Cell Reselection

WCDMA L1 Tutorial

Cell Reselection Overview

WCDMA Layer 1 Tutorial4/13/2011

Cell Reselection2

Introduction

• Process by which a UE detects, evaluates, and camps on

a better neighbor when already camped on a cell– Idle Mode, CELL_PCH, URA_PCH

– CELL_FACH

• Suggested Reading– TS 25.304

– TS 25.133

– TS 25.331

– Systems Memos by Messay Amerga• http://lvcrpprd.qualcomm.com/livelink/livelink?func=ll&objId=25722527&objAction=browse&sort=name

• Deviation from Specification is highlighted in Red


Cell Reselection3

Message Flow Diagram

l1m_state = PCH/FACH

RRC L1

CHY_ACQ_REQ

CPHY_SETUP_CNF (success)

Read SIBs

CPHY_CELL_TRANS_CNF (success)

ACQ Procedures

CPHY_SETUP_REQ (BCH/PCCPCH)

CPHY_SETUP_REQ (PCCPCH_N/BCH_N)

CPHY_CELL_TRANS (cell camp on cell 0)

CPHY_ACQ_CNF (success)

Pilot Dies/Neighbor Cell becomes strongerCPHY_CELL_RESELECTION_IND (cell 1)


CPHY_CELL_TRANSITION_REQ (reselection success)

Set up SCCPCH on new Cell

CPHY_CELL_TRANS_CNF (success)

CPHY_CELL_PARM_REQ

CPHY_CELL_SELECTION_REQ

CPHY_CELL_PARM_REQ

CPHY_CELL_MEAS_REQ

Cell selection/cell reselection parameters

CPHY_CELL_SELECTION_CNF

Evaluate Cell Selection Criteria (S Values)

CPHY_SETUP_REQ (SCCPCH)

l1m_state = PCH


CPHY_CELL_MEAS_REQ

SIB parms, neighbor cell listCPHY_DRX_REQ

l1m_state = PCH_SLEEP (Cell Selection/Reselection Evaluation every DRX

Cycle)

CPHY_DRX_REQ

l1m_state = BCH

l1m_state = ACQ


Cell Reselection4

S Criteria

• Squal > 0 AND Srxlev > 0 to camp on a cell

• Squal = Ec/Io – Qqualmin– Ec/Io > Qqualmin to camp

– Ec/Io is measured by UE

– Qqualmin is from SIB3

• Srxlev = RSCP – Qrxlevmin – max(UE_TXPWR_MAX_RACH – P_MAX, 0)

– RSCP should be greater than a minimum RSSI

– When RF output power of the UE is less than what the UE may use in the cell,

then UE should be closer to NodeB

– RSCP is measured by UE

– Qrxlevmin and UE_TXPWR_MAX_RACH is from SIB3


Cell Reselection5

SIB3 Parameters

• Sintrasrch (optional)– Measure intra-frequency neighbor cells when Squal <= Sintrasrch

– Always measure intra-frequency neighbor cells when not specified

• Sintersrch (optional)– Measure inter-frequency neighbor cells when Squal <= Sintersrch

– Always measure inter-frequency neighbor cells when not specified

• SsearchRAT (optional)– Measure inter-RAT neighbor cells when Squal <= SsearchRAT

– Always measure inter-RAT neighbor cells when not specified

• Qhyst1s– Used in ranking serving cell based on RSCP

• Qhyst2s– Used in ranking serving cell based on Ec/Io.

• Qqualmin– Minimum required quality measure based on Ec/Io

• Qrxlevmin– Minimum required quality measure based on RSCP


Cell Reselection6

SIB3 Parameters

• UE_TXPWR_MAX_RACH– Maximum allowed UL TX power

• Treselection– Time for which the neighbor cell should meet cell reselection criteria for UE to

reselect

• Cell Selection and Reselection Quality Measure– Ec/Io or RSCP

– Specifies which measurement quantity ranking should be based on


Cell Reselection7

SIB11 Parameters

• Neighbor List– UE will also detect neighbors not specified in the list and reselect to it (FACH)

• Idle Mode support for detected cells still under discussion

• Qoffset1s,n– Quality Offset used to rank cell based on RSCP

• Qoffset2s,n– Quality Offset used to rank cell based on Ec/Io

• UE_TXPWR_MAX_RACH– Maximum allowed UL TX Power for neighbour cell

• Qqualmin– Minimum required quality measure based on Ec/Io

• Qrxlevmin– Minimum required quality measure based on RSCP


Cell Reselection8

Serving Cell Ranking

• RSCP Ranking– UE implementation same as specified in 25.304

• Rank_s = RSCP + Qhyst1

• Ec/Io Ranking– UE implementation same as specified in 25.304

• Rank_s = Ec/Io + Qhyst2


Cell Reselection9

Neighbor Cell Ranking (RSCP)

• FDD cells– Rank_n = RSCP – Qoffset1

• UE implementation same as specified in 25.304

• GSM cells– Rank_n = Filtered RSSI – Qoffset1

• Filtered RSSI is running average of 4 samples

• UE follows specification if serving cell S criteria meets

– Rank_n = Filtered RSSI – MIN( 10, Qoffset1 )

• UE deviates from specification when Serving Cell fails S criteria

• Prevents UE from staying on bad 3G cell when network setting, Qoffset1, is

unreasonably high

• If Inter-frequency or GSM neighbors are present– Always perform RSCP ranking first, irrespective of measurement quantity

– If RSCP ranking yields FDD cell as best cell, re-rank FDD cells based on Ec/Io

if measurement quantity is set to Ec/Io


Cell Reselection10

Neighbor Cell Ranking (Ec/Io)

• FDD Cells– Deviates from specification (Rank_n = Ec/Io – Qoffset2)

– Rank_n = Ec/Io – MAX( Qoffset2 + Qhyst2, Qhyst2_add ) + Qhyst2

• Qhyst2_add (additional hysteresis) based on serving cell Ec/Io

• Qhyst2_add = 2 dB, if Ec/Io < -12dB

= (14+Ec/Io) dB, if -12dB < Ec/Io < -10dB

= 4dB, if Ec/Io > -10dB

• For more information:– “Suppressing Idle Mode Re-selections based on CPICH measurements,” by

Messay Amerga

– Discusses why hysteresis is applied based on observed signal strength


Cell Reselection11

Reselection Criteria (GSM)

• When Serving Cell Meets S criteria– Rn > Rs, and Srxlev > 0, for Treselection

– Choose cell that meets above condition for evaluation with other cells

• When Serving Cell Fails S criteria– Neighbor cell Srxlev > 0 for Treselection

– Choose cell that meets above condition for evaluation with other cells


Cell Reselection12

Reselection Criteria (FDD)

• When Serving Cell meets S criteria– RSCP Ranking and Measurement Quantity is RSCP

• Rn > Rs, and neighbor cell meets S criteria for Treselection

• Choose cell that meets above condition for evaluation with other cells

– RSCP Ranking and Measurement Quantity is Ec/Io

• Rn > Rs, and neighbor cell meets S criteria


• Treselection is incremented during Ec/Io re-ranking

• When Serving Cell fails S criteria– RSCP Ranking and Measurement Quantity is RSCP

• Neighbor cell meets S criteria for Treselection


– RSCP Ranking and Measurement Quantity is Ec/Io

• Neighbor cell meets S criteria


• Treselection is incremented during Ec/Io re-ranking


Cell Reselection13

Choosing Best Cell

• RSCP Ranking and Measurement Quantity is RSCP– Choose best ranked cell from cells selected for reselection evaluation

• RSCP Ranking and Measurement Quantity is Ec/Io– Choose best ranked cell from cells selected for reselection evaluation

– If best cell is FDD cell, re-rank based on Ec/Io and choose best cell

• GSM Cell– If BSIC of best cell not verified, verify BSIC

– If BSIC has changed, check to see if <ARFCN,BSIC> is in neighbor list

• Reselect only to cells in neighbor list

– If above conditions fail, choose next best GSM cell to reselect


Cell Reselection14

Out Of Service

• Idle Mode– Serving cell fails S criteria continuously for 12s

• FACH– Serving cell fails S criteria continuously for 4s

• CPHY_OUT_OF_SERVICE_INDICATION sent to RRC– RRC performs Cell Selection

• If UE was in Idle Mode, enter Idle mode on new cell

• If UE in CELL_FACH enter CELL_FACH on new cell

– RRC performs Cell Update on new cell

• Deviation from specification– OOS timer is not incremented when RRC is reading SIBs of neighbor cell

• May cause OOS timer to expire later than 12s

– Reselection given priority over OOS


Cell Reselection15

Reacquisition Algorithm during DRX

• In Idle Mode, UE wakes up and

reacquires serving cell

• If Reacquisition fails– UE performs a modified cell reselection

algorithm

– Treselection not taken into

consideration to save time of missed

pages

Wake up

Perform Reacq

List Search

Serving Cell

Reacquired?

Perform Normal

Cell Reselection

Procedure

Intra-f Nbrs

Present?

Search Intra-f

nbrs and rank

Best nbr meet

S criteria?

Reselect

to

Neighbor

Step 1/2/3 (Full)

Search on serv

frequency

Serv Cell

Found?

Rank any intra-f

nbrs found

Best nbr meet

S criteria?

Inter-f nbrs

present?

Perform inter-f

searches

Best nbr meet

S criteria?

GSM nbrs

present?

Perform GSM

meas and rank

Best nbr meet

S criteria?

OOS Timer

Expired?

Increment OOS

TimerGo To Sleep

Send OOS

YesNo

No

No

No

No

No

No

No

No

No

Yes

YesYes

Yes

Yes

YesYes

Yes

Yes


Cell Reselection16

Cell Reselection Algorithm

Perform Active

set search

Determine if Active

set meets cell

selection

Have

measurement

conditions been

met?

No Cell reselection

neededno

Search all scheduled

intra-freq, inter-freq and

inter-RAT monitored cells

For each searched cell,

compute on :

R = Q -Qoffset nmeas,n

For the Active cell

compute:

R = Q + Qhystsmeas,s

rank all cells according to

Rs for serving cell and Rn

for neighbor cells

Is bc

serving cell?

Cell reselection

indication to RRC

no

Tsr,BC >

Treselection?

yes

n=0

Are

S and

S

> 0?

Increment

Tsr,n

Clear Tsr,n

exclude n from

ranked list

Any other

neighbors?

n++

yes

yes

bc=best cell

no

qual,n

rxlev,n

Has

Cell Selection

failed for N DRX

cycles?

no

Yes

no

Is bc

serving

cell?

bc=next

ranked cell

Use CPICH RSCP

and GSM RSSI meas

to compute Qmeas,n

yes

Use CPICH Ec/Io and

to compute Q meas,n

Is bc GSM

cell?

no

meas

quality

set to Ec/Io and

multiple frequencies

in Monitored

list?

no

yes

no

yes

RRC indication

no

yes

Qmeas

computed using

RSCP?

yes

no


Cell Reselection17

Full Search Timer

• Step 1/2/3 is also called Full Search– Searches entire PN space (10ms) to get cell position

– Used to discover timing and energy of ASYNC cells

• Idle Mode– Done when Serving Cell and all Neighbor Cells < -16 dB

– Every 30s for intra-frequency and Squal < Sintrasrch

– Every 30s for inter-frequency and Squal < Sintersrch

– Done when serving cell Squal falls below Sthreshold for the first time and

there are only ASYNC neighbors present

• FACH– Every 360ms


Cell Reselection18

Measurement Rules (Idle Mode)

• Measurements are started when Squal <= Sthreshold– Sthreshold is Sintrasrch, Sintrasrch, and SsrchRAT,m for intra-frequency,

inter-frequency and inter-RAT searches

• Measurements are started when S criteria fails for Nserv

DRX cycles– In this case, the above measurement rule is ignored

• Measurements are also started when reacquisition fails– Treselection is also not taken into account in this case


Cell Reselection19

W2G Reselection (Idle Mode)

• When reacquisition fails– Delay reselection to GSM by 2 DRX cycles

• Reselect if serv cell ECIO < -20 dB or RxAGC < -95 dBm– In Idle Mode, S criteria of serving cell must fail for 5s

• Optimizations featurized (FEATURE_DELAY_3G_TO_2G)

• UE can handle BSIC mismatches– Reselects to cell with same ARFCN but different BSIC, if specified in SIB11

• Only one cell is BSIC reconfirmed– Spec specifies 4 cells to be reconfirmed


Cell Reselection20

Measurements in FACH

• UE always performs measurements– Without regard to Sintrasrch, Sintersrch or SsearchRAT

– Spec compliant, since according to 25.304

• If Sx > SsearchRAT m, UE need not perform measurements on cells of RAT "m".

• UE checks if Squal < Sthreshold before reselecting– Makes sure we don’t reselect if Squal > Sthreshold

• Intra-frequency cells measurements done every 80ms– Can be pre-empted by FACH measurement occasions

– Step 1/2/3 search can stretch timing

• Inter-frequency and GSM measurements are done during FACH

measurement occasions– Inter-frequency and GSM measurements alternate

– RACH transmissions and Intra-frequency search can reserve FACH measurement

occasions

• Causes UE to “lose” FACH measurement occasions

• UE can detect and reselect to cells not specified in SIB11– Reselection parameters defaulted to use serving cell values


Cell Reselection21

Barred Cells Support

• Implementation is 25.304 Compliant

• SIB 3 parameters (Cell Access Restriction IE)– Cell Barred

– Intraf reselection Indicator

– T-barred value

– Cell Reservation

•


Cell Reselection22

Barred Cell Suport in IDLE Mode

• Serving Cell Barred– Trigger Immediate reselection by simulating reacq failure

– Ignore S-thresholds

– Ignore reselection timer

– Serving cell not considered for ranking and hence reselection is triggered if a neighbor is suitable.

– If no neighbor is suitable for reselection trigger OOS

• Neighbor Cell Barred– Measurements are not made as long as the neighbor is barred.

– Neighbor barred cell is excluded from reselection ranking.

– If the frequency is barred, all cells in the frequency not considered for measurements and reselection ranking.

• Acquistion– Acquistions (except those for Handovers) are not allowed on barred cells.


Cell Reselection23

FACH Mode Barred


Cell Reselection24

Software Flow Chart (Idle Mode)

Wake Up

srchzz_prepare_for_wake_up()

- restore fingers

- start aset srch

srchzz_aset_srch_done()

- calculate serviing cell eng

Serving Cell

max_eng[0] >

path_thresh?

Perform reacquisition failure algorithmsrchcr_start_nset_srch_cmd( SRCHCR_REACQ_FAIL_CR_SRCH)

srchzz_declare_reacq_status_drx(TRUE, TRUE)

- send reacq success status to DRX

Do DRX PICH Processing and call

srchcr_start_cell_reselection_eval()

Do Aset Evaluation

Check if neighbor measurements required

srchcr_aset_cell_select_reselect_eval()

NO

YES


Cell Reselection25

Software Flow Chart (FACH Mode)

srchfach_proc_srch_ops()

- Handle search heartbeat events

- ASET 20ms, NSET 80ms

Aset search

timer expired?

Any search in

progress?

srch_aset_srch_due = TRUE

Perform aset search

srchcr_aset_srch_done()

- get aset results

srchfach_next_srch_cmd()

- check if step 1/2/3 due

- check if triage due

srch_cell_resel_eval_

due = TRUE?

Nset search

timer expired?

Triage due

timer expired?

Any search in

progress?

srch_fing_triage_due = TRUE

srchcr_aset_cell_select_reselect_eval()

- Perform aset eval

- perform intra-f neighbor searching and

evaluation

srch_cell_resel_eval_due = TRUE

YES

YES

YES

YES

NO

YES

NO

NO

YES

NO


Cell Reselection26


srch_aset_cell_select_reselect_eval()

-Perform aset eval

srchcr_det_neigh_srch()

-Determines if nbr search needed

-Intra, inter or GSM

srchcr_prepare_srched_cells()

-initialise cells for search

srchcr_start_n_srch()

initialise cells for search

Intra search

reqd?

srchcr_start_intra_f_srch() Inter search

reqd?

Is fiull search

condition met()?

InterRAT reqd?

Need full search?lim_put_local_cmd()

-Sets nset srch done

A B C D E

YES

NO

YES

NO

NO

NO

YES

YES

YES

G

F

NO


Cell Reselection27


srchcr_start_inter_f_srch()Do Step1,2 & 3 search

srchcr_nset_srch_cmd()

- Pick strongest and rem cells and

do list search.

srchcr_inter_f_nset_srch_cmd()

-Pick strongest & rem cells and

do list search

srchcr_start_gsm_srch()

-GSM search

Send meas cmd to DSP

BA D C E


Cell Reselection28


srchcr_nset_list_srch_done()

- Called when list srch results from

dsp are available only for intra-f

srchcr_intra_f_post_list_srch_dump()

-Cal Ecio for the rslts

srchcr_reset_proc_start_n_srch()

-Process rslts, determine new search

Is intra-f srch

in progress?

Is Inter-f srch

in progress?

srchcr_proc_intra_f_srch()

-Process rslts of intra-f

srchcr_sort_nset()

- Sort the results by energy

srchcr_nset_intra_f_cell_reselect_eval()

- Evaluate the rank of s-cell and n-cells

and increment or reset Tresel accordingly

G

YES

NO

srchcr_proc_inter_f_srch()

-Process rslts of inter-f

srchcr_sort_inter_f_nset()

- Sort the results by energy

srchcr_nset_inter_f_cell_reselect_eval()

- Evaluate the rank of s-cell and n-cells

and increment or reset Tresel accordingly

NO

YES


Cell Reselection29

Files List

File Description

Srchcr.h Function prototypes, data structures, and enums

Srchcr.c Cell Reselection main implementation

Srchzz.c Search wake up and sleep functions (Idle Mode)

Srchfach.c Search kickoff point in FACH. FACH measurement

occasion implementation

Srchcrgsm.h Cell Reselection GSM measurements (Idle) related

declarations

Srchcrgsm.c Cell Reselection GSM measurements (Idle) related

implementation. Command functions and callback

functions to read results.

Srchgsmdrv.h

srchgsmdrv.c

Scheduler for GSM measurements. Wrapper for GL1.


Cell Reselection30

F3 Messages

• Start Cell Reselection– srchcr.c 06824 Start Cell Reselection...

• Idle Mode• Reacquisition (after DRX wake up)

– srchzz.c 01860 <---- Reacq: eng(105824)pos(289021)psc(8)----->

• Reacquisition succeeds

– srchzz.c 01662 [18399] srch rsp DRX:stat 1 (slew -2)

• Reacquisition fails

– srchzz.c 01921 Reacq list search failed 4496 6464

• Start Aset Evaluation

– srchcr.c 07249 CR Aset Eval:freq 10689 PSC 8 tot_eng 105824

• Start Cell Reselection Evaluation (conditions for measurements met)

– srchcr.c 07294 CR Start:2*squal=25,srxlev=36,sintr_int=16

• Intra-f and GSM searches are due

– srchcr.c 07296 CR srch due Intra 1 Inter 0 GSM 1

• Serving cell rank based on RSCP

– srchcr.c 07353 CR RANK:(RSCP) rank_s -53,PSC 8,2*rscp -126

• Serving cell rank based on ECIO

– srchcr.c 07362 CR RANK:(ECIO) 2*rank_s -7,PSC 8,2*ecio-15


Cell Reselection31

F3 Messages

• Idle Mode (Continued)• Cell Reselection not evaluated (conditions not met)

– srchcr.c 07383 CR not eval:2*squal=21,Nserv=0,sintr_int=10

• Rank of neighbor cell based on RSCP

– srchcr.c 04357 CR RANK:(RSCP) 2*RSCP -168,PSC 27,qoff1 0

– srchcr.c 04360 CR RANK:(RSCP) rank_n -84,2*sq_n -63,srxlv_n -84

• Rerank FDD cells based on ECIO

– srchcr.c 03273 Rerank FDD cell based on ECIO

• FDD reranking did not find any best cells

– srchcr.c 03299 FDD rerank returned NULL

• Rank of neighbor cell based on ECIO

– srchcr.c 02519 CR RANK:(ECIO) 2*rank_n -63,PSC 27,2*ecio-63

• Rank of neighbor cell based on ECIO for Inter-frequency

– srchcr.c 02595 CR RANK IF:(ECIO) 2*rank_n -63,PSC 27,2*ecio-63

• Rank of GSM neighbor cell (based on RSSI)

– srchcr.c 06346 GSM rank -72, s_rxlev_n 43 arfcn 13

• TmeasureGSM expired

– srchcr.c 05943 CR:TmeasGSM xpired, sinterrat 20


Cell Reselection32

F3 Messages

• Idle Mode (continued)• Treselection started on neighbor cell

– srchcr.c 04407 CR:Start Tresel on PSC 9

– srchcr.c 06366 CR:Start Tresel on ARFCN 13

• Treselection reset on neighbor cell– srchcr.c 02571 CR:Reset Tresel on PSC 27

– srchcr.c 06398 CR:Reset Tresel on ARFCN 90

• Treselection Incremented on neighbor cell– srchcr.c 04427 CR:Inc Tresel on PSC=8 t=256 frames Tresel=5

• Cell Reselection Evaluation done– srchcr.c 06100 CR EVAL nbr searching done

• No best cell found during this evaluation– srchcr.c 03400 No best cell found

– srchcr.c 09179 Did not find suitable ncell to reselect

• Start GSM Cell BSIC Identification– srchcr.c 06490 Start BSIC identification

• End of GSM BSIC Identification– srchcrgsm.c 00620 GSM ACQ clnp done:cur_gfn=45

• Cell Reselection Indication– srchcr.c 09069 CEL RESEL IND:GSM BSIC ncc0 bcc 0 ARFCN 13

– srchcr.c 08999 CEL RESEL IND:Fr 10689 psc 9


Cell Reselection33

F3 Messages

• FACH• Serving cell evaluation started

– srchcr.c 07249 CR Aset Eval:freq 10689 PSC 8 tot_eng 110976

– srchcr.c 07294 CR Start:2*squal=25,srxlev=41,sintr_int=16

• CRNTI is valid for FACH Measurement Occasions

– rrcllcoc.c 09264 Valid C-RNTI in CC

• FACH Measurement Occasion parameters

– srchfach.c 02753 FACH meas oksn: Ntti 1, M_REP 16, C_RNTI 1

• FACH inter-frequency measurement due

– srchfach.c 03556 FACH meas oksn SW due at 1520 for Inter-freq to meas at

1521

• FACH inter-frequency measurement (step 1)

– srchcmmeas.c 01999 Starting interF 10830 step1

• FACH inter-frequency results (step 1)

– srchcmdrv.c 00930 SRCHCM:Step1 peak 0 egy 48932 pos 1160

– srchcmmeas.c 02697 Step1Done #Peak 13 NoCell 13 RSSI -69 dBm

– srchcmmeas.c 01490 Selecting PSCpeak 0 posCx8 1160 egy 48932


Cell Reselection34

F3 Messages

• FACH (continued)• FACH inter-frequency measurements (list search)

– srchcmmeas.c 02124 Starting PSCACQlistSrch F 10830 SCR 144

• FACH inter-frequency measurements (reconfirmation)

– srchcmmeas.c 02155 Starting ReconfListSrch

– srchcmmeas.c 03272 Cell->DETECTED SCR 144 posCx8 83080 egy 66768

• FACH GSM measurement due

– srchfach.c 03545 FACH meas oksn SW due at 1534 for GSM to meas at 1537

• FACH GSM RSSI measurement

– srchcrgsm.c 02868 FACH GSM meas proceed with RSSI

• FACH GSM BSIC Identification

– srchcrgsm.c 03468 FACH GSM meas proceed with BSIC Id

• FACH GSM BSIC verified or not

– srchcr.c 10882 BSIC verified?: 0


Cell Reselection35

F3 Messages

• FACH (continued)• FACH GSM rank

– srchcr.c 10878 FACH GSM rank -110, s_rxlev_n -9 arfcn 90

• FACH inter-frequency rank based on RSCP

– srchcr.c 02905 CR RANK:(RSCP) 2*RSCP -156,PSC 9,qoff1 0

– srchcr.c 02908 CR RANK:(RSCP) rank_n -78,2*sq_n 21,srxlv_n 21

• FACH inter-frequency rank based on ECIO

– srchcr.c 02505 CR RANK:(ECIO) 2*rank_s -6,PSC 8,2*ecio-14

– srchcr.c 02595 CR RANK IF:(ECIO) 2*rank_n -19,PSC 9,2*ecio-19


Cell Reselection36

F3 MESSAGES

• Step1 Peak Elimination• Eliminates same Step1 Peaks from Step1 srch result and (ASET or NSET) cells

– srchcr.c 1661 Stp1 cnt: before Elimination 25

– srchcr.c 1679 Stp1 cnt: after Elimination 20

• Sorting – Intra frequency• Number of sorted intra frequency cells

– srchcr.c 09311 Sorted 2 cells

• Interfreq messages• Cell reselection not evaluated – reason : CR not enabled or inter-f cells not

present– srchcr.c <line no> Inter-f Nset not evaled

• Cell reselection evaluated– srchcr.c <line no> Inter-f NSET eval for cell resel

• When sorting entire Inter-f set– srchcr.c <line no> Sorting Inter-freq NSET cnt=<value>

– srchcr.c <line no> Sorting Inter-f NSET

l


Cell Reselection37

F3 MESSAGES

• Inter-f messages continued

• If any sorted cells have 0 energy, they are indicated via this message

– srchcr.c <line no> Netwk sync nbr <value> fr <value> not found

– srchcr.c <line no> Sorted <value> cells freq <value> f_idx <value>

• Cell reselection indications

• Found better cell than the present serving cell

– srchcr.c <line no> Found next best ranked cell

• Reselection indication given to RRC with the Freq and PSC value

– srchcr.c <line no> CEL RESEL IND:Fr <value> psc <value>

– srchcr.c <line no> CEL RESEL IND:GSM BSIC <ncc,bcc>=2,3 ARFCN 12

• Reselection indication given for a GSM cell with ARFCN and ncc & bcc

– srchcr.c <line no> Did not find next best GSM cell


Cell Reselection38

F3 MESSAGES

• Neigbhour searches evaluations

• To do full inter-f search with sync and async cells

– srchcr.c <line no> Do inter-f full srch sync <value> async <value>

• In FACH mode – if aset or all sync neigbhours have less than -16dB or no nbrs

– srchcr.c <line no> Full Srch tmr exp, do Full Srch

• In Idle mode – if aset or all sync neigbhours have less than -16dB or no nbrs

– srchcr.c <line no> Cells weak, do step 1/2/3


Cell Reselection39

F3 MESSAGES

• GSM– srchcr.c <line no> Sorting GSM nset <value> cells

• search for BSIC id aborted due to cell being weak

– srchcr.c <line no> ARFCN %d too weak for BSIC id

• Wait for timer expiry before GSM timing is slammed after waking up

– srchcr.c <line no> waiting for GSM time ready <value>

– srchcr.c <line no> No GSM nbr cells

– srchcr.c <line no> Pending resel: No GSM search

– srchcr.c <line no> No GSM neighbors to search

– srchcr.c <line no> CR:TmeasGSM xpired, sinterrat <value>

– srchcr.c <line no> BSIC verif tmr xpired, sinterrat <value>

– srchcr.c <line no> aset srch going on. Not making it inactive

– srchcr.c <line no> CR Res for ARFCN <value>

– srchcr.c <line no> GSM PScan: idx=<value> burst=<value> rssi/16=<value>


Cell Reselection40

F3 MESSAGES

• Rudimentary messages– srchcr.c <line no> sync nset <value> async nset <value> uset <value>

– srchcr.c <line no> Start Cell Reselection...

– srchcr.c <line no> Cell trans in prog, no cell resel eval

– srchcr.c <line no> Inc num drx=<value> last gsm srch=<value>


Cell Reselection41

Q & A

Documents

Cell Reselection