View
349
Download
49
Category
Preview:
DESCRIPTION
This document contains...Common procedure of network optimization Data collectionEvaluation of networkNetwork optimizationIntroduce of network optimization tools
Citation preview
2023年4月17日 1
GSM Radio Network Optimization(How To Optimization Network)
2023年4月17日 2
Wireless Network Optimization
Common procedure of network
optimization
Data collection
Evaluation of network
Network optimization
Introduce of network optimization tools
Let’s Begin!
2023年4月17日 3
Common Procedure of GSM Network Optimization
Data collection before optimization Network evaluation before
optimization Optimization scheme The design of optimization
implementation scheme Network evaluation after
optimization Light adjustment solution Evaluation before completion Experience communion
2023年4月17日 4
Data Collection
• Data collection of current network; • Performance data and traffic from OMC-R
;
• Driving test data; • Test data in special place; • Feedback from the subscribers ; • A interface and a-bis interface trace
data by signal analysis equipment ;• Usage of all kinds of data
2023年4月17日 5
Data Collection Of Current Network-1
• Parameters of BSC : e.g. Max Capacity 、 Phase2+ support ?etc.
• Parameters of BTS equipment and
Antenna_feeder : e.g. BTS Max power output, Max Site type 、 Loss of components of antenna and feeder etc.
• Special function of equipment : e.g. Distinctive
handover arithmetic.
• Wireless propagation Environment :Clutter ( Dense city 、 Common city 、 Sparse city 、 Suburb 、 Village );Landform ( platform 、 hill 、 Land and Waters etc. )。Electronic map is necessary sometimes ;
2023年4月17日 6
Data Collection Of Current Network-2
• Engineering Data : Longitude,latitude of sites 、 Altitude 、 Site type ( Capacity Configuration )、Antenna height 、 Parameters ( Gain 、、 Front_back ratio 、 Horizontal 3db Beam width 、 Vertical 3db Beam width 、 Electrical down tilt )、 Azimuth of Antenna 、 Length of feeder; TMA, Booster, Repeater used etc. ;
• Wireless Resource Parameters :( MCC+MNC+LAC+CI )、 BTS Output power 、 Frequency Hopping 、 BSIC 、 cell selection parameters 、 cell reselection parameters 、 handover parameters 、 BA 、 neighbor cell list 、 SDCCH Configuration 、 LAC and PCH 、 Location Update etc. ;
2023年4月17日 7
OMC-R Performance Data and Traffic Statistical
Data
Statistical data on busy time
Data kinds : SDCCH Assign 、 Allocate 、 seizure Success Rate and number of
success TCH Assign 、 Allocate 、 seizure Success Rate and number of
success TCH Handover Success Numbers and Success Rate ; TCH Handover Success Numbers and Success Rate Between
Dual-band; TCH Call Drop numbers and Drop rate TCH call drop reason (LAPD ,Radio Link etc.) SDCCH Congestion and traffic per subscriber TCH Congestion and traffic per subscriber Usable rate of TRX
2023年4月17日 8
Test_Object And Classification
• DT test: the quality evaluation of the whole network;• Frequency scanning test: checking internal or
external interference ;• CW test: propagation model correction test;• Cell reselection border test;• Cell handover border test;• Interference cause confirmation;
MacrocellMacrocell
MicrocellMicrocell
2023年4月17日 9
Test data_main content
Mode of mobile ( No Service , Idle , Dedicated );
The co-ordinate of site ( longitude and latitude );
RxLev , C1 、 C2 ; RxQual 、 FER 、 BER ,TA ( Only in Dedicated mode ) etc. ;
Decoding information and other information of neighbor cell ;
L3 ( Layer3 ) information ; From the layer 3 information ,the whole communication procedure can be traced ;
The reselection information
2023年4月17日 10
CQT Test
• The special place• Indoor test
2023年4月17日 11
Feedback from the subscribers
The time ;
The place ;
The problem description ;
The solution ;
The contact information of the subscriber ;
2023年4月17日 12
A_Interface Data
The handover data of each cell ;
The information of location update ;
The information of call drop ;
The traffic ;
2023年4月17日 13
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
2023年4月17日 14
The usage of all kinds of data
• Data collection of current network : the basic of network optimization;
• OMC-R performance data and traffic statistical data : the information shows the network quality as a whole ;
• Drive test : the information shows the network quality as a whole and the quality of particular place,but the result is random.
• Test in special place : to find the special problem and test in hot spot ;
• Feedback from the subscribers : complementary information and the final information ;
• Collection data from signal analysis equipment : you can get the information of the whole network and detail information , but lack of the information of downlink um interface and the location information ;
2023年4月17日 15
Evaluation of Network
• Evaluation of the whole network
• Finding reason of the particular problem
2023年4月17日 16
Evaluation of the whole network-1
The coverage rate of the whole network ;
The quality rate of the whole network ; The handover success rate of the whole
network SDCCH Assign 、 Allocate 、 seizure Success
Rate and number of success ; TCH 、 Assign 、 Allocate 、 seizure Success
Rate and number of success ; TCH Handover Success Number and Success
Rate ; TCH Handover Success Number and Success
Rate Between Dual-band TCH Call Drop number and Drop rate ; TCH call drop reason (LAPD ,Radio Link
etc.) ; SDCCH Congestion and traffic per
subscriber ; TCH Congestion and traffic per subscriber ; Useable rate of TRX ;
2023年4月17日 17
Evaluation of the whole network-2
• Difference indicators partition TCH Congestion : 0%~2% , 2%~5% , 5%~10% , 10%~20% , >20% ;
TCH Handover Success Rate :<60% , 60%~80% , 80%~90% , 90%~95% , >95% ;
TCH Drop Rate : <1% , 1%~2% , 2%~5% , 5%~10% , >10% ;
Traffic Per Channel : <0.2 , 0.2~0.3 , 0.3~0.4 , 0.4~0.5 , 0.5~0.6 , >0.6 ;
Through the statistical Method ,we can find the bad cell.
2023年4月17日 18
Special problem
Blind coverage area ; The area with bad quality ; The area which call drops often ; The reason of drop ; The cell handover success rate ; The TA Distributing ; The congestion of the cell ;
2023年4月17日 19
Network optimization
Rudder of network optimization
Common procedure of optimization
Wireless parameter optimization
Wireless resource parameter
optimization
2023年4月17日 20
Network Optimization—Rudder 1
One must analyses problem systematically in network optimization : Network is a system , Any partial adjustment must be thought in a whole network, negative effect must be thought over 。 Specially for the Frequency ,antenna(Wireless parameters) ;
Try your best to reduce the risk of Optimization :1. Avoid adjusting the network frequency continuously. 2. Using the software and equipment to simulate the
result of network optimization 3. Test in partial area 4. The good implementation procedure is
needed,Especially when the adjustment job lasts long time , the adjustment must be executed step by step.
5. Backup of the current network data6. Adjust in the lowest traffic time7. Explain to the Subscribers if necessary.
2023年4月17日 21
First the global problem ,next the particular problem :
The global Problems must be thought about first for example the congestion of the whole network.Next the problems in special place be thought about.
First the Wireless parameters ( Engineering Parameters,Next the wireless resource Parameters.
From the hot areas to others : The main problems to minor problems 。
Network Optimization—Common Rule 2
2023年4月17日 22
Common Procedure
Checking network engineering parameters : Antenna and feeder : the mistake connection of
feeder. The antenna type : The Engineering parameters of antenna : the
Height /Azimuth/down tilt of antenna.
The exact and detailed data is the base of network optimization 。
Checking Wireless resource parameters :CGI = MCC + MNC + LAI + CI 。BSIC AND Frequency resource 。
2023年4月17日 23
Common Procedure2
Confirming the probable range of the main problem according to the network evaluation report.
Finding the probable problems Analyze the main problems Give the solution and implementation
2023年4月17日 24
Wireless parameters
Types of wireless parameters : mainly ( RF ) Parameters , including the Parameters of antenna 、 height of antenna 、 azimuth 、 Down tilt 、 output power of BTS 、 Frequency 。 Others , the propagation Environments 。
The method of adjustment : Using the drive test software and network plan software can increase the accuracy of adjustment.
The main problems : The Coverage problems :The weak signal , the overshoot ,the overlay ; The interference: co-channel and adjacent channel interference ; The balance of traffic 。
2023年4月17日 25
•BTS output power
•The loss of feeder System
•The antenna type
•The engineering parameters : Azimuth 、 Down tilt
•Path Loss
Coverage
• Factors of coverage:
2023年4月17日 26
Coverage-Path Loss1
1. Height of antenna : according to 20lg(h /30) ,the higher antenna the less path loss 。
2. Clutter : The building is more ,the path loss is more 。3. The landform : plain,hill 。 4. Forest influence : About 10 db loss if the microwave propa
gates the forest in 20meters 。
Factors of Path
2023年4月17日 27
5. Water surface effect: The signal loss near water is very small and is close to the loss in free space ; the loss on water surface becomes larger farther away from the shore, for the phase difference between the direct wave and the wave reflected by the water surface is 180 degree, while the intensities are almost the same, hence the received signal is very weak.
6. Obstacle : Diffraction loss is caused by obstacles like hills and buildings. The diffraction loss can be calculated by principle of Huygens. Buildings near to the BS will cause larger shadows, while shadows caused by buildings far away are smaller because of the multi-path propagation effect.
7. Loss through buildings : It varies significantly with buildings of different cities, structures and materials. Usually, for 900MHz , the loss is 12~17dB (15dB is usually used) ; for 1800MHz , the loss is 18~20dB. The loss also varies with different floors of a building: Usually, the loss reduces about 2dB every floor up. In cold areas, the walls of builds are usually rather thick, and the loss for 900MHz is about 18~20dB.
8. Propagation distance : Within 1~20km , the propagation loss is 40dB/dec ; longer than 20km, the loss is about 50~60dB/dec.
Coverage-Path Loss2
2023年4月17日 28
Coverage-Antenna type
1. Gain2. Polarized : Vertical Polarized 、 Dual_
Polarized 。 3. Vertical and horizontal 3db Beam width 。 4. Front_Back Ratio5. Electrical Down tilt 。
The important Technology Parameters
60° (eg) Peak
Peak - 3dB
Peak - 3dB
3dB Beamwidth
2023年4月17日 29
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 width )
4. The tilt of Omni_Antenna ;
5. The height of antenna ;
6. The antenna type : For example :the gain is too low ;
7. The Path Loss is big : Landform or forest ;
8. The wrong type of antenna ;
WHY No signal ?
2023年4月17日 30
The common method to increase the signal strength
1. Increase Output Power 。
2. Reduce the Loss of antenna and feeder ;
3. Use the high gain antenna if possible ;
4. Change the azimuth of the antenna ;
5. Change the down tilt of the antenna.
6. Higher the Height of antenna ;
7. Add new site ;
8. Use Repeater;
2023年4月17日 31
indoor Coverage
• Macro cell
• Micro cell indoor
• Distributed system indoor
• Repeater and leaking line
2023年4月17日 32
Local Unit
Remote Unit
BTS
Splitter
Cable
Fiber
Cable
Antenna
Coverage indoorCoverage indoor
2023年4月17日 33
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
2023年4月17日 34
1. Some area covered by two or more cells is needed between two cell : 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 wireless parameters , plan coverage area
for each cell carefully .Just like adjust the down tilt of antenna and output power of BTS 。
Coverage Overlap
2023年4月17日 35
The interference problems
1. Noise2. Call Drop3. Low Handover Success Rate 4. Can’t Page information increase
The Problems brought by the interference
2023年4月17日 36
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 antenna
Reduce the interference
Object : Increase the signal of main service cell ,reduce the signal strength of interference
2023年4月17日 37
Antenna Down tilt
1. Think about the vertical beam width of antenna.
2. Calculate method : dh/tg(a-t/2) ,d: radius of cell covering , h the effective height of antenna , a the down tilt degree , t : the vertical beam width of antenna 。
3. The above formula , need 。
Calculate the down tilt degree of antenna
Height of antenna
Comparative height
Down tilt Distance to site
Cell No. Remark
37 57 10 1088 Wuzhi_A The geographic situation is uneven.
2023年4月17日 38
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 muchelectro- down tiltNo down tilt
2023年4月17日 39
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. BCCH use the continuous frequency used by BCCH
only.3. BCCH not frequency hopping.
Main point of frequency optimization
2023年4月17日 40
Wireless Resource Parameters Optimization
1. The content of wireless resource parameters :, Set at OMC_R ,About the parameters how to use wireless resource , e.g. CGI 、 CCCH combine method 、 PCH blocks 、 SDCCH 、 cell select parameters 、 cell reselect parameters 、 cell handover parameters 、 power control parameters etc..
2. How to adjust the wireless resource parameters :Analysis the performance data ,drive test data to get a resolved method.
3. the problems can be dealt with : capacity /call drop / others 。
2023年4月17日 41
TCH Congestion
1. MORE TRX , Calculate by Erl_B 。
2. Reduce the coverage Area ;
3. Adjust the Selection Parameters for example :RAM 。
4. Adjust the reselection Parameters for example: CRO 。
5. Adjust the Handover Parameters for example: UPLEV 。
6. Directional Retry ;
2023年4月17日 42
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
1. SDCCH/42. SDCCH/8
SDCCH Channel Method
Increase the SDCCH channel number
The solution to solve SDCCH congestion
LAC
2023年4月17日 43
Power control
Control TRX Max output power
Static power control
1. Reduce the noise of whole cell2. Reduce the power of MS
Dynamic Power Control
2023年4月17日 44
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
2023年4月17日 45
900 micro 1800 micro
GSM900 macro
GSM1800 macro
P-cell P-cell
Dual_Band Network
1. Provide a method for big capacity2. Use the same site location of GSM 900M , Cost is low ;
Strongpoint
1. Handover parameters 。2. Reselect parameters for traffic ;
Method of optimization
2023年4月17日 46
Tool Introduction
• Planning soft : planmastertm2.0 ;
• Drive test tools : TEMS , SAFCO , ANTPILOT ;
• Signal analysis equipment : ocean ;
GPS
2023年4月17日 47
PlanMasterTM2.0
1. Evaluate the radio environment by coverage analysis, co-channel interference analysis, and adjacent channel interference analysis. Simulate and analyze the adjustment effect of radio parameters for optimization.
2. Adopt e-map to make the most of the distribution information of landforms, natural features and buildings to determine the antenna down tilt more reliably.
3. Provide the set of adjacent cells of each cell after the radio parameters are adjusted.
4. Discover radio problems by analyzing the Drive test data.
Function
2023年4月17日 48
PlanMasterTM2.0
Overshooting coverage
BS8107A
2023年4月17日 49
PlanMasterTM2.0
Overlap coverage
BS8101A service area including
BS8105 、BS8102 、 BS810
8 etc.
2023年4月17日 50
PlanMasterTM2.0
Interference Interference analysis
2023年4月17日 51
PlanMasterTM2.0
Drive test analysis
Drive test analysis
2023年4月17日 52
PlanMasterTM2.0Drive test analysis
2023年4月17日 53
Ant
Received signal level
2023年4月17日 54
AntRxqual
2023年4月17日 55
Ant
Handover
2023年4月17日 56
Ant
Data replay
2023年4月17日 57
OCEAN
Data statistics at A interface-Failure rate of TCH channel
The statistics shows the rate of abnormally released TCH after the TCH assignment command is given, including reasons like TCH assignment failure and TCH call drop. The TCH failure rate showed in the figure is : 2.7%.
2023年4月17日 58
OCEAN
Data statistics at A interface-Failure rate of TCH connection
The statistics shows the rate of abnormally released TCH after the TCH connection is established, including reasons like TCH call drop. The TCH connection failure rate showed in the figure is :0.6%.
2023年4月17日 59
OCEAN
Data statistics at A port –Handover success rate
For most cells, the handover success rate is above 95%. This function reflects the handover success rate between any two cells
2023年4月17日 60
OCEAN
A-bis interface-Coverage across cells
For the Mechanical Factory District 3, there are some calls for TA 20 , while there is no call from TA 10 to TA 20, which is definitely an island phenomenon.
2023年4月17日 61
OCEAN
A-bis interface-Interference
Sometimes there is fairly strong interference for some time slots in the District 3 of the Police Hospital. It is because the remote areas like District 3 of the Police Hospital are covered by co-channel cells, or adjacent-channel cells of strong intensity, and when the handset uses channels of co-channel or adjacent-channel cells, it is inevitable for the handset signal to interfere some time slots of the cell.
2023年4月17日 62
OCEAN
A-bis interface-Interference
For the District 3 of the Police Hospital, RQ is larger than 2 when the received level is still 85dBm , which shows that there is significant interference in the cell.
2023年4月17日 63
OCEAN
Measure report analysis:
1. Fault phenomenon: the signal coverage of the BS in Qidu of Chizhou Unicom, Anhui, is comparatively weak, but there is no alarm.
2. Problem location: shut down the power control of uplinks and downlinks of this BS , and trace the measure reports of some call processes at the A-bis interface of the BS with the signaling analyzer. According to the principle of equal loss for uplinks and downlinks, use the following formula:
rvDownrvUpmsoutAnt PPPP Take the average from many measure reports to
determine whether the output power at the transmitting end of the antenna is normal
3. Result of data analysis: the output power is comparatively small.
4. Solution: Replace the power amplifier, and it can be settled.
2023年4月17日 64
Recommended