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Transcript of 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
WCDMA Layer 1 Tutorial4/13/2011
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_SETUP_CNF (success)
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_SETUP_CNF (success)
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
• Choose cell that meets above condition for evaluation with other cells
• 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
• Choose cell that meets above condition for evaluation with other cells
– RSCP Ranking and Measurement Quantity is Ec/Io
• Neighbor cell meets S criteria
• Choose cell that meets above condition for evaluation with other cells
• Treselection is incremented during Ec/Io re-ranking
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
•
WCDMA Layer 1 Tutorial4/13/2011
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.
WCDMA Layer 1 Tutorial4/13/2011
Cell Reselection23
FACH Mode Barred
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
Cell Reselection26
Software Flow Chart (Idle Mode)
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
WCDMA Layer 1 Tutorial4/13/2011
Cell Reselection27
Software Flow Chart (Idle Mode)
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
WCDMA Layer 1 Tutorial4/13/2011
Cell Reselection28
Software Flow Chart (Idle Mode)
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
WCDMA Layer 1 Tutorial4/13/2011
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.
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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
WCDMA Layer 1 Tutorial4/13/2011
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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
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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
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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>
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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>
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Q & A