OMF000501 GSM RN Optimization ISSUE1.4

Course ContentsConcept of RN optimization KPI of radio network Work flow of RN optimization Parameter adjustment principles RN optimization tools introduction Common problems of RN optim

OMF000501 GSM RN Optimization ISSUE1.4

OMF000501 GSM RN Optimization ISSUE1.4

Wireless Training Department

Course Contents

Concept of RN optimization

KPI of radio network Work flow of RN optimization Parameter adjustment principles

RN optimization tools introduction Common problems of RN optimization

 Parameter and hardware adjustment

 Optimization result confirm and reporting

The purpose is increasing the utilization of network resources and solving the existing and potential problem on the network, identifying solutions for future network planning.

Concept of RN Optimization

Capacity

Coverage Quality

Optimize

Concept of RN Optimization

Due to the mobility of subscribers and complexity of radio wave propagation, most of network problems are caused by increasing subscribers and the changing environments

RN Optimization is a continuous process that is required as the network evolves

Concept of RN Optimization

In the following case, the network should be optimized

 New network or expansion on existing network

 The network quality decreased seriously and there are many complaints from subscribers

 An event occurs suddenly which affects the network performance seriously

 The number of subscribers increased and affects the network performance gradually

Concept of RN Optimization

TRAFFIC STATISTICS DRIVE TEST

CUSTOMER COMPLAINTS

OPTIMIZE

• Input for Optimization

Concept of RN optimization

KPI of radio network

Work flow of RN optimization Parameter adjustment principles

RN optimization tools introduction Common problems of RN optimization

Course Contents

KPI of Radio Network

 KPI (KEY PERFORMANCE INDICATORS)

 Indicates overall performance of network over a period of time

 Good way to monitor network trends and anticipate future problems

 Data obtained from drive test and traffic statistics

KPI of Radio Network

 Typical Radio Network KPI

BTS3

BTS4

BTS1

BTS2

KPI Parameter Source

Handover Success Rate OMC/Drive test

Call Setup success rate OMC/Drive test

Concept of RN optimization KPI of radio network

Work flow of RN optimization

Parameter adjustment principles

RN optimization tools introduction Common problems of RN optimization

Course Contents

Flow Chart of Network Optimization

Concept of RN optimization KPI of radio network

Work flow of RN optimization

Parameter adjustment principles

RN optimization tools introduction Common problems of RN optimization

Course Contents

Parameter Adjustment Principles

IDENTIFY PROBLEM

MAKE CHANGES

MONITOR EFFECT

MAKE CHANGES

• Parameter adjustment procedure

Parameter Adjustment Principles

Handover

Orientation

Antenna D-tilt Antenna

Height

Parameter Adjustment Principles

Adjustment of cell data parameters

 Adjust the cell parameters according to the features of actual radio channel traffic and signaling load The parameters are for cell select,cell reselect,call setup, handover etc, so as to improve the overall network performance and service quality to the end user

 Another basic principle of radio parameter adjustment is to maximize the current network resource, traffic sharing in the the whole network, increase the utilization of the equipment, so as to increase the profit-investment ratio

Parameter Adjustment Principles

According to the feature of problem to be solved, there are two types of radio parameter adjustment.

 Solve static problems: Analyze the average traffic and signaling flows of the network and solve the network problems that existed long time

 Solve traffic overload and congestion problems during some special period caused by special events

Concept of RN optimization KPI of radio network

Work flow of RN optimization Parameter adjustment principles

RN optimization tools introduction

Common problems of RN optimization

Course Contents

Driving Test Tools

The following are the frequently used drive test tools:

 TEMS and GIMS

 Ant Pilot and GSM 2000

 SAFCO Walkabout & SAFCO OPAS

 TS9951

 NEPTUNE

Driving Test Tools

Drive test Tool application

 Identify specific problems in the network

 Attend to customer complaints

 Perform network benchmarking with other operators

 Collect periodic network data for reporting

 Check coverage in new areas

Driving Test Tools

Example: Drive test data

Spectrum Analyzer

Spectrum analyzer

 The spectrum analyzer is mainly used to test the characteristics

of frequency, including spectrum, power of the adjacent channel, and frequency scanning etc

OMC Traffic Statistics

OMC Traffic Statistics

BSC performance measurement functions

TCH statistics

Drop measure

Low HO suc r

ate

HO measurement

Drop call measure

Rx_q & Rx_l

measure

statistics List of alarm

Concept of RN optimization KPI of radio network

Work flow of RN optimization Parameter adjustment principles

RN optimization tools introduction

Common problems of RN optimization Course Contents

Common Problems of RN Optimization

The three most important performance criterias are coverage, capacity quality they mainly correspond to the following netwo

Common Problems Coverage

Coverage

 Coverage hole

 Coverage hole may exist when coverage areas of two BTS

do not overlap or there are some big obstacles in the coverage area, this lead to no signal or very poor signal level

 Over shooting

 In the actual network, the high BTS antenna can propagate far away along a road and serve in area which it’s not suppose to serve in; which result in the "isolate Island" problem

Common Problems Coverage

Check and solve the coverage problem:

 Power control measurement Function ( Statistics)

 Receiving Level Measurement Function ( Statistics)

 Cell Measurement Function ( Statistics)

 Inter-cell Handover Measurement Function ( Statistics)

Common Problems Coverage

Check the coverage problem:

 Call Drop Measurement Function ( Statistics)

 Defined Adjacent Measurement Function (Statistics)

 Undefined Adjacent Measurement Function ( Statistics)

 Outgoing Inter Cell Handover Measurement Function ( Statistics)

 Rx Level data ( Drive test)

Common Problems Coverage

Coverage Problem Solution:

 Adjust Radio parameters

 Adjust antenna parameters

 Use booster, low loss combiner and tower mount amplifier

 Add new site (last resort)

Common Problems Capacity

Capacity

 TCH congestion

o radio resource available ) on OMC traffic statistics data, or compar

e the busy hour traffic of each cell with the calculated capacity in diff erent GoS to judge the situation of traffic congestion

 Traffic balance

S and MS.

Common Problems Interference

How to locate the interference

 Interference band in TCH Measurement Function (

Statistics)

 Receiving Level Measurement Function ( Statistics)

 Rx_Qual ( Drive test)

Common Problems Interference

How to locate the interference

 Ratio of handovers for uplink/downlink quality ( Statistics)

 Receiving Quality Measurement (Statistics)

 Call drop measurement function ( Statistics)

 Too many handover failure and reestablishment failures ( Statistics)

Common Problems Interference

Check and solve the interference problems

 Check the place with interference and conversation quality by drive test

 Use spectrum analyzer to find out the interference in the frequency band

 Enable frequency hopping, DTX and power control functions

 Check and eliminate equipment problems (if any)

Common Problems Interference

Means to decrease the interference :

 Increase the reuse distance between the co-frequency and adjacent frequencies

 Decrease the transmitting power of BTS

 Adjust the antenna height, azimuth, down-tilt

 Use the anti-interference technologies, such as frequency hopping, power control, DTX, and so on

Common Problems Handover

Common handover problems:

 Handover failure and handover delay lead to bad quality or call drop

 Frequent handover decreases the conversation quality and increases system signaling load

 Unreasonable proportion of outgoing inter-cell handover to incoming inter-cell handover results in imbalanced traffic

Common Problems Handover

Check and solve handover problems:

 Check the handover parameters (OMC)

 Inter-cell Handover Measurement Function (Statistics)

 Undefined Adjacent Cell Measurement Function (Statistics)

 Outgoing Inter Cell Handover Measurement Function (Statistics)

 Incoming Inter Cell Handover Measurement Function (Statistics)

 TCH Measurement Function (Statistics)

Common Problems Handover

Causes of abnormal handover and solutions:

 The outgoing inter cell handover threshold is too low

 The adjacent cells is congested

 There are undefined adjacent cells relationship

 The handover hysteresis and handover priority are not reasonable

 The handover statistics times N and P are not set reasonable

 In HCS network coexisting with other vendor’s cells, the external cell’

s parameters (such as LAC, CI and BCCH) must be corrected

Common Problems —Call Drop

 TCH call drop

 During the GSM network operation, call drop is the main reason the subscribers complain It usually refers to the call dropped after TCH channel seized or conversation connected, which can

be located via traffic statistics or drive test

 There are many call drop causes Such as poor signal strength, interference and improper parameters

 There are two important counters related call drop, radio link timeout (RLT downlink) and SACCH multi-frame number (uplink) sent in system information These two counters should

be set properly according to the traffic and coverage

Common Problems —Dual-band Network

Optimization for dual-band network

 Take the following special approaches when optimize the band network, most of the approaches are same as single-band network optimization:

the features of two network are basically same Parameters such as CRO can be set flexibly according to the traffic, thus can balance the traffic and avoid cell congestion.

area code, CRH and CRO should be set properly to avoid frequent location update.

Common Problems —Dual-band Network

Dedicate mode Idle mode Calling mode

Cell select Direct retry

Hand over

Cell reselect

• Dual band network optimization elements

Questions

 Please write down KPI for normal network

 Please write down the work flow for radio network optimization

 How to do for traffic balance