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3G Radio KPI Optimization

Operator : Megafone

Country : Russia

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Optimization Area Overview

The entire optimization region is divided

into 6 cluster.

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Major Issues Observed:

1. Active HS-DSCH Throughput.

2. PS NRT RAB SR.

3. RRC access failures due to overshooting

4. AC issues with shortage of UL DCH.

5. CE Shortage

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Active HS-DSCH Throughput ImprovementOptimisation has been carried out to improve the performance of ActiveHS-DSCH Throughput improvement in the network.The following parameter modifications has been implemented:

Considerable improvement observed in Throughput during post analysis.

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Throughput Improvement: (RNC LEVEL)

Parameterimplementation

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PS NRT RAB SRPerformance of CSSR PS NRT RAB has been observed to be below thethreshold.It was concluded that the reason for the fails is due to RNC.

ICSU Logs with triggering condition “RAB_STP_FAIL_PS_DATA_INTERA” wascollected using Fishing Macro. We noticed that there was 4 RNC internal fails.

NRMPRB returned a nack for the GTPu tunnel request, as the request here wasto create DCH 0/0.

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PS NRT RAB SRNRM matches the IU IP address with configured IP address for that IU id. HereNRM has not found the IP address received for IU branch from IU object pointerwhich received from rak_modify_param_s message in iu_items.

NRM sents IP based subnet id as 0, when there are no GTPU units (EIPUs areused for GTP tunnels) or IP addresses are configured wrongly in GTPU (or IPoAchannels in GTPU are not in working state).In this network, we are using EIPU. This implies that this IP address has not beenconfigured for IU branch.

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PS NRT RAB SRThe specified IP is the SGSN U-Plane IP received in RANAP RAB AssignmentRequest. There are more than 1 IPs used, thus corresponding IPs should beconfigured in RNC and IU Object

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PS NRT RAB SR

After defining the correct IP address in the SGSN, the CSSR PS NRT has beenimproved.

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RRC Access FailuresRRC access failures has been observed in few sites. PRACH distributionsamples shows that the site is overshooting. Physical optimisation has beenrecommended for those sites and the KPI shows improvement.

PRE – PRACH Distribution

POST – PRACH Distribution

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RRC Access Failures

Radio FR and overshooting were reduced after physical optimization .

Physicaloptimisation done

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UL DCH failure rate

Variations has been observed in HSDPA SR for few sites in the network.The

root cause for the variation is due to UL DCH fails.The following parameter modifications has been implemented in such sites.

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Parameter modification done.

Post analysis shows that theUL DCH failure rate reducedeven though there has beenincrease in the HS-DSCHselections.

UL DCH failure rate

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CE shortage

RRC setup failures due to BTS has been observed in some of the sites in theoptimisaion area.This was because of the shortage of CE in the WBTS.

The KPI improved after increasing the CE in the WBTS.

CE added

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Tools Used in 3G Optimization

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Multi-Vendor Neighbor Audit – ENAPS Tool:

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Multi-Vendor Parameter Audit – Excel Tool:

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Traffic Forecast Tool:

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Thanks