HO Handover Fails Poor Coverage

8/13/2019 HO Handover Fails Poor Coverage

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ASSIST SolutionThis 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 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

ProductFamily:

Radio Controllers

Product: BSC2

BSC2iBSC3iBSCEBSCiTCSMTCSM2 E/A

Description:Handover failsDuring a call, the mobile moves away from test BTS coverage. The call is released withoutperforming any handover.

Solution: 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 78Ext. BTS = frequency BCCH 86

Handover is a Intra-MSC HOtest BTS -> BSC(a) -> MSC(a) -> 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 10:08:18RADIO NETWORK CONFIGURATION IN BSC: E P B F T R C D-CHANNEL BUSY ADM OP R ET- BCCH/CBCH/ R E S O&M LINK HR FR

LAC CI HOP STA STATE FREQ T PCM ERACH X F U NAME ST /GP

===================== === ====== ==== == ==== =========== = = = ===== == === ===

BCF-128 TALK-FAMILY U WO 2 OM128 WO 30131 28001 BTS-128 U WO 0 0

BT28001 N 2

TRX-001 U WO 78 0 33 MBCCH+CBCH 2 TRX-002 L BL-USR 100 0 33 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 OFBTS-128 BT28001

ENABLE INTRA HO INTERF UL ...... Y ENABLE INTRA HO INTERF DL ...... YENABLE PWRBUDGET HANDOVER ...... Y ENABLE MS DISTANCE PROCESS ..... YENABLE SDCCH HANDOVER .......... N ENABLE UMBRELLA HANDOVER ....... NENABLE FAST AVE CALL SETUP ..... N ENABLE FAST AVE PC ............ . NENABLE FAST AVE HO ............. N

MIN INT BETWEEN HO REQ ............. 05 s HO PERIOD UMBRELLA ....... 06MIN INT BETWEEN UNSUCC HO ATTEMPT .. 03 s HO PERIOD PBGT ........... 06

AMH TRAFFIC CONTROL MCN ........ N AMH TRAFFIC CONTROL IUO ........ NAMH TRHO PBGT MARGIN ........... N

AVERAGING WINDOW SIZE ADJ CELL ..... 06 NUMBER OF ZERO RESULTS ... 2ALL ADJACENT CELLS AVERAGED ........ N

HO AVERAGING LEV DL WINDOW SIZE ............ 10 WEIGHTING .... 2HO AVERAGING LEV UL WINDOW SIZE ............ 10 WEIGHTING .... 2HO AVERAGING QUAL DL WINDOW SIZE ............ 01 WEIGHTING .... 2HO AVERAGING QUAL UL WINDOW SIZE ............ 01 WEIGHTING .... 2

MS SPEED AVERAGING ............. 04

HO THRESHOLDS QUAL DL RX QUAL ...... 3.2% - 6.4% PX .. 04 NX .. 06HO THRESHOLDS QUAL UL RX QUAL ...... 3.2% - 6.4% PX .. 04 NX .. 06

HO THRESHOLDS LEV DL RX LEVEL ........... . -098 dBm PX .. 03 NX .. 04HO THRESHOLDS LEV UL RX LEVEL ........... . -098 dBm PX .. 03 NX .. 04HO THRESHOLDS LEV UL FOR RAPID FIELD DROP . -110 dBm PX .. 00 (DISABLED)ENABLE ENHANCED RAPID FIELD DROP ........... DIS (DISABLED)THRESHOLD DEEP DROPPING EDGE ............... 10 dB PX .. 02 NX .. 03DEEP DROPPING EDGE MONITORING WINDOW ....... 2MODIFIED AVERAGING WINDOW .............. .... 2MODIFIED NUMBER OF ZERO RESULTS ........... . 1ENHANCED RAPID FIELD DROP DURATION ......... 10 s

HO THRESHOLDS INTERFERENCE DL RX LEVEL ..... -090 dBm PX .. 03 NX .. 04HO THRESHOLDS INTERFERENCE UL RX LEVEL ..... -090 dBm PX .. 03 NX .. 04

andover fails>Poor coverage https://sharenet-ims.inside.nokiasiemensnetworks.com/livelink/livelink/fe...

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MS DISTANCE AVERAGING PARAM WINDOW SIZE ..... 20MS DISTANCE HO THRESHOLD PARAM MS RANGE MAX .... 63 PX .. 10 NX .. 16MS DISTANCE HO THRESHOLD EXT. CELL MAX ......... 63MS DISTANCE HO THRESHOLD EXT. CELL MIN ......... 02

SUPER REUSE ESTIMATION METHOD ........... .. NONE (METH. NOT USED IN THIS CELL)ENABLE INTER FRT HANDOVER .............. ... DIS (DISABLED)INTERFERING CELL AVERAGING WINDOW SIZE .... 10INTERFERING CELL NUMBER OF ZERO RESULTS ... 2ALL INTERFERING CELLS AVERAGED ............ NSUPER REUSE GOOD C/I THRESHOLD ............ 17 dB PX .. 08 NX .. 10SUPER REUSE BAD C/I THRESHOLD ............ 10 dB PX .. 02 NX .. 06MINIMUM BSIC DECODE TIME .................. 10ENABLE TCH ASS SUPER IUO ............. ..... 0MINIMUM INTERVAL BETWEEN UNSUCC IUO HO .... 20 sMINIMUM INTERVAL BETWEEN IUO HO REQ BQ .... 10 sSUPER REUSE GOOD THRESHOLD RX LEVEL ....... -080 dBm PX .. 08 NX .. 10SUPER REUSE BAD THRESHOLD RX LEVEL ........ -085 dBm PX .. 02 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 ......... 6MS SPEED DETECTION STATE ............. ..... 0

COMMAND EXECUTED

(3) Check if adjacent cells have been created correctly

ZEAO:;

DX 200 BSC(a) 2001-04-03 15:53:39ADJACENT CELL DATA

BTS-128 BT28001 HAS ADJACENT CELL :

BTS IS NOT DEFINED TO THIS BSS

LOCATION AREA CODE.....................(LAC)....30021CELL IDENTIFICATION....................(CI).....29602

NETWORK COLOUR CODE....................(NCC).... 6BACKGROUND NETWORK COLOUR CODE.........( BNCC)... -BTS COLOUR CODE......... .............. .(BCC).... 2

BACKGROUND BTS COLOUR CODE....... ......(BBCC) ... -FREQUENCY NUMBER OF BCCH...............(FREQ)... 86BACKGROUND 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 -65 ...... freq. 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 32 -99 32 (1st adjacent cell) xx xx xx xx (2nd adjacent cell) freq. Rx power

(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


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CLEAR CODE : 0B13H(from NED: RADIO INTERFACE FAILURE - Failure occurred in the radio or A-bisinterface. This usually happens when the mobile station is located in anarea of poor coverage.)

CLEAR INFO : AIF_SS 0001H 0312H(from NED: Detected by AIFPRB - 0001H : Re-establishm ent request waitingtimer 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 -65ext. BTS -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

CreatedDate:

2004-12-09T10:37:17Z

Modified by: Script User Database

ModifiedDate:

2004-12-09T10:37:18Z

Originalrelated(Electra)ticket Id:

BSC:1022

Geniusticket Id:

43548

Attachment1:

1022_trace.txt

©Nokia Siemens Networks 2007


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HO Handover Fails Poor Coverage

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