6 Mobility

(1)

Soc Classification level Soc Classification level

Mobility in LTE

Radio Network Design for

Roll-Outs (RN

DR)



_{Connected Mode Mobility}_{Connected Mode Mobility}



(2)

(3)

Connected Mode Mobility

(4)

Connected Mode Mobility

•

OverviewOverview

–

Mobility supported in different releasesMobility supported in different releases

–

Mobility triggersMobility triggers

–

Mobility ThresholdsMobility Thresholds

•

Connected Mode Mobility typesConnected Mode Mobility types

–

Intra and Inter-frequency HandoversIntra and Inter-frequency Handovers

–

S1 Handover S1 Handover

–

IRAT Handover to WCDMAIRAT Handover to WCDMA

–

eNACC to GSMeNACC to GSM

–

RRC Connection Release with RedirectRRC Connection Release with Redirect

–

(5)

Overview

•

Procedures supported:Procedures supported:

–

Handover:Handover: Transfer of an ongoing call/data session from a cell Transfer of an ongoing call/data session from a cell to anotherto another without call interruption. Handovers in LTE are:

without call interruption. Handovers in LTE are:

o

o Network controlledNetwork controlled o

o UE assistedUE assisted o

o Hard handovers: Only a connection exist to one cell at a timeHard handovers: Only a connection exist to one cell at a time

–

Redirection:Redirection: SimilaSimilar to hanr to handoverdover,, but rebut requirquires connes connection ection relearelease priose prior to ther to the transfer the ongoing call

transfer the ongoing call

–

Cell change:Cell change: procedure dedicated for call transfer from LTE to GSM; procedure dedicated for call transfer from LTE to GSM; it requiresit requires connection release

connection release Licensing:

Licensing:

•

All IRAT HO, inter-frequency HO, CSFB to UTRAN/GERA All IRAT HO, inter-frequency HO, CSFB to UTRAN/GERAN via redirect and S1N via redirect and S1 handovers are optional features:

handovers are optional features:

•

When enabled they are activated for the whole eNodeBWhen enabled they are activated for the whole eNodeB

•

If deactivated the eNB does not If deactivated the eNB does not configure UE to measure other technologies/configure UE to measure other technologies/ frequencies so handover is not

(6)

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

Mobility supported in different Releases

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: FDD:

(7)

Soc Classification level

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

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

Events A4 and B1 are not supported in RL30

(8)

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)

threshold3 threshold3a

(9)

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 RSRP serving B2 trigger B2 thold 1 B2 thold 2 move direction Inter-RAT Neighbour cell signal

(10)

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

RSRP (dBm) No m easurements

except serving cell

Intra_–LTE measurements

Intra –LTE + Inter

Freq measurements

Intra_–LTE + Inter Freq + WCDMA measurements

Intra –LTE + Inter

Freq + WCDMA + GSM measurements Th4 Th2_GSM Th2_WCDMA Th2_InterFreq Th1 Th2a RRC Connection Release and re-direction threshold2InterFreq Event A2 threshold4

(11)

Intra- and Inter-frequency Handover Thresholds

Serving cell (not including neighbour cell thresholds)

(12)

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

(13)

IRAT (WCDMA) handover thresholds

Serving cell

Threshold1 RSRP for serving cell decreases Threshold2InterFreq When RSRP is below Threshold2InterFreq, UE starts measurements on other frequencies. Threshold2a RSRP increases When RSRP is above Threshold2a, UE stops measurements on other frequencies (including IRAT) Threshold3 When RSRP is below Threshold3, UE will perform HO to neighbour. (Assuming that neighbour is better than threshold3a and A5 handover is activated) 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. Threshold2Wcdma When RSRP is below Threshold2Wcdma, UE starts measurements on WCDMA frequencies in addition to other LTE frequencies (Intra+ InterFrequencies) -50 -90 -118 -119 -120 b2Threshold1Utra Threshold4

(14)

IRAT (eNACC) handover thresholds

Serving cell

Threshold1 RSRP for serving cell decreases Threshold2InterFreq When RSRP is below Threshold2InterFreq, UE starts measurements on other frequencies. RSRP increases When RSRP is above Threshold2a, UE stops measurements on other frequencies (including IRAT)

Threshold3

When RSRP is below

Threshold3, UE will perform HO to neighbour. (Assuming that neighbour is better than threshold3a and A5 handover is activated)

When serving RSRP is below b2Threshold1GERAN, UE performs eNACC to GSM

neighbour (Assuming that RSSI of GERAN neighbour is better than b2Threshold2RssiGERAN Threshold2GERAN When RSRP is below Threshold2GERAN, UE starts measurements on GERANfrequencies -50 -90 -118 -119 -120 b2Threshold1GERAN Threshold4

(15)

(16)

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)

LNBTS

LNCEL

LNHOIF

•

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

(17)

A3 event based Handover

Intra-Frequency

Signal level (RSRP) serving cell ( Ms) intra-frequency neighbour cell ( Mn) time hysA3Offset a3Offset

•

Intra-frequency better coverage based (A3) handover event evaluation Mn – hysA3Offset > Ms + a3Offset

Event A3 condition fullfilled, UE sends measurement

report Measurement

Report MeasurementReport

a3ReportInterval a3TimeToTrigger

a3Offset

Better cell HO margin for RSRP LNCEL; -15…15; 0.5; - dB hysA3Offset Hysteresis of HO Margin LNCEL; 0..15; 0.5; - dB a3TimeToTrigger LNCEL; 0..5120ms; -; 320ms(8) a3ReportInterval LNCEL; 120ms..60 min; -; 240ms (1) Parameters involved:

(18)

A3 event based Handover

Inter-Frequency

Signal level (RSRP or RSRQ) serving cell ( Ms) inter-frequency neighbour cell ( Mn) time hysA3OffsetRsr(p/q)InterFreq a3OffsetRsr(p/q)InterFreq

•

Inter-frequency better coverage/quality based (A3) handover event evaluation Mn – hysA3OffsetRsr(p/q)InterFreq > Ms + a3OffsetRsr(p/q)InterFreq

Event A3 condition fullfilled, UE sends measurement

report Measurement

Report MeasurementReport

a3ReportIntervalRsr ( p/q)InterF req a3TimeToTriggerRsr(p/q)InterFreq

a3OffsetRsrp/qInterFreq

Better cell HO margin for RSRP/Q LNHOIF; 0..15; 0.5; - dB

hysA3OffsetRsrp/qInterFreq

Hysteresis of HO Margin LNHOIF; 0..15; 0.5; - dB

measQuantInterFreq

def. which quantity to use for event A3

LNHOIF; RSRP, RSRQ; both; RSRP

(19)

•

Intra-frequency coverage based (A5) handover event evaluation Ms + hysThreshold3 < threshold3

and

Mn – hysThreshold3 > threshold3a

A5 event based Handover

Intra-Frequency

Signal level (RSRP) serving cell ( Ms) intra-frequency neighbour cell ( Mn) hysThreshold3 time a5TimeToTrigger hysThreshold3

event A5 condition fullfilled

UE sends measurement report _Measurement

Report Measurement_Report

hysThreshold3 Hysteresis of HO Margin LNCEL; 0..15; 0.5; - dB threshold3 LNCEL; 0..97; 1; - dB threshold3a LNCEL; 0..97; 1; - dB a5TimeToTrigger LNCEL; 0..5120ms; -;320ms a5ReportInterval LNCEL; 120ms..60 min; 240ms Parameters involved:

(20)

•

Inter-frequency coverage based (A5) handover event evaluation Ms + hysThreshold3InterFreq < threshold3InterFreq

and

Mn – hysThreshold3InterFreq >

threshold3aInterFreq

A5 event based Handover

Inter-Frequency

Signal level (RSRP) serving cell ( Ms) inter-frequency neighbour cell ( Mn) hysThreshold3InterFreq time a5TimeToTriggerInterFreq hysThreshold3InterFreq

event A5 condition fullfilled

UE sends measurement report _Measurement

Report Measurement_Report

hysThreshold3InterFreq Hysteresis of HO Margin LNHOIF; 0..15; 0.5; - dB threshold3InterFreq LNHOIF; 0..97; 1; - dB threshold3aInterFreq LNHOIF; 0..97; 1; - dB

(21)

Example of successful intra-freq HO

(22)

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

(23)

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. measIdToAddModList { { measId 1, measObjectId 1, reportConfigId 1 }, { measId 2, measObjectId 1, reportConfigId 2 }, }, quantityConfig { quantityConfigEUTRA { } }, measGapConfig release : NULL, s-Measure 90, 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 message c1 : rrcConnectionReconfiguration : { rrcConnectionReconfiguration-r8 : { measConfig { measObjectToAddModList { { measObjectId 1, measObject measObjectEUTRA : { carrierFreq 2075, allowedMeasBandwidth mbw25, presenceAntennaPort1 TRUE, neighCellConfig '00'B }

(24)

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.

(25)

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

(26)

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)

(27)

(28)

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

RL20

•

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)

(29)

(30)

Inter RAT Handover to WCDMA

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)

RL30 RL25TD

•

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)}

(31)

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

Leaving conditions 1. Ms - Hys > Thresh1

or

2. Mn + Ofn + Hys < Thresh2 Ms -> RSRP of serving cell

Mn -> RSCP/EcN0 of neigbour cell

Thresh1 -> b2threshold1Utra -> refers to signal level of serving cell Thresh2 -> b2threshold2UtraRSCP/EcN0 -> refers to signal level of neighbour cell

Hys -> hysB2ThresholdUtra -> hysteresis to prevent ping-pong effect between

entering and leaving conditions; parameter common for both serving and neigbour cell

Ofn -> OffsetFreqUtra -> refers to neighbour cell only

reportConfigInterRAT

(32)

Inter-RAT Handover to WCDMA

Event B2

Entering condition:

RSRP,s < b2threshold1Utra – hysB2thresholdUtra AND

(33)

Inter-RAT Handover to WCDMA Flow

MME

Measurement Report

RRC Connection Reconfiguration

RRC Connection Reconfiguration Complete

LTE, Source:CelI WCDMA, Target Cell

Handover Command Measurement Report

MobilityFromEUTRAcommand

HandoverToUTRANComplete

Triggered EventA2

New MeasConfig used for IRAT Handover

Triggered EventB2

Handover Preparation

(34)

Inter-RAT Handover to WCDMA

Triggered EventA2

(35)

(36)

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

(37)

eNACC to GSM

Event B2

Entering Condition:

RSRP,s < b2threshold1GERAN – hysB2ThresholdGERAN AND RxLev,n > b2theshold2RssiGERAN+ hysB2ThresholdGERAN

Entering conditions 1. Ms + Hys < Thresh1

and

(38)

Layering Strategy. Theoretical Study

eNACC procedure parameter

recommendations

•

Scope:Scope:

•

• Suggest parameter settings for LTE eNACC procedure (theoretical assumptions)Suggest parameter settings for LTE eNACC procedure (theoretical assumptions)

•

Assumptions:Assumptions:

–

– Continuous GSM 900MHz coverage ensuredContinuous GSM 900MHz coverage ensured

–

– Partial LTE 2600 MHz coveragePartial LTE 2600 MHz coverage

•

Design Goals:Design Goals:

–

– Maximize users throughputMaximize users throughput

–

– Ping-pong effect eliminationPing-pong effect elimination

–

– Maximize UE time within LTE coverageMaximize UE time within LTE coverage

–

– Minimize necessary time for GSM cellMinimize necessary time for GSM cell measurement

measurement

–

– Minimize time necessary for cellMinimize time necessary for cell reselection from LTE to GSM reselection from LTE to GSM

Detailed information for parameter settings in this and other several mobil

Detailed information for parameter settings in this and other several mobil ity scenarios isity scenarios is available within the PKDB scenarios:

(39)

Procedure Criteria

Event A2 to activate GERAN measurements: Event A2 to activate GERAN measurements:

•

• RSRP,s < threshold2GERANRSRP,s < threshold2GERAN – – hysThreshold2GERANhysThreshold2GERAN

•

• duringduring a2TimeToTriggerActGERANMeasa2TimeToTriggerActGERANMeas

Event B2 for eNACC procedure: Event B2 for eNACC procedure:

•

• RSRP,s < b2threshold1GERANRSRP,s < b2threshold1GERAN – – hysB2ThresholdGERANhysB2ThresholdGERAN ANDAND

•

• RxLev,n > b2theshold2RssiGERAN+ hRxLev,n > b2theshold2RssiGERAN+ hysB2ThresholdGERANysB2ThresholdGERAN

•

• duringduring b2TimeToTriggerGERANMeasb2TimeToTriggerGERANMeas

Hysteresis Hysteresis values values assumed to be assumed to be 0 dB 0 dB

(40)

Parameter Values Proposal

RSSI threshold RSSI threshold in GERAN in GERAN relative to -110 relative to -110

(41)

Conclusions

•

threshold2GERAN = b2Threshold1GERAN:threshold2GERAN = b2Threshold1GERAN: when

when event A2 event A2 is triggereis triggered (measurd (measuring foring for GSM neighbours) the event B2 (eNACC) GSM neighbours) the event B2 (eNACC) could also be

could also be triggeredtriggered

•

Measuring time for GSM cell is limitedMeasuring time for GSM cell is limited (reducing the impact in t

(42)

(43)

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

(44)

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)

(45)

RRC Connection Release with Redirect

(46)

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

(47)

CSFB

(48)

CSFB to UTRAN or GSM via redirect

RL20

CSFB: Circuit Switched Fallback IE: Information Element

•

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

MOC: Mobile Originated Calls

•

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

(49)

CS Fallback Signalling Example

MOC in ECM_Connected

UE needs to be IMSI attached

UE starts Initial Access procedure and sends

E xtended S ervice Reques t

message with S ervice Typeset to “mobile originating CS fallback”

eNB sends

“RRCConnectRelease” message with redirect information of WCDMA Frequency to be used for redirection

Further examples (ECM_IDLE, MTC) in:

https://sharenet-ims.inside.nokiasiemensnetworks.com/Overview/D4376 59035

(50)

Mobility Parameter Settings

Examples from real cases

(51)

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:

(52)

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

(53)

(54)

•

Idle Mode Mobility

–

Cell Selection

–

LTE intra-frequency Reselection

–

LTE inter-frequency Reselection

(55)

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

•

SIB1 is used to transmit cell selection parameters

LNCEL: qRxLevMinOffset

Typically 0 (only used when camping in VPLMN)

VPLMN: Visited PLMN

Max(LNCEL:pMaxOwnCell - P_max from UE (*) , 0)

Srxlev = Qrxlevmeas – (Qrxlevmin + Qrxlevminoffset) – P_compensation

Measured value

LNCEL:qRxLevMin Typically -130dBm

(*) P_max from UE : UE class specific max. UL Tx power; 23 dBm

pMaxOwnCell (SIB1)

Used to calculate P_compensation

(56)

-S – Criterion Cell Selection

•

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

P_compensation = max(pMaxOwnCell – P_max from UE, 0)

I am outside I am inside, but I have not enough  

•

qrxLevMin can be set up

differently for intra frequency, inter frequency and IRAT:

(57)

Cell Reselection

Process Overview

Measurements trigger

Evaluate cell reselection criteria “R”

Execute cell reselection

Different reselection cases

depending on the priorities of the neighbour frequency layers (inter-frequency

and inter-RAT)

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)

(58)

(59)

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

•

Qrxlevmeas< - 68 dBm

•

UE will start to measure intra-frequency neighbours when RSRP is worse than - 68 dBm

-130 dBm

(60)

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

–

Rank_{serving cell} = Measured RSRP_{serving cell} + LNCEL:qHyst

–

Rank_{neighbour cell} = Measured RSRP_{neighbour cell} – IAFIM:qOffsetCell

•

Re-selection if :

–

Rank_{neighbour cell} > Rank_{serving cell} for tReselEutr and

–

More than 1 second has elapsed since the UE camped on the current serving cell

RSRP,n > RSRP,s + qHyst +

(61)

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...62dB,step2dB - 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...16dB,step2dB -

-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

(62)

Intra Frequency cell Reselection

Parameter Summary (2/2)

MOC Parameter Name

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,step1 - -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

(63)

(64)

Inter frequency cell reselection

Triggering Measurements

•

Measurement trigger depends on the absolute priorities of the serving and non-serving 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:

(65)

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

•

Qrxlevmeas <=-118 dBm

•

UE will start to measure inter-frequency neighbours when RSRP is worse than -118 dBm

-130 dBm

(66)

Inter Frequency Reselection

R-criteria: Equal priority between layers

•

Similar to intra frequency

•

A frequency-specific offset for equal priority E-UTRAN frequencies can be

RSRP,n > RSRP,s + qHyst + qOffset

(67)

Inter Frequency Reselection

R-criteria: Reselection to lower priority layers

•

If the neighbour cell layer has lower priority, the reselection will happen if:

Srxlev_neighbour> IRFIM:interFrqThrL && Srxlev_serving < LNCEL:threshSrvLow Where:

Srxlev_n = QrxlevMeas_n – IRFIM:qRxLevMinInterF – P_compensation

Srxlev_s= QrxlevMeas_s – LNCEL:qRxLevMin + LNCEL: qRxLevMinOffset – 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. Qrxlevmeas_s <

qRxLevMin

+

thresholdSrvLow

–

qR xL evMinOffs et +

P_compensation

AND

(68)

Inter frequency cell reselection

Example of reselection to lower priority

-130

LNCEL:qRxLevMin = -130 dBm

LNCEL:threshSrvLow = 10

If suitable neighbour (*) cell is found, reselection will be performed when RSRP decreases under -120 dBm

-120 -118

Inter frequency measurements will be started at -118 dBm LNCEL:sNonIntrSearch = 12 -140 RSRP decreases Pcompensation =0 LNCEL:qRxLevMinOffset =0

(69)

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:

Srxlev_neighbour> IRFIM:interFrqThrH Where:

Srxlev_neighbour= Qrxlevmeas – IRFIM:qRxLevMinInterF – P_compensation

•

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. Qrxlevmeas_neighbour >

qRxLevMinInterF

+

interFrqThrH

(Assuming P_compensation = 0)

(70)

Inter Frequency cell Reselection

Parameter Summary (1/3)

MOC Parameter Name

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,step1 - 1 LNCEL threshSrvLow Threshold f or the serving frequency used in

reselection evaluation towards lower priority EUTRAN frequency or RAT

0...62 dB, step 2 dB - 2

LNCEL qrxlevminintraF

Minimum required RX RSRP level for the intra-frequency neighbouring E-UTRA cells.

(Qrxlevmin in 36.304)

-140...-44 dBm, step 2 dBm - -130_dBm IRFIM qRxLevMinInterF Minimum required Rx RSRP level for the

neighbouring EUTRA cells on this carrier frequency

-140...-44 dBm, step 2 dBm

- -68 dBm

IRFIM dlCarFrqEut eUTRAN frequency 0...65535, step 1 - -IRFIM eutCelResPrio Absolute priority of the EUTRA carrier frequency 0...7, step 1 - 5

(71)

Inter Frequency cell Reselection

Parameter Summary (2/3)

MOC Parameter Name

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

(72)

Inter Frequency cell Reselection

Parameter Summary (3/3)

MOC Parameter Name

GMC Value

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-specif ic antenna ports are used in all neighbouring cells.

- true

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 E-UTRAN 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

(73)

(74)

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 t o GSM:

–

GFIM/GNFL parameters are broadcasted in the SIB7

LNBTS

LNCEL

UFFIM

LNBTS

LNCEL

GFIM

GNFL

(75)

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

(76)

Inter RAT cell reselection

R-criteria

•

Reselection to a higher priority RAT will happen if:

WCDMA: Srxlev_neighbour> UFFIM:utraFrqThrH GSM: Srxlev_neighbour> GFIM:gerFrqThrH

•

Reselection to a lower priority RAT will happen if:

•

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. GSM:

Srxlev_neighbour> GFIM:gerFrqThrL && Srxlev_serving < LNCEL:threshSrvLow WCDMA:

Srxlev_neighbour> UFFIM:utraFrqThrL && Srxlev_serving < LNCEL:threshSrvLow

(77)

Inter RAT cell reselection

R-criteria

•

Srxlev_neighbouris referred to the candidate cell:

•

GSM: Srxlev_neighbour= 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

(78)

LTE

3G cell reselection, signalling example

UE is in LTE

UE is in 3G

(79)

Inter-RAT cell Reselection

Parameter Summary (1/3)

MOC Parameter Name

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,step1 - 1 LNCEL threshSrvLow Threshold f or 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 0...16383, step 1 -

(80)

-Inter-RAT cell Reselection

Parameter Summary (2/3)

MOC Parameter Name

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 E-UTRA 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

(81)

-Soc Classification level

Inter-RAT cell Reselection

Parameter Summary (3/3)

MOC Parameter Name

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,step1 -

-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 neighbou ring 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 -

(82)

-Example Idle Mode Parameter settings

Priorities, triggering conditions

MOC Parameter Value Comments LNCEL sIntraSearch 62 LNCEL sNonIntrSearch 16 LNCEL qrxLevMin -130 dBm LNCEL Qhyst 3 dB LNCEL threshSrvLow 10 LNCEL tReselEutr 1s

LNCEL cellReSelPrio 7 LTE2600 layer 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 WCDMA layer UFFIM qRxLevMinUtra -119 dBm

(83)

LTE 2600, absolute priority 7

Idle mode reselection

-130 qrxLevMin = -130 dBm -114 -68 sNonIntrSearch = 16 -140 sIntraSearch = 62 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

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

LNCEL:threshSrvLow = 10 IRFIM:interFrqThrL = 20

IRFIM:qRxLevMinInterF= -130dBm

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

LNCEL:threshSrvLow = 10 UFFIM:utraFrqThrL = 10

UFFIM:qRxLevMinUtra= -119 dBm

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

RSRP decreases

(84)

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

(85)

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