour.
(Assuming that neighbour
is better than threshold3a
and A5 handover is
activated)
Threshold2Wcdma
RSRP for
serving cell
decreases
When RSRP is below
Threshold2Wcdma, UE
starts measurements
on WCDMA
frequencies in addition
to other LTE
frequencies (Intra+
InterFrequencies)
Threshold1
-90
-50
When RSRP is above
Threshold2a, UE stops
measurements on
other frequencies
(including IRAT)
Threshold2a
Soc Classification level
12
© Nokia Siemens Networks
-118
-119
Threshold4
b2Threshold1Utra
When serving RSRP is
below b2Threshold1Utra
UE performs HO to
WCDMA neighbour
(Assuming that RSCP or
EcNo of WCDMA
neighbour is better than
b2Threshold2Utra
Rscp/EcNo.
-120
RSRP increases
IRAT (eNACC) handover thresholds
Serving cell
Threshold2GERAN
When RSRP is below
Threshold2GERAN, UE
starts measurements on
GERANfrequencies
Threshold2InterFreq
When RSRP is below
Threshold2InterFreq,
UE starts
measurements on
other frequencies.
Threshold3
When RSRP is below
Threshold3, UE will perform
HO to neighbour. (Assuming
that neighbour is better than
threshold3a and A5 handover
is activated)
RSRP for
serving cell
decreases
Threshold1
Threshold4
b2Threshold1GERAN
When serving RSRP is below
b2Threshold1GERAN, UE
performs eNACC to GSM
neighbour (Assuming that RSSI
of GERAN neighbour is better
than b2Threshold2RssiGERAN
-90
-50
When RSRP is above
Threshold2a, UE stops
measurements on other
frequencies (including IRAT)
Threshold2a
Soc Classification level
13
© Nokia Siemens Networks
-118
-119
-120
RSRP increases
Intra and inter frequency handovers
Soc Classification level
14
© Nokia Siemens Networks
Handovers
Two main types of handovers in LTE:
Better Cell Handover or A3 Handover
– It aims to keep the UE always on best cell (measured by RSRP/RSRQ), e.g.
HO to another cell happens when neighbour cell becomes more than 4 dB
better than serving cell
Coverage Handover, or A5 Handover
– When serving cell RSRP gets below a certain threshold (e.g.-95 dBm RSRP)
AND neighbour cell RSRP gets better than an absolute threshold (e.g. -92 dBm
RSRP)
• They can be intra and inter frequency (different
parameters) and intra or inter eNodeB
• They can be enabled/disabled on cell level:
Inter-frequency HO parameters are defined in
LNIFHO object whereas Intra-frequency HO
parameters are defined in LNCEL object
Soc Classification level
15
© Nokia Siemens Networks
LNBTS
LNCEL
LNHOIF
A3 event based Handover
Intra-Frequency
• Intra-frequency better coverage based (A3) handover event evaluation
Mn – hysA3Offset > Ms + a3Offset
Parameters
involved:
hysA3Offset
Signal
level
intra-frequency
neighbour cell
(Mn)
Hysteresis of HO Margin
LNCEL; 0..15; 0.5; - dB
(RSRP)
hysA3Offset
a3Offset
Better cell HO margin for RSRP
LNCEL; -15…15; 0.5; - dB
a3Offset
serving cell (Ms)
time
Event A3 condition fullfilled,
UE sends measurement
report
a3ReportInterval
a3TimeToTrigger
Measurement
Report
Measurement
Report
a3TimeToTrigger
a3ReportInterval
LNCEL; 0..5120ms; -; 320ms(8)
LNCEL; 120ms..60 min; -; 240ms (1)
Soc Classification level
16
© Nokia Siemens Networks
A3 event based Handover
Inter-Frequency
• Inter-frequency better coverage/quality based (A3) handover event evaluation
Mn – hysA3OffsetRsr(p/q)InterFreq > Ms + a3OffsetRsr(p/q)InterFreq
measQuantInterFreq
Signal
level
(RSRP
or
RSRQ)
def. which quantity to use
for event A3
LNHOIF; RSRP, RSRQ;
both; RSRP
hysA3OffsetRsrp/qInterFreq
inter-frequency
neighbour cell
(Mn)
Hysteresis of HO Margin
LNHOIF; 0..15; 0.5; - dB
hysA3OffsetRsr(p/q)InterFreq
a3OffsetRsrp/qInterFreq
a3OffsetRsr(p/q)InterFreq
Better cell HO margin for RSRP/Q
LNHOIF; 0..15; 0.5; - dB
serving cell (Ms)
time
Event A3 condition fullfilled,
UE sends measurement
report
a3TimeToTriggerRsr(p/q)InterFreq
Measurement
Report
a3ReportIntervalRsr(p/q)InterFreq
Measurement
Report
a3TimeToTriggerRsrp/qInterFreq
a3ReportIntervalRsrp/qInterFreq
LNHOIF; 0..5120ms; -; not used
LNHOIF; 120ms..60 min; -; not used
Soc Classification level
17
© Nokia Siemens Networks
A5 event based Handover
Intra-Frequency
• Intra-frequency coverage based (A5) handover event evaluation
Ms + hysThreshold3 < threshold3
and
Mn – hysThreshold3 > threshold3a
Parameters
involved:
Signal
level
(RSRP)
hysThreshold3
intra-frequency
neighbour cell
(Mn)
hysThreshold3
Hysteresis of HO Margin
LNCEL; 0..15; 0.5; - dB
threshold3a
LNCEL; 0..97; 1; - dB
threshold3
LNCEL; 0..97; 1; - dB
hysThreshold3
serving cell (Ms)
time
event A5 condition fullfilled
UE sends measurement report
a5TimeToTrigger
a5TimeToTrigger
Soc Classification level
18
© Nokia Siemens Networks
LNCEL; 0..5120ms; -;320ms
Measurement
Report
Measurement
Report
a5ReportInterval
LNCEL; 120ms..60 min; 240ms
A5 event based Handover
Inter-Frequency
• Inter-frequency coverage based (A5) handover event evaluation
Ms + hysThreshold3InterFreq < threshold3InterFreq
and
Mn – hysThreshold3InterFreq > threshold3aInterFreq
Signal
level
(RSRP)
hysThreshold3InterFreq
Hysteresis of HO Margin
LNHOIF; 0..15; 0.5; - dB
hysThreshold3InterFreq
inter-frequency
neighbour cell
(Mn)
threshold3aInterFreq
LNHOIF; 0..97; 1; - dB
threshold3InterFreq
LNHOIF; 0..97; 1; - dB
hysThreshold3InterFreq
serving cell (Ms)
time
event A5 condition fullfilled
UE sends measurement report
a5TimeToTriggerInterFreq
a5TimeToTriggerInterFreq
Soc Classification level
19
© Nokia Siemens Networks
LNHOIF; 0..5120ms; -; -
Measurement
Report
Measurement
Report
a5ReportIntervalInterFreq
LNHOIF; 120ms..60 min; -; -
Example of successful intra-freq HO
Step 1: UE sends measurement report on PCI 274
Soc Classification level
20
© Nokia Siemens Networks
Example of successful intra-freq HO
Step 2: UE gets RRCConnectionReconfiguration on DL and replies with
an RRCConnectionReconfigurationComplete on UL
Note that for a successful HO, this happens twice. The first
RRCConnectionReconfiguration comes from the source cell and the
second one from the target
Soc Classification level
21
© Nokia Siemens Networks
Measurement Reports
• Measurement reports
refer to a measurement
Id (measId)
• A measId is defined by
a measurement Object
(e.g. a frequency) and
a reportConfig (an
Event)
• Measurement
configuration
information is sent to
the UE in the RRC
Connection
Reconfiguration Msg.
Soc Classification level
22
© Nokia Siemens Networks
measIdToAddModList
{
{
measId 1,
measObjectId 1,
reportConfigId 1
},
{
measId 2,
measObjectId 1,
reportConfigId 2
},
},
quantityConfig
{
quantityConfigEUTRA
{
}
},
measGapConfig release :
NULL,
s-Measure 90,
Presentation / Author / Date
message c1 : rrcConnectionReconfiguration :
{
rrcConnectionReconfiguration-r8 :
{
measConfig
{
measObjectToAddModList
{
{
measObjectId 1,
measObject measObjectEUTRA :
{
carrierFreq 2075,
allowedMeasBandwidth mbw25,
presenceAntennaPort1 TRUE,
neighCellConfig '00'B
}
reportConfigId 2,
reportConfig reportConfigEUTRA :
{
triggerType event :
{
eventId eventA5 :
{
a5-Threshold1 threshold-RSRP : 30,
a5-Threshold2 threshold-RSRP : 32
},
hysteresis 0,
timeToTrigger ms640
},
triggerQuantity rsrp,
reportQuantity sameAsTriggerQuantity,
maxReportCells 8,
reportInterval ms240,
reportAmount infinity
}
Connected mode mobility
Exercise: inter-frequency A3
• An operator has an existing LTE network on 2600MHz and on 1800MHz
• LTE1800MHz network has more sites than 2600MHz network. They have 20MHz
BW on 2600 and only 10MHz BW on 1800, so they want to keep the traffic as long
as possible on the 2600MHz layer
• For 1800MHz cells, LNHOIF settings towards the 2600MHz layer are as follows:
– LNHOIF:hysA3OffsetRsrpInterFreq = 2dB
– LNHOIF:a3OffsetRsrpInterFreq = 2dB
Exercise
1. Define suitable values for a3OffsetRsrpInterFreq and hysA3offsetRsrpInterFreq
for the LTE2600 cells towards the 1800MHz layer and explain why.
Soc Classification level
23
© Nokia Siemens Networks
Connected mode mobility
Ping-pong RSRP/RSRQ A3
• Simultaneous activation of RSRP and RSRQ A3 handovers between two different
layers may lead to ping pong HO between these layers. For example, in the
previous network example case:
– RSRP is better on 1800: lower frequency ->lower free space loss and penetration loss
– RSRQ is better on 2600: less interference due to lower number of sites
• A UE on a 1800 site when measuring a 2600 neighbour with better RSRQ it
performs HO to 2600 site. Once on 2600, the UE measures an 1800 site with
better RSRP, performs HO to 2600
Exercise
1. Considering the below settings, suggest two possible solutions to avoid the ping
pong (remember, operator wants to keep traffic in 2600 as long as possible):
Settings for 1800 cells:
– LNHOIF (2600MHz):hysA3OffsetRsrp(/Rsrq)InterFreq = 2dB
– LNHOIF (2600MHz):a3OffsetRsrp(/Rsrq)InterFreq = 2dB
Settings for 2600 cells:
– LNHOIF (1800MHz):hysA3OffsetRsrp(/Rsrq)InterFreq = 3dB
– LNHOIF (1800MHz):a3OffsetRsrp(/Rsrq)InterFreq = 3dB
Soc Classification level
24
© Nokia Siemens Networks
Presentation / Author / Date
Connected mode mobility
Exercise: inter-frequency A5 handover
• An operator has an existing LTE network on 2600MHz. Additionally, they want to
launch LTE on 1800MHz also. They have 20MHz BW on 2600 and only 10MHz
BW on 1800, so they want to keep the traffic as long as possible on the 2600MHz
layer.
• Thresholds on LTE2600 cells are:
– Threshold1: 90
– Threshold3: 45
– Threshold3a: 48
• Operator wants that UEs start measuring LTE1800 cells when RSRP is worse than
-100dBm.
– Identify the new thresholds that need to be considered on 2600 cells and define
suitable values
– Based on new threshold values... Is there any change required in threshold3
and threshold3a values?
– Idenfity suitable thresholds for intra and inter-frequency A5 handover for the
LTE 1800 cells (remember that operator’s strategy is to keep the traffic as long
as possible on the 2600MHz layer)
Soc Classification level
25
© Nokia Siemens Networks
S1 handover
Soc Classification level
26
© Nokia Siemens Networks
RL15TD
Intra LTE Handover via S1
Extended mobility option to X2 handover
• Applicable for intra and inter frequency HO
and only for inter-eNB HO
• DL Data forwarding via S1
• Handover in case of
– no X2 interface between eNodeBs, e.g.
not operative, not existing or because
blacklisted usage
– eNodeBs connected to different CN
elements
• For the UE there is no difference whether the HO is executed via X2 or S1
interface
• HO reasons ‘better cell HO’ (A3) and ‘coverage HO’ (A5) are supported
• MME and/or SGW can be changed during HO (i.e. if source and target
eNodeB belong to different MME/S-GW)
Soc Classification level
27
© Nokia Siemens Networks
Presentation / Author / Date
Feature ID(s): LTE54
RL20
IRAT HO to WCDMA
Soc Classification level
28
© Nokia Siemens Networks
Inter RAT Handover to WCDMA
RL25TD
RL30
• IRAT hard handover from LTE to WCDMA PS domain through S1 interface
• Phases:
1. Handover initiation:


eNB starts a HO to WCDMA following a received measurement report with event B2
Max. 8 cells reported (strongest first) that create the TCL (target cell list)
2. Handover preparation:

Resource allocation on target side (E-RAB
parameters mapped into PDP context)
3. Handover execution:

UE moves into WCDMA cell after receiving
‘MobilityfromEUTRACommand’ message
4. Handover completion:

Release of S1 connection and internal
resources after successful HO (no timers
expired)
Soc Classification level
29
© Nokia Siemens Networks
Presentation / Author / Date
Inter-RAT Handover to WCDMA
Event B2
• Handover from LTE to WCDMA is triggered by poor LTE radio coverage and
sufficient WCDMA cell radio signal quality
• Radio conditions for serving and neigbour cells are defined with event B2
Entering conditions
1. Ms + Hys < Thresh1
and
2. Mn + Ofn – Hys > Thresh2
Ms
Mn
Thresh1
Thresh2
Hys
-> RSRP of serving cell
-> RSCP/EcN0 of neigbour cell
-> b2threshold1Utra
-> b2threshold2UtraRSCP/EcN0
-> hysB2ThresholdUtra
Ofn
-> OffsetFreqUtra
Leaving conditions
1. Ms - Hys > Thresh1
or
2. Mn + Ofn + Hys < Thresh2
reportConfigInterRAT
-> refers to signal level of serving cell
-> refers to signal level of neighbour cell
-> hysteresis to prevent ping-pong effect between
entering and leaving conditions; parameter common for both
serving and neigbour cell
-> refers to neighbour cell only
measObjectUTRA
Soc Classification level
30
© Nokia Siemens Networks
Inter-RAT Handover to WCDMA
Event B2
Entering condition:
RSRP,s < b2threshold1Utra – hysB2thresholdUtra AND
utraRSCP/EcNo,n > b2theshold2UtraRscp/EcNo- offsetFreqUtra + hysB2ThresholdUtra
Soc Classification level
31
© Nokia Siemens Networks
Presentation / Author / Date
Inter-RAT Handover to WCDMA Flow
MME
LTE, Source:CelI
Measurement Report
WCDMA, Target Cell
Triggered EventA2
RRC Connection Reconfiguration New MeasConfig used for IRAT Handover
RRC Connection Reconfiguration Complete
Measurement Report
Triggered EventB2
Handover Preparation
MobilityFromEUTRAcommand
HandoverToUTRANComplete
Soc Classification level
32
© Nokia Siemens Networks
Handover Preparation Successful
Handover Command
Inter-RAT Handover to WCDMA
Triggered EventA2
Triggered EventB2
Soc Classification level
33
© Nokia Siemens Networks
eNACC to GSM
Soc Classification level
34
© Nokia Siemens Networks
eNACC to GSM
Network Assisted Cell Change to GSM
• Similar feature to HO to WCDMA:
• IRAT Measurements triggered via event A2/A1 (activated/deactivated)
• Triggered by event B2 (although using different parameter values)
• Difference: it is not a handover procedure
• UE goes first into GSM RRC Idle mode and starts the RRC Connection Setup
procedure in GSM
• Network Assisted: GSM system information
of 2G target cell is sent to UE (giving a gain
of ~1s in the process but with significant
service interruption)
• Maximum number of GSM cells to be
reported is hardcoded to 8
Soc Classification level
35
© Nokia Siemens Networks
Presentation / Author / Date
eNACC to GSM
Event B2
Entering Condition:
RSRP,s < b2threshold1GERAN – hysB2ThresholdGERAN AND
RxLev,n > b2theshold2RssiGERAN+ hysB2ThresholdGERAN
Soc Classification level
36
© Nokia Siemens Networks
Presentation / Author / Date
Entering conditions
1. Ms + Hys < Thresh1
and
2. Mn– Hys > Thresh2
Layering Strategy. Theoretical Study
eNACC procedure parameter recommendations
Detailed information for parameter settings in this and other several mobility scenarios is
available within the PKDB scenarios: http://pkdb1.emea.nsn-net.net:8080/pkdbWebToolLTE/
• Scope:
• Suggest parameter settings for LTE eNACC procedure (theoretical assumptions)
• Assumptions:
– Continuous GSM 900MHz coverage ensured
– Partial LTE 2600 MHz coverage
• Design Goals:
–
–
–
–
Maximize users throughput
Ping-pong effect elimination
Maximize UE time within LTE coverage
Minimize necessary time for GSM cell
measurement
– Minimize time necessary for cell
reselection from LTE to GSM
Soc Classification level
37
© Nokia Siemens Networks
Presentation / Author / Date
Procedure Criteria
Event A2 to activate GERAN measurements:
• RSRP,s < threshold2GERAN – hysThreshold2GERAN
• during a2TimeToTriggerActGERANMeas
Event B2 for eNACC procedure:
• RSRP,s < b2threshold1GERAN – hysB2ThresholdGERAN AND
• RxLev,n > b2theshold2RssiGERAN+ hysB2ThresholdGERAN
• during b2TimeToTriggerGERANMeas
Soc Classification level
38
© Nokia Siemens Networks
Hysteresis
values
assumed to be
0 dB
Parameter Values Proposal
RSSI threshold
in GERAN
relative to -110
Soc Classification level
39
© Nokia Siemens Networks
Presentation / Author / Date
Conclusions
• threshold2GERAN = b2Threshold1GERAN:
when event A2 is triggered (measuring for
GSM neighbours) the event B2 (eNACC)
could also be triggered
• Measuring time for GSM cell is limited
(reducing the impact in throughput)
Soc Classification level
40
© Nokia Siemens Networks
Presentation / Author / Date
RRC Connection Release with Redirect
Soc Classification level
41
© Nokia Siemens Networks
RRC Connection Release with Redirect
Event A2
• When serving RSRP falls below threshold4 for a time a2TimeToTriggerRedirect
the RRC connection is released and UE redirects to the E-UTRA or inter-RAT
carrier frequency with highest priority (if several redirection objects defined)
regardless of the signal strength of the target carrier
• UE capabilities are considered when performing redirect
Soc Classification level
42
© Nokia Siemens Networks
Presentation / Author / Date
RRC Connection Release with Redirect
• It is possible to define different redirection (REDR) objects and different priorities
between those objects
• eNB selects the target frequency for redirect based on the priorities configured for
frequency layers
• If the highest priority layer is not supported by UE according to capabilities
reported earlier, then the next highest priority layer is selected.
• Redirection is ‘blind’: UE does not measure on the target frequency for redirection
before the connection is released.
• If there is no coverage in the target frequency the connection drops
• Note: Priority 1 is highest! (unlike for the cell reselection priority parameters
where 7 is highest)
Soc Classification level
43
© Nokia Siemens Networks
Presentation / Author / Date
RRC Connection Release with Redirect
Signalling
Soc Classification level
44
© Nokia Siemens Networks
Presentation / Author / Date
RRC Connection Release with Redirect
Performance (LTE -> 3G)
• Test results (FTP DL session and streaming session) show that user impact of
Redirect is minimal and end user will not notice the RRC release with redirect
Effects:
• FTP: couple seconds gap in the transmission is noticed while connection is
redirected to 3G
• Streaming (YouTube): redirection is not noticeable. No gaps in sound/picture
Soc Classification level
45
© Nokia Siemens Networks
Presentation / Author / Date
CSFB
Circuit Switched Fallback
Soc Classification level
46
© Nokia Siemens Networks
Presentation / Author / Date
CSFB to UTRAN or GSM via redirect
RL20
• Required when there is no Conversational Voice support on LTE side
• Redirection from LTE to UTRAN or to GSM during the call setup. MOC and
MTC setup supported
• EPC must support
CS inter-working for
mobility
management and
paging
• Redirection by RRC connection release message with a
RedirectedCarrierInfo IE that enforces the UE to search for any cell first at the
highest priority UTRA carrier or within BCCH carrier set for GSM
• After termination of the CS call, UEs supporting CS fallback may stay in current
RAT of camp back into the LTE carrier
CSFB: Circuit Switched Fallback
IE: Information Element
MOC: Mobile Originated Calls
MTC: Mobile Terminated Calls
Soc Classification level
47
© Nokia Siemens Networks
CS Fallback Signalling Example
MOC in ECM_Connected
Further examples (ECM_IDLE, MTC) in:
https://sharenetims.inside.nokiasiemensnetworks.com/Overview/D4376
59035
UE needs to be
IMSI attached
UE starts Initial Access
procedure and sends
Extended Service Request
message with Service
Type set to “mobile
originating CS fallback”
eNB sends
“RRCConnectRelease”
message with redirect
information of WCDMA
Frequency to be used
for redirection
Soc Classification level
48
© Nokia Siemens Networks
Mobility Parameter Settings
Examples from real cases
Soc Classification level
49
© Nokia Siemens Networks
Presentation / Author / Date
Example of Mobility Parameter Settings
Compilation of real cases (1/2)
• Examples show that mobility related parameters are particularly project dependant
even cell/area dependant and it is not possible to establish a ‘common’ value
• In order to trigger the A5 handover (coverage) it is necessary that:
(threshold3a – threshold3) + 2*hysThreshold3 < a3offset +hystA3Offset
Soc Classification level
50
© Nokia Siemens Networks
Presentation / Author / Date
Example of Mobility Parameter Settings
Compilation of real cases (2/2)
•
•
•
•
Mobility Thresholds
Thresholds are relative to -140dBm
98 value means ‘not used’
It is possible to further optimize the values during early drive tests and once the
networks are launched
98: not used
Soc Classification level
51
© Nokia Siemens Networks
Presentation / Author / Date
Idle mode mobility
Soc Classification level
52
© Nokia Siemens Networks
Presentation / Author / Date
Contents
• Idle Mode Mobility
– Cell Selection
– LTE intra-frequency Reselection
– LTE inter-frequency Reselection
– Inter RAT Reselection
Soc Classification level
53
© Nokia Siemens Networks
Presentation / Author / Date
Cell Selection
• Procedure that allows the UE to camp on a cell
• UE searches for a suitable cell (belonging to the selected PLMN, not barred,
belonging to a TA not forbidden and that satisfies the S-criteria):
• The UE selects a cell if Srxlev > 0
VPLMN: Visited PLMN
LNCEL: qRxLevMinOffset
Typically 0 (only used when camping in VPLMN)
Srxlev = Qrxlevmeas – (Qrxlevmin + Qrxlevminoffset) – P_compensation
Max(LNCEL:pMaxOwnCell - P_max from UE (*) , 0)
Measured value
LNCEL:qRxLevMin
Typically -130dBm
(*) P_max from UE : UE class specific
max. UL Tx power; 23 dBm
• SIB1 is used to transmit cell selection parameters
Soc Classification level
54
© Nokia Siemens Networks
Presentation / Author / Date
pMaxOwnCell (SIB1)
Used to calculate
P_compensation
LNCEL; -30..33dBm; 1dBm; -
S – Criterion Cell Selection
P_compensation = max(pMaxOwnCell – P_max from UE, 0)
• P_compensation provides a contribution only if the UE has less TX power
capabilities than allowed in the radio cell
• If P_compensation > 0 the S-criteria is more difficult to achieve as Qrxlevmeas
needs to be higher
• P_compensation avoids UEs camping on cells for which they have insufficient
power to access (towards cell edge)
• qrxLevMin defines the cell size
• qrxLevMin can be set up
differently for intra frequency,
inter frequency and IRAT:
I am
outside


I am inside,
but I have
not enough
power
Soc Classification level
55
© Nokia Siemens Networks
E.g. pMaxOwnCell: 33 dBm in GMC files
Presentation / Author / Date
Cell Reselection
Process Overview
Measurements trigger
UE measures neighbour cells only when the
RSRP signal level is below some threshold
Measurements trigger is based primarily on
absolute priorities of serving and non serving
frequency layers (inter freq and inter RAT)
Evaluate cell reselection
criteria “R”
Execute cell reselection
Soc Classification level
56
© Nokia Siemens Networks
Different reselection cases
depending on the priorities of the neighbour
frequency layers (inter-frequency
and inter-RAT)
Intra frequency cell reselection
Soc Classification level
57
© Nokia Siemens Networks
Intra frequency cell reselection
Triggering Measurements
• When a UE is camped on a cell it looks for better candidate cells for reselection
according to sIntrasearch parameter:
• If Srxlev > sIntraSearch : UE doesn’t measure the neighbour cells
• If Srxlev <= sIntraSearch : UE starts to measure neighbour cells on the same
frequency
• Example:
– LNCEL: sIntraSearch is 62 dB
– LNCEL: qrxlevmin is -130 dBm
– LNCEL: qRxLevMinOffset is 0
– pCompensation is 0
Srxlev = Qrxlevmeas – (Qrxlevmin + Qrxlevminoffset) - pcompensation
-130 dBm
• Qrxlevmeas< - 68 dBm
• UE will start to measure intra-frequency neighbours when RSRP is worse than
- 68 dBm
Soc Classification level
58
© Nokia Siemens Networks
Intra frequency cell reselection
R-Criterion (Ranking Criterion)
• Once the measurements for neighbour cells have been triggered the UE will rank
the measured cells according to the R-Criterion
– Rankserving cell = Measured RSRPserving cell + LNCEL:qHyst
– Rankneighbour cell = Measured RSRPneighbour cell – IAFIM:qOffsetCell
• Re-selection if :
– Rankneighbour cell > Rankserving cell for tReselEutr and
– More than 1 second has elapsed since the UE camped on the current serving
cell
RSRP,n > RSRP,s +
qHyst +
qOffsetCell
Soc Classification level
59
© Nokia Siemens Networks
Presentation / Author / Date
Intra Frequency cell Reselection
Parameter Summary (1/2)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
LNCEL
sIntrasearch
Defines the threshold (in
dB) for intra-frequency
measurements
0...62 dB, step 2 dB
-
62
LNCEL
qrxlevMin
Minimum required RX
RSRP in the cell
-140...-44 dBm, step 2 dBm
-
-130
dBm
LNCEL
qRxLevMinOffset
Affects the minimum
required RX level in the
cell
2...16 dB, step 2 dB
-
-
LNCEL
pMaxOwnCell
Used to calculate
Pcompensation
-30...33 dBm, step 1 dBm
-
33
LNCEL
qHyst
Provides the hysteresis
value in dB for ranking
criteria in the cell
reselection procedure.
0dB (0), 1dB (1), 2dB (2), 3dB (3), 4dB (4), 5dB
(5), 6dB (6), 8dB (7), 10dB (8), 12dB (9), 14dB
(10), 16dB (11), 18dB (12), 20dB (13), 22dB (14),
24dB (15)
-
1dB
LNCEL
tReselEutr
Cell reselection timer
value
0...7 s, step 1 s
-
1
Soc Classification level
60
© Nokia Siemens Networks
Presentation / Author / Date
Intra Frequency cell Reselection
Parameter Summary (2/2)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
IAFIM
intrFrBCList
Intra-frequency blacklisted cell list
IAFIM
rangeIntraPci
Number of PCIs in the range
(including start PCI). Value n4
corresponds with 4, n12
corresponds with 12 and so on.
The UE applies value 1 if the field
is absent, in which case only the
physical cell identity value
indicated by start applies.
n4 (0), n8 (1), n12 (2), n16 (3), n24 (4),
n32 (5), n48 (6), n64 (7), n84 (8), n96 (9),
n128 (10), n168 (11), n252 (12), n504
(13), Not Used (14)
-
n8
IAFIM
startIntraPci
Lowest PCI in the range
0...503, step 1
-
8
IAFIM
intrFrNCList
Intra-frequency neighbouring cell
list
IAFIM
physCellIdNcl
Unique cell identification in a
neighbouring cell list
0...503, step 1
-
-
IAFIM
qOffsetCell
Cell-specific offset (in dB) that is
used in the cell reselection
procedure
-24 dB (0), -22 dB (1), -20 dB (2), …, -6
dB (9), -5 dB (10), -4 dB (11), -3 dB (12),
-2 dB (13), -1 dB (14), 0 dB (15), 1 dB
(16), 2 dB (17), 3 dB (18), 4 dB (19), 5
dB (20), 6 dB (21), …,20 dB (28), 22 dB
(29), 24 dB (30)
0 dB
(15)
2dB
Soc Classification level
61
© Nokia Siemens Networks
Presentation / Author / Date
Inter frequency cell reselection
Soc Classification level
62
© Nokia Siemens Networks
Inter frequency cell reselection
Triggering Measurements
• Measurement trigger depends on the absolute priorities of the serving and nonserving layers
• The priority of the serving layer is defined in the parameter LNCEL:cellReSelPrio
• For each neighbouring frequency/layer, it is necessary to define the corresponding
priority: IRFIM:eutCelResPrio (7 is highest priority, 0 is lowest)
• For equal priority frequency layers it is possible to define an offset with
IRFIM:qOffFrq
• If IRFIM:eutCelResPrio > LNCEL:cellReSelPrio then measurements of the
neighbour cell are mandatory
• If IRFIM:eutCelResPrio <= LNCEL:cellReSelPrio then measurements are
performed when RSRP of serving cell is below sNonIntrsearch threshold:
Srxlev <= sNonIntrsearch
Soc Classification level
63
© Nokia Siemens Networks
Presentation / Author / Date
Inter frequency cell reselection
Triggering Measurements
• UE starts inter-frequency measurements when Srxlev <= sNonIntrSearch
• sNonIntrsearch is a valid threshold for inter-frequency and inter-RAT
measurements
• Example:
– LNCEL: sNonIntrSearch is 12 dB
– LNCEL: qRxLevMin is -130 dBm
– LNCEL: qRxLevMinOffset is 0
– pCompensation is 0
Srxlev = Qrxlevmeas – (Qrxlevmin + Qrxlevminoffset) - pcompensation
-130 dBm
• Qrxlevmeas <=-118 dBm
• UE will start to measure inter-frequency neighbours when RSRP is worse than
-118 dBm
Soc Classification level
64
© Nokia Siemens Networks
Inter Frequency Reselection
R-criteria: Equal priority between layers
• Similar to intra frequency
RSRP,n > RSRP,s +
qHyst + qOffset
• A frequency-specific offset for equal priority E-UTRAN frequencies can be
considered:
Soc Classification level
65
© Nokia Siemens Networks
Qoffset = qOffCell,n + qOffFreq
Presentation / Author / Date
Inter Frequency Reselection
R-criteria: Reselection to lower priority layers
• If the neighbour cell layer has lower priority, the reselection will happen if:
Srxlevneighbour > IRFIM:interFrqThrL && Srxlevserving < LNCEL:threshSrvLow
Where:
Srxlevn = QrxlevMeasn – IRFIM:qRxLevMinInterF – P_compensation
Srxlevs= QrxlevMeass – LNCEL:qRxLevMin + LNCEL: qRxLevMinOffset –
P_compensation
Qrxlevmeass < qRxLevMin + thresholdSrvLow – qRxLevMinOffset +
P_compensation
AND
Qrxlevmeas n > qRxLevMinInterF + interFrqThrL + P_compensation
•
•
The criterias above have to be fullfilled during a time interval IRFIM:interTResEut
And the UE must have been camped in the current cell more than 1 sec.
Soc Classification level
66
© Nokia Siemens Networks
Presentation / Author / Date
Inter frequency cell reselection
Example of reselection to lower priority
Inter frequency measurements
will be started at -118 dBm
LNCEL:qRxLevMin = -130 dBm
LNCEL:sNonIntrSearch = 12
-118
RSRP decreases
-120
-130
Pcompensation =0
LNCEL:qRxLevMinOffset =0
LNCEL:threshSrvLow = 10
If suitable neighbour (*) cell is found, reselection will be
performed when RSRP decreases under -120 dBm
(*) suitable neighbour-> RSRPn > qRxLevMinInterF +interFreqThrL
Soc Classification level
67
© Nokia Siemens Networks
-140
Inter Frequency Reselection
R-criteria: Reselection to higher priority layers
• If the neighbouring cell layer has higher priority than the serving layer,
reselection will happen if:
Srxlevneighbour > IRFIM:interFrqThrH
Where:
Srxlevneighbour = Qrxlevmeas – IRFIM:qRxLevMinInterF – P_compensation
Qrxlevmeasneighbour > qRxLevMinInterF + interFrqThrH
(Assuming P_compensation = 0)
• The criteria above must be satisfied for a time period equal to IRFIM: interTResEut
• And the UE must have been camped in the current cell more than 1 sec.
interFrqThrH > interFrqThrL > threshSrvLow
Soc Classification level
68
© Nokia Siemens Networks
Presentation / Author / Date
Inter Frequency cell Reselection
Parameter Summary (1/3)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
LNCEL
sNonIntrsearch
Defines the threshold (in dB) for inter-frequency
and inter-RAT measurements
0...62 dB, step 2 dB
-
2
LNCEL
qrxLevMin
Minimum required RX RSRP in the serving cell
-140...-44 dBm, step 2
dBm
-
-130
dBm
LNCEL
qRxLevMinOffset
Affects the minimum required RX level in the
serving cell
2...16 dB, step 2 dB
-
-
LNCEL
pMaxOwnCell
Used to calculate P_compensation
-30...33 dBm, step 1 dBm
-
33 dBm
LNCEL
cellReSelPrio
Absolute priority of the serving layer. 0 means
the lowest priority.
0...7, step 1
-
1
LNCEL
threshSrvLow
Threshold for the serving frequency used in
reselection evaluation towards lower priority
EUTRAN frequency or RAT
0...62 dB, step 2 dB
-
2
LNCEL
qrxlevminintraF
IRFIM
qRxLevMinInterF
IRFIM
dlCarFrqEut
IRFIM
eutCelResPrio
Soc Classification level
69
© Nokia Siemens Networks
Minimum required RX RSRP level for the intrafrequency neighbouring E-UTRA cells.
(Qrxlevmin in 36.304)
Minimum required Rx RSRP level for the
neighbouring EUTRA cells on this carrier
frequency
-140...-44 dBm, step 2 dBm
-130
dBm
-
-140...-44 dBm, step 2
dBm
-
-68 dBm
eUTRAN frequency
0...65535, step 1
-
-
Absolute priority of the EUTRA carrier frequency
0...7, step 1
-
5
Presentation / Author / Date
Inter Frequency cell Reselection
Parameter Summary (2/3)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
IRFIM
interFrqThrH
Threshold used by the UE when reselecting
towards a higher priority frequency X than the
currently serving frequency
0...62 dB, step 2 dB
-
34
IRFIM
interFrqThrL
Threshold used in reselection towards
frequency X priority from a higher priority
frequency
0...62 dB, step 2 dB
-
2
IRFIM
interTResEut
EUTRA Cell Reselection Timer
0...7 s, step 1 s
-
4
IRFIM
intFrBCList
Inter-frequency blacklisted cell list
IRFIM
rangeInterPci
Number of PCIs in the range (including start
PCI). Value n4 corresponds with 4, n12
corresponds with 12 and so on. The UE
applies value 1 if the field is absent, in which
case only the physical cell identity value
indicated by start applies.
n4 (0), n8 (1), n12 (2), n16
(3), n24 (4), n32 (5), n48 (6),
n64 (7), n84 (8), n96 (9),
n128 (10), n168 (11), n252
(12), n504 (13)
-
n4
IRFIM
startInterPci
Lowest PCI in the range
0...503, step 1
-
200
IRFIM
physCellIdNcl
Unique cell identification in a neighbouring cell
list
0...503, step 1
-
IRFIM
intFrNCList
Inter-frequency neighbouring cell list
Soc Classification level
70
© Nokia Siemens Networks
Presentation / Author / Date
Inter Frequency cell Reselection
Parameter Summary (3/3)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
-
true
IRFIM
interPresAntP
Used to indicate whether all the neighbouring
cells use Antenna Port 1. When set to TRUE, the
UE may assume that at least two cell-specific
antenna ports are used in all neighbouring cells.
IRFIM
measBdw
Maximum allowed measurement bandwidth
common for all neighbouring cells on a
carrier frequency. The values mbw6, mbw15,
mbw25, mbw50, mbw75, mbw100 indicate 6, 15,
25, 50, 75 and 100 resource blocks respectively.
6mbw (0), 15mbw (1),
25mbw (2), 50mbw (3),
75mbw (4), 100mbw (5)
-
50mbw
IRFIM
pMaxInterF
Pmax to be used for the neighbouring E-UTRA
cells on this carrier frequency. If Pmax is absent,
the maximum power according to the UE
-30...33 dBm, step 1 dBm
-
10dBm
IRFIM
qOffFrq
Frequency-specific offset for equal priority EUTRAN frequencies.
-24 dB (0), -22 dB (1), -20
dB (2), …-6 dB (9), -5 dB
(10), -4 dB (11), -3 dB (12), 2 dB (13), -1 dB (14), 0 dB
(15), 1 dB (16), …, 20 dB
(28), 22 dB (29), 24 dB (30)
0dB (15)
1dB
IRFIM
qOffCell
Cell-specific offset (in dB) that is used in the cell
reselection procedure.
This specifies the offset between two cells.
-24 dB (0), -22 dB (1), -20
dB (2), …, -1 dB (14), 0 dB
(15), 1 dB (16), 2 dB (17), 3
dB (18), …,20 dB (28), 22
dB (29), 24 dB (30)
-
2dB
Soc Classification level
71
© Nokia Siemens Networks
Presentation / Author / Date
Inter RAT cell reselection
Soc Classification level
72
© Nokia Siemens Networks
Inter RAT cell reselection
• Inter RAT cell reselection is idle mode mobility from LTE to another radio access
technology (RAT), e.g. WCDMA or GSM
• UFFIM is the managed object class for idle mode parameters LTE to WCDMA:
– UFFIM parameters are broadcasted in the SIB6
• GFIM/GNFL are the managed object classes for idle mode parameters LTE to
GSM:
– GFIM/GNFL parameters are broadcasted in the SIB7
LNBTS
LNBTS
LNCEL
LNCEL
UFFIM
GFIM
GNFL
Soc Classification level
73
© Nokia Siemens Networks
UFFIM: UTRA Frequency Idle Mode Parameters
GFIM: GERAN Frequency Idle Mode Parameters
GNFL: GERAN Neighbours Frequency List
Inter RAT cell reselection
Measurements Trigger
• IRAT cell reselection procedure and related parameters are similar to those for
inter frequency cell reselection
• Similar to the inter frequency case, there is the priority concept (7 is highest
priority, 0 is lowest):
– The priority of serving cell is defined with LNCEL:cellReSelPrio
– The priority of the neighbouring cell is defined:
 For WCDMA: UFFIM: uCelResPrio
 For GSM: GFIM: gCelResPrio
• If UFFIM: uCelResPrio/GFIM: gCelResPrio > LNCEL:cellReSelPrio then
measurements of the neighbour WCDMA/GSM cell are mandatory
• If UFFIM: uCelResPrio/GFIM: gCelResPrio <LNCEL:cellReSelPrio then
measurements are performed when RSRP of serving cell is below
Snonintrasearch threshold (same as per inter-frequency):
Srxlev <= SNonIntrsearch
Soc Classification level
74
© Nokia Siemens Networks
Inter RAT cell reselection
R-criteria
• Reselection to a higher priority RAT will happen if:
WCDMA:
GSM:
Srxlevneighbour > UFFIM:utraFrqThrH
Srxlevneighbour > GFIM:gerFrqThrH
• Reselection to a lower priority RAT will happen if:
WCDMA:
Srxlevneighbour > UFFIM:utraFrqThrL &&
Srxlevserving < LNCEL:threshSrvLow
GSM:
Srxlevneighbour > GFIM:gerFrqThrL &&
Srxlevserving < LNCEL:threshSrvLow
utraFrqThrH > utraFrqThrL > threshSrvLow
gerFrqThrH > gerFrqThrL > threshSrvLow
•
The criterias above have to be fullfilled during a time interval UFFIM:tResUtra
for WCDMA and GFIM:tResGer for GSM
•
And the UE must have been camped in the current cell more than 1 sec.
Soc Classification level
75
© Nokia Siemens Networks
Presentation / Author / Date
Inter RAT cell reselection
R-criteria
• Srxlevneighbour is referred to the candidate cell:
• GSM: Srxlevneighbour = QrxlevMeas – Qrxlevmin – P_compensation
Where:
QrxlevMeas = RSSI
Qrxlevmin = GNFL:qRxLevMinGer
• UMTS: Srxlev = QrxlevMeas – Qrxlevmin – P_compensation
Where:
QrxlevMeas = CPICH RSCP
Qrxlevmin = UFFIM:qRxLevMinUtra
Additionally Squal > 0 required for UMTS FDD
Squal = QrxlevMeas – Qqualmin
Qrxlevmeas = CPICH Ec/No
Qqualmin = UFFIM:qQualMinUtra
Soc Classification level
76
© Nokia Siemens Networks
Presentation / Author / Date
LTE  3G cell reselection, signalling example
UE is
in LTE
UE is
in 3G
Soc Classification level
77
© Nokia Siemens Networks
Inter-RAT cell Reselection
Parameter Summary (1/3)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
LNCEL
sNonIntrsearch
Defines the threshold (in dB) for inter-frequency
and inter-RAT measurements
0...62 dB, step 2 dB
-
2
LNCEL
qrxLevMin
Minimum required RX RSRP in the serving cell
-140...-44 dBm, step 2
dBm
-
-130
dBm
LNCEL
qRxLevMinOffset
Affects the minimum required RX level in the
serving cell
2...16 dB, step 2 dB
-
LNCEL
pMaxOwnCell
Used to calculate P_compensation
-30...33 dBm, step 1 dBm
-
33 dBm
LNCEL
cellReSelPrio
Absolute priority of the serving layer. 0 means
the lowest priority.
0...7, step 1
-
1
LNCEL
threshSrvLow
Threshold for the serving frequency used in
reselection evaluation towards lower priority
EUTRAN frequency or RAT
0...62 dB, step 2 dB
-
2
UFFIM
tResUtra
UTRA cell reselection timer
0...7, step 1
-
-
UFFIM
utrFddCarFrqL
List of UTRA FDD carrier frequencies
-
-
UFFIM
dlCarFrqUtra
DL Utra frequency
-
-
Soc Classification level
78
© Nokia Siemens Networks
Presentation / Author / Date
0...16383, step 1
Inter-RAT cell Reselection
Parameter Summary (2/3)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
UFFIM
pMaxUtra
UTRA Maximum Allowed Transmit Power
-50...33 dBm, step 1 dBm
-
-
UFFIM
qQualMinUtra
minimum required quality level in the cell in dB.
Not applicable to TDD cells or GSM cells or EUTRA cells
-24...0 dB, step 1 dB
-
-
UFFIM
qRxLevMinUtra
minimum required RX level in the cell in dBm
-119...-25 dBm, step 2 dBm
-
-
UFFIM
uCelResPrio
Absolute priority of the UTRA carrier frequency
Equal priorities between RATs are not
supported according to [3GPP 36.304].
0...7, step 1
UFFIM
utraFrqThrH
Threshold used by the UE when reselecting
towards a higher priority frequency X than the
current serving frequency
0...62 dB, step 2 dB
-
-
UFFIM
utraFrqThrL
Threshold used in reselection towards the
frequency X priority from a higher priority
frequency
0...62 dB, step 2 dB
-
-
GFIM
tResGer
GERAN cell reselection timer
0...7 s, step 1 s
-
-
GNFL
bandInd
Indicator to distinguish the GERAN frequency
band in case of ARFCN values associated with
either GSM 1800 or GSM 1900 carriers
gsm1800 (0), gsm1900 (1)
-
-
Soc Classification level
79
© Nokia Siemens Networks
Presentation / Author / Date
-
Inter-RAT cell Reselection
Parameter Summary (3/3)
MOC
Parameter
Name
Description
Range and step
Default
value
GMC
Value
GNFL
gCelResPrio
Absolute priority of the GERAN carrier frequency
Equal priorities between RATs are not supported
according to [3GPP 36.304].
0...7, step 1
-
-
GNFL
gerArfcnVal
Each ARFCN value explicitly listed
0...1023, step 1
-
-
GNFL
gerFrqThrH
Threshold used by the UE when reselecting
towards a higher priority frequency X than the
currently serving frequency
0...62 dB, step 2 dB
-
-
GNFL
gerFrqThrL
Threshold used in reselection towards frequency
X priority from a higher priority frequency
0...62 dB, step 2 dB
-
-
GNFL
pMaxGer
Maximum allowed transmission power for
GERAN on an uplink carrier frequency.
Applicable for the neighbouring GERAN cells on
this carrier frequency.
If pmaxGERAN is absent, the maximum power
according to the UE capability is used.
0...39 dBm, step 1 dBm
-
-
GNFL
qRxLevMinGer
Minimum required RX level in the cell in dBm
-115...-25 dBm, step 2 dBm
-
-
Soc Classification level
80
© Nokia Siemens Networks
Presentation / Author / Date
Example Idle Mode Parameter settings
Priorities, triggering conditions
MOC
Parameter
Value
LNCEL
sIntraSearch
62
LNCEL
sNonIntrSearch
16
LNCEL
qrxLevMin
-130 dBm
LNCEL
Qhyst
3 dB
LNCEL
threshSrvLow
10
LNCEL
tReselEutr
1s
LNCEL
cellReSelPrio
7
IAFIM
qOffCell
0 dB
IRFIM
interFrqThrH
22
Relative to IFFIM:qRxLevMinInterF
IRFIM
interFrqThrL
20
Relative to IFFIM:qRxLevMinInterF
IRFIM
qRxLevMinInterF
-130 dBm
IRFIM
interTResEutr
1s
IRFIM
eutCellResPrio
6
LTE1800 layer
UFFIM
utraFrqThrL
10
Relative to UFFIM:qRxLevMinUtra
UFFIM
utraFrqThrL
10
Relative to UFFIM:qRxLevMinUtra
UFFIM
tResUtra
1s
UFFIM
ucelResPrio
5
UFFIM
qRxLevMinUtra
-119 dBm
Soc Classification level
81
© Nokia Siemens Networks
Comments
LTE2600 layer
WCDMA layer
LTE 2600, absolute priority 7
Idle mode reselection
qrxLevMin = -130 dBm
sIntraSearch = 62
sNonIntrSearch = 16
RSRP decreases
-68
-114
-130
-140
When RSRP < -68 dBm UE starts
to measure intra-freq neighbours
When RSRP < -114 dBm UE starts to
measure on LTE1800 and WCDMA
LNCEL:Qhyst = 3dB
IAFIM: qOffestCell = 0dB
LNCEL:threshSrvLow = 10
IRFIM:interFrqThrL = 20
IRFIM:qRxLevMinInterF= -130dBm
LNCEL:threshSrvLow = 10
UFFIM:utraFrqThrL = 10
UFFIM:qRxLevMinUtra= -119 dBm
Reselection to LTE1800 cell will
happen:
1. When serving is below -120dBm
AND LTE1800 neighbour’s RSRP is
better than -110 dBm
2. For a time
IRFIM:intertResEutr = 1s
3. AND more than 1 s has elapsed
since the UE camped in the
current cell
If no suitable LTE1800 cell found, then
reselection to WCDMA will happen
1. When serving cell is below -120
dBm and neighbouring WCDMA cell
RSCP > -109 dBm
2. For a time UFFIM:tResUtra = 1s
3. AND more than 1 s has elapsed
since the UE camped in the current
cell
Reselection to other LTE2600 cell
will happen:
1. When neighbour is 3dB better
than serving
2. For a time
LNCEL:tReselEutr = 1s
3. AND more than 1 s has
elapsed since the UE camped
in the currrent cell
Rn > Rs + qoff + hys
Soc Classification level
82
© Nokia Siemens Networks
Srxlev, n > qRxLevMinInter/Utra + interFrqThrhL
Srxlev, s < qRxLevMin + threshSrvLow
Exercise
Idle mode reselection, priorities
• Previous slide shows, for the case of LTE 2600 cells, when reselection to another
LTE2600 cell, to LTE1800 cells and to 3G cells would happen based on the
example settings given.
• Similarly, indicate for the case of LTE1800 when reselection would happen to:
– Other LTE 1800 cells (intra frequency reselection)
– LTE2600 cells (inter frequency reselection)
– 3G (inter RAT reselection)
• Note1: You can use previous slide (for LTE2600) as a template
• Note: Consider that LTE1800 has priority 6
Soc Classification level
83
© Nokia Siemens Networks
Presentation / Author / Date
Example of Idle Mode Parameter Settings
Compilation of real cases
• Values should be used as
examples rather than a
reference as it is likely they
are not optimized
Soc Classification level
84
© Nokia Siemens Networks
Testing notes
Terminals and Measurement Tools (Jan2012)
• Nemo is better than XCAL as it provides more information. XCAL also requires a
license upgrade to support Qualcomm chipset
• Terminals:
• ZTE MF820 with the following SW/FW
 Firmware : BD_ZTE_MF820V1.0.0.0B12
Software : PCW_TEAGLBLTEP18EMV1.0.0B15
 Cost: 265 EUR
• ZTE poor performance:
• When 2 LTE layers (LTE1800 and LTE2600) it camps on LTE1800 even if parameters
are set to camp in LTE2600
• Frequent crashes
• Difficult communication with ZTE
• Bandrich UE (C501, Qualcomm chipset):
•
•
•
•
Requires engineering mode to see L3 messages (2600 eur vs. 140 eur normal mode).
Known issues: https://twiki.inside.nokiasiemensnetworks.com/bin/view/LTESyVe/BandrichC501
Inter frequency HO not supported
Idle Mode IRAT between LTE and GSM not supported
Soc Classification level
85
© Nokia Siemens Networks
Presentation / Author / Date