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Transcript of Tools for Optimization GSM
8/14/2019 Tools for Optimization GSM
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Main Tools for Radio Network
Optimization GSMStatistic Handling Tool
OSS Recording Tool
Cell Data Design Tools
Field Measurement
Cell Planning Tool
Field Measurement Analysis
NWS (C); SPOS&Turle, Statics (I)
PMR, RNO package (C)
CNA (C); IPOS, BSSTool (I)
TEMS only!!!
TEMS Cellplanner (C); MCOM (I)
TEMS, MapInfo (C); MCOM (I)
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Model Tuning
Network Integration Test
Design & Rollout
Initial Tuning
Training
Operation & Improvement
Verification of Network Changes
Network Feature Optimization
Traditional Optimization
GPRS PerformanceVerification
Where does TEMSINVESTIGATION fit in
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Network Integration Test
When a site is integrated to BSC it is tested
• Call set up test• Timeslot test, forced call test
DESIGN & ROLLOUT PHASE
* TEMS Pocket is the preferred tool for Network Integration Test
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Initial Tuning
• Produce Coverage Plot
• Identify Coverage Holes• Identify Interference Area
• Optimize Neighbor Relations
• Find Hardware/Installation Problems
• Verify Parameter Setting
DESIGN & ROLLOUT PHASE
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GPRS Performance VerificationDESIGN & ROLLOUT PHASE• Application Performance Test
• WWW, FTP, WAP etc.• Mobility Test
• Cell Reselection, RA Update
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Traditional Optimization
• Investigate & Trouble-shooting Specific Areas
• Neighbor Relation Optimization• Coverage Issues
OPERATION & IMPROVEMENT
PHASE
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Network Feature Optimization
Parameter Settings:
• MS, BTS Power Control• HCS
• Idle Mode Behavior
• Locating Algorithm
• Frequency Hopping
• Intra-cell Handover
OPERATION & IMPROVEMENT
PHASE
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Verification of Network Changes
Did a certain change in the network give desired results?
• New coverage area?• Less interference?
• Better speech quality?
• Is handover possible?
OPERATION & IMPROVEMENT
PHASE
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?
Clear objective
Why should thismeasurement bedone
Preparations Collect Data Analyze
Check equipment
Get input files
Prepare route
External Antenna?
Save logfile
Take notes
Monitor
Find problemareas
Find solutions
What should bechanged?
Report
Give answerto objective
Changes inNetwork
TEMS Measurement & Analyzing
Process
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?
Clear objective
Why should thismeasurement bedone
Preparations
Check equipment
Get input files
Prepare route
External antenna?
Possible Objectives
• Coverage analysis• Trouble shooting• Scanning• Verify network changes
Measurement Will Depend onObjective
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Drive Test
• Large areas
• Specific areasWalk Test
Scanning
Performing Measurements withTEMS
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INPUT
Plots & Report
- Signal Strength
- Quality
Trouble Report /
Area for furtherinvestigation
Acceptance
New sites on air
Frequency Re-plan
BSC Re-homing
OUTPUTINPUT MEASUREMENT
Drive definedroute/area
Record Logfile
Long / Short calls
Assure no data loss
Drive Test
- Large area
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Manipulate
- Forced handover
- Lock on to Frequency
- Layer 3 messages
Analysis on-spot
Rectify & Verify on-spot
OUTPUTINPUT Measurement
Statistics
Customer complain
Large area drive testTrouble Report
Trouble Report
- Identified problem
- Solution
Drive Test
- Specific area
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Statistics
Customer complain
Micro cell planning
Indoor cell planning
OUTPUTINPUT Measurement
Add file marks (GPS)
Scanning
Trouble Report
Planning Report
- Antenna location
- Frequency
- HCS setting
Walk Test
* TEMS Light is the preferred tool for indoor cell planning
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Finding a newfrequency
Area Network
Scanning
OUTPUTINPUT Measurement
Received SS ondifferent ARFCNplot
New frequency
TEMS INV inscanning mode
Set ARFCN to scan
Scanning
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Analyzing Measurements
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Post-Processing TEMS LogfilesTEMS
Log files
StatisticsReport
GeographicalPresentation
Analysis
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Low Signal Strength• Interference• Handover• Call Setup Failure• Dropped Call•
Misc.
Problem Cases
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Signal Strength CaseINPUT
Large area DT
Specific area DT
Post-Processing
Analysis
TEMSLogfiles
• Identify areas with low signal strength e.g. SS < -100dBm (outdoor)
• Look at RxLev distribution (for acceptance)
• Compare with design level or new requirements
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• Shadowed Antenna
• Antenna Direction
•
Antenna Height / down tilt• Output Power
• Missing Neighbor Relation
•
Site Location• Faulty Hardware e.g. antenna & TMA
• Cell is down
Signal Strength Case –
Possible Reasons
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Shadowed Antenna Faulty Hardware
Height/down Tilt
Output Power
Visit site
Check antenna installation
Is there a better antennaposition at same site?
Add reduce down tilt?
Can antenna be placedlower or higher to givebetter coverage?
Check output power
ParametersBSPWRT - NON BCCH FREQ
BSPWRB - BCCH FREQ
Site Location
Possible to move site?
New antenna location atsame site? Is it necessaryto expand and build a newsite?
Check alarm & BTS Error
logVisit site
Signal Strength Case –
Analysis
Missing Neighbor
Is the call dragged?
Is low SS due to missingneighbor relations
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• Change parameter BSPWR , BSPWRT.
• Add neighbor relation.
• Physical changes:• Antenna direction
• Antenna height, tilt or position
• New site as last option.
Signal Strength Case –
Possible Solutions
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INPUT
Large area DT
Identify areas with Rxqual > 5
Identify source using Map and STS
New drive test around problem area?
Specific area DT
Post-Processing
Analysis
Interference Case
TEMSLogfiles
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From logfile & map :
What channel group suffer from interference? HOP or Non HOP?
• Check Current channel information in TEMS INV, hoppingchannel and hopping frequency.
Where does the interference come from? Cell name?
• Study map and logfile, look for co-channel or adjacent channelinterference.
Does the interference lead to lower SQI?
• Look at SQI measurement during high RxQual.
Use STS & RNO to assist analysis.
Interference Case –
Logfile analysis
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BCCH 590 BCCH 590
High site
BCCH 590
BCCH 590
BCCH 595
BCCH 600 CASE 1
CASE 2
Types of Interference • Co - Channel interference• Adjacent Interference
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• Poor frequency plan• No dominant cell --> low C/I ---> increased Rxqual• Frequency Hopping is off• External interference e.g. jammer
Example of high Rxqualdue to low Signal Strength
Interference Case – Possible Reasons
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Interference Case –
Possible solutions• Enable Frequency Hopping or add frequencies to
Hopping group.
• Enable BTS Power Control, MS power control andmake it less aggressive.
• Change frequency of interferer or interfered cell: – Possible to find new frequency by using TEMS
Scanning.
• Down tilt or change antenna of interferer.
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INPUT
Large area DT
Specific area DT
Post-Processing
Analysis
Look for:
Repeated handover (Ping Pong)
Repeated Intra-cell handover
Handover failure,
Unrealistic handover
Handover Case
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Repeated Handover (Ping Pong) - Examples
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Repeated Handover (Ping Pong)
- Possible Reason 1
Merry-go-round Handover, Offset >Hysterisis
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Repeated Handover (Ping Pong)
- Possible Reason 2 • Offset only in one direction e.g A-B for Inter
BSC relation
CELL A CELL B
A -> B OFFSET = -5dB
BSC 2BSC 1
No B -> A OFFSET
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No dominant Server
Repeated Handover (Ping Pong) –
Other Possible Reasons• No dominant server• Locating penalty settings
e.g. PSSBQ, PTIMBQ• Too small hysterisis
setting
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Antenna direction
Antenna Tilts
Plan for new site
Change Locating Parameter e.g.KHYST or LHYST
Repeated Handover (Ping Pong) – Possible Solutions
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Change Parameter, KHYST or LHYST
Hysterisis CELL A CELL B
HandoverFrom A to B
Repeated Handover (Ping Pong)
– Possible Solution
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Check layer 3 message
Handover command BSC correct?
Check reason for handover SS, RXQUAL
Target cell?
Handover Case –
Handover Reversion
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Duplicates of BSIC BCCH combinations in neighboring list
610_31 610_31
610_12
606_33
608_32
608_32
Serving cell Neighbor cell 1
Road
Neighbor cell 2
Handover command?
Handover Reversion
– Common Reason
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Uplink interference in target cell
Downlink interference at MS
Solutions
Interference Investigation
• MRR
• Statistics
• Scanning
Handover Reversion
– Other Reasons
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Possible Reasons
Wrong intra-cell handover settings
External Uplink Interference
Possible Solutions
Consider to change parameters:
• SSOFFSETUL, SSOFFSETDL
• QOFFSETUL, QOFFSETDL
A wrong setting of parameters will cause “unnecessary” IHO
Turn off Intra-cell Handover?
Handover Case – Repeated Intra-cell Handover
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Handover Case – Unrealistic Handover
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Possible Reasons
Wrong locating settings, in Serving or Target cell
Note: Could be on purpose e.g. Dual Band network with HCS
Solution
• Fix locating settings e.g. MSRXSUFF, BSRXSUFF
Unrealistic Handover – Reason & Solution
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Call Setup Failure
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Call Setup Failure –
Input Activities, Initial TuningActivities
Initial Tuning(Acceptance Test)
Troubleshooting
(Customercomplaint etc.)
Measurement Type•Large Area Drive Test•Short Call Sequences
Post-Processing Output
•Statistics Report•Geographical Reportshowing failure positions
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Call Setup Failure –
Input Activities, TroubleshootingInput Activities
Initial Tuning(Acceptance Test)
Troubleshooting
(Customercomplaint etc.)
Measurement Type•Small Area Drive Test
•Lock on problem cell’s BCCH •Force handover to the cell
Post-Processing Output
•Geographical Report (ifnecessary)
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Call Setup Failure Analysis- Initial Tuning Scenario
• Check the TEMS statistics report (Blocked Call)if there is Call Setup Failure.
• If yes, identify the problem cells and whichlogfile from geographical report.
•
Replay the logfile and jump to the Blocked Callevent.• Check if there is any successful call setup to the
problem cell.
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Call Setup Failure Analysis
- Initial Tuning Scenario cont.• Review the layer 3 messages to check at which
sequence the failure occur (random access,SDCCH, TCH assignment etc.).
• Check STS report on the problem cell. Is thereany traffic (SDCCH & TCH) in the cell, SDCCH& TCH seizures, congestion etc.
• Check fault report & CDD configuration.
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Call Setup Failure Analysis- Possible reasons with ranking
• Low Signal Strength• Interference• High Congestion on SDCCH• High Congestion on TCH• Transmission Fault• Faulty TRU/Hardware•
Central Processor Overload• Software File Congestion
• Cell is not defined in MSC .
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Call Setup Failure Analysis- Possible solutions
• Low signal strength Signal strength analysis.• Interference Interference analysis.• High Congestion on SDCCH:
Define more SDCCHs.Activate adaptive configuration of logical channel
feature and immediate assignment to TCH.• High Congestion on TCH:
Add capacity/Tune coverage array.
Activate assignment to worse cell.
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Failed Call Setup (Blocked Call)
Example
Multiple Channel Requests.
Successful Random Access after thethird try.
Congestion in SDCCH.
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Dropped Call Case
- Input• Statistics Report• Note from drive test.
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Dropped Call Case
- Analysis• From plot, identify which & where in logfile
the dropped call occurs.• In the log file, Jump the drop call event.• Check if there is a disrupt in the recording. If
yes could be a false drop due to TEMSmobile disconnection during recording!!!
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Dropped Call Case- Analysis (cont)
• Check the Radio environment just before drop: – If High Rxqual for a longer period of time and RLINKT expire
Interference problem. – If Low SS DL, SS DL < MS SENS ( -104dBm) low signal strength problem. – If TA > 63 too far from the cell.
• If DL radio is good, check the TX power. If there is MS powerdown regulation when the MS is close to the cell. If full power
suspect uplink interference or antenna, TMA problem.• Verify or isolate the problem using STS (Drop call and reasons).
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From TEMS Logfile
• Good Signal strength DL, Good Rxqual DL
• No call set up possible unless very close to site = high SS
• Dropped call when SS < approx. -75dBmAnalysis
• Since DL SS & Rxqual is good
Suspect UL problems e.g. external uplink interference
Conclusion
TMA power turned off
Miscellaneous Case 1
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From TEMS Logfile
• TCH has lower Signal strength than BCCH (Own BCCH included inBA-list )
• BTS power control = OFF
Miscellaneous Case 2
CHG0 B C C H
T C H
T C H
T C H
T C H
T C H
T C H
S D C C H \ 8
CHG1 T C H
T C H
T C H
T C H
T C H
T C H
T C H
T C H
Configuration/cellSEKTOR A
SEKTOR B
SEKTOR C
Conclusion
Antenna cable for TCH is swapped between sectors (CDU-A)
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From TEMS Logfile
• Fail to perform Call Setup
Analysis
• Check if any success call setup to the same cell No
• Check if handover is possible Yes
• Suspected wrong cell definition in MSC but Cell is properlydefined in MCS and LA
Conclusion
• Corrupted block in MSC
Miscellaneous Case 3
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GPRS Measurement Activities• GPRS Performance Prediction• GPRS Field Measurement
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GPRS Performance Prediction- Overview• GPRS RNAP Service uses TEMS Inv to predict
following performance: – Throughput – Cell Reselection & Routing Area Update
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GPRS Throughput Prediction• Perform Throughput prediction for each
coding scheme
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Cell Reselection Prediction• Dedicated mode drivetest
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Cell Reselection Prediction• BCCH Scanning• Simulate the cell update with different CRH
valuesCRH = 4 dB CRH = 8 dB
CRH # HO
0 365
2 246
4 211
6 178
8 156
10 147
12 138
14 130
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GPRS Field Measurement- Procedure
Set up files Cell definitionsPreparations
TEMS,IP Sniffers
…
Dig maps
Excel
Mapinfo
Graphical
presentation of route
Charts / Tables
Report
?GIMS
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GPRS Field Measurement- Application Performance Test
• Attached performance – Attached Time = Attach Complete msg – Attach
Request msg – Attach Success Rate
• PDP context activation performance – PDP context activation = Activate PDP Context
Accept msg – Activate PDP context request• Throughput on RLC level• Dela
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GPRS Application Test Tools
• General – Windump, Commview, Ethereal, Protocol Analyser
for Gb• PING
– MS DOS ping command• WWW
– IE, Netscape• FTP
– DOS FTP, WS_FTP, TEMS built in sequence
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GPRS Field Measurement- Mobility Performance
Investigation• Number of Cell Reselection & RA Update• TCP Outage Time•
Cell Reselection Failure
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Mobility test CRH = 4, CRO = 4
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Cell Reselection Sample ReportRouting Area Time Cell Target
CellReselection
timeResult Comments
BSC1 16:30:42 D0241A D0241C 2 s OK NABSC1 16:33:18 D0241B D0242A 2 s OK NABSC1 16:35:04 D0242A D0248C 21 s OK This cell reselection was
made to a cell located quitefar away (not the closest),
thus the RxLev was quitebad!BSC1 16:37:44 D0244B D0248C -- NA No throughput before or
after the cell reselection.This is due to that the cellDF0242B were halted by
some reason!BSC1 16:38:11 D0248C D0244B -- Failed The through put was never
resumed and the FTP
connection was aborted bythe ftp-server!
.