05) Radio Network Optimization

transcript

中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn

Radio Radio Network Network

OptimizationOptimization

Radio Optimization procedure

Concept of radio optimization Evaluation of network Common procedure of

optimization Parameter adjustment Common questions

Let’s Begin!

Concept of optimization

• To work out various network problems after the the network put into service through different technical method to keep the system running in a good state.

• Adjust different type of parameters MSS parametersTrunk circuit parametersRadio cell engineering parametersRadio resource parameters

Concept of optimization

• The following cases need to optimize the network

After the network was put into service or just finish expansion

The quality decrease greatly or too much customer complaints

When subscribers changed and affect the network quality significantly

Unexpected events decrease the network quality

Focus on

Capacity

Coverage

Quality

Concept of radio optimization

Evaluation of network

Common procedure of optimization

Parameter adjustment

Common questions

Let’s Begin!

Evaluation of Network Main radio network indices

Voice quality

Call drop rate

Congestion rate

Channel assign,allocate,seizure success rate

Coverage rate

Call success rate

Handover success rate

Concept of radio optimizationEvaluation of networkCommon procedure of optimizationParameter adjustmentCommon questions

Let’s Begin!

Network data collection

Optimization report

Make optimization plan

Analyze traffic data

Collect DT data

Integrated analysis

Evaluate OMC&DT

Common questions

Let’s Begin!

Adjust radio parameters

• Radio engineering parameters optimization• Radio resource parameters optimization

Radio engineering parameters

• Antenna para: Gain, Diversity mode, 3dB bandwidth

• Cell physical para: Height, Downtilt, Azimuth• Frequency plan adjustment: Frequency reuse mod

e, BCCH\TCH carrier frequency• Others: Propagation model,output power of BTS

Radio resource parameters

Network identification parameters:(Id)CGI,BSIC,LAI

System control parameters (Traffic)CBA.CBQ,RLT

Cell selection parameters(Access)C1,C2

Network function parameters(HF,DTX)LIMIT,INTAVE

Data Collection

•Data collection of current network

•Performance data and traffic from OMC-R

•Driving test data

•CQT:Test data in special place

•Feedback from the subscribers

•A-interface and A-bis interface signaling data

Collection of Collection of performance dataperformance data

The performance data got from OMCR

Driving test• DT test: the quality evaluation of the whole network;• Frequency scanning test: checking external

interference ;• CW test: propagation model correction test;• Cell reselection border test;• Cell handover border test;• Interference source confirmation;

MacrocellMacrocell

MicrocellMicrocell

CQT Test

• The special place• Indoor test

Feedback from the subscribers

The time ； The place ； The problem description ； The solution ； The contact of the describer ；

A_Interface Data

The handover data of each cell ；

The information of location update ；

The information of call drop ； The traffic ；

A-bis data

The main information you can get ： The whole signal procedure ； The uplink signal between MS and Network ； From the analysis of measure report ： the distributing

information of RXLEV 、 quality and number of measure report ； TA distributing information ； the information of balance between uplink and downlink ；

All of the signal information between BTS and BSC

Common questions

Let’s Begin!

Common questions

• Coverage• Interference• Congestion• Handover• Call drop

•BTS Output

•The loss of ant_feeder System

•The antenna type

•The engineering parameters ： Azimuth 、 Down tilt

•Path Loss

Coverage

• Factor of coverage:

The Reason of weak signal

1. BTS Output Power 。 2. The loss of Feeder_Antenna ， Alarm of VSWR ；3. Between the Directional antennas （ Outside of Horizontal 3dB Beam widt

h ） 4. The tilt of Omni_Antenna ； 5. The height of antenna ； 6. The antenna type ： For example :the gain is too small ； 7. The Path Loss is big ： Landform or forest ；8. The Mistake mount of antenna ；

WHY No signal ？

1. Phenomenon ： The coverage area of one cell is divided into two or more parts.

2. Reason ： The coverage is overshooting.

3. Result ： bring call drops if the some neighbor relations are not defined. frequent handover ； The congestion because of the big coverage ； The island area often have interferences ；

4. Solution ： Reduce the coverage,adjust the down tilt of the cell etc.

CELL A CELL B

ISLAND

Lonely Island

1. Some area covered by two or more cells is needed ： The area can provide coverage area continuously and handover well 。

2. The Overlap Area is Suitable for 20%~30% to the whole coverage area. If the overlap coverage area is big, the error handovers and call drops appear possibly.

3. Solution ：Adjust the Radio parameters ， plan coverage area for each cell careful

ly .Just like adjust the down tilt of antenna and output power of BTS 。

Coverage Overlap

The interference problems

1. Noise2. Call Drop3. Low Handover Success Rate 4. Unsuccessful Paging information

increase

The Problems brought by the interference

1. Increase the signal of BTS2. Reduce the coverage area of the main cell3. Good frequency Plan.4. Select the suitable antenna5. Adjust Down tilt of the interference cell 6. Adjust the height of antenna7. DPC,FH,DTX

Reduce the interference

Object： Increase the signal of main service cell ,reduce the signal strength of interference

Down tilt

Unsuitable big direct down tilt can bring big problems through the alternant coverage.

We suggest that we use direct and electro-down tilt together if the down tilt is too much.

Down tilt too much electro- down tiltNo down tilt

Frequency Planning

1. Solve the co-channel problem2. Solve the adjacent channel problem

The problems solved by Frequency optimization

1. The regular BCCH Reuse :at least 4*3 ， better 5*3.2. The continuous frequency used by BCCH only.3. BCCH not frequency hopping.

Main point of frequency optimization

TCH Congestion

1. MORE TRX ， Calculate by Erl_B 。 2. Reduce the coverage Area ； 3. Adjust the Selection Parameters for exam

ple :RxAM 。 4. Adjust the reselection Parameters for exam

ple: CRO 。5. Adjust the Handover Parameters for examp

le: UPLEV 。

SDCCH Congestion

1. Location update frequently 。 2. High traffic

The Reason of SDCCH Congestion

1. At the border of location2. Alone cell3. High traffic 。

SDCCH Congestion Cell Features

Increase the SDCCH channel number

The solution to solve SDCCH congestion

Adjacent cell

1. At MOST :32 ；2. Enough is OK ,At first,you can define many ,and reduce some ；3. If some adjacent cell is left, maybe cause the handover success rate is

low,and if the adjacent cell is important, call drop increase 。

The neighbor relation

1. The map；2. Drive test

Define the neighbor relation

Call drop

1. Field intensity ；2. interference ；3. Wrong parameters

The reason of call drop

1. RLT timer； Important parameter related to call drop

05) Radio Network Optimization

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