The document discusses various aspects of mobility in LTE networks, focusing on intra-LTE and inter-frequency mobility, as well as IRAT (Inter-Radio Access Technology) mobility. It outlines mobility events, measurement configurations, signaling flows, and advanced mobility features that enhance handover processes and session continuity based on user conditions and network quality. Additionally, it introduces concepts like service-triggered mobility and mobility control in poor coverage areas, detailing specific threshold configurations for different mobility events.

1. NPO VCT Ericsson LTE
1 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
Virtual Session 2

2. Contents
2 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
• Mobility Overview
• Intra-LTE Intra Frequency Mobility
• Intra-LTE Inter Frequency and IRAT Mobility
• Advanced Mobility Features
• CSFB

3. Mobility
Overview
3 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

4. Mobility
Overview
Mobility
Session
Continuity
Target is not prepared
UE released using
rrcConnectionRelease
message
Can be blind or
measurement based
Handover
Target is prepared
Handover through
rrcReconfiguration
Procedure
Can be blind or
measurement based
Mobility
Intra-LTE
Intra-Freq over X2
or S1
Inter-Freq over X2
or S1
IRAT
4 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

5. Mobility Events
LTE Events
• A1: Serving cell becomes better than
absolute threshold
• A2: Serving cell becomes worse than
absolute threshold
• A3: Neighbor cell becomes offset better
than serving cell
• A4: Neighbor cell becomes better than
threshold
• A5: Serving cell becomes worse than
absolute threshold1 AND neighbor cell
becomes better than absolute threshold2
• A6: Neighbor cell becomes offset better
than SCell
IRAT Events
• B1: IRAT Neighbor becomes better than
threshold
• B2: Serving cell becomes worse than
threshold1 AND IRAT neighbor becomes
better than threshold2
5 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

6. Measurement Configuration
• Measurement configuration is done using the rrcConnectionReconfiguration message
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7. Measurement Configuration Message Example
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8. 8 © 2018 Nokia
Measurement Configuration Message Example
NPO VCT Ericsson LTE - Virtual Session 2

9. Intra-LTE Intra Frequency Mobility
9 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

10. Intra-Frequency Handover
Related Parameters
UeMeasControl.sMeasure [0]
ReportConfigEUtraBestCell.a3offset [30 (3 dB)]
ReportConfigEUtraBestCell.triggerQuantityA3 [RSRP]
ReportConfigEUtraBestCell.hysteresisA3 [10 (1 dB)]
ReportConfigEUtraBestCell.timeToTriggerA3 [40 ms]
EUtranCellFDD.minBestCellHoAttempts [1]
EUtranCellRelation.cellIndividualOffsetEUtran [0 dB]
EUtranCellRelation.isHoAllowed [TRUE]
Rrc.t304 [1000 ms]
ENodeBFunction.tRelocOverall [5 s]
Related Counters
EUtranCellRelation.pmHoPrepAttLteIntraF
EUtranCellRelation.pmHoPrepSuccLteIntraF
EUtranCellRelation.pmHoExeAttLteIntraF
EUtranCellRelation.pmHoExeSuccLteIntraF
Event A3 Entry Condition
Event A3 Exit Condition
10 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

11. Intra-Frequency Handover Signaling Flow – X2 Handover Case
11 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

12. Intra-Frequency Handover Signaling Flow – S1 Handover Case
12 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

13. Intra LTE Inter Frequency Mobility
and IRAT Mobility
13 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

14. Overview of Coverage Based Mobility
Inter-Frequency and IRAT
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15. Inter Frequency Mobility
15 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
• Can be
• Measurement based or blind
• Session continuity or handover [Two separate
features]
• A2/A1 used in all cases
• If measurement based, we will use A3 or
A5
• For blind handover we use
coverageIndicator to identify target cell,
parameter is set to COVERS for the
desired cell to be the target of blind
handover
Licensed Features
OptionalFeatureLicense=InterFreqSessionContinuity
FeatureState=CXC4010770
OptionalFeatureLicense=InterFrequencyLteHandover
FeatureState=CXC4010974
Related Parameters
EUtranFrequency
EUtranFreqRelation
• connectedModeM
obilityPrio [7]
• interFreqMeasTy
pe [0 (EVENT_A5)]
• mobilityAction [1
(HANDOVER)]
•voicePrio [0]
ueMeasControl
• allowRelease
Qci1 [FALSE]
• sMeasure [0]
• ueMeasure
mentsActive
[FALSE]

16. IRAT Mobility
16 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
• Can be
• Measurement based or blind
• Session continuity or handover [Two separate
features]
• A2/A1 used in all cases
• If measurement based, we will use B2
• For blind handover we use
coverageIndicator to identify target blind
cell
• No PS Handover to GSM, only session
continuity available
Licensed Features
OptionalFeatureLicense=WcdmaSessionContinuity
FeatureState=CXC4010616
OptionalFeatureLicense=WcdmaHandover
FeatureState=CXC4011011
Related Parameters
utranFrequency
utranFreqRelation
• connectedModeM
obilityPrio [6]
• mobilityAction [2
(HANDOVER)]
•voicePrio [0]
ueMeasControl
• allowRelease
Qci1 [FALSE]
• sMeasure [0]
• ueMeasure
mentsActive
[FALSE]
•a5B2MobilityTimer [0 ms]
utranCellRelation

17. MO Structure
17 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

18. Event A2
Applies to both Inter-Frequency and IRAT
Related Parameters
ReportConfigEUtraBadCovPrim
• a2ThresholdRsrpPrim [-140 dBm]
• a2ThresholdRsrqPrim [-195 (-19.5 dB)]
• hysteresisA2Prim [10 (1 dB)]
• timeToTriggerA2Prim [640 ms]
• triggerQuantityA2Prim [0 (RSRP)]
ReportConfigEUtraBadCovSec
• a2ThresholdRsrpSec [-140 dBm]
• a2ThresholdRsrqSec [-195 (-19.5 dB)]
• hysteresisA2Sec [10 (1 dB)]
• timeToTriggerA2Sec [640 ms]
• triggerQuantityA2Sec [1 (RSRQ)]
Both primary and secondary A2 event
criteria are sent to UE, anyone of them
alone can trigger bad coverage
Event A2 Entry Condition
Event A2 Exit Condition
Both
18 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

19. Event A5
Applies to Inter-Frequency
Related Parameters
ReportConfigA5
• a5Threshold1Rsrp [-140 dBm]
• a5Threshold1Rsrq [-195 (-19.5 dB)]
• a5Threshold2Rsrp [-136 dBm]
• a5Threshold2Rsrq [-195 (-19.5 dB)]
• hysteresisA5 [10 (1 dB)]
• timeToTriggerA5 [640 ms]
•triggerQuantityA5 [0 (RSRP)]
EUtranFreqRelation
• qOffsetFreq [0]
EUtranCellRelation
• cellIndividualOffsetEUtran
[0]
19 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

20. Inter Frequency Event A3
Applies to Inter-Frequency
Related Parameters
ReportConfigEUtraIFBestCell
• a3offset [30 (3 dB)]
• hysteresisA3 [10 (1 dB)]
• timeToTriggerA3 [40 ms]
• triggerQuantityA3 [0 (RSRP)]
Event A3 Entry Condition
Event A3 Exit Condition
20 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

21. Event B2
Applies to IRAT
Related Parameters
ReportConfigB2Utra
• b2Threshold1Rsrp [-140 dBm]
• b2Threshold1Rsrq [-195 (-19.5 dB)]
• b2Threshold2EcNoUtra [-240 (-24 dB)]
• b2Threshold2RscpUtra [-115 dBm]
• hysteresisB2 [10 (1 dB)]
• timeToTriggerB2 [640 ms]
•triggerQuantityB2 [0 (RSRP)]
ReportConfigB2Geran
• b2Threshold1Rsrp [-140
dBm]
• b2Threshold1Rsrq [-195 (-
19.5 dB)]
• b2Threshold2Geran [-110
dBm]
• hysteresisB2 [10 (1 dB)]
• timeToTriggerB2 [640 ms]
• triggerQuantityB2 [0 (RSRP)]
21 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

22. Event A1
22 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
UE is no longer considered in poor coverage
Two Event A1 measurements are configured
in UE by eNodeB, correspond to the two
Event A2 measurements for poor coverage
𝐌𝐬 − 𝐇𝐲𝐬𝐭 >
𝐓𝐡𝐫𝐞𝐬𝐡𝐨𝐥𝐝
Event A1 Trigger Condition
Related Parameters
ReportConfigA1Prim
• a1ThresholdRsrpPrim [-136 dBm]
• a1ThresholdRsrqPrim [-195 (-19.5 dB)]
• hysteresisA1Prim [10 (1 dB)]
•timeToTriggerA1Prim [640 ms]
ReportConfigA1Sec
• a1ThresholdRsrpSec [-136
dBm]
• a1ThresholdRsrqSec [-195 (-
19.5 dB)]
• hysteresisA1Sec [10 (1 dB)]
• timeToTriggerA1Sec [640 ms]

23. 23 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
ueMeasurementsActive
(per Cell)
Feature (per eNodeB) +
covTriggerdBlindHoAllowed
(per Cell) +
mobilityAction
(per frequencyRelation)
mobilityAction
(per frequencyRelation)
connectedModeMbilityPrio
voicePrio
(per frequencyRelation)
a5B2MobilityTimer
(per Cell)

24. Advanced Mobility Features
24 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

25. Advanced Mobility Features
25 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
Service Triggered
Mobility
• Allows setting
handover
thresholds per QCI
• Events
A1/A2/A5/B2
Mobility Control at
Poor Coverage
• Introduces
inner/outer search
zone and critical
zone
• Allows
measurement of
multiple inter-
frequency and
IRAT frequencies
Multi-Layer Service-
Triggered Mobility
• Introduces setting
handover
thresholds per
frequency
• Dependent on
Mobility Control at
poor coverage

26. Feature: Service Triggered Mobility
26 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
• Feature allows setting handover
thresholds per QCI
• Each QCI profile holds offsets for the
thresholds for Event A1, Event A2, Event
A5, and Event B2.
• Feature triggers:
• Before configuring the measurements
[Calculates offset based on UE QCIs]
• Whenever one or several bearers are set up,
released, or modified for a certain UE for
which measurements were previously
configured
Licensed Feature
OptionalFeatureLicense=ServiceTriggeredMobility
FeatureState=CXC4011059
Related Parameters
QciProfilePredefined.measReportConfigParams
• a1ThresholdRsrpPrimOffset [0]
• a1ThresholdRsrpSecOffset [0]
• a1ThresholdRsrqPrimOffset [0]
• a1ThresholdRsrqSecOffset [0]
• a2ThresholdRsrpPrimOffset [0]
• a2ThresholdRsrpSecOffset [0]
• a2ThresholdRsrqPrimOffset [0]
• a2ThresholdRsrqSecOffset [0]
• a5Threshold1RsrpOffset [0]
• a5Threshold1RsrqOffset [0]
• a5Threshold2RsrpOffset [0]
• a5Threshold2RsrqOffset [0]
• b2Threshold1RsrpUtraOffset [0]
• b2Threshold1RsrqUtraOffset [0]
• b2Threshold2EcNoUtraOffset [0]
• b2Threshold2RscpUtraOffset [0]

27. Feature: Service Triggered Mobility
Example of reconfiguration scenario
Setting up Event A5
UE has QCI2 and
QCI5
New bearer is setup
with QCI7
New bearer is setup
with QCI7
2 QCI7 bearers
released
QCI2 modified to
QCI7
27 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

28. Feature: Mobility Control at Poor Coverage
Feature Highlights
• Introduces search zone along the edge of
the cell followed by critical coverage Zone
• UE can search for several inter-frequency
and IRAT target frequencies
• Search zone measurements can also be
used by ANR to add new relations
Licensed Feature
OptionalFeatureLicense=MobCtrlAtPoorCov
FeatureState=CXC4011345
Related Parameters
EUtranCellFDD
• mobCtrlAtPoorCovActive [FALSE]
• ueMeasurementsActiveIF [FALSE]
• ueMeasurementsActiveUTRAN [FALSE]
• ueMeasurementsActiveGERAN [FALSE]
•ueMeasurementsActiveCDMA2000 [FALSE]
ueMeasControl
• bothA5RsrpRsrqCheck [FALSE]
• allowReleaseQci1 [FALSE]
• a5B2MobilityTimer [0]
• excludeInterFreqAtCritical [FALSE]
• inhibitB2RsrqConfig [FALSE]
• searchEffortTime [40 (4 s)]
ctive
ueMeasurementsActiveIF
ueMeasurementsActiveUTRAN
ueMeasurementsActiveGERAN
ueMeasurementsActiveCDMA2000
28 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

29. 29 © 2018 Nokia NPO VCT Erics son LTE - Virtual Session 2
Feature: Mobility Control at Poor Coverage
Search Zone Measurement
inhibitA2SearchConfig
NOT_INHIBIT
INHIBIT_A2SEARCH_RSRQ
INHIBIT_A2SEARCH_RSRP
Search Threshold
ReportConfigSearch
• a1a2SearchThresholdRsrp
• a1a2SearchThresholdRsrq
• hysteresisA1A2SearchRsrp
• hysteresisA1A2SearchRsrq
• timeToTriggerA1Search
• timeToTriggerA1SearchRsrq
• timeToTriggerA2Search
• timeToTriggerA2SearchRsrq
Critical Threshold
ReportConfigSearch
• a2CriticalThresholdRsrp
• a2CriticalThresholdRsrq
• hysteresisA2CriticalRsrp
• hysteresisA2CriticalRsrq
• timeToTriggerA2Critical
• timeToTriggerA2CriticalRsrq
• a2CriticalThrQci1RsrpOffset
• a2CriticalThrQci1RsrqOffset
The report configurations for search zone measurements
are also affected by features Service Triggered Mobility
and Multi-Layer Service-Triggered Mobility.

30. Feature: Mobility Control at Poor Coverage
Outer Search Threshold
ReportConfigSearch
• a2OuterSearchThrRsrpOffset
• a2OuterSearchThrRsrqOffset
ueMeasControl
• lowPrioMeasThresh
30 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
The UE only uses an
inner/outer search zone if
there are low priority frequency
relations
The report configurations for
critical measurements are not
affected by features Service
Triggered Mobility or Multi-
Layer Service-Triggered
Mobility.
Before entering Inner Search Zone, UE doesn’t know outer search
zone or critical zone thresholds
What If, when UE reports Inner Search Zone, RSRP/RSRQ has
reduced rapidly to meet the outer search or critical zone
thresholds?
checkA2SearchLevel

31. 31 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

32. At Step 6
eNodeB Stops event A2 search measurement that triggered entering into search zone
eNodeB will start the following measurements
eNodeB NOT configured for
outer search zone
Event A1 with same trigger quantity as
reported event A2
Event A2 critical coverage measurement
with same trigger quantity as reported
event A2
Event A5 or A3 for Inter-Frequency LTE
Event B2 for IRAT frequencies
eNodeB Configured for outer
search zone and event reported
is for inner search zone
Event A1 with same trigger quantity as
reported event A2
Event A2 Outer Search measurement with
same trigger quantity as reported event A2
Event A5 or A3 for high priority Inter-
Frequency LTE
Event B2 for high priority IRAT frequencies
eNodeB Configured for outer
search zone and reported event
is for outer search zone
Event A2 critical coverage measurement
with same trigger quantity as reported
event A2
Event A5 or A3 for low priority Inter-
Frequency LTE
Event B2 for low priority IRAT frequencies
32 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

33. 33 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

34. Steps 7, 8 and 9
Step 7
UE was in search zone for one quantity
(RSRP or RSRQ) and now triggered
search zone for the other
eNodeB configured with outer search
zone and UE is already in inner search
zone
Step 8 – QCI1 bearer
setup
a5B2MobilityTimer Restarted
If UE in search zone for RSRP all “Target
Good Enough” measurements using
RSRP are replaced by new
measurements of frequencies based
on voicePrio
If UE in search zone for RSRQ all
“Target Good Enough” measurements
using RSRQ are replaced by new
measurements of frequencies based
on voicePrio
Step 9 – QCI1 bearer
released
a5B2MobilityTimer Restarted
If UE in search zone for RSRP all “Target
Good Enough” measurements using
RSRP are replaced with new
measurements of frequencies based
on connectedModeMobilityPrio
If UE in search zone for RSRQ all
“Target Good Enough” measurements
using RSRQ are replaced with new
measurements of frequencies based
on connectedModeMobilityPrio
34 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

35. 35 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

36. Step 10 – Good Coverage Reported
Event A1 reported
by UE – Three
Cases
UE in search Zone
only due to RSRP
UE in Good RSRP
and RSRQ
UE in search zone
only due to RSRQ
UE in good RSRP
and RSRQ
UE in search zone
due to both RSRP
and RSRQ
UE Remains in
36 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
search zone for
the other quantity
In all cases, all events based on the triggered quantity, RSRP or RSRQ, are removed from the UE and replaced by the
corresponding A2 search measurement
If UE is in good coverage for both quantities, the a5B2MobilityTimer is canceled and the eNodeB waits for event A2 search
measurement reports

37. 37 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

38. Notes on Steps 14
Step 14:
If bothA5RsrpRsrqCheck is set to TRUE, the eNodeB uses an extended check of A5 “Target Good Enough” measurements
before handover according to the following:
◾ RSRP measured value must be higher than either of the following calculated expressions:
◾ RSRQ measured value must be higher than either of the following calculated expressions:
38 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

39. Notes on Step 17
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40. Feature: Multi-Layer Service-Triggered Mobility
40 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
• Feature replaces Service Triggered Mobility
• Mobility Control at Poor Coverage Must be
active for this feature to function
• QCI specific thresholds for entering search
zone
• This feature can enable the serving cell to
have different A5-T1/B2-T1 threshold and
different A5-T2/B2-T2 threshold per
target frequency relation
Licensed Feature
OptionalFeatureLicense=MultiLayerServTriMobility
FeatureState=CXC4011815

41. 41 © 2018 Nokia NPO VCT Ericsson L TE - Virtual Session 2
Feature: Multi-Layer Service-Triggered Mobility
A5 and B2 Thresholds per Target Frequency Relation A1A2Search, A5 and B2 thresholds for different QCI

42. Feature: Multi-Layer Service-Triggered Mobility
Mobility Threshold Offset for A1Search and A2Search
42 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

43. Feature: Multi-Layer Service-Triggered Mobility
Mobility Threshold Offset for A5 and B2
43 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

44. Feature: Multi-Layer Service-Triggered Mobility
Mobility Threshold Offset for A5 and B2
44 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

45. Extra Slide: Relations Between Thresholds
Following should be take into consideration when configuring thresholds
45 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

46. CS Fallback
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47. Feature: CS Fallback to GERAN and UTRAN
47 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
• One of the coverage-triggered session
continuity features to GERAN or UTRAN
should be active for this feature to
operate
• GERAN/UTRAN frequency relations
have to
be defined
• Target Frequency Selected based on UE
capabilities and csFallbackPrio parameter
for each frequency
Licensed Feature
OptionalFeatureLicense=CsfbToGeranUtran
FeatureState=CXC4010956
Related Parameters
UtranFreqRelation
•csFallbackPrio
GeranFreqGroupRelation
• csFallbackPrio

48. Signaling for CSFB – UE In Connected Mode – MT Call
48 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2

49. Signaling for CSFB – UE In Idle Mode – MT Call
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50. Signaling for CSFB – MO Call
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51. Feature: Measurement-Based CSFB Target Selection
51 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2
Feature allows eNodeB to redirect the UE to
the highest prioritized frequency based on
measurements
Feature also allows definition of alternative
target frequencies if the measurement times
out
Licensed Feature
OptionalFeatureLicense=MeasBasedCsfbTargetSelection
FeatureState=CXC4011664
Related Parameters
ReportConfigCsfbUtra
• thresholdEcNo
• thresholdRscp
• timeToTrigger
•Hysteresis
ENodeBFunction
• csfbMeasFro
mIdleMode
UeMeasControl
•csfbHoTargetSearchTimer UtranFreqRelation
and GeranFreqGroupRelation
• altCsfbTargetPrio

52. Feature: Measurement-Based CSFB Target Selection
52 © 2018 Nokia NPO VCT Ericsson LTE - Virtual Session 2