HO|Hando andove verr fails> ils>P Poor oor cove overag rage
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ASSIST Solution This document consist a generic solution or workaround for a technical problem or a question concerning Nokia Siemens Networks products. The information is to be used for troubleshooting and the decision to implement these instructions must must always be made with consideration. In most cases it is necessary to modify the instructions to correspond the current network environment and situation. If you don't fully understand the solution or are not sure how to implement the instructions, please ask help from the document creator or your local support center.
Title:
HO|Handover fails>Poor coverage
Status:
Active
Visibility:
Public
Product Family:
Radio Controllers
Product:
Description:
Solution:
BSC2 BSC2i BSC3i BSCE BSCi TCSM TCSM2 E/A Handover fails During a call, the mobile moves away from test BTS coverage. The call is released withoutperforming any handover.
DESCRIPTION OF THE ENVIRONMENT WHERE THE PROBLEM OCCOURRED. The mobile is moving within an indoor environment. The test BTS provide single room coverage, while an external BTS (on air) covers a larger cell.Within the building, mobiles are normaly served by external BTS. Test BTS is used only for testing pourposes. Test BTS = frequency BCCH 78 Ext. BTS = frequency BCCH 86 Handover is a Intra-MSC HO test BTS -> BSC(a BSC(a) ) -> MSC(a) -> MSC(b) MSC(b) -> BSC(b) ->
ext. BTS
TROUBLESHOOTING. (1) Check if BCF, BTS and TRXs on test BTS are working correctly. ZEEI:; DX 200 BSC(a) 2001-04-04 RADIO NETWORK CONFIGURATION IN BSC: F R
ADM OP LAC
CI
HOP STA STATE
FREQ
T
10:08:18
ET- BCCH/CBCH/ PCM ERACH
E P B T R C D-CHANNEL R E S O&M LINK X F U NAME
BUSY HR FR
ST
/GP
===================== === ====== ==== == ==== =========== = = = ===== == === ===
BCF-128 TALK-FAMILY 30131 28001 BTS-128 BT28001
U U
WO WO
U L
WO BL-USR
2 OM128 WO 0
N TRX-001 TRX-002
2 78 100
0 0
33 MBCCH+CBCH 33
2 2
COMMAND EXECUTED
(2) Check if the handover parameters are correct ZEHO:BTS=1&&248; DX 200
BSC(a)
2001-04-03
15:54:40
HANDOVER CONTROL PARAMETERS OF BTS-128 BT28001 ENABLE ENABLE ENABLE ENABLE ENABLE
INTRA HO INTERF UL ...... PWRBUDGET HANDOVER ...... SDCCH HANDOVER .......... FAST AVE CALL SETUP ..... FAST AVE HO .............
Y Y N N N
ENABLE ENABLE ENABLE ENABLE
MIN INT BETWEEN HO REQ ............. 05 s MIN INT BETWEEN UNSUCC HO ATTEMPT .. 03 s AMH TRAFFIC CONTROL MCN ........ N AMH TRHO PBGT MARGIN ........... N
AVERAGING AVERAGING AVERAGING AVERAGING
LEV LEV QUAL QUAL
DL UL DL UL
WINDOW WINDOW WINDOW WINDOW
SIZE SIZE SIZE SIZE
INTRA HO INTERF DL ...... MS DISTANCE PROCESS ..... UMBRELLA HANDOVER ....... FAST AVE PC ............ .
Y Y N N
HO PERIOD UMBRELLA ....... 06 HO PERIOD PBGT ........... 06
AMH TRAFFIC CONTROL IUO ........ N
AVERAGING WINDOW SIZE ADJ CELL ..... 06 ALL ADJACENT CELLS AVERAGED ........ N HO HO HO HO
NUMBER OF ZERO RESULTS ... 2
............ ............ ............ ............
10 10 01 01
WEIGHTING WEIGHTING WEIGHTING WEIGHTING
.... .... .... ....
2 2 2 2
MS SPEED AVERAGING ............. 04 HO THRESHOLDS QUAL DL HO THRESHOLDS QUAL UL
0
RX QUAL ...... 3.2% RX QUAL ...... 3.2% -
6.4% 6.4%
PX .. 04 PX .. 04
NX .. 06 NX .. 06
HO THRESHOLDS LEV DL RX LEVEL ........... . HO THRESHOLDS LEV UL RX LEVEL ........... . HO THRESHOLDS LEV UL FOR RAPID FIELD DROP . ENABLE ENHANCED RAPID FIELD DROP ........... THRESHOLD DEEP DROPPING EDGE ............... ............... DEEP DROPPING EDGE MONITORING WINDOW ....... MODIFIED AVERAGING WINDOW .............. .... MODIFIED NUMBER OF ZERO RESULTS ........... . ENHANCED RAPID FIELD DROP DURATION .........
-098 -098 -110 DIS 10 2 2 1 10
HO THRESHOLDS THRESHOLDS INTERFERENCE INTERFERENCE DL RX LEVEL LEVEL ..... HO THRESHOLDS THRESHOLDS INTERFERENCE INTERFERENCE UL RX LEVEL LEVEL .....
-090 dBm PX PX .. 03 -090 dBm PX PX .. 03
dBm PX .. 03 NX .. 04 dBm PX .. 03 NX .. 04 dBm PX .. 00 (DISABLED) (DISABLED) dB PX .. 02 NX .. 03
s NX .. 04 NX .. 04
HO|Handover fails>Poor coverage
MS MS MS MS
DISTANCE DISTANCE DISTANCE DISTANCE
https://sharenet-ims.inside.nokiasiemensnetworks.com/livelink/livelink/fe...
AVERAGING PARAM WINDOW SIZE ..... HO THRESHOLD PARAM MS RANGE MAX .... HO THRESHOLD EXT. CELL MAX ......... HO THRESHOLD EXT. CELL MIN .........
SUPER REUSE ESTIMATION METHOD ........... .. ENABLE INTER FRT HANDOVER .............. ... INTERFERING CELL AVERAGING WINDOW SIZE .... INTERFERING CELL NUMBER OF ZERO RESULTS ... ALL INTERFERING CELLS AVERAGED ............ SUPER REUSE GOOD C/I THRESHOLD ............ SUPER REUSE BAD C/I THRESHOLD ............ MINIMUM BSIC DECODE TIME .................. ENABLE TCH ASS SUPER IUO ............. ..... MINIMUM INTERVAL BETWEEN UNSUCC IUO HO .... MINIMUM INTERVAL BETWEEN IUO HO REQ BQ .... SUPER REUSE GOOD THRESHOLD RX LEVEL ....... SUPER REUSE BAD THRESHOLD RX LEVEL ........
NONE DIS 10 2 N 17 10 10 0 20 10 -080 -085
20 63 63 02
PX .. 10
NX .. 16
(METH. NOT USED IN THIS CELL) (DISABLED)
dB dB
s s dBm dBm
PX .. 08 PX .. 02
PX .. 08 PX .. 02
NX .. 10 NX .. 06
NX .. 10 NX .. 06
LOWER SPEED LIMIT .......... ............. .. 0 ( 0 km/h ) UPPER SPEED LIMIT .......... ............. .. 0 ( 0 km/h ) MS SPEED THRESHOLD PX ......... 3 MS SPEED THRESHOLD NX ......... MS SPEED DETECTION STATE ............. ..... 0
6
COMMAND EXECUTED
(3) Check if adjacent cells have been created correctly ZEAO:; DX 200 BSC(a) ADJACENT CELL DATA BTS-128 BT28001
2001-04-03
15:53:39
HAS ADJACENT CELL :
BTS IS NOT DEFINED TO THIS BSS LOCATION AREA CODE.....................(LAC)....30021 CELL IDENTIFICATION....................(CI).....29602 NETWORK COLOUR CODE....................(NCC).... 6 BACKGROUND NETWORK COLOUR CODE.........( BNCC)... BTS COLOUR CODE......... .............. .(BCC).... 2 BACKGROUND BTS COLOUR CODE....... ......(BBCC) ... FREQUENCY NUMBER OF BCCH...............(FREQ)... 86 BACKGROUND FREQUENCY NUMBER OF BCCH....(BFR EQ).. HO MARGIN PBGT......... .............. ..(PMRG).. 6 dB HO MARGIN LEV.......... .............. ..(LMRG).. 3 dB HO MARGIN QUAL......... .............. ..(QMRG).. 0 dB ENABLE HO MARGIN LEV QUAL..............(MRGS).. Y HO PRIORITY LEVEL...... .............. ..(PRI)... 3 HO LOAD FACTOR........ ............. ....(OF).... 0 RX LEV MIN CELL........................(SL)....-104 dBm HO LEVEL UMBRELLA......................(AUCL)..- 47 dBm MS TX PWR MAX CELL....... .............. (PMAX).. 35 dBm SYNCHRONIZ ED........... .............. ..(SYNC).. N TRHO TARGET LEVEL......................(TRHO).. N (NOT IN USE) ADJACENT CELL LAYER....................(ACL)... N (NOT IN USE) FAST MOVING THRESHOLD..................(FMT)... 0 (NOT IN USE) MS PWR OPT LEVEL.......................(POPT).. N (NO OPTIMIZATION) CELL TYPE..............................(CTY)... GSM CHAINED ADJACENT CELL...... ............( CHAIN). N HO TARGET AREA......... .............. ..(HOTA).. 0 DIRECTED RETRY THRESHOLD...............(DRT)...-100 dBm COMMAND EXECUTED
(4) Handover parameters are right and adjacent cell data merges with the external BTS data.
(5) Using NET MONITOR software tool on NOKIA mobile, check the frequency number of BCCH serving themobile (1st field, test page 01) ex:
78 freq.
-65 Rx power
......
(6) Using NET MONITOR software tool on NOKIA mobile, check if the neighbouring cells are heard bymobile (1st field, 1st row, test page 03 - and following rows) ex:
86 xx freq.
32 xx
-99 32 xx xx Rx power
(1st adjacent cell) (2nd adjacent cell)
(7) Adjacent cell is heard by mobile (freq. BCCH 86). It means that adjacent cell data is correct in BSC and mobile can measure adjacent cell coverage onthe Air interface.
(8) On the MSC(a) serving the BSC(a) serving the test BTS, set a trace of the mobile. ZMVT:MSISDN=(mobile
number):TYPE=ALL,REF=1;
(9) Perform a call from the mobile, then start moving away from test BTS, while trace is taken.
(10) Look to the trace in MSC(a), focusing on CALL FASE informations. (attached file TRACE.TXT)
(11) As the trace shows, the releasing of the call is due to
HO|Handover fails>Poor coverage
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CLEAR CODE : 0B13H (from NED: RADIO INTERFACE FAILURE - Failure occurred in the radio or A-bis interface. This usually happens when the mobile station is located in an area of poor coverage.) CLEAR INFO : AIF_SS 0001H 0312H (from NED: Detected by AIFPRB - 0001H : Re-establishm ent request waiting timer has expired (GSM 08.08 specification)
(11-a) This means that the handover is never initiated, the call is released before even to try tohands over to the adjacent cell. (11-b) The "Re-establishment request waiting timer" is used when the mobile goes out thecoverage to re-establish the call within that time before to release it.
(12) Check alarms on BSC(a), MSC(a), MSC(b) and BSC(b) with ZAHO; There are not any active alarms related to handover failures, wrong adjacent cell information andso on.
(13)Looking again to NET MONITOR software tool on NOKIA mobile, compare the test BTS Rx power tothe external BTS (adjacent cell) Rx power. test BTS ext. BTS
-65 -99
(14) The adjacent cell Rx power is very low. While the mobile is moving within a building, the external coverage maight became poor veryburstly.
RESULT OF THE ABOVE ANALYSIS The call is released because the mobile moves far from test BTS to an adjacent cell coverage area,where the coverage is too poor so the HO is even not initiated.
TESTING THE PROBLEM SOLVED Performing the same HO test in different days, it happens successful. It depends on poor coverage of the adjacent cell indoor the building.
1 How does the problem affect traffic? Circuit switched calls affected (LU,CS data,speech and HO) 2 What area of daily operations does the problem belong to? No effect on dailyoperations 3 What area of maintenance does the problem belong to? No maintenance activitiesaffected 4 What area of configuration management does the problem belong to? Radio networkconfiguration (A-bis) Created by:
RD Transfer
Created Date:
2004-12-09T10:37:17Z
Modified by: Script User Database Modified Date:
2004-12-09T10:37:18Z
Original related (Electra) ticket Id:
BSC:1022
Genius ticket Id:
43548
Attachment 1022_trace.txt 1: ©Nokia Siemens Networks 2007
