78140081-GSM-PPT

Performance Improvement of Operational GSM and GPRS Network

Aug 2010

• Introduction

• Network Architecture – GSM

• Logical Channels

• Call Process

• GSM Network KPIs

• Optimization Process

• Summary

2

Contents

INTRODUCTION

Mobile Telecommunication is one of the fastest growing & most demanding of all telecommunication technologies

Quality of a Mobile Telecommunication Network is measurement by its Key Performance Indicators (KPIs)

Increase in subscriber base Increase in number of Base stations Degradation of KPIs Degradation of NW Quality Customer dissatisfaction

Optimization of NW improves KPI Improves NW Quality Improves Customer Satisfaction

Different Optimization process for different KPIs

Network Architecture -GSM

GSM /GPRS BSS

BTS

BSC

BTS

BSC

PCU

SS7 SMS system

PSTNISDN

Internet,Intranet

MSC/VLR GMSC

HLR/AUC

SGSN

CG BG

GGSN

GPRS backbone

Other PLMN

A

Gb

Gi

Gp

C/D/Gs

Gr/Gs/Gd/Ge Gc

Ga

Abis

Um

MS

MS

OMC

LOGICAL CHANNELS

LOGICALCHANNELS

COMMONCHANNELS

DEDICATED CHANNELS

BROADCAST CHANNELS

COMMONCONTROLCHANNELS

DEDICATED CONTROL CHANNELS

TRAFFIC CHANNELS

FCCH BCCHSCH SDCCH SACCH FACCH

PCH AGCHRACH TCH/F TCH/EFRTCH/H

CALL PROCESS

MOBILE ORIGINATING CALL Request for Service Authentication Ciphering Equipment Validation Call Setup Handovers Call Release

MOBILE TERMINATING CALL PAGING Authentication Ciphering Equipment Validation Call Setup Handovers Call Release

GSM NETWORK KPIs

NETWORK KPIs SDCCH Assignment Success Rate SDCCH Completion Rate TCH Congestion TCH Assignment Success Handover Success Rate RX Quality DL TCH Completion Rate PAGING SUCCESS Rate

Each KPI is assigned a specific TARGET

Each BTS in the Network should achieve the TARGET for ALL the KPIs.

Corrective Actions to be taken if target not met.

SDCCH ASSIGNMENT SUCCESS RATE

SDCCH Channel is used To exchange signaling messages between BTS and Mobile Station Location Updation ( Registration of the Mobile Station in the Network) Send and Receive SMS

SDCCH Assignment Failures are mainly due to Congestion in SDCCH Channels (more subscribers competing for SDCCH

Channels) Alarm Conditions Frequent Registration near the Network borders

SDCCH COMPLETION RATE

After SDCCH Channel is successfully assigned by the Network, if signalling could not be completed between the Network and Mobile Station, then SDCCH drop occurs.

SDCCH Completion Failures are due to Poor RF Conditions

TCH CONGETION

After signaling is completed on the SDCCH Channel, when there are no free Traffic Channels, TCH Congestion occurs

TCH Congestion occurs Insufficient Traffic Channels Hardware alarm conditions

TCH ASSIGNMENT SUCCESS RATE

When the Traffic Channel is successfully assigned to the Mobile Station, TCH Assignment Success Rate is considered good.

Failure in assigning Traffic channel are due to Congestion Poor RF Conditions Alarm conditions

HANDOVER

Handover ensures call to continue when a mobile moves from one cell to another Handover makes the mobile station really roam Handovers are caused by

RxLev (Signal strength , uplink or downlink) RxQual (BER on data) O & M intervention Timing Advance Traffic or Load balancing

Handover Failures are caused by Poor RxLev (Signal strength , uplink or downlink) of Serving cell Improper Neighbour definition Poor RxQual (BER on data) Excessive congestion in target cell

RX_QUALITY

Quality of the ongoing call is measured by both Mobile Station and BTS.

Two Types Downlink RX Quality

Measured by Mobile Station Uplink RX Quality

Measured by BTS

RX Quality is affected by Poor frequency plan Poor Link Imbalance between BTS and MS Alarm conditions

TCH COMPLETION RATE

TCH Completion Rate is good when all calls are successfully completed and released by the subscriber.

Degradation of TCH Completion Rate are due to Sudden drop in RX Level of Serving cell Alarm conditions Fluctuation link between BSC and BTS

PAGING SUCCESS RATE

Network sends Paging Request to the Mobile Station when there is an Incoming Call Incoming SMS

When Mobile responds to the paging, then the Paging Request is SUCCESS. If not then it is a FAILURE

Paging Failures occurs due to Mobile Station in no coverage area Poor RF conditions leading to PAGING RESPONSE from MS not reaching the

Network Location of Mobile Station not know to the Network.

Impact of Traffic

Increase in Traffic affects the Performance of Network Short Term Growth

Sudden increase in traffic for short duration Festivals, New Year, Sports etc. Airports

Long Term Growth Gradual Increase in Subscriber base

OPTIMIZATION OF THE NW

Optimization is the process of improving the operation of the network To better utilize available infrastructure to provide the best possible quality of service

to Customers. Optimization process maximizes the efficiency and operability, of the existing installed

infrastructure. Optimization process integrates all infrastructures so that it operates seamlessly, it

configures the network, sets parameters so as to maximize the performance of the network.

An ideal Optimization process utilizes the minimum cost, time & resources to increase the efficiency of the network.

OPTIMIZATION TECHNIQUES

Optimization of the Network can be performed by Field Measurements

Drive test conducted by measuring the various KPIs across the NW Corrective actions based on the drive test

Analyzing statistical performance reports collected and taking corrective actions

Tuning different GSM parameters and improving the KPIs

Corrective actions based on the daily Alarm report

Enabling New Features to improve the Performance of the NW

SUMMARY

Increase in Subscriber base Increase in Traffic Increase in Congestion Degradation in KPI

To Improve Customer Satisfaction, Quality of the NW should be improved

Quality of NW depends on the KPIs

To maintain the KPIs Target, continuous monitoring and Optimization of the NW is essential. Tuning of different Network parameters Enabling different features Physical changes in the Antenna direction Corrective actions based on drive test Corrective actions based on Alarm report ,daily/weekly Network reports &

statistics

Thank you