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Radio Radio Network Network
OptimizationOptimization
中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn
Radio Optimization procedure
Concept of radio optimization Evaluation of network Common procedure of
optimization Parameter adjustment Common questions
Let’s Begin!
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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
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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
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Focus on
Capacity
Coverage
Quality
中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn
Radio Optimization procedure
Concept of radio optimization
Evaluation of network
Common procedure of optimization
Parameter adjustment
Common questions
Let’s Begin!
中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn
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
中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn
Radio Optimization procedure
Concept of radio optimizationEvaluation of networkCommon procedure of optimizationParameter adjustmentCommon questions
Let’s Begin!
中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn
Common procedure of optimization
Network data collection
Optimization report
Make optimization plan
Analyze traffic data
Collect DT data
Integrated analysis
Evaluate OMC&DT
中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn
Radio Optimization procedure
Concept of radio optimization
Evaluation of network
Common procedure of optimization
Parameter adjustment
Common questions
Let’s Begin!
中兴通讯学院 www.univ.zte.com.cwww.univ.zte.com.cnn
Adjust radio parameters
• Radio engineering parameters optimization• Radio resource parameters optimization
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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
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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
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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
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Collection of Collection of performance dataperformance data
The performance data got from OMCR
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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
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CQT Test
• The special place• Indoor test
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Feedback from the subscribers
The time ; The place ; The problem description ; The solution ; The contact of the describer ;
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A_Interface Data
The handover data of each cell ;
The information of location update ;
The information of call drop ; The traffic ;
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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
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Radio Optimization procedure
Concept of radio optimization
Evaluation of network
Common procedure of optimization
Parameter adjustment
Common questions
Let’s Begin!
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Common questions
• Coverage• Interference• Congestion• Handover• Call drop
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•BTS Output
•The loss of ant_feeder System
•The antenna type
•The engineering parameters : Azimuth 、 Down tilt
•Path Loss
Coverage
• Factor of coverage:
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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 ?
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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
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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
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The interference problems
1. Noise2. Call Drop3. Low Handover Success Rate 4. Unsuccessful Paging information
increase
The Problems brought by the interference
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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
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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
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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
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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 。
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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
LAC
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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
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Call drop
1. Field intensity ;2. interference ;3. Wrong parameters
The reason of call drop
1. RLT timer; Important parameter related to call drop
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