Optimization Cases

[usama0795]

I think this forum LACs different optimization cases encounterd during day-to-day optimization......kindly follow the format if you have any issues related to any vendor would be really helpful and do share graphical stats as it looks good....

Vendor: ********
Issue: Increase in Intra cell Ho Losses
Investigation Outcome: intra_cell_ho stats analysis shows that intra_cell_equip_fail dropped to zero same day when intra_cell_ho_lostms increased for the problematic sites. Where as intra_cell_equip_fail remained same at rest of the sites of the BSC.It seems that value of bssmap_t10 was set higher then assign_successful for the effected sites before. While when brought to normal resulted into the drop of intra_cell_equip_fail and increase in intra_cell_ho_lostms issue. The bssmap_t10 should be set to a lower value than the assign_successful timer, otherwise the SSM could terminate the assignment before the RRSM has time to establish on the channel. Further if bssmap_t10 > assign_successful then INTRA_CELL_HO_LOST_MS will be converted to INTRA_CELL_EQUIP_FAIL (INTRA_CELL_LOST_MS is pegged upon t10 expiry). Which is why when the bssmap_t10 value got normal the actual value of intra_cell_ho_lostms started pegging/appearing. In addition value of parameter hr_intracell_ho_allowed was changed from 2 to 1

**hr_intracell_ho_allowed = When the value of mentioned parameter is 2 half rate intra cell quality HOs are enabled but to Full Rate only / When the value of mentioned parameter is 1 half rate intra cell quality HOs are disabled and inter cell HO occurs when quality is degraded.


28596

[usama0795]

Vendor: Huawei
Issue: TBF Assignment Success Rate for EDGE fluctuates frequently ranging from 97% to 20% and impacting cluster level stats.
Investigation Outcome: As per trace information collected for the effected cell degradation corresponds to a single TLLI (highlighted below in the snapshot), issue is being caused by a single abnormal mobile , it's capacity doesn't match Class 10 which it submits to BSS, so it can't occupy the assign channel properly, and re-apply new EDGE Uplink channel.
Solution: IMSI was blocked from Core end.

2860728608

[usama0795]

Vendor: NSN
Issue: High Drop Call Rate on one VSAT Site.
Investigation Outcome: High TCH_TR_Fail (Number of Transactions that are ended due to Transcoder Failure) on the site. BER Trace was on higher side due to VSAT media but indicated no issue with Hardware. Alarm analysis showed Alarm: BTS AND TC UNSYNCHRONIZATION CLEAR CALLS ON ABIS INTERFACE with supplemenatray infomation idicating PCM No XX is problemetic.
Solution: Check the transmission between the BTS and the BSC (and transcoder). Check other active alarms concerning the BTS and the BSC (and transcoder) transmission or transcoder plug-in units. Correct the faults causing the alarms. External PCM Circuit : XX / Site : YY / TRX : ZZ.

286092861128610

[usama0795]

Vendor: ********
Issue: Degraded Incoming Handover Success Rate (IHSR) of a site
Investigation Outcome: No handware issue on the site Path Balance/BER/FER/Losses no change in trend only degradation in IHSR. Neighbor statistics + BCCH/BSIC analysis showed neighboring site persisting with same BCCH and BSIC.
Solution: Change BCCH of neighboring cell.


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[justdream]

Vendor: Huawei
Issue: TBF Assignment Success Rate for EDGE fluctuates frequently ranging from 97% to 20% and impacting cluster level stats.
Investigation Outcome: As per trace information collected for the effected cell degradation corresponds to a single TLLI (highlighted below in the snapshot), issue is being caused by a single abnormal mobile , it's capacity doesn't match Class 10 which it submits to BSS, so it can't occupy the assign channel properly, and re-apply new EDGE Uplink channel.
Solution: IMSI was blocked from Core end.



Dear Usama0795, which tool you have used to get above trace?

[usama0795]

Hi JustDream this i got from the Trace Files from LMT BSC6000....

[justdream]

Hi JustDream this i got from the Trace Files from LMT BSC6000....
Do you have tool to analyze (not only read) Trace files?

[khatib86]

Dear Osama,

your explanation is very good, please if you have more share it

[oswe]

Vendor: Huawei
Issue: Throughput limited in some sites to a lower-than-configured value
Investigation Outcome: during general checkings Ive found some sites where I couldnt explain why the IuB throughput was limited (see graph) to a value LOWER than configured.
asked many guys from transport network they say "nothing is wrong".

Solution: one transport engineer noted that after re-configuring the site from 4E1s to 2E1s, the MUX´s configuration was not properly reduced to 2E1s. So many months later they reduce the config in the MUX to 2E1s and voilla!!! it seems it was stucked... who knows... now we have the 3.8Mbps expected in IuB.

[miles12]

Hi Usama...
Greeting!!!

In my huawei network, intracell ho failure increase...
What can be the reason and how can i analysis (counter wise analysis) this in huawei netw...

BR
MS
:)

[usama0795]

Hi Miles, kindly find attached counters for Huawei filter all counters having term Intra in counter description and take out % of each failure....disable Intra Cell HO Allowed where necessary if cells Handover success rate is good or check if HO failures are high from DCS to GSM or vice versa make it hard to go from either DCS to GSM or GSM to DCS whichever the case.....and u can check level threshold from AMR FR to AMR HR etc.....

[usama0795]

nah i used the tool to take out the trace and made sense of the messages sent myself doesnt have anything for analysis....maybe someother Huawei expert on the forum can help out as when I used to work with Huawei there was this chinese guy who had this trace analysis tool which used for reference many In-Built traces for multiple Failures and Succesful calls with hundereds of scenario and compared to the trace which u uploaded and pin pointed the error....kept on asking him for that tool but didnt give it to me.....

[usama0795]

Vendor: Huawei
Issue: UL TBF ASR degraded to zero
Investigation Outcome: PDCH equipped on the cell appear to be stuck as no new TBF establishment request is entertained with PDCH utilization increased to 100%.After soft reset PDCH equipped on the site appear to be faulty state re-mapping of PDCH yielded no result. 100% UL TBF Congestion GPRS on the cell.
Solution: Hard reset to the cell and verify E1 patching as high number of Out-of-Sync frames/Empty TRAU frames persisting on the cell.

28692

[usama0795]

Vendor: Huawei
Issue: High DCR and Low CSSR
Investigation Outcome: Severely degraded Uplink Quality for TRX 9 with severe occurrence of LAPD Protocol Error.
Solution: Kindly verify environmental conditions for the cell / remove all the active alarms / VSWR Check / Tx-Rx Calibrations / RSL Stability.

286932869428695

[usama0795]

Vendor: Huawei
Issue: High DCR and Poor Intra_cell_ho_succs_rate
Investigation Outcome: Severely degraded Uplink Quality and dowlink quality of 4 of the 6 TRX equipped on the site. Severly degraded path balance of the cells.
Solution: Kindly verify environmental conditions for the cell / remove all the active alarms / VSWR Check / Tx-Rx Calibrations.

28786

[usama0795]

Vendor: ********
Issue: Degraded MSC Assignment Attempt Rate degradaing Call Setup Success Rate
Investigation Outcome: Degradation is common for all cells in the BSC. Issues is not with availability of CICs since 120 extra CIC available and no MMS is OOS. From MSC side sending Assignment_Request in response to connection_requests from BSS has decreased. Further analysis showed MTL Tx and Rx utilization seem imbalanced.
Solution: Lock and unlock all the MTLs at the same time from BSS and MSS.

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