Connected Mode Mobility
Overview
Handovers Introduction
Handovers in LTE are:
• Hard handovers: resources are prepared in the target cell before the UE is commanded to move to
the target cell
• Lossless: Packets are forwarded from the source to the target cell.
• Network controlled: The target cell is selected by the network not by the UE. The handover control
is in the e-UTRAN not in the Core Network.
• UE-assisted: Measurements are made and reported by the UE to the network although it is the
network (eNodeB) which triggers those measurements.
• Late path switch: Only when the inter eNodeB handover is successful, the packet core is involved
(X2 required).
Connected Mode Mobility Options
•
Intra-LTE (or Intra-RAT) handovers:
– Intra frequency handovers → within the same frequency band. There are 2 scenarios :
Intra-eNodeB handover (i.e. inter sector/ intra site)
Inter-eNodeB handover (i.e. inter site)
Inter-eNodeB handover can happen via the X2 interface or via the S1 interface. The DL data forwarding over
X2 is applied for lossless data path switching.
– Inter-frequency handovers that allow service continuity for LTE deployments in different frequency
bands and also for LTE deployments within one frequency band but with different centre frequencies.
• Inter-RAT handovers:
• These are the handovers to other radio access technologies (RAT) to provide continuous PS coverage:
• LTE HO to WCDMA
• LTE HO to/from GSM
• LTE HO to/from HRPD (3GPP2)
• Network assisted cell change (NACC) to GSM
• Unlike in the handover procedure no resources are prepared in the target system. The UE will enter GSM in
RRC Idle mode and start the RRC Connection Setup procedure in GSM
HO Process Overview
Measurements activation/de-activation
UE continuously monitors the serving cell. Events A2/A1* are used
to activate/de-activate neighbors measurements when radio
conditions are getting worse
Event based neighbor reports
The reports of neighbors are triggered by A3 & A5 events for intra-RAT
neighbors and B2 event for the inter-RAT neighbors
Measurement Reports from UE
The “Measurement Report” message contains a prioritized list of
neighbors (best neighbor first)
HO target & mode selection in eNodeB
HO execution
eNodeB decides the urgency of HO and identifies a prioritized list of
HO target cells. The eNodeB selects the target cell for HO as well as
the handover mode.
The HO/NACC mode could be:
-Intra eNB HO
-Intra LTE inter eNB via X2
-Intra LTE inter eNB via S1
-HO to WCDMA
-NACC to GSM
* LTE standard supports events A1-A5 & B1, B2
NACC= network assisted cell change
Measurements Management
Measurement Concept (1/2)
•
•
Intra-LTE (Intra-frequency & inter-frequency) measurements
RSRP & RSRQ as event-triggering & reporting quantity
•
Resulting configurable events for reporting to E-UTRAN
– Event A2/A1: Serving cells RSRP down/upcrossing certain RSRP threshold
– Event A3: Neighbor cell’s RSRP is a predefined offset better than serving cell’s RSRP
– Event A5: Serving cell’s RSRP downcrossing certain threshold, while neighbor cell’s RSRP
upcrossing an other threshold
RSRP
RSRP
RSRP
A3 trigger
A2 trigger
A5 trigger
A5 thold 2
A3 offset
A2 threshold
RSRP serving
move
direction
RSRP serving
move
direction
A5 thold 1
RSRP serving
move direction
Measurement Concept (2/2)
•
•
•
•
Inter-RAT measurements
RSRP or RSRQ as event-triggering & reporting quantity for LTE serving cell
For Inter-RAT reports trigger RSSI is used in case of GERAN and CPICH RSCP or CPICH EC/N0 in case of
UMTS
Event B2: Serving cell`s RSRP downcrossing threshold 1, while neighbor cell RSSI or CPICH RSCP or
CPICH Ec/No upcrossing threshold 2
Signal
Level
B2 trigger
B2 thold 2
Inter-RAT
Neighbor cell
signal
B2 thold 1
RSRP serving
move direction
Intra-frequency Measurements Activation/De-activation
•
•
•
UE continuously monitors the serving cell RSRP
eNodeB configures the neighbour measurements using different thresholds
RSRP > Threshold1 (3GPP: s-measure) => no measurements of neighbours
UE does not measure nor
report any neighbor cells
(applicable to intra-, interfrequency and also interRAT case)
RSRP of
serving cell
threshold1
If RSRP of serving cell is
greater than th1, only serving
cell is measured
LNCEL; 0..97dB; 1dB; -
threshold1
threshold1
-140 dBm
UE measures intra-frequency
neighbors. Inter-frequency / interRAT
see below.
time
Absolute power level: -140 dBm + threshold1
Example: if threshold 1 = 55dB -> RSRP = -140dBm + 55 dB = -85 dBm
Inter-frequency Measurements Activation
•
•
Threshold2 activates the inter-frequency measurements (event A2)
Hysteresis & time to trigger could be set
threshold2InterFreq
Trigger for inter-frequency
measurements
RSRP of
serving cell
LNCEL; 0..97dB; 1dB; -
threshold2InterFreq
Hysteresis
UE measures inter-frequency
neighbors and reports A3 or A5 if
respective condition(s) are met
hysThreshold2InterFreq
-140 dBm
Hysteresis of
Threshold2InterFreq
LNCEL; 0..15dB; 0.5dB; -
Activate Interfrequency
measurement
a2Time
To
Trigger
time
a2TimeToTriggerActInte
rFreqMeas
Duration for which the event
A2 must be valid
LNCEL; 0ms..5120ms; -; -
Inter-frequency & Inter-RAT Measurements Activation
•
•
Similarly there are different RSRP thresholds for the activation of the inter-frequency and/or inter-RAT
(GERAN or UMTS) measurements
Also different hysteresis and time to trigger could be set
Threshold2:
threshold2InterFreq
threshold2Wcdma
threshold2GERAN
RSRP of
serving cell
threshold2
Hysteresis
UE measures inter-frequency
neighbors (and reports A3 or A5)
and potentially mesures inter-RAT
neighbors (and reports B2)
-140 dBm
Activate Inter-frequency
or potentially Inter-RAT
measurement
a2Time
To
Trigger
Hysteresys:
Time to Trigger:
hysThreshold2InterFreq
a2TimeToTriggerActInterFreqMeas
hysThreshold2Wcdma
a2TimeToTriggerActWCDMAMeas
hysThreshold2GERAN
a2TimeToTriggerActGERAN
time
Measurement Activation
radio coverage by RSRP decreases
RSRP (reported)
Threshold2GERAN
Intra-frequency
& Interfrequency &
GERAN & UMTS
measurements
Threshold2Wcdma
Intra-frequency
& Interfrequency &
UMTS
measurements
Threshold2InterFreq
Intra-frequency
& Interfrequency
measurements
Threshold1
Intrafrequency
measurements
only
No neighbors
measurements
except the
serving cell
Assumptions* for this example:
Threshold2GERAN < Threshold2Wcdma < Threshold2InterFreq< Threshold1
threshold2InterFreq
threshold2GERAN
threshold2Wcdma
Trigger for inter-frequency
measurements
Trigger for GERAN
measurements
Trigger for WCDMA
measurements
LNCEL; 0..97dB; 1dB; -
LNCEL; 0..97dB; 1dB; -
LNCEL; 0..97dB; 1dB; -
* Please note that this is an example only. The priority of the measurements activation could be set-up by using the appropriate threshold settings
Inter-frequency & Inter-RAT Measurements De-activation
•
Common Threshold2a for the de-activation of inter-frequency and inter-RAT
(GERAN or UMTS) measurements (event A1)
threshold2a
RSRP of
serving cell
Stop inter-frequency
measurements
LNCEL; 0..97dB; 1dB; -
Threshold2a
Hysteresis
a1Time
To
Trigger
De-activate Inter-frequency
measurement
time
-140 dBm
hysThreshold2a
a1TimeToTriggerDeactInterMeas
Hysteresis of Threshold2a
Duration for which event A1 must be valid
LNCEL; 0..15dB; 0.5dB; 2dB
LNCEL; 0..5120ms; -; -
Connected Mode – Measurement Activation Parameter
Category
Parameter
Intra Frequency Start Measurement
Start Measurement
Inter Frequency
Hysteresis Start Meas.
Time To trigger
Start Measurement
Inter RAT UMTS
Hysteresis Start Meas.
Time To trigger
Start Measurement
Inter RAT GSM
Hysteresis Start Meas.
Time To trigger
Huawei
Parameter Name
Time To trigger
EID
Parameter Name
[HoMeasComm] SMeasure
[HoMeasComm] SMeasureInd
[LNCEL] threshold1
[UeMeasControl] sMeasure
[InterFreqHoGroup]
InterFreqHoA2ThdRsrp
[LNCEL] threshold2InterFreq
[ReportConfigEUtraBadCovPrim]
a2ThresholdRsrpPrim
ZTE
Parameter Name
[EUtranCellMeasurement]
intraFHOMeasCfg
[UeEUtranMeasurement]
thresholdOfRSRP
[EUtranCellMeasurement]
openInterFMeasCfg
[UeEUtranMeasurement]
thresholdOfRSRP
[InterFreqHoGroup]
InterFreqHoA1A2Hyst
[InterFreqHoGroup]
InterFreqHoA1A2TimeToTrig
[ReportConfigEUtraBadCovPrim]
[UeEUtranMeasurement] hysteresis
hysteresisA2Prim
[ReportConfigEUtraBadCovPrim]
[LNCEL]
[UeEUtranMeasurement]
timeToTrigger
a2TimeToTriggerActInterFreqMeas
timeToTriggerA2Prim
[InterRatHoCommGroup]
InterRatHoA2ThdRsrp
[ReportConfigEUtraBadCovPrim]
a2ThresholdRsrpPrim
[InterRatHoCommGroup]
InterRatHoA1A2Hyst
[InterRatHoCommGroup]
InterRatHoA1A2TimeToTrig
[InterRatHoCommGroup]
InterRatHoA2ThdRsrp
[InterFreqHoGroup]
InterFreqHoA1A2Hyst
[InterRatHoCommGroup]
InterRatHoA1A2TimeToTrig
Stop Measurement
Inter Freq & Inter
RAT
Hysteresis Stop Meas
Nokia
Parameter Name
Default
Value
-80 dBm
-112 dBm
[LNCEL] hysThreshold2InterFreq
[LNCEL] threshold2Wcdma
[LNCEL] hysThreshold2Wcdma
[LNCEL]
a2TimeToTriggerActWcdmaMeas
[LNCEL] threshold2GERAN
[LNCEL] hysThreshold2GERAN
[LNCEL]
a2TimeToTriggerActGERANMeas
[LNCEL] threshold2a
Start Meas - hysteresis
[LNCEL] hysThreshold2a
[LNCEL]
a1TimeToTriggerDeactInterMeas
[EUtranCellMeasurement]
openRatFMeasCfg, wcdmaMeasCfg
[UeEUtranMeasurement]
thresholdOfRSRP
-114 dBm
[ReportConfigEUtraBadCovPrim]
[UeEUtranMeasurement] hysteresis
hysteresisA2Prim
[ReportConfigEUtraBadCovPrim]
[UeEUtranMeasurement]
timeToTrigger
timeToTriggerA2Prim
[ReportConfigEUtraBadCovPrim]
a2ThresholdRsrpPrim
[EUtranCellMeasurement]
openRatFMeasCfg, geranMeasCfg
[UeEUtranMeasurement]
thresholdOfRSRP
[ReportConfigEUtraBadCovPrim]
[UeEUtranMeasurement] hysteresis
hysteresisA2Prim
[ReportConfigEUtraBadCovPrim]
[UeEUtranMeasurement]
timeToTrigger
timeToTriggerA2Prim
[ReportConfigA1Prim]
a1ThresholdRsrpPrim
[ReportConfigA1Prim]
hysteresisA1Prim
[ReportConfigA1Prim]
timeToTriggerA1Prim
[EUtranCellMeasurement]
closedInterFMeasCfg
[UeEUtranMeasurement]
thresholdOfRSRP
[UeEUtranMeasurement] hysteresis
[UeEUtranMeasurement]
timeToTrigger
-108 dBm
Intra Frequency HO - Better Cell HO
Better Cell Handover
• Better Cell Handover aims to keep the UE always on best cell
(measured by RSRP)
• Based on 3GPP reporting event „A3“:
Event A3 defines relative offset LNCEL: a3-offset
Timer to Trigger LNCEL: a3-TimeToTrigger
Reporting Interval LNCEL: a3-ReportInterval
RSRP at serving cell + a3Offset < RSRP at neighbor cell
• Better Cell Handover can be enabled / disabled:
enableBetterCellHo
LNCEL; 0 (false), 1 (true);
1 (true)
Handovers Event A3 used for Better Cell HO
RSRP at serving cell + a3Offset < RSRP at neighbor cell
RSRP
a3Offset
LNCEL; -15..15dB; 0.5dB; -
RSRP Neighbor Cell
A3 condition met
a3ReportInterval
the interval with which measurement reports are repeatedly
sent
a3offset
LNCEL; 120ms (0), 240ms (1), 480ms (2), 640ms (3), 1024ms
(4), 2048ms (5), 5120ms (6), 10240ms (7), 1min (8), 6min (9),
12min (10), 30min (11), 60min (12); -
Serving Cell RSRP
time
a3TimeToTrigger
LNCEL; 0ms (0), 40ms (1),
64ms (2), 80ms (3), 100ms (4),
128ms (5), 160ms (6), 256ms
(7), 320ms (8), 480ms (9),
512ms (10), 640ms (11),
1024ms (12), 1280ms (13),
2560ms (14), 5120ms (15); -
a3TimeToTrigger
a3Report Interval
Measurement
Report
reporting condition met
after Time To Trigger
Measurement
Report
eNB
Better Cell HO Parameter
Category
Parameter
Switch
A3 Offset
Better Cell HO
Intra Freq
Hysteresis A3
Report Interval
Time to Trigger
Switch
A3 Offset
Better Cell HO
Hysteresis A3
Inter Freq
Report Interval
Time to Trigger
Huawei
Parameter Name
[ENodeBAlgoSwitch]
HoAlgoSwitch IntraFreqCoverHoSwitch
[IntraFreqHoGroup]
IntraFreqHoA3Offset
[IntraFreqHoGroup]
IntraFreqHoA3Hyst
[IntraRatHoComm]
IntraFreqHoRprtInterval
[IntraFreqHoGroup]
IntraFreqHoA3TimeToTrig
[ENodeBAlgoSwitch]
HoAlgoSwitch InterFreqCoverHoSwitch
[InterFreqHoGroup]
InterFreqHoA3Offset
Nokia
Parameter Name
EID
Parameter Name
ZTE
Parameter Name
Default
Value
[LNCEL] enableBetterCellHo
[LNCEL] a3Offset
[ReportConfigEUtraBestCell]
a3offset
[LNCEL] hysA3Offset
[ReportConfigEUtraBestCell]
hysteresisA3
[LNCEL] a3ReportInterval
[LNCEL] a3TimeToTrigger
[ReportConfigEUtraBestCell]
timeToTriggerA3
[CellMeasGroup]
intraFHOMeasCfg
[UeEUtranMeasurement]
a3Offset
[UeEUtranMeasurement]
hysteresis
[UeEUtranMeasurement]
reportInterval
[UeEUtranMeasurement]
triggerQuantity
3 dB
320 ms
[LNBTS] actIfHo
[LNHOIF]
a3OffsetRsrpInterFreq
[ReportConfigEUtraIFBestCell]
a3offset
[LNHOIF]
[ReportConfigEUtraIFBestCell]
hysA3OffsetRsrpInterFreq
hysteresisA3
[LNHOIF]
a3ReportIntervalRsrpInterFre
q
[LNHOIF]
[ReportConfigEUtraIFBestCell]
a3TimeToTriggerRsrpInterFre
timeToTriggerA3
q
[CellMeasGroup]
interFHOMeasCfg
[UeEUtranMeasurement]
a3Offset
[UeEUtranMeasurement]
hysteresis
3 dB
[UeEUtranMeasurement]
reportInterval
[UeEUtranMeasurement]
triggerQuantity
320 ms
Intra Frequency HO - Coverage HO
Coverage Handover
•
Coverage Handover is used to HO to other eUTRA cell in case:
– serving cell RSRP gets below an abolute threshold and (&&)
– neighbor cell RSRP gets better than an absolute threshold
• Based on 3GPP reporting event „A5“:
3GPP „ThresholdEUTRA“ used to define absolute RSRP level for
a) serving cell: LNCEL: threshold3 and
b) neighbor cell: LNCEL: threshold3a
Timer to Trigger LNCEL: a5-TimeToTrigger
Reporting Interval LNCEL: a5-ReportInterval
•
Better Cell Handover can be enabled / disabled:
enableCovHo
LNCEL; 0 (false), 1 (true);
1 (true)
3GPP event A5 is UE optional; eNB knows from feature group bits
Handovers Event A5
Coverage Handover
RSRP
RSRP at serving cell < threshold3
AND (&&)
RSRP at target > threshold3a
threshold3a
Serving Cell RSRP
threshold3a
threshold3
LNCEL; 0..97dB; 1dB; Baseline is -140dBm
threshold3
LNCEL; 0..97dB; 1dB; -
threshold3
threshold3a
Baseline is -140dBm
Neighbor Cell RSRP
-140 dBm
a5TimeToTrigger
LNCEL; 0ms (0), 40ms (1),
64ms (2), 80ms (3), 100ms (4),
128ms (5), 160ms (6), 256ms
(7), 320ms (8), 480ms (9),
512ms (10), 640ms (11),
1024ms (12), 1280ms (13),
2560ms (14), 5120ms (15); -
time
a5TimeToTrigger
a5Report Interval
Measurement
Report
a5ReportInterval
LNCEL; 120ms, 240ms, 480ms,
640ms, 1024ms, 2048ms,
5120sm, 10240ms, 1min, 6min,
12min, 30min, 60min; -
Measurement
Report
eNB
Intra Frequency HO – HO Over S1
Intra-LTE Handover via S1 (LTE54)
• S1 based handover is only applicable for inter-eNB handover
• LTE inter-eNB handover can be executed without X2 interface usage in following scenarios:
– no X2 connectivity existing between Source and Target eNB (or blacklisted by operator)
– MME or S-GW change required when routing via Core Network
• User data traffic and signaling messages are indirectly send via core nodes (MME and S-GW)
• For UE there is no difference whether HO is executed via X2 or S1 interface
actLTES1Ho
Activate Intra LTE hadover over S1
LNBTS; true(1), false(0); - ; false(0)
prioTopoHO
Define priorities between the 3 topology
options for intra LTE handover
LNBTS; all equal (0), intra eNB HO prior
inter eNB HO (1), intra prior X2 prior S1 (2),
low prio S1 (3); all equal (0)
S1
S1
SAE-GW
MME
S1 Handover Preparation
This is a basic S1 handover utilizing the same MME.
1.The source eNB configures the UE measurement
procedures with an RRC RECONFIGURATION
2. UE is triggered to send MEASUREMENT REPORT to
the source eNB. It can be event triggered or periodic.
3. Source eNB makes handover decision based on UE
report + load and service information.
4. The source eNB issues a S1 HANDOVER REQUIRED
to the MME
5. MME identifies Target eNB and sends a S1
HANDOVER REQUEST.
6. The target eNB performs admission control.
UE
Source Target
MME
1. RRC Reconfiguration
RRC Reconfiguration Complete
2. Measurement report
3. HO
decision
4. HO Required
5. HO request
6. Admission
control
SGW
S1 Handover Execution
7. The target eNB configures resources and sends a S1 HO
REQUEST ACK.
8. Various GTP signalling is used to update S-GW and create
forwarding tunnel.
9. MME forwards the HO information to the source eNB in a S1
HANDOVER COMMAND.
10. Source eNB generates the RRC RECONFIGURATION
towards UE informing it to move to the target cell.
11. Source eNB starts forwarding packets to target eNB via S1
(Indirect Forwarding).
12. UE performs the final synchronisation to target eNB and
accesses the cell via RACH procedure.
DL pre-synchronisation is obtained during cell identification and
measurements.
13. Target eNB gives the UL allocation and timing advance
information.
UE
Source Target
MME
SGW
7. HO Request Ack
8. GTP Signalling
9. HO Command
10. RRC Reconfiguration
11.Forward
packets to
target
12. Synchronization
13. UL allocation and timing advance
S1Handover Execution/Completion
14. UE sends RRC RECONFIGURATION COMPLETE to
target eNB.
15. The source eNB sends a eNB STATUS TRANSFER
carrying PDCP status information towards the MME for
relaying to the target eNB.
16. MME uses a MME STATUS TRANSFER to pass PDCP
status information to target eNB.
17. The target eNB informs the MME that the handover has
been successful using HANDOVER NOTIFICATION.
18. The MME informs the source eNB to release the UE
context using a UE CONTEXT RELEASE COMMAND.
19. The source eNB confirms with a UE CONTEXT RELEASE
COMPLETE.
20. Following S1 based handover, if the Tracking Area had
changed, the UE performs a Tracking Area Update.
UE
Source Target
MME
SGW
14. RRC Reconf. Complete
15. eNB Status Transfer
16. MME Status Transfer
17. Handover Notification
18. UE Context Release Command
19. UE Context Release Complete
20.
Inter Frequency HO
Inter-frequency HO
Overview
• UE needs to support both bands and inter-frequency HO
• Service continuity for LTE deployment in different frequency bands as
actIfHo
enables the feature Inter
Frequency Handover
LNBTS; disabled (0),
well as for LTE deployments within one frequency band but with
enabled (1); -; enabled (1)
different center frequencies
• The UE performs the measurements as configured by eNodeB:
eutraCarrierInfo
eutraCarrierInfo parameter specifies the inter-frequency band
Mid-frequency of neighboring cell used in
Measurement Configuration
• The trigger for this procedure is:
LNHOIF; 0..65535; 1; – better neighbor cell (frequency) coverage (A3, RSRP)
– better neighbor cell (frequency) quality (A3, RSRQ)
– limited serving cell (frequency) & sufficient neighbor cell (frequency) coverage
(A5)
• Measurement gaps
– if needed then gap pattern 0 is used (6ms gap each 40ms)
A3 event based Handover
• inter-frequency better coverage/quality based (A3) handover event evaluation
Mn – hysA3OffsetRsr(p/q)InterFreq > Ms + a3OffsetRsr(p/q)InterFreq
hysA3OffsetRsrp/qInterFreq
Hysteresis of HO Margin
LNHOIF; 0..15; 0.5; - dB
Signal
level
inter-frequency
neighbor cell
(Mn)
hysA3OffsetRsr(p/q)InterFreq
(RSRP
or
RSRQ)
measQuantInterFreq
def. which quantity to use
for event A3
LNHOIF; RSRP, RSRQ;
both; RSRP
a3OffsetRsrp/qInterFreq
a3OffsetRsr(p/q)InterFreq
Better cell HO margin for RSRP/Q
LNHOIF; 0..15; 0.5; - dB
serving cell (Ms)
a3TimeToTriggerRsrp/qInterFreq
LNHOIF; 0..5120ms; -; not used
time
a3TimeToTriggerRsr(p/q)InterFreq
Event A3 condition fullfilled,
UE sends measurement report
Measurement
Report
Measurement
Report
a3ReportIntervalRsr(p/q)InterFreq
a3ReportIntervalRsrp/qInterFreq
LNHOIF; 120ms..60 min; -; not used
A5 event based Handover
• inter-frequency coverage based (A5) handover event evaluation
Ms + hysThreshold3InterFreq < threshold3InterFreq
and
Mn – hysThreshold3InterFreq > threshold3aInterFreq
hysThreshold3InterFreq
Signal
level
Hysteresis of HO Margin
LNHOIF; 0..15; 0.5; - dB
(RSRP)
hysThreshold3InterFreq
inter-frequency
neighbor 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
LNHOIF; 0..5120ms; -; -
Measurement
Report
Measurement
Report
a5ReportIntervalInterFreq
LNHOIF; 120ms..60 min; -; -
Nokia - InterInter-frequency Load balancing
Nokia – Load Balancing Feature
Load supervision and CAC calculation
Load Measurement
Load supervision and CAC calculation
CAC (Composite Available Capacity) Calculation
Parameter Structure
Common & Feature dedicated structure
Activation Condition
Load Information Exchange
RSR (Resource Status Report)
RSR (Resource Status Report)
RSR Initiate (start)
RSR (Resource Status Report)
RSR Initiate (stop)
LTE1841 AMLE
Active AMLE state conditions
AMLE
Candidate UE Selection
AMLE
Measurement
AMLE
HO PREPARATION
AMLE
HO PREPARATION
Result Detail
LTE 1841 AMLE
Mobility Offsets
LTE Mobility Offsets
Overview
• Target: optimize the intra-LTE mobility (intra & inter-frequency) by
applying different offsets for different target cells
• Extension for the A3 and A5 reporting events
• There are different offsets as follows:
• Cell specific and frequency specific
• For the serving cell and for the neighbors cells
• For the intra-frequency and for the inter-frequency case
• New object introduced: LNREL (Relation of LNCEL to neighbor cell)
cellIndOffServ
Cell individual offset of own
serving cell
LNCEL; -24..24dB; ; 0dB
cellIndOffNeigh
Cell individual offset of neighbor
cells
LNREL; -24..24dB; ; 0 dB
offsetFreqIntra
Offset for the EUTRA serving
frequency
LNCEL; -24..24dB; ; 0dB
offsetFreqInter
Offset for the EUTRA neighbor
frequency
LNHOIF; -24..24dB; ; 0 dB
Example: Cell Individual Offsets Impact on Event A5
RSRP serving + cellIndOffServ < threshold3
AND (&&)
RSRP target + cellIndOffNeigh > threshold3a
RSRP
cellIndOffNeigh
threshold3a
LNREL; -24..24dB; ; 0 dB
Serving Cell RSRP
cellIndOffServ
LNCEL; -24..24dB; ; 0dB
threshold3
threshold3a
threshold3
Neighbor Cell RSRP
time
a5TimeToTrigger
a5Report Interval
Measurement
Report
Measurement
Report
eNB
-140 dBm
Mobility Offset - Parameter
Category
Parameter
CIO Serving Cell
CIO Neighbor
Mobility Offset
Huawei
Parameter Name
Nokia
Parameter Name
[Cell] CellSpecificOffset
[EutranIntraFreqNCell]
CellIndividualOffset
[EutranInterFreqNCell]
CellIndividualOffset
[LNCEL] cellIndOffServ
[LNREL] cellIndOffNeigh
Offset Intra Feq
[Cell] QoffsetFreq
[LNCEL] offsetFreqIntra
Offset Inter Feq
[EutranInterNFreq]
QoffsetFreq
[LNHOIF] offsetFreqInter
EID
Parameter Name
ZTE
Parameter Name
Default Value
[EUtranCellRelation]
cellIndividualOffsetEUtran
[EUtranRelation] cellIndivOffset
0
[EUtranFreqRelation]
qOffsetFreq
[EUtranCellRelation]
qOffsetCellEUtran
[EUtranRelation] qofStCell
[EUtranRelation] qofStCell
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