3G Knowledge Sharing
July 8, 2022 | Author: Anonymous | Category: N/A
Short Description
Download 3G Knowledge Sharing...
Description
3G KNOWLEDGE SHARING
BASICS
WCDMA Channels
Voice Call Flow RNC
UE
CN
User decides to originate a call RACH RAC H process: proc ess: accessing the system
RACH Procedures RRC Connection Request
RRC connecti connection: on: establishing dedicated control link
Negotiation with CN
RRC Connection Con nection Setup Setup RRC Connection Con nection Setup Complete Authentication Authentic ation and Security Procedures Procedures UL Direct Transfer Transfer DL Direct Transfer Transfer
[CC: Setup] [CC : Call Proceeding] Request Reque st tto o establish RAB
Radio Bearer Bea rer Setup Radio Bearer Bea rer Setup Setup Complete Comple te RB Se Setu tup: p: establishing dedicated payload link
DL Direct Transfer Transfer
[CC : Alerting]
Call Release
UMTS Intra-Frequency Reselection
, = C / , = C / = = C
C – I I
1: 1 < I M 2: C1 < C2 3: C1 < C2 < C3
SintraSearch
1
2
3
4
3 ( = 1 ) C3
Reselection to to GSM UMTS Inter-RA Inter-RAT Reselection
Q meas,s = Serving Cell RSCP Q meas,n = Neighbor Cell RSSI Q offset = offset for neighbor frequency Q hyst = hysteresis for serving Cell
UTRAN Intra-Frequency Handover Procedure UE
RNC RB Setup Complete Measurement Control UTRAN configures event 1a, 1b and 1c Applies new measurement configuration Starts intra-freq measurements
Event 1a triggered
Measurement Report (1a) Active Set Update
UE adds new cell in to active set
Event 1b triggered
Active Set Update Complete
Measurement Report (1b) Active Set Update
UE removes a cell from active set
UTRAN decides to add new cell into active set
Active Set Update Complete
UTRAN decides to remove a cell from active set
UTRAN to GERAN Inter-RAT Handover UE
RNC RB Setup Complete Inter-RAT MCM (2d, 2f) Applies new measurement configuration Starts intra-freq measurements
Measurement Report (2d) Physical Channel Reconfig. (CM Config.) Physical Channel Reconfig. Complete 3 CM Patterns:
Inter-RAT MCM (GSM cells, CM Act., 3a)
GSM RSSI BSIC Ident.
Applies new measurement configuration Starts inter-RAT measurements
Measurement Report (3a) Handover from UTRAN command UE connects to GSM
BSIC Reconfirm.
WCDMA Events
Event
Description
Event Type
Event 1a
Active set Addition
For SHO
Event 1b
Active set deletion
For SHO
Event 1c
Replacement of active set cell
Event 1d
Change of best cell
For SHO
Event 2d
Compressed mode trigger
iRAT
Event 2f
Compressed mode exit
Event 3a
iRA iRAT T execut execution ion
Event 1d(HS)
Change of serving HS cell
For SHO
iRAT
iRAT
HS cell Change
GOLDEN PARAMETERS
iRAT
Idle Mode Measurements
qOffset1sn(MO: GSM qOffset1sn(MO: relation) : 5 dB
-6 dB
Qhyst, 2sn
FDD_Rscpmin FDD_Rscpmin(Threshold (Threshold for GtoU GtoU re-sele re-selection) ction) -106 dBm
FDD_Qmin(Threshold FDD_Qmin(Threshold for GtoU GtoU re-sele re-selection) ction) -111 dBm Qhyst, 1sn 2 dB -113 dBm
-115 dBm
QRxlevelMin
Ec/No
RSCP Cell Selection & Re-selection parameters
iR iRA AT Ev Even ents ts – Ec Ec/N /No o CS only -12 dB
CS + PS Multi RAB -13 dB
2f Hysteresis2f/2
2f Hysteresis2f/2
-13 dB
-14 dB
UsedFreqRelThresh2fEcNo
UsedFreqRelThresh2fEcno
UsedFreqThresh2dEcNo -15 dB
-15 dB
ServiceOffset2dEcno
Hysteresis2d/2
-16 dB
UsedFreqThresh2dEcno
-16 dB
2d
Hysteresis2d/2
-17 dB
2d
3a 3a If GSM RSSI > 95 dBm
2d
Start GSM Measurements
2f
Stop GSM Measurements
3a
iRAT iRA T HO excution excution
If GSM RSSI > 95 dBm
Delay the iRAT iRAT for PS only services by setting serviceoffset2dEcno as -6 ( -21 dB)
iRA RAT T Even ents ts – RS RSCP CP CS only -105 dB
CS + PS Multi RAB 2f
-106 dB
Hysteresis2f/2
2f Hysteresis2f/2
-106 dB
-107 dB
UsedFreqRelThresh2fRscp
UsedFreqRelThresh2fRscp
UsedFreqThresh2dRscp
-109 dB Hysteresis2d/2
-110 dB
UsedFreqThresh2dRscp
-109 dB
ServiceOffset2dRscp
2d
-110 dB Hysteresis2d/2
-111 dB
2d
3a 3a If 95GSM dBmRSSI > If GSM RSSI > 95 dBm 2d
Start GSM Measurements
2f
Stop GSM Measurements
3a
iRAT iRA T HO excution excution
Delay the iRA iRAT T for PS only services by setting serviceoffset2dRscp as -6 ( -115 dBm)
iRAT Even entts – UE Tx Tx powe werr CS + PS Multi RAB CS only
6b
6b
-104
ueTxPowerThresh6b
ueTxPowerThresh6b
18 dBm
18 dBm
-105 dBm
6d
dBm Max UE Tx power I C < F2+ ( E ) AD G I > 95 B
6d Max UE Tx power
3a
I C < F2+ 2+ ( E ) AD G I > 95 B
For PS only services Event Event 6d trigger should be set as – 110 dBm dBm
3a
Connected Mode Parameters Parameter usedFreqThresh2dRscp usedFreqThresh2dEcno
Description Threshold for event 2d for the used frequency frequ ency when the measurement quantity is RSCP. Event 2d is used to activate compressed mode Threshold for event 2d for the used frequency when the measurement quantity is Ecno. Event 2d is used to activate compressed mode
Recommended Setting -109 -15
hysteresis2d
The hysteresis parameter determines when any event is trigerred as well as re-trigerred and de-trigerred
2 dB
timeToTrigger2dRscp
Period of time during which the Event 2d triggering condition must be satisfied before transmission of the MEASUREMENT REPORT message can occur
64 640 0 ms
timeToTrigger2dEcno
Period of time during which the Event 2d triggering condition must be satisfied before transmission of the MEASUREMENT REPORT message can occur
64 640 0 ms
usedFreqRelThresh2fRscp
Relative threshold for event 2f versus event 2d for the used frequency when the measurement measurem ent quantity is RSCP. Event 2f is used to deactivate compressed mode
3 dB
usedFreqRelThresh2fEcno
Relative threshold for event 2f versus event 2d for the used frequency when the measurement measurem ent quantity is
2 dB
CPICH Ec/No. . Event 2f is used to deactivate compressed mode
hysteresis2f
The hysteresis parameter determines when 2f event is trigerred as well as re-trigerred and de de-trigerred. -trigerred. A relatively higher value of hysteresis helps to avoid re-trigerring the same event several times unde underr fluctuating radio conditions
2 dB
timeToTrigger2fRscp
Period of time during which the Event 2f triggering condition must be satisfied before transmission of the MEASUREMENT REPORT message can occur
1280 ms
timeToTrigger2fEcno
Period of time during which the Event 2f triggering condition must be satisfied before transmission of the MEASUREMENT REPORT message can occur
1280 ms
gsmThresh3a
It represents the minimum required GSM RSSI for reliable handover to GSM
-95 dBm
serviceOffset2dRscp
Service-specific offset for event 2d when the measurement meas urement quantity is RSCP
0(CS only and (CS+PS) MultiRAB) /-6 for PS only
serviceOffset2dEcno
Service-specific offset for event 2d when the measurement m easurement quantity is Ecno
0(CS only and (CS+PS) MultiRAB) /-6 for PS only
IRAT T parameter paramet er settings setti IRA ngs in Delhi F2E
15 B
C
F2
108 B
2 2E E
0
F2E
2 B
2 2
2
F2
3 B
2
0
2
0
3 3
0
88 B
3 3E
0
0
F
102 B
F
12 B
/+ AB
C+ AB
3,7
3,7
3,5,1113 3,5,1113
C IA H : C : • E: 15 B • : 110 B C+ AB: • E: 18 B 22B • : 111B 113 B 115 B + AB: • E: 18 B 22B • : 111B 113 B 115 B
C IA H C+ AB. I DC
SOFT HANDOVER
Soft Handover Parameters Parameter
Description
Recommended Settings
Remarks With too low value, cells of relatively good quality may not trigger an Event 1a and will have no chance of inclusion inclusio n in the active set, which may lead to poor call quality and, ultimately, a call drop. If parameter is set to a value too large, cells of relatively poor quality may trigger an Event 1a and be unnecessarily included in the active set, therefore degrading downlink capacity
reportingRange1a
Threshold used for addition-window in evaluation criteria for event type 1a
3 dB
reportingRange1b
Threshold used for drop window in evaluation criteria for event type 1b
10(5dB)
hysteresis1c
hysteresis1d
Hysteresis used in replacement threshold in evaluation criteria for event 1c to avoid ping pong effects
2(1dB)
Hysteresis used for change of best cell c ell evaluation criteria for event type 1d
15(7.5dB)
With too large value, cells of relatively poor quality may not trigger an Event 1b and capacity will be degraded. If parameter is set to a value too small, cells of relatively good quality may trigger an Event 1b 1 b prematurely, thereby negatively affecting call quality If parameter is set to a value too large, cells of relatively good quality may not trigger an Event 1c and will not replace repl ace cells of relatively poor quality, therefore degrading downlink capacity. If parameter is set to a value too small, cells of quality only marginally better than that of an active set cell may m ay trigger an Event 1c, therefore increasing signaling load without appreciably improving the combined active set cells’ cells ’ quality
Too low value will trigger frequent change of best bes t cells causing UE to send measurement reports
the quantity the UE measures to measQuantity1
timeToTrigger1a
evaluate the triggering of measurement reports for intrafrequency handover events
2(EcNo)
Time between detection of event 1a 11(320 ms) /10 (200 and sending the measurement report ms) for the same
----
If parameter is too small, monitored cells of relatively re latively low average quality, but whose received CPICH EC/N0 exhibits rapid and large fluctuations, fluc tuations, may trigger MEASUREMENT REPORT message transmission transm ission and be added to the active set. If parameter is too large, the UE will delay d elay transmission of MEASUREMENT REPORT message corresponding to monitored or detected cells of relatively re latively good quality.
Coverage
Power Mapping for R99 Services Relative RL power
maxPwrMax 4 dB interPwrMax 3.5 dB
minPwrMax 0 dB
Min Rate
Max Rate
64 Kbps
Inter-Rate
RL Rate
eulNonServHwRate, no macrodiversity macrodivers ity gain is obtained
128 / 384
eulNonServingCellUsersAdm
Admission threshold for the number of E-DCH users having this cell as nonserving cell.When the number of E-DCH non-serving non-s erving users in the cell is on the limit set by this parameter, a reconfiguration of one of these users from 10ms TTI EUL to 2ms TTI EUL will be rejected and the connection will be reconfigured to DCH/HS.
100
HSUPA
Used as a switch to turn, the Dynamic Code Allocation feature, on or off by setting its value to true or false enable enab le code multiplexing between users in the same TTI Parameter that defines the maximum number of HS-PDSCH codes that are allocated in a cell
60/80 6 dB / 8 dB 2, 3 TRUE 15
5760
numHsScchCo ScchCodes des & numHsP numHsPdschCod dschCodes es numHs HC 64 DL DLK01 K01 NC HC = 1
I:
• L C • I E 15
• C HC=1 HC=1 64 AM AM 13. 14 13 .
114 HC -95dBm in busy hour In DLGGN02: 5.2 % cells in RNC is having average RSSI > -95dBm in busy hour
SummarySummary-IRA IRAT T Rate • I DLGGN01, DLGGN01, DLK01 DLK01 DLGGN02 EI DLKL01 C C • I DLKL01 • F C+ AB , % C E . • CICH IA IA EI • 7 4. % EI IA C . • C IA IA C 15 B EI 110 B C. C. A CICH , EI IA . • L CICH C . .
Summary-CS DCR Rate • • •
• • • • • • • •
CS DCR DCR of of all 4 RNCs RNCs are are very very good. good. CS call drop rate is abou aboutt 0.46 0.46 % & 0.51 % in RNC DLOKL01 & RNC DL DLVKP01 VKP01 respecti respectively vely CS cal calll dro drop p rate rate is abo about ut 0.6 0.67 7 % & 0.4 0.49% 9% in RN RNC C DL DLGGN GGN01 01 & RNC RNC DLG DLGGN GN02 02 respectively CS-D CS -DCR CR Fr From om Net Netwo work rk Cou Count nter ers s & GPE GPEH H logs logs (A (Ana naly lysis sis on 4 RN RNCs Cs)) • Abo About ut 54 54 % to to 63 % of call call dro drops ps are are due due to to other other rea reason son cat catego egory ry acros across s all all 4 RNC RNCs s • Abo About ut 17 17 % to to 25 % of call call dro drops ps are are acco account unted ed for Upli Uplink nk Sy Sync nc acros across s all all 4 RN RNCs Cs DLG LGGN GN01 01 is ha havi ving ng ve very ry po poor or UL RS RSSI SI.. • 25 25% % cells cells in RN RNC C is is hav havin ing g ave avera rage ge RSS RSSII > -95 -95dB dBm m in bu busy sy hou hourr DLOKL DL OKL01 01 is hav having ing hig high h per percen centag tage e of of poo poorr RSC RSCP P sam sample ples s tha than n oth other er RN RNCs Cs • 46 % cells cells ha havin ving g mor more e than than 15 15 % sam sampl ples es(( < -99 -99 dBm) dBm) dur durin ing g busy busy hou hourr DLGG DL GGN0 N01 1 and and DLOK DLOKL01 L01 is als also o hav having ing hig high h num number ber of dro drops ps due to mis missin sing g nei neighb ghbors ors DLGG DL GGN0 N02 2 is havi having ng cel cells ls whic which h contr contribu ibutes tes to very very hig high h drops drops due to cong congest estion ions s 66% of CS dro drops ps in in netw network ork is is happ happen ening ing in Mul MultiR tiRAB AB cal calls. ls. Ou Outt of 66% Mul MultiR tiRAB AB dro drops, ps, 42 %drops are captured in CS+PS(0/0). DLGGN01 DLG GN01 is having having very high high unspec unspecified ified drops drops.. Analy Analysis sis of those drop drops s points points to the very very high UL RSSI in the cells of DLGGN01 There The re are are very very hig high h numb number er of of unsp unspecif ecified ied dro drops ps in in Mult MultiRA iRAB B due to net netwo work rk conf configu igurat ration ion issue. Separate case study is presented on this issue. i ssue. Besides Besid es phy physical sical optim optimizatio ization n , UL RSSI RSSI,, IRA IRAT T relat related ed para paramete meters rs and and call call reesta reestablishm blishment ent parameters might need tuning.
Summary-HS DCR L DL • I H . L3, L2 L1 • GGN01 K01 H DC DC NC • 4 GGN02 KL01 NC
H DC > 3%. A (7) H DC > 3% . • 54% H • 78% L3 . L3 , 84% H FACH • 20% H L 2 LC % H DL (L1) • 15 • L3 18 L1 9 . I NC L1 18 • C I • I M
Summ mmar aryy- Cs & PS PS CSS CSSR R Su C C 4 NC . A NC C C > 99%. B C C C AB > 99%. C 4 NC . A 4 NC C > 98%. I NC C C . DLGGN01 C : 97.07% NC C AB, . M A . .
– 92% C AB 01 01 01 01 A A – 75% C AB 02 02 01 01 A
A NC. M 4 NC . C NC. . H C D DC C 3 C 1 AB . I 2 .
IRAT IRA T Rate(Key Rate(Key findings) findings)
Compressed mode Trigger distribution distribution • In DLGGN01 ~64 % of Compressed modes are triggered because of poor EcIo • In DLVKP01 ~55 % of Compressed modes are triggered because of poor EcIo • In DLGGN02 ~48% of Compressed modes are triggered because of poor EcIo wh while ile in DLOK DLOKL01, L01, majority of CM triggered because of poor RSCP
Compressed mode Triggers: (DLGGN01-GPEH stats)
• F C+ MAB , CM %E . L MAL C+ AB C , E MAB
• F DLKL01, C CM
Top cellscells- IRA IRAT T rate(DLGGN0 rate(DLGGN01 1& DLVKP01)
Very high % of EcIo samples< -14dB Very low CPICH power with respect to Max power
At 100% loading
• Too low CPICH power ratio(some cells have less than 2 %) is the major reason of very poor EcIo. • CPICH power needs to be tuned in these cells to reduce the IRAT IRAT rate. Increase in CPICH should be done with w ith down tilting and on cluster of cells to minimize the overshooting and capacity blockings.
Hig High h UE Tx Tx Po Power wer trigg triggered ered CM CM in CS+PS CS+PS multiR mul tiRAB AB sta states tes but but no IRA IRAT T • F C+ AB , E % E ( 6D) • IA IA E : + ( 4) + 5, = 107B C 3 . E 108 E L I • C IA IA H E : 2 2 C+ AB : 4( C) • • 2 C: 108 B • ( ( E ): 5 A E CM Recommendation is to reduce serviceoffset2drscp serviceoffset2drscp for CS + PS multiRABs, so that possibility of UE trigger early IRAT HO is higher. This will improve UL RSSI and UEs will stay for shorter time in compressed mode
Ser Servic viceof eoffse fsett for PS ser servic vices es • I AB 7 4 EI: 19B AB. • I IA IA .
C AB
E : 0
1056
19.40463065
C
: 2
361
6.633590592
C
E : : 2
153
2.811466373
C
: : 4
140
2.57 .572583609 C C + M AB AB
E : : 2 E :: 4
325 309
5.97 .972069092 C+ C+ M AB 5.67 .678059537 C+ C+ M AB AB
E : 4
1552
28.51892687
( ( 1 1115B) B)
1032
18.96 .96361632
: 10
5
0.091877986
E : : 10
474
8.710033076
Frequent 2d and 2f
•
•
Frequent 2d and 2fs events are observed in the network even within in compressed mode. Current se settings of of hysteresis2d and hysteresis2f are 0
HS DCR(KEY FINDINGS)
HS drop drop cau cause se distr distribu ibutio tionn- all 4 RNC RNCs s HS Drop causes Channel Switching Drops Maxi Ma ximu mum m numb number er of RL RLC C ret retra rans nsmis missi sion ons s is re reac ache hed d Radio Connection Supervision - expiry of timer hsDschRcLostT Unspecified Radio link failure indication leading to a release with cause other than transport Active Set Update complete message not received addition High Speed-Downlink Shared Channel (HS-DSCH) Cell Change failure Active Set Update complete message not received replacement
No of drops 4460 1628 16 28 1221 804 73 42 35 27
Missinfailure g neighTimer bor T_cellchange Cell change outgoing T _cellchange expires Othe Ot herr Ra Radi dio o Li Link nk Co Cont ntro roll (R (RLC LC)) un unre reco cove vera rabl ble e er erro ror. r. Active Set Update complete message not received deletion. Cell lock indication. Transport issue Congestion Failure
22
IRA IR AT ou outg tgoi oing ng fa fail ilur ure e - Ti Time merr T_ T_re relloc oc_o _ov ver eral alll ex expi pirres Measurement control faiure
2 1 8352
Total
~54 % of HS drops are during state transition L1 and L2 timeouts contribution is 14.6% and 19.5% resp.
11 10 8 3 3 2
Sub causes: Channel Switching drops Channel switching failure: Sub causes
Total no of drops
PROCEDURE_TIMEOUT
4329
CELL_UPDATE_IN_DRNC
109
Unspecified channel switch failure
6
NODE_INTERNAL_FAILURE_6
5
GENERAL_FAILURE_IN_PROCEDURE
4
REQUESTE TED D_REQUEST_ T_TY TYP PE_NOT_ T_S SUPPOR ORTE TED D
4
NODE_INTERNAL_FAILURE_2
1
NODE_RESOURCE_NOT_AVAILABLE_1 PROCEDURE_EXECUTION_TERMINATED_EXTERN AL
1
Total
4460
Out of all Channel switch drops 78% of drops are purely Layer 3 procedure timeouts
1
Sub causes: Channel Switching drops Procedure timeout Cause: Procedure Timeout
Percentage of drops
INACTIVITY(expiry INACTIVITY(ex piry of hsdschinactivityTimer)
83.8
INCREASE_ACTIVITY_UL
8 .8
INCREASE_ACTIVITY_DL
6 .2
EUL/HS to EUL/HS(Mobility)
0 .8
DECREASE_ACTIVITY_UL
0 .3
UL_SOFT_CONGESTION
0 .1
FALLBACK_TO_R99
0 .1
Out of all L3 procedure timeouts, 83.8% drops are happening during HS to FACH transition ~ 15 % of procedure timeouts are during FACH to HS transition 24.8 % of L3 procedure timeouts are happened at UL RSSI< -95 dBm
Proced Procedure ure Timeou Timeoutt- Inact Inactivity ivity(Poor (Poor UL RSSI RSSI)) • /
RBR for reconfiguring to FACH
There was no cell update from thereceived UE probably because of high UL RSSI
,, 1 1 • 1 . • . .
Cause 2: Impact of SRB on HS Maximum number of RLC retransmissions is reached
Maximum number of RLC retransmissions is reached Current procedure running while L2 Timer Total drops Percentage expiry( Total contribution to drops: 19.5%) HS CE CELL CHANGE EXECUTION
1018
62.57
INCREASE ACTIVITY UL
228
14.01
EUL2ms to EUL 10ms
140
8.60
RLC failure(L2 timeout) timeout) without without any ongoing ongoing procedure running
130
7.99
INCREASE ACTIVITY DL
28
1.72
RL_ADDITION
26
1.60
RL_REPLACEMENT
22
1.35
RAB failure after successful admission
13
0.80
FALLBACK_TO_R99
10
0.61
INACTIVITY(hsdschinactivitytimer)
5
0.31
RL_DELETION
4
0.25
RANAP_CAUSE_NORMAL
3
0.18
• LC ( LC )/ L C (LC) AN • 62% H E. LC • 27% LC L I < 95 B , • B H , H B DL. H
Case study-HS cell change failures due to RLC timeout( Very poor poor EcIo in servin serving g cell) cell)
Averge EcIo(Source cell): -19.18 Averge -19.18 dB Average EcIo(Target cell): -13.6 dB
Averge RSCP(Sourc Averge RSCP(Source e cell): -92.4 -92.4 dB Average RSCP(Target cell): -86.21 dB
Since hsQualityestimate : RSCP and hsHysteresis1d: 5dB so HS cell change is performed if RSCP of target cell is 2.5(ie.5/2) dB higher than source cell which can be seen from the above RSCP comparison chart. But in the the network at the same time time EcIo of source cells was too low(average: -19.18 dB) that UEs didn’t acknowledge Physical channel reconfiguration and the RLC timed out during HS CC procedures. Since SRB on HS is activated, there is not any SHO gain for SRB in DL.
Case study-HS cell change failures due to RLC timeout MR: 1a
•
Addition successful
MR: 1d
HS serving cell change started
•
•
EcIo of EcIo current serving cell: 19dB
• Call dropped
UE wa was on on Cel Celli lid d:5 :58 875 759( 9(Ec EcIIo: -17dB and RSCP: -84 dBm. It was only only cell in the Aset. UE triggered measurement report for 1a for cell: 23869(EcIo:-12 dB, RSCP: -78dBm). SHO: addition was successful UE no now tri trig gge gere red d ch cha ang nge e of serving cell on the basis of RSCP and1dsent measurement report for RNC in initi tia ated change of serving cell by sending PhysicalChannel Reconfiguration, Reconfigurat ion, but meanwhil mean while e EcIo of current current cell became too low( -19dB) that Physical Channel Reconfiguration Reconfigurat ion might have not decoded by the UE. RNC tr tried ma maximum retransmission before declaring RLC timeout. Ongoing Cell change was also
failed and call dropped.
Cause 3: Connection SuRadio Supe perv rvis isio ion n - Ex Expi piry ry of timer hsDschRcLostT
Radio Conn Connection ection Supe Supervision rvision - Expiry of timer timer hsDschRcLostT
L/DL •
Current procedure running while hsDschRcLostT hsDschRcLostT Total drops expired(Total contribution contribution to HS drops: 14.6%)
• •
Radio link Failure without any procedure running HS_CELL_CHANGE_EXECUTED
529 160
Poor qu quality detected(2d): EUL2ms to to EUL 10 10ms
141
RAB failure af a fter successful admission
139
RL_ADDITION
100
RL_REPLACEMENT
61
INCREASE_ACTIVITY_UL
33
RL_DELETION
23
INCREASE_ACTIVITY_DL
12
FALLBACK_TO_R99
6
INACTIVITY(HS to FACH)
6
RANAP_CAUSE_NORMAL DECREASE_ACTIVITY_UL
5 1
UL_SOFT_CONGESTION
1
31.4 % of RCS drops are happened at UL RSSI< -95 dBm There were also very high number of HS cell change executions failed during
• L1(DL) • 43% L3 • I , , L3 . L3 (18/15 ) L1 (9). B L1 L3 18 . E I , E . I E
these L1 procedure timeouts
DCH ( 2) NC.
L3 timer keeping context in RNC too long Measurement report 1a
• E H 1 : 6165(C 98B, EI: 13B)
•
Successful SHO Failed Cell change
2.5 B (1) NC , EL 2 • NC 2 10
• NC Channel switching from EUL 2ms to 10 ms Change of serving cell
3 (18 )
L3 timer keeping context in RNC too long • M , F C 1(22B, 104B), C 2(23 B, 104B) 3( 23 B, 104 B). • N C: 254 ( 7B, 88B) E 1. E • B DL
rlFailureT rlFai lureT expir expired ed
hsdschRcLost expired
Serving cell and change failed dropped call
. . DL L L E(N313 ) • F I I C (LF: (LF: 1 ) I C C • I
DL DL : 9 NC. I : C . I C DL . B NC L3 (18 ) . • F L3 (18 ), NC H .
( ), ), • C : 1 ( , C 1 3 .. . . H , , 2 .
CAUSE 4: UNSPECIFIED DROPS
Unspecified H ( C : 9.4%) 1% 1% 1% 1%
1%
0% 0%
7%
EEEDEE ENED NDEINENALFAILE 2 CEDEIME NALICABLE EENALCLENC DINGFAILE NDEINENALFAILE 6
88%
GENEALFAILEIN CEDE IBAAL2EFAILE EME LGICALEINME AGE
• I 88% NC :
• , . These types of drop behavior confirms that there are several instants where UE came earlier in idle mode(by UE’s L1/L2) timer expiry and initiate new interactive interactiv e sessions before RNC terminate the old session. RLC timers and parameter values yet to be received from vendor. Needs to check UE’s as well as RNC’s L2 settings if they are aligned with L1 and L3 settings and if there is scope for improvement. Also Also since call reestablishme reestablishment nt for PS is not available in Ericsson W13B and UE’s L1 timer: n313(1s)+ n313(1s)+ T313(5s), possibility of UE coming in idle mode early because of poor DL is higher.
RNC s L1 timer: timer: noutsync noutsync (100ms) + rlFalureT(1s) rlFalureT(1s) +hsDchRcLost(9s)
(KEYCS FINDINGS) DCR
CS Call Drop Reasons Distribution per each RNC RNC DLGGN01 CS Call Drop Reasons Distribution D 6% D
D IA 6%
D 0%
3%
RNC DLGGN02 CS Call Drop Reasons Distribution D D2% IA
D 5%
7% D 8%
D 18%
D 19% D 67%
RNC DLOKL01 CS Call Drop Reasons Distribution Drop call soft handover 3% Drop call IRAT 9% Drop call uplink sync 17%
Drop call missing nbr 4% Drop call congestio n 0% Drop call other 67%
D 59%
About 58 % to 63 % of of call drops are not not defined (other) (other) across all 4 RNCs About 17 % to 25 % of call drops are accounted for Uplink Sync across all 4 RNCs RNC DLVKPO1 has 12 % of call drops due to IRAT RNC DLGGN01 DLGGN01 has 9 % of call drops due to Soft handover & missing neighbor RNC DLGGN02 DLGGN02 has 8 % of call drops due to call congestion
RNC DLVKP01 CS Call Drop Reasons Distribution
D D 2% IA 12%
D 25%
D 2% D 1%
D 58%
orst st cel celll – mi miss ssin ing g neig neighb hbor ors s Wor (DLGGN01) C DLF3B
N01 missing nbrs
A A % D D % D D % D D % D D IA IA % D D % D D 2.193977444
0%
28%
10%
10%
2%
50%
There were 4 CS call drop captured during the recording period for DLFP3BX due to missing neighbors. There were 4 different PSCs detected for each drop.
orst st ce cell ll – mi miss ssin ing g Wor neighbors(DLOKL01)
OKL01 missing neighbors
•
•
There Ther e was was not not an any y cal calll dro drop p cap captu ture red d in GPEH for this cell because there was not any missing neighbor detected at greater 12 dB EcIo relative to serving servthan ing cell. Buthigher there there were 20 samples of two missing neighbors recoreded at greater than 6dB relative to serving cell.Average EcIo of these samp samples les were were 7.5 dB higher than serving cell and average RSCP of these missing neighbors were 10 dB higher than serving cell. Cell Ce ll id id iden enti tifi fied ed fo forr the these se mis issi sing ng neighbors through site database is coming more than 3.5 km. So need to to check the overshooting of these cells. Also needs to check whether some new cells of the PSC: 83 and 35 came
nearby to serving cell: 41600
Drop due to conge congestio stionn- Top cell: cell: DLGGN02
3.7 ADCH . F HDA ( HDA ) ADCH . 3 B CICH (34 B). ADCH signaling
Recommendation: set minPwrMax for these 2 cells: 0 dB
. C , H H AB . C . H : 4 GB H AB : 13000
CS drops due to IRA IRAT T failures • NC: DLK01 DLK01 DLKL01 IA IA . DLK01 DLK01 12% DLKL01 9% IA IA . • A IA(3G 2G), E 2G 3G 5 (NC : ). ). NC . • I GM (: (: 74B)
• IA IA NC . • • E / 3G 2G (5) • N 2G IA IA H DL (5) • C BCCH/BIC BCCH/BIC (. BC BCCH/BIC E
*A IA H GEH 3 C(DGG01,DK01,DK01)
CS drops due (abnormal call:to1)IRAT MR: 3a(ncc: 6, bcc:5, bcch: 7)
• E DL M 3 2G
Resource reservation in 2G cell
IRAT HO command
5 sec
• BC 2G C. • NC A ACA E IA H. NC 5.
RNC didn’t receive any insync insy nc frame from from UE. This means UE probably left the 3G and tried to synchronize 2G
RNC didn’t receive Handover complete from the BSC and UE didn’t return to old 3G channel within 5 sec and call dropped
• IA IA H 3G 5 NC .
CS drops due to IRAT(abnormal call: 2) MR : 3a Resource reservation in 2G cell
Measurement reports 3a
Serving cell EcIo: 19dB, RSCP: -94 dBm 5 sec Measurement reports 3a
Dropped call
• E DL M 3 2G • BC 2G C. • NC A ACA E IA H. NC 5. • B E IA H DL M : 3 M • E 3G 5 5 , NC H 2G BC,
Recommendation •
Co BCCH BCCH/BS /BSIC IC needs needs to be be check checked ed for the cel cells ls havi having ng IRA IRAT T fail failures ures at very good 2G RSSI
•
Since IRA Since IRAT T HO thre threshol shold d for CS+P CS+PS(0/ S(0/0) 0) -17d -17dB/-1 B/-112dB 12dBm, m, poss possibi ibilit lity y of decoding failure of IRAT IRAT HO command from the network is higher. IRAT IRAT HO threshold for CS+ PS(0/0) can be aligned with CS only . Probabi Pro babilit lity y of of succe successf ssful ul IRA IRAT T hand handove overr in in poor poor cov coverag erage e can be improved by increasing trelocoverall to 7 sec, if UE took longer time to decode IRAT IRAT HO command from fr om the network
•
CS callCS & MRAB drop distribution GPEH C CA & AB D DIIBI DIIBI CAED CAED F GEH C C 12.2 + I 64H 3%
C C. (12.212.2) + I. (16H) 21%
C C 12.2 + I 00 42%
C C 12.2 34%
Majority of MRAB call drops captured from GPEH are from CS +PS 0/0 66% of CS drops drops in network network is happening happening in MultiRAB MultiRAB calls. Out Out of 66% MultiRAB MultiRAB drops drops,, 42 %drops are captured in CS+PS(0/0).
MRAB analysis
MRAB drops: drops: Below are are the major major causes of MRAB drops: drops: • • • •
Cha hann nnel el Sw Swit itch chin ing g: 26.6 % Proc Pr oced edur ure e Tim imeo eout ut(L (L1) 1):: 20 20.1 .1 % Unspe Un specifi cified( ed(ma major jority ity of CS nor norma mall rele release ase in hig high h UL UL RSSI scenario) : 17.3 % IRAT tre treloc locov overa erall ll (5s (5sec) ec) expiry: 12 %
MRAB-Unspecified drops • M : 1.) FACH C+(0/0) . . DLGGN01 L I
2.) A H / MAB. 80 % DLKL01 DLK01 . .
L1 Procedure timeouts • UTRAN RL fail failure ure detect detection ion is contr controlle olled d by the Radi Radio o Connec Connection tion Supe Supervis rvision ion (RCS) and Radio Link Set (RLS) Supervision functions: after receiving nOutSyncInd nOutSync Ind consecutiv consecutive e frames, frames, UTRAN UTRAN starts starts timer rlFailureT . If rlFailureT expires,tothe RLSWhen function the connection as out-of-sync and report RL Failure RNC. RL considers Failure is received, the SRNC starts timer dchRcLostT and if this timer expires the connection is considered lost by RCS. The total time for UTRAN to detect RL Failure: nOutSyncInd nOutSyncInd ** 10msec + rlFailureT rlFailureT + + dchRcLostT • The These se dr drop ops s are are due due to to UL/ UL/DL DL co cove vera rage ge iss issue ue • The These se dro drops ps are peg pegged ged due to L1( L1(dch dchRcL RcLost ostT) T) timeo timeout ut • It has also been obse observed rved lik like e in in HS DCR RCS drop drops s , after L1 time timerr expi expiry ry network is not releasing the call till L3 timer expiry of 18 sec. This is leading to extended call sessions maintained for the UEs in the network keeping Iu resources, UE context etc. It may also impact paging for voice because UE seems to be in idle while network will page via DCH (paging type2) as its session is alive in the RNC. These L3 procedures are identified as Active set update, Radio bearer reconfiguratio reconfiguration(multiRAB), n(multiRAB), HS cell change(multiRAB).
L3 timer keeping context in RNC too long
• : 20B C 112B 1. .
• B
18 sec
A . (313 ) • C ( : 1 ) • C : 10 C. : C . B C 3 (18 ) .
• 3 (18 ), C . RNC has released this call with cause: L1 timer expiry(from its internal event). But from signaling, we can see that RNS didn’t release the call after L1 expiry but L3 expiry. Need to check behavior with vendor. Since these types of HS drops are higher in number, it might impact paging type 2 success rate.
CS &FINDINGS) PS CSSR (KEY
Admission Vs After Admission Failures Count of After Admission
Count of Admission
Failures
Failures
DLGGN01
19334
1734
DLGGN02
9125
2836
DLOKL01
19910
6909
DLVKP01
18748
1626
RNC
After admission failures are distributed in all cells across the RNCs but majorityfailures of Admission are contributed by few cells in each RNC.
ADMISSION FAILURES
Admission Failures contribution
Cell- WPRO WPROTCX TCX (Admis (Admission sion failure failure due to to lack lack of DL CE) C I
C
C
DG G01
C AB 1959.45
•
786.55
•
A F
A
•
40.14
• A
DL CE
numHsCodeResources: This parameter reserves the resource ids available for HSDPA in DUW board. Each resource id provides• 30 HS-PDSCH codes per site • 128 CEs for DL R99 including ADCH Each DUW 20 board provides 5 resource ids out of which 1 resource id is reserved for EUL Out of remaining 4 resource ids, numHsCodeResources reserve the resource id for HS which provides codes for HS. Remaining resource ids will be available for R99 which provides CEs for DL R99 including ADCH. Since 1 sector site has 16 HS PDSCH codes, so numHsCodeResource numHsCodeR esources s for single sector site should should not be set greater than 1. If value is set greater than 1 then there will be shortage of DL CEs in the DL
Cell: WPROTCX • Cu Curr rren entt sit site e is ha hav vin ing go onl nly yo one ne se sect ctor or • All Fai Failur lures es are happe happeni ning ng becaus because e of short shortag age e of of DL DL C CE E • availableRbsChannelElementsDownlink parameter availableRbsChannelElementsDownlink parameter is showing value 83. This means that only 83 DL CEs are available from Hardware limit of 384 DL CEs. • Wr Wron ong g pa para rame mete terr setti tting of numHsCodeResources numHsCodeResources is is found in the cell. Current setting of numHsCodeResources numHsCodeResources is is 3. Recommended value of numHsCodeResources numHsCodeResources is is 1 for single sector site. • Since Since sit site e is hav having ing DUW DUW 20 board board hav having ing 5 rreso esour urce ce ids. ids. 1 Resource id is reserved for EUL. 3 resource ids are reserved for HS(numHsCodeResources HS( numHsCodeResources is is 3), So only 1 resource id is left for
Recommendation: Set numHsCodeResources:1
R99 service which can provide only 128 CEs in the DL. After subtracting ADCH reservation CEs, only 83 DL CEs are available which is too less for a site.
Cell- CENT CENTRAX RAX and CENTRAY(Admi CENTRAY(Admission ssion failure failure due to lack of DL Power) C I
CEA
C
DGG02
C AB
3.7 ADCH . F HDA ( HDA ) ADCH . 3 B CICH (34 B). . C , H H AB . C .
5402.45
A F 402.18
A 7.44
A
H : 4 GB H AB : 13000 ADCH signaling
Recommendation: Recommenda tion: set minPwrMax minPwrMax for these 2 cells: cells: 0 dB
AFTER ADMISSION FAILURES
After admission failures: RRC(GPEH analysis) PS and CS RRC Failures •
•
• •
Majo Majori rity ty of RRC RRC and and RA RAB B fail failur ures es were were in th the e “Failure after admission” category. Since there are not any specific counters are available to distinguish among these failures, analysis of these has been done on GPEH data. RRC: RRC: Unsp Unspec ecif ifie ied d fail failur ures es ar are e po poin inti ting ng towards network issue in which without waiting for the response from the UE, network is releasing the call after successful admission. RRC: RRC: Pro Proce cedu dure re Tim imeo eout uts s are are pure purely ly coverage related failures Alll Iub Al Iub setu setup p fail failur ures es in DLVK DLVKP0 P01 1 an and d DLOKL01 are contributed by 1 site in each RNC.
After admission cause
DLVKP0 DLGGN DLGGN DLOKL0 1 01 02 1
Unspecified
655
1037
380
786
Procedure Timeout
204
457
147
199
IUB_AAL2_SETUP_FA ILURE
45
0
0
30
RRC: Unspecified Call 1 •
The These typ type of of fa fail ilur ure es are very high in the network and these are not coverage dependent. RNC is releasing the calls itself without waiting the response of RRC_Connection_Setup from UE.
Call 2 •
Need to check with Ericsson regarding these failures
UL RSSI: -98 dBm and DL EcIo: -13dB are also very good.
L2 –RLC timeout •
•
RNC in init itia iatted the RAB procedure by sending Radio Bearer Setup to UE but RBS Complete message is not received from the UE. UL RSSI at the time of failure was: -82 dBm RNC tried maximum retransmission before declaring RLC timeout and RAB setup was failed
CS-- L1 Tim ime eout RCS L3 timer keeping context alive despite L1 timeout
•
RNC in init itiiated the RAB procedure by sending Radio Bearer Setup to UE and started L3 timer of 18sec but RBS Complete message is not received from the UE.
•
L 1 su sugetting perv pervis isio ion n sho shows tha thatt after nOutSync frames and after expiry hsdschRcLostT(9sec), RNC generated event which says RRC connection should be released. But RNC is not releasing the call at this time and releasing the call after L3 timer(18 sec).
THANK YOU
View more...
Comments
