Post on 14-Nov-2014
description
transcript
Main Tools for Radio Network Optimization GSM
Statistic 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)
Radio Network Growth Flow
Model Tuning
Network Integration Test
Design & Rollout
Initial Tuning
Training
Operation & Improvement
Verification of Network Changes
Network Feature Optimization
Traditional Optimization
GPRS Performance Verification
Where does TEMS INVESTIGATION fit in
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
Initial Tuning
• Produce Coverage Plot
• Identify Coverage Holes
• Identify Interference Area
• Optimize Neighbor Relations
• Find Hardware/Installation Problems
• Verify Parameter Setting
DESIGN & ROLLOUT PHASE
GPRS Performance Verification
DESIGN & ROLLOUT PHASE
• Application Performance Test
• WWW, FTP, WAP etc.
• Mobility Test
• Cell Reselection, RA Update
Traditional Optimization
• Investigate & Trouble-shooting Specific Areas
• Neighbor Relation Optimization
• Coverage Issues
OPERATION & IMPROVEMENT PHASE
Network Feature Optimization
Parameter Settings:
• MS, BTS Power Control
• HCS
• Idle Mode Behavior
• Locating Algorithm
• Frequency Hopping
• Intra-cell Handover
OPERATION & IMPROVEMENT PHASE
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
?
Clear objective
Why should this measurement be done
Preparations Collect Data Analyze
Check equipment
Get input files
Prepare route
External Antenna?
Save logfile
Take notes
Monitor
Find problem areas
Find solutions
What should be changed?
Report
Give answer to objective
Changes in Network
TEMS Measurement & Analyzing Process
?
Clear objective
Why should this measurement be done
Preparations
Check equipment
Get input files
Prepare route
External antenna?
Possible Objectives
• Coverage analysis• Trouble shooting• Scanning• Verify network changes
Measurement Will Depend on Objective
Drive Test
• Large areas
• Specific areas
Walk Test
Scanning
Performing Measurements with TEMS
INPUT
Plots & Report
- Signal Strength
- Quality
Trouble Report /
Area for further investigation
Acceptance
New sites on air
Frequency Re-plan
BSC Re-homing
OUTPUTINPUT MEASUREMENT
Drive defined route/area
Record Logfile
Long / Short calls
Assure no data loss
Drive Test - Large area
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 test Trouble Report
Trouble Report
- Identified problem
- Solution
Drive Test- Specific area
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
Finding a new frequency
Area Network
Scanning
OUTPUTINPUT Measurement
Received SS on different ARFCN plot
New frequency
TEMS INV in scanning mode
Set ARFCN to scan
Scanning
Analyzing Measurements
Post-Processing TEMS Logfiles
TEMSLogfiles
Statistics Report
Geographical Presentation
Analysis
Low Signal Strength
• Interference
• Handover
• Call Setup Failure
• Dropped Call
• Misc.
Problem Cases
Signal Strength Case
INPUT
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
• 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
Shadowed Antenna Faulty Hardware
Height/down Tilt
Output Power
Visit site
Check antenna installation
Is there a better antenna position at same site?
Add reduce down tilt?
Can antenna be placed lower or higher to give better coverage?
Check output power
Parameters
BSPWRT - NON BCCH FREQ
BSPWRB - BCCH FREQ
Site Location
Possible to move site?
New antenna location at same site? Is it necessary to expand and build a new site?
Check alarm & BTS Error log
Visit site
Signal Strength Case – Analysis
Missing Neighbor
Is the call dragged?
Is low SS due to missing neighbor relations
• 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
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 TEMS
Logfiles
From logfile & map:
What channel group suffer from interference? HOP or Non HOP?
• Check Current channel information in TEMS INV, hopping channel and hopping frequency.
Where does the interference come from? Cell name?
• Study map and logfile, look for co-channel or adjacent channel interference.
Does the interference lead to lower SQI?
• Look at SQI measurement during high RxQual.
Use STS & RNO to assist analysis.
Interference Case – Logfile analysis
BCCH 590BCCH 590
High site
BCCH 590BCCH 590
BCCH 595
BCCH 600 CASE 1
CASE 2
Types of Interference• Co - Channel interference• Adjacent Interference
• Poor frequency plan• No dominant cell --> low C/I ---> increased Rxqual• Frequency Hopping is off• External interference e.g. jammer
Example of high Rxqual due to low Signal Strength
Interference Case – Possible Reasons
Interference Case – Possible solutions
• Enable Frequency Hopping or add frequencies to Hopping group.
• Enable BTS Power Control, MS power control and make 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.
• Redo frequency plan.
• Add new site.
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
Repeated Handover (Ping Pong)- Examples
Repeated Handover (Ping Pong) - Possible Reason 1
Merry-go-round Handover, Offset > Hysterisis
Repeated Handover (Ping Pong) - Possible Reason 2
• Offset only in one direction e.g A-B for Inter BSC relation
BSCBSC
CELL A CELL B
A -> B OFFSET = -5dB
BSC 2BSC 1
No B -> A OFFSET
No dominant Server
Repeated Handover (Ping Pong) – Other Possible Reasons
• No dominant server• Locating penalty settings
e.g. PSSBQ, PTIMBQ• Too small hysterisis
setting
Antenna direction
Antenna Tilts
Plan for new site
Change Locating Parameter e.g. KHYST or LHYST
Repeated Handover (Ping Pong) – Possible Solutions
Change Parameter, KHYST or LHYST
Hysterisis
CELL A CELL B
Handover From A to B
Repeated Handover (Ping Pong) – Possible Solution
Check layer 3 message
Handover command BSC correct?
Check reason for handover SS, RXQUAL
Target cell?
Handover Case – Handover Reversion
Duplicates of BSIC BCCH combinations in neighboring list
610_31610_31
610_12
606_33
608_32
608_32
Serving cell
Neighbor cell 1
Road
Neighbor cell 2
BSCHandover command?
Handover Reversion – Common Reason
Uplink interference in target cell
Downlink interference at MS
Solutions
Interference Investigation
• MRR
• Statistics
• Scanning
Handover Reversion – Other Reasons
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
Handover Case – Unrealistic Handover
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
Call Setup Failure
Call Setup Failure – Input Activities, Initial Tuning
Activities
Initial Tuning(Acceptance Test)
Troubleshooting (Customer
complaint etc.)
Measurement Type•Large Area Drive Test•Short Call Sequences
Post-Processing Output•Statistics Report•Geographical Report showing failure positions
Call Setup Failure– Input Activities, Troubleshooting
Input Activities
Initial Tuning(Acceptance Test)
Troubleshooting (Customer
complaint etc.)
Measurement Type•Small Area Drive Test•Lock on problem cell’s BCCH•Force handover to the cell
Post-Processing Output•Geographical Report (if necessary)
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 which logfile from geographical report.
• Replay the logfile and jump to the Blocked Call event.
• Check if there is any successful call setup to the problem cell.
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 there any traffic (SDCCH & TCH) in the cell, SDCCH & TCH seizures, congestion etc.
• Check fault report & CDD configuration.
Call Setup Failure Analysis- Troubleshooting Scenario
• Before performing drive test, check STS report & fault report.
• If can not identify the problem, perform drive test.
• During measurement, lock the BCCH of the problem cell.
• Review the layer 3 messages to check at which sequence the failure occur (random access, SDCCH, TCH assignment etc.).
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.
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.
Failed Call Setup (Blocked Call) Example
Multiple Channel Requests.
Successful Random Access after the third try.
Congestion in SDCCH.
Dropped Call Case- Input
• Statistics Report
• Note from drive test.
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 TEMS mobile disconnection during recording!!!
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, SSDL < MSSENS ( -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 power down 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).
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. -75dBm
Analysis
• Since DL SS & Rxqual is good
Suspect UL problems e.g. external uplink interference
Conclusion
TMA power turned off
Miscellaneous Case 1
From TEMS Logfile
• TCH has lower Signal strength than BCCH (Own BCCH included in BA-list)
• BTS power control = OFF
Miscellaneous Case 2
CHG0
BC
CH
TC
H
TC
H
TC
H
TC
H
TC
H
TC
H
SD
CC
H\8
CHG1 TC
H
TC
H
TC
H
TC
H
TC
H
TC
H
TC
H
TC
H
Configuration/cellSEKTOR A
SEKTOR B
SEKTOR C
Conclusion
Antenna cable for TCH is swapped between sectors (CDU-A)
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 properly defined in MCS and LA
Conclusion
• Corrupted block in MSC
Miscellaneous Case 3
GPRS Verification & Optimization
with TEMS Investigation
GPRS Measurement Activities• GPRS Performance Prediction
• GPRS Field Measurement
GPRS Performance Prediction- Overview
• GPRS RNAP Service uses TEMS Inv to predict following performance:– Throughput– Cell Reselection & Routing Area Update
GPRS Throughput Prediction• Perform Throughput prediction for each
coding scheme
Cell Reselection Prediction• Dedicated mode drive
test
HO types LA HO (10) HO int. (220) LA HO at BQ (1) HO int. at BQ (11) BSC3 serving Other BSC
Cell Reselection Prediction• BCCH Scanning
• Simulate the cell update with different CRH values
CRH = 4 dB CRH = 8 dB
CRH # HO0 3652 2464 2116 1788 15610 14712 13814 130
GPRS Field Measurement- Procedure
Set up files Cell definitionsPreparations
TEMS,IP Sniffers
…
Dig maps
Excel
Mapinfo
Graphicalpresentation of route
Charts / Tables
Report
?GIMS
GPRS Field Measurement- Type of Measurements
• Application Performance Test– Ping– WWW– FTP– WAP
• Mobility Performance Investigation– Cell Reselection– RA Update
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
• Delay
• Number of PDCH allocated
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
• WAP– Winwap
GPRS Field Measurement- Mobility Performance
Investigation
• Number of Cell Reselection & RA Update
• TCP Outage Time
• Cell Reselection Failure
Mobility test CRH = 4, CRO = 4
Cell Reselection Sample ReportRouting Area Time Cell Target
Cell Reselection
time Result Comments
BSC1 16:30:42 D0241A D0241C 2 s OK NA BSC1 16:33:18 D0241B D0242A 2 s OK NA BSC1 16:35:04 D0242A D0248C 21 s OK This cell reselection was
made to a cell located quite far away (not the closest), thus the RxLev was quite
bad! BSC1 16:37:44 D0244B D0248C -- NA No throughput before or
after the cell reselection. This is due to that the cell DF0242B were halted by
some reason! BSC1 16:38:11 D0248C D0244B -- Failed The through put was never
resumed and the FTP connection was aborted by
the ftp-server!
.