Network Monitoring and Optimization Rajendra Radio Network Design [email protected] 02-03 September 2004 Network Optimization
Nov 21, 2014
Network Monitoring and Optimization
Rajendra
Radio Network Design
02-03 September 2004 Network Optimization
1. RF Optimization2. Network KPIs Overview3. Optimization Flow4. Tems Investigation 4.15. Drive Test Measurement and Analysis6. Optimization Expert (RNO)7. Reporting
Agenda
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RF OPTIMIZATION
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RF Optimization
What is it ..?the fine-tuning of all system parameters and antenna configurations to attainoptimum quality in the built network.
How to achieve..?By carrying out drive tests and other RF measurements to determine optimal settings for system parameters whilst meeting network specification
What the Output’s are ..?• Report containing the final parameter setting• History of changes• Final site configuration data along with graphical plot showing the actual measurement report
RF OPTIMIZATION
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Optimization Tasks include :
1. Reviewing any site and network design object set2. Discussing the routes that will be using for performing drive test3. Determining the setting default network parameter4. Identifying the neighboring of each cell5. Reviewing the frequency planning6. Completing site audit to ensure that all RF equipment has been correctly
installed and located7. Executing test to verify the correct operation of all air interface parameter8. Carriout baseline drive test9. Analyse and identify problem from drive test data10. Investigate and analyse each problem area ( interference and cell coverage)
Note : Every change should be test individually and noted to ensure there is no degradation on the surrounding network
Network KPI’s Overview
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Input for the RF Optimization :
1. Key Performance Statistic such as Dropped call, Handover failure and Blocking
2. Customer Complain
1. Accessibility Random Access ( > 99.6% Good)SDCCH Drop ( < 0.8 % Good)TCH Assignment ( > 99.8% Good)SDCCH Congestion TCH Congestion
2. RetainabilityCall Drop ( < 1.3 % Good)Call Minutes Per Call Drop ( > 106.9 Second Good)
3. IntegrityHandover ( > 97.2% Good)
Network KPI’s Overview
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Optimization Flow
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Daily Brief KPIanalysis
Is TCHAssignment
<x%?
Perform TCHAssignment
analysis
Is CellCongestion
>x%?Yes Yes
Is DroppedCalls >x%
No
Yes
End
Is SDCCH/TCHcongestion
<x%
Is HO <x%Goto HOanalysis
GotoCongestion
analysis
No
No
Yes
Yes
GotoCongestion
analysis
Has Siteperformanceimproved?
Clear off TroubleTickets
Yes
No
Some processhere to catch the
rest
No
PerformDropped Call
analysis
No
Network KPI’s Overview
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Drop Call Problem
Cause :
1. Coverage2. Handover3. Interference4. Uplink and Downlink Unbalance cause by antenna and feeder system5. Transmission Failure6. Unreasonable Parameter setting7. Equipment Failure
Network KPI’s Overview
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Dropped Calls on TCHDropped Calls on TCH
Bad LocatingParameterSetting?
Is PowerRegulation
used properly?
Is the PowerBalanced?
Is DTXused?
Is FrequencyHopping Used?
Check Output Power
Check Dropped call reason
BadQuality?
Low SignalStrength?
B
TimingAdvance?
SuddenDrop?
Other?
No
Yes
Yes
Yes
Yes
No
No
No
No
No
Correct ParameterSetting
Correct powerregulation
parameters
Adjust outputpower
Introduce DTX
ActivateFrequencyHopping
PerformInterference
Analysis
Perform lowSignal
Strengthanalysis
Check sitelocation &
TALIM
Yes
No
No
No
No
Yes
Yes
Yes
End
B
Check Lost Handover
Most droppedcalls duringhandover?
Check site position
Dragon site?
Check BTS Error log
HW fault?
Check link quality& synchronisation
Transmissionfault?
Best serverexists?
Check MS problem
Perform drive test
Perform CTR recordings
Perform site survey
Check antenna installation
Performhandoveranalysis
Remove site orchange frequency
Swap & repair HW
Perform linkinvestigation
Add site
No
No
No
No
Yes
No
Yes
Yes
Yes
Yes
Check reason forsudden loss
Investigatepossible Hardware
fault
Drop Call Flow Analysis
Network KPI’s Overview
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Handover Problem
Cause :
1. Improper antenna installation2. Interference 3. CO BCCH and CO BSIC4. Unreasonable parameter setting5. Congestion on the destination cell6. Equipment failure ( TRX` Performance Deterioration)7. Uplink and Downlink Unbalance
Network KPI’s Overview
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Handover Analysis
Handover analysis
Check successfulhandovers per Cell
Is success <x%?
Check handoveractivity
More than yhandoverspeformed?
Check site location,site to site distance,
co-sited?
Priority Cell?high traffic
Checkhandover flow
Unevenflow?
Difference inperformance in out-
and incoming?
Focus on baddirection
A
A
External?Start Inter BSC/MSC analysis
High ratio ofurgency
handovers?
High ratio of losthandovers?
High ratio ofreversion?
End
No
Yes
No
No
No
Yes
Yes
Yes
No
Yes
No
Yes
No
Yes
NoNo
No
InterferenceAnalysis
Does up or down linkinterference exist?
Yes
Does co-channel exist?
Handover relatedparameters such as
relations, missing relations,BA-List, BSIC, hystersis,offsets, etc set correctly?
Ping PongHandovers?
Correct parametersettings
Ping ponganalysis
No
Does cell havehardware problem?
Is Target Cellcongested?
Fix faulty hardware
Congestionanalysis
No
Yes
Yes
Yes
Yes
No
ChangeFrequency
Yes
Select worstrelation
Handover Flow Analysis
Tems Investigation 4.1
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Key Feature in Tems Investigation
1. C/I and C/A Measurement2. In Building Positioning3. Identification Interference source 4. Channel Verification Tool for testing traffic channel5. Frequency Scanning6. Decoding and Modification of layer 3 Signaling7. Cell Reselection and handover behavior8. Logging and Export9. Summary of Logfile in .HTML
Tems Investigation 4.1
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Workspace and Worksheets
Toolbars
Status Bar
Menu bar
Navigator
Interference MeasurementCarrier to Interference (C/I) Measurement
- In Idle and dedicated mode- In hopping and non hopping networks- Per used TS
Carrier to Adjacent (C/A)- In Idle and dedicated mode- On frequency hopping with 2 MS’s
Tems Investigation 4.1
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The C/I parameter enables the identification offrequency exposed to particular high level interference
Tems Investigation 4.1
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FER, RXQUAL and DTX Measurement
RxQual is a value between 0-7 where each value corresponds to an estimated number of bit error in number of burts
RxQual Bit Error Rate, BER
0 BER < 0.2 %
1 0.2% < BER < 0.4%
2 0.4%< BER < 0.8%
3 0.8%< BER < 1.6%
4 1.6%< BER < 3.2%
5 3.2%< BER < 6.4%
6 6.4%< BER <12.8%
7 12.8%< BER
Tems Investigation 4.1
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DTX DL Rate indicate in percent how many TCH frames that were not sent to the mobile station during the last SACCH multi frameDTX DL Rate varies from 0 to 96% ( never reach 100%)
DTX DL Rate (%)=(number of silent blocks/total number of blocks)*100
*Total number of blocks = 24
DTX DL Rate information element can be used to investigate “silent call” problem in the network.
Tems Investigation 4.1
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FULL and SUB Values
The FULL values are based on upon all frames on the SACCH multiframe whether they have been transmitted from the base station or not.
The SUB values are based on the mandatory frames on the SACCH multiframe i.e frames that always must be transmitted
If DTX DL is used in the network, the SUB set must be usedIf DTX DL is not used in the network , the FULL values are preferred
Tems Investigation 4.1
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Frame Erasure Rate (FER)
FER rate is a value between 0 and 100% and is calculated and presented in TEMS once each SACCH Multiframe (Synchronous with the RxQual values) and calculated on the TCH and SACCH Blocks
FER FULL% = (Number of blocks with incorrect CRC/25)*100
Total number of blocks on a full rate TCH channel is 24 TCH +1SACCH =25 FER SUB % = (Number of blocks with incorrect CRC/2 )*100
Total number of blocks on a full rate TCH channel is 2 TCH +1 SACCH =2
Tems Investigation 4.1
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BER/Timeslot ( %)
BER parameter gives the bit error rate for each used timeslot that calculated by summing the number of bit errors for each of the 24 blocks included in the BER the dividing the sum by the total number of bits in the 24 blocks.
BER % = (total number of bits error in 24 blocks/total number of bits in 24 blocks) * 100
Tems Investigation 4.1
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Tems Investigation 4.1
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Quality Identification
RxQual : transforming the bit error rate (BER) into a scale from 0 to 7 (see GSM 05.08). Acceptable RxQual range is 0-3 ( basic measurement)RxQual : doesn’t reflect to speech quality
SQI : can produce unbiased prediction of the speech quality, independently of channel conditions
Computation of SQI involves :-Bit Error Rate-Frame Error Rate-Data on handover events-Statistic on distribution of these parameters
Tems Investigation 4.1
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Interference Identification
Co-Channel Interference is usually by far the most common type of interference encountered in a GSM network
SQI Level decreased suddenlyC/I Level decreased suddenlyRxQual increased until 6-7
Tems Investigation 4.1
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Interference Source Identification 1
Tems Investigation 4.1
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Interference Source Identification
Traditional Of Methods of tracing co-Channel Interference-Temporarily shutdown base station -Repeatedly modifying the frequency planning
Effect :-Disturb network traffic-Cause inconvenience to subscribers New feature in TEMS Investigation 4.1 offer a way to spot interferes -without resorting to such heavy handed and costly methods-Without any performance loss
Tems Investigation 4.1
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Interference Identification
HOW IT WORKS…?
Main task Interference identification :
-To determine the base station color code ( BCC) = TSC ( Training Sequence Code) that is found in the middle of GSM Burst.
-Do Interference Scan
-Knowing The BCC/TSC reduce the number of possible interferers by factor 8
-Many proposed cell as candidates can be rule out simply ( too far from disturbed cell, and topology features of the area).
Tems Investigation 4.1
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Interference Identification
Outcome of Interference Scan
Tems Investigation 4.1
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Interference Identification
Eliminating Remote Candidates
Tems Investigation 4.1
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Troubleshooting :• BCCH Scanning on the problem area• Replace interfered BCCH with low interference BCCH channel as temporary•Lock the interfered BCCH to get the interfered cell or do scanning on the interfered BCCH including with BSIC decoding
Display on the map :- Co-Channel - Adjacent Channel- Scan Channel including BSIC Scanning
Tems Investigation 4.1
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Interference Identification
Problem area with measurement statistic
• High RxQual• Low SQI• High BER• High Signal Strength
Tems Investigation 4.1
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Interference Source Identification 2
Co-Channel might come from : 12912
Tems Investigation 4.1
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Channel Verification* Allow to check the availability a set of traffic channel.
Tems Investigation 4.1
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Channel Verification Properties
Tems Investigation 4.1
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Improved Site Presentation on the map
- Show neighbor cells - Show serving cell - Show to neighbor lines
Tems Investigation 4.1
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Cell Definition File in *.cel format
Tems Investigation 4.1
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Frequency Scanning and Neighbor List Scanning
Tems Investigation 4.1
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CW ScanningAdjacent Scan Bar Chart
Tems Investigation 4.1
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Logfile Summary and Analysis
Tems Investigation 4.1
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Logfile Statistics
Standard Drive Test Report
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Table of Drive Test Report
1 Executive summary2 Test conditions2.1 Purpose of the drive test2.2 Site Data2.3 Drive route3 Test results3.1 Reference to attached plots3.2 Reference to attached listings of statistics collected during the drive test4 OSs Statistics4.1 Daily reports from NMC4.2 SRP reports5 Performance and optimisation summary6 action points6.1 Change Requests6.2 Other actions7 Conclusions8 References
RNO
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Radio Network Optimization
RNO is a collection of several radio network optimization applications in OSS
•FAS Frequency Allocation Support•FOXFrequency Optimization eXpert•NCSNeighbouring Cell Support•NOXNeighbouring cell list Optimization eXpert•MRRMeasurement Result Recording
RNO
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Radio Optimization Expert (RNO-MRR)
a tool for measuring the radio characteristics of the connections between MSs and the network. MRR records information on the radio characteristics of the dedicated channels and calculates statistics on the data recorded
•Supervision of the network performance •Troubleshooting of the network •Comparison of the network performance before and after a change is made to the network
RNO
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Radio Optimization Expert (RNO-FAS)
FAS is an optional feature that helps the operator achieve good frequency allocations and minimize the interference levels in the radio network with a minimum of effort.
RNO
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Radio Optimization Expert (RNO-FAS)
FAS is an optional feature that helps the operator achieve good frequency allocations and minimize the interference levels in the radio network with a minimum of effort. • To find frequencies in
order to add or expand a cell (frequency planning).
• To improve the cell plan and/or frequency plan due to capacity and/or quality problems (optimization).
• To supervise the interference level in a certain area (supervision).
• To verify improvement after a frequency change (verification).
RNO
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NCS (Neighbouring Cell Support) is a tool that helps users to specify adequate neighbouring cell relations for each cell in the radio network
•to find neighbouring cell relations to a new cell (network planning) •to find missing neighbouring cell relations in the active BA-List (network optimization) •to find neighbouring cell relations to be removed from the active BA-List (network optimizati on) • to evaluate neighbouring cell relations (network supervision).
Tems Investigation 4.1
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THE END
Tems Investigation 4.1
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