2G Tuning Activity Process Flow Drivetest Analysis
2G Tuning Activity Process Flow Drivetest Analysis NTS NETWORK INDONESIA Table of Contents 1 1.1 1.2 1.3 2 2.1 2.2 2.3 3 3.1 3.2 4 4.1 4.2 5 5.1 5.2 6 6.1 6.2 7 7.1 7.2 8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 9 9.1 9.2 9.3 10 10.1
Low Signal strength Problem ................................................................... 3 Design and Acceptance Signal Strength Criteria for NTS 2G. ................ 3 Low Signal Strength Troubleshooting Process Flow: .............................. 4 Low Signal Strength Troubleshooting Solution Table ............................. 4 RXQUAL Problem .................................................................................... 5 Acceptance RXQUAL level for NTS 2G................................................... 5 RxQual Troubleshooting Solution Table .................................................. 6 RxQual Troubleshooting Process Flow: .................................................. 7 Call Setup Success Rate Problem ........................................................... 8 Call-Set-Up Success Troubleshooting Process Flow: ........................... 10 Call-Set-Up Success Troubleshooting Solution Table .......................... 11 SDCCH Congestion Problem ................................................................. 12 SDCCH Congestion Troubleshooting Process Flow ............................. 12 SDCCH Cong Problem Troubleshooting Solution Table ....................... 13 SDCCH Drop Problem ........................................................................... 15 SDCCH Drop Troubleshooting Process Flow ........................................ 15 SDCCH Drop Problem Troubleshooting Solution Table ....................... 15 TCH Congestion problem....................................................................... 17 TCH Congestion Troubleshooting Process Flow .................................. 17 TCH Congestion Troubleshooting Solution Table ................................. 19 Drop Call Problem .................................................................................. 19 Drop Call Troubleshooting Process Flow .............................................. 20 Drop Call Problem Troubleshooting table .............................................. 21 Handover Problems................................................................................ 22 Handover Analysis Process Flow .......................................................... 22 No or few Handover Attempts ................................................................ 24 No or few Handover Attempts troubleshooting table ............................. 24 Unsuccessful Handovers Process Flow ................................................ 25 Unsuccessful Handovers Troubleshooting Table .................................. 28 Handover Reversions Troubleshooting Table ....................................... 29 Ping Pong Handovers Troubleshooting Table ....................................... 29 Inter MSC Handover Analysis ................................................................ 30 GPRS Throughput Analysis ................................................................... 32 GPRS Throughput Troubleshooting Process flow ................................. 32 GPRS Throughput Troubleshooting Table ............................................ 32 GPRS Parameters to Check for ............................................................. 33 Contributers ............................................. Error! Bookmark not defined. Members.................................................. Error! Bookmark not defined.
1
Low Signal strength Problem
1.1
Design and Acceptance Signal Strength Criteria for NTS 2G.
2G Coverage – Design Levels CBD
Dense Urban
Urban
Suburban
Rural
Open [Hwy.]
Bins >= 95%
Bins >= 95%
Bins >= 95%
Bins >= 95%
Bins >= 95%
Bins >= 95%
-64.0 dBm
-66.0 dBm
-70.0 dBm
-75.0 dBm
-80.0 dBm
-85.0 dBm
Environment
RSSI [dBm]
Table 1: 2G Design Level
Low signal strength analysis is very much depending on the design and acceptance criteria referring to the above table. Based on the acceptance value the following scenario are to be put into consideration. For drive test data additional of -6dBm to be add up to make it more into realistic value and this will determine until what received level (in dBm) could be considered as “low signal strength problem”. Table 2: 2G Acceptance Level 2G Coverage – Acceptance Levels Environment
RSSI [dBm]
Environment
CBD Dense Urban Urban Suburban Rural Open(Hwy)
CBD
Dense Urban
Urban
Suburban
Rural
Open [Hwy.]
Bins >= 95%
Bins >= 95%
Bins >= 95%
Bins >= 95%
Bins >= 95%
Bins >= 95%
-71.0 dBm
-73.0 dBm
-75.0 dBm
-78.0 dBm
-84.0 dBm
-88.0 dBm
Acceptance Level
Additional
Drive test acceptance level for Signal Strength
-71dBm -73dBm -75dBm -78dBm -84dBm -88dBm
-6dBm -6dBm -6dBm -6dBm -3dBm -3dBm
dBm
-77dBm -79dBm -81dBm -84dBm -87dBm -91dBm
1.2
Low Signal Strength Troubleshooting Process Flow:
RXLEV problem A
Antenna Installation
Antenna Location
YES
Check antenna placement
YES
Istallation error?
Check for possible swap feeder ect.
NO NO
Site Location Alarm
YES
YES
Check coverage objective
Island Site?
Alarm occurred?
Perform troubleshooting
NO NO
Coverage Performance
Server NO YES
Coverage Issue?
YES
Check hardware No dominant server?
Rivert issue to cell plan
NO
Parameter End YES
Parameter Setting Correct?
Check parameter as in CDD and defined.
NO
Neighbour
YES
Missing neighbours suspected?
Check neighbour parameter
NO
A
1.3
ANTENNA
Low Signal Strength Troubleshooting Solution Table Possible Reason ANTENNA HEIGHT - could mean a too large service area. ANTENNA LOCATION - will cover large areas. A large coverage area might mean that the cell takes a lot of traffic. Lower antenna if there is no risk for loss of coverage (no coverage at all).
SITE LOCATION
COVERAGE PERFORMANCE
PARAMETER SETTING
NEIGHBOUR
INSTALLATION
ALARM
NO DOMINANT SERVER
2
ANTENNA TILT - Tilting of the antenna or changing antenna type may also decrease the coverage area. CHECK COVERAGE OBJECTIVE – The main purpose the site were constructed at the area. TMA – May not functioning properly. UL/DL IMBALANCE ANTENNA TYPE – Wrong antenna installed, different band etc. FEEDER TYPE – Wrong feeder type. BLOCKING/SURROUNDING SCENARIO – EIRP from antenna been block by building, trees or billboards. BSPWRB/T – Low output power may cause low RF ACCMIN – Setting of ACCMIN not to be too high such as -110. CRO – Cell reselection parameter, work together with TO and PT. TO - Defines a negative offset applied to CRO. PT - Value indicates that the cell reselection offset is negative and that the temporary offset is ignored. Note: The setting only affects GSM phase 2 mobile. MPWR – Maximum transmitter power of the TX at the power amplifier (PA) output. MPWR must be specified for each transmitter in the TG. CHECK NEIGHBOUR PARAMETER – Check for the correct setting. MBCCH IDLE/ACTIVE – Frequency define same as the neighboring frequency. SWAPPED CELL SWAPPED TX/RX SWAPPED TRU SWAPPED FEEDER – Feeder from different sector been connected to wrong sector. RX DIVERSITY LOST VSWR – From BSC alarms ( Threshold value = 1.3) TRANSMISSION If no dominant cell or similar signal strengths of a few cells found during drive test, it is recommended to add BTS.
RXQUAL Problem
Traditionally RXQUAL measure has been use to measure the downlink speech quality performance of a GSM network. 2.1
Acceptance RXQUAL level for NTS 2G.
It has been a conclusion that from drive test result, which ever sample of RXQUAL > 3 with the following clutter type received level environment should be taken into consideration of
troubleshooting with improvement as the result. This term applies for all environments which are BDC, Dense Urban, Suburban, Urban, Rural and Open (Hwy).
Environment CBD Dense Urban Urban Suburban Rural Open(Hwy)
Acceptance Level (design) -71dBm -73dBm -75dBm -78dBm -84dBm -88dBm
Acceptance level (DT) -77dBm -79dBm -81dBm -84dBm -87dBm -91dBm
RXQUAL Value >3 >3 >3 >3 >3 >3
If the signal strength is lower the above indicator in any particular clutter, RXQUAL problems may not be solved first until the coverage issues are attended. If the signal strength is greater than the above indicators, all RXQUAL problems will be solved first.
2.2
RxQual Troubleshooting Solution Table
FREQUENCY PLAN
COVERAGE PERFORMANCE
Possible Reason BCCH – Check BCCH frequency BSIC – Check BSIC MIAO – Incorrect value HSN – Unplanned value HOPPING – Check if the frequency hopping on or off. If more than 1 TRU, turn on the frequency hopping.
NEIGHBOUR
ANTENNA HEIGHT/DIRECTION – The height should be limit especially in CBD area and the direction should be correct as planned RND. ANTENNA TILT/TYPE –Recommend electrical tilt, not to be more than 8 degree down tilt. COVERAGE OBJECTIVE – Check the objective from Radio Network Design. SURROUNDING BLOCKING – Possible to do site visit to check either for obstacle in front of antenna such as building, hills or billboards. MISSING NEIGHBOUR RELATION – Check for undefined neighbor relation. TOO MANY NEIGHBOUR RELATION – This will lead to inaccuracy of sample rxlev in measurement to be send from MS. WRONG BSIC DECODING – BSIC should be unique for every cell. CO-BCCH & CO-BSIC – Will result to very bad quality and always end up with drop call and handover failure. NEIGHBOUR POWER SETTING - If the interference is downlink (causing by other BTS interference), Check BTS power regulation.
If any poor setting found, correct parameter setting. PARAMETER
LOCATING URGENCY BSPWRB/T IHO – Intracell handover usually indicates bad quality and high signal strength. High number of intracell handover shows a bad quality cell and if possible, you can reduce the number of intracell handover of MAXIHO to a smaller value based on the channel group. BSPWR CONTROL – Check for the correct setting. MSPWR CONTROL - Check for the correct setting. DTX: DTXD & DTXU - Check if DTX feature is on or off. If off, turn the DTX feature on. This will save the battery in the MS and reduce the interference.
ALARM
TRU FAULTY – TRU faulty should be replace PATH BALANCE RX/TX VSWR – Threshold value 1.3
CONGESTION
CONGESTION – Upgrade capacity
EXTERNAL UPLINK INTERFERENCE
Check from the statistics or scanning drive if there is any pattern of bad quality reason. For example, for surveillance purpose, the CCTV or might be turn on during night time only. In this case statistic monitoring should be on hourly data.
EXTERNAL DOWNLINK INTERFERENCE
If external interference problem occurs, do drive test and frequency scanning. Report the usage of the frequency to the relevant authorities.
FREQUENCY PLANNING
UN-USE FEATURES
RE-LOOK STRATEGY – Plan hopping channel group again with more frequencies, include more frequencies in BCCH group. Improve frequency plan with additional spectrum. IRC - The purpose of Interference Rejection Combining is to improve performance on the uplink in radio environments limited by interference. IRC minimizes the disturbance an interferer by combining the signal received on diverse antenna and suppressing the interfering signal. BCCH TYPE REUSE -
2.3
RxQual Troubleshooting Process Flow:
RXQUAL problem A
Frequency Congestion
Frequency issue
YES
YES
Check frequency Pure congestion
Upgrade capacity
NO NO
Coverage External frequency
YES
Coverage Performance?
YES
Check antenna location, tilt?
External downlink?
Scan frequency
NO NO
Neighbour Re-look frequency planning strategy YES
Neighbour issue?
Check neighbour parameter ect
Un-use features
IRC, BCCH type re-use
NO
Parameter End YES
Parameter Setting Correct?
Check parameter as in CDD and defined.
NO
Alarm
YES
Alarm exist?
Alarm troubleshooting
NO
A
3
Call Setup Success Rate Problem Call Set-up Success Rate - The probability that a connection can be established within a specified transmission tolerance, to the correct destination, with a given time interval, when requested by MS. This KPI will be measured per cluster with drive test short calls in dedicated mode.
The measurement will be extracted from Layer 3 messages starting from Channel Request up to Alerting. Repetitive Channel Requests will be excluded due to the fact that a single subscriber call attempt may generate multiple Channel Requests. Formula:
CSSR (%) = No. of Successful Call Establishments X 100 % No. of Call Attempts – x
No. of Successful Call Establishments - Measured from Layer 3 Message, Alerting, unsuccessful are those request which timed out and blocked due to no available SDCCH or TCH resources. X – the repeated “Channel Request” No. of Call Attempts - Measured form Layer 3 Message, Channel Request. Repeated channel request is excluded. Two Call Set-up Success Scenarios: 1.
MS Originated Call to a PSTN (Fixed Line)
CSSR (%) = No. of Successful Call Establishments(MOC) X 100 % No. of Call Attempts (MOC) – x (MOC) - This assumes a seamless connection between the network and the PSTNetwork. Successful Establishment is until the Network have sent the Alerting confirmation to the MOC.
MOC- PSTN
2.
MS originated Call to a Mobile Terminated Call
CSSR (%) = No. of Successful Call Establishments(MTC) X 100 % No. of Call Attempts (MOC) – x (MOC)
- CSSR will measure its success from MOC’s channel request but only until the MTC has confirmed to the network an Alerting Message. Note that Successful Establishment is taken for the MTC. -
MOC- MTC
3.1
Call-Set-Up Success Troubleshooting Process Flow:
Call set-up Process starts from Random Access towards the Alerting stages. Hence, the process will pass thru RACH Access, SDCCH Transactions and TCH Assignment.
Low CSSR
RXQUAL RXLEV Problem?
Y
See 1. RXQUAL Problem Troubleshooting. 2. Low Signal Strength Troubleshooting
N
SDCCH congestion ?
Y
See SDCCH Congestion Troubleshooting
N
SDCCH Drop?
Y
See SDCCH Drop Troubleshooting
N
TCH Congestion ?
Y
See TCH Congestion Troubleshooting
N
HW Problem?
Y
Escalate to O&M
N End
3.2
Call-Set-Up Success Troubleshooting Solution Table
No.
PROBLEM
1
Interference
2
SDCCH Congestion
3 4
5
4
SDCCH Drop Rate TCH Congestion
Hardware Problems
DESCRIPTIONS 1. MS is retransmitting its channel requests, BTS cannot decode the messages sent MS vice versa. Timer T3126 often encountered. 2. High ICM Band when check on STS and on real time network. -MS has successfully sent the channel Request message and received an Immediate Assignment Reject Message. T3126 has expired after the maximum number of channel request has been sent. MS while establishing connection on SDCCH, SDCCH drop its connection. Call establishment failed due to no TCH resource can be allocated MS – MS is not sending channel request message after the call sequence has been initiated BTS HW and others – faulty HW tends to have an intermittent connection and degrades connection performance.
SOLUTION See RXQUAL or Low signal Strength Troubleshooting
See SDCCH Congestion Troubleshooting
(See SDCCH Drop Troubleshooting) (See TCH Congestion Troubleshooting) Escalate to O&M: - Faulty TRU, Combiners, feeders, antenna and etc. - High Transmission SLIPs.
SDCCH Congestion Problem 4.1
SDCCH Congestion Troubleshooting Process Flow
SDCCH Congestion
Check Parameter Settings
N
Adjust Parameters
Settings Ok?
Y LAC Border Cell?
Y
Y
Adjust Hysteresis
Improved?
N
N
Radio Network Features
ACLC Activated?
Y Activate Feature
End
N
Upgrade SDCCH
N SDCCH Maximum?
Y
Upgrade TRU
Activate Feature
N Increase SDCCH Active?
Y
Improved?
END
4.2
SDCCH Cong Problem Troubleshooting Solution Table
No.
Item
Remarks
1
Parameter Adjustments
SDCCH Measurement Filters
2
Border Cell
3
Activate Adaptive Configuration of Logical Channels
4
5
Cell might be more attractive than other cells Cell caters more traffic than normal, such as locations updates
Descriptions Filters might be too aggressive or having so much delay in provide reliable measurements. This should be standardized with the network unless it is necessary to modify. Filters: SSEVALSI, QEVALSI, SSRAMPSI Check parameters: CRO, PT, TO, ACCMIN etc
Check parameter: CRH
Dynamic allocation of SDCCH Resource
Activate feature
Activate Increase SDCCH Capacity
SDCCH is at maximum which is equal to the number of TRU installed
Activating this feature needs a redimensioning of TRH/TRU resource in BSC level. Hence, the draw back is the decrease on TRH capacity but savings on the TRU resources. Parameters: MAXNOSDCCHTRX ** Combined SDCCH is not considered due to an assumption of high paging load and to avoid paging deletion.
TRU Upgrade
Features can’t compensate traffic demand
Upgrade TRU resource to upgrade SDCCH
5
SDCCH Drop Problem 5.1
SDCCH Drop Troubleshooting Process Flow
SDCCH Drop
Check Parameter Settings
Parameter Settings Ok?
Y Adjust Parameters
N Y Interfered?
See RXQUAL Problem Troubleshooting
N Weak Coverage?
Y
See low Signal Strength Problem Troubleshooting
N HW Problem?
Y
Escalate to O&M
N Cell Plan Review
5.2 No.
End
SDCCH Drop Problem Troubleshooting Solution Table PROBLEM
DESCRIPTIONS
SOLUTION
1
Parameter Adjustments
2
Interference
3
Weak coverage
4
5
Hardware Problems
Cell Coverage Review
SDCCH Measurement Filters
MS is experiencing interference despite of good coverage. No dominant Server, area is obstructed or far from sites SDCCH connections is disrupted, quality and coverage is intermittent.
High Timing Advance
Obstruction
Filters might be too aggressive or having so much delay in providing reliable measurements. This should be standardized with the network unless it is necessary to modify. Filters: SSEVALSI, QEVALSI, SSRAMPSI See RXQUAL Problem Troubleshooting See Low signal Strength Problem Troubleshooting Escalate to O&M: - Faulty TRU, Combiners, feeders, antenna and etc. - High Transmission SLIPs. Perform an MRR analysis to review cells coverage and coverage scope. 1. High Antenna – down tilt, lowering location 2. High Antenna Gain – change out to lower gain antenna 3. High BTS power – power down 1. Consider antenna relocation 2. Consider site relocation 3. Consider site nomination
6
TCH Congestion problem 6.1
TCH Congestion Troubleshooting Process Flow
TCH Congestion
Check Parameter Settings
N Adjust Parameters
Settings Ok?
Y
Y Add Neighbours
Missing Neighbours?
N Compute for TCH Utilization
Y Check Transcoder Utilization/Congestion
GOS > 5%
Redimension Transcoder Resource
Imbalance?
N Review HW Alarms
Radio Network Features
HR/FR Activated?
Y
Dynamic Mode Adaptation Active?
N
Y
CLS Active?
N
Activate Feature
Activate Feature
Y
N Activate Feature
Y Thresholds so High?
Cell Plan Review
N Y Monitor KPI
N Improved?
TRU Upgrade
6.2
TCH Congestion Troubleshooting Solution Table
No.
PROBLEM
1
Parameter Settings Review
2
Missing Neighbors
3
Compute Utilization
4
Hardware Problem
5
Inactive Dynamic Full Rate/ Half Rate Feature
Activate Feature
Activate to increase TCH BPCs.
6
Inactive DYMA
Activate Feature
Activate Feature in increase FR/HR Flexibility
7
Inactive ACLC
Activate Feature
Activate Feature on selected Neighbors (Low utilization and good handover success rate)
TRU Upgrade
Current traffic is beyond its capacity and traffic balancing is optimum
TRU upgrade Reassess DYMA, CLS and HR/FR resources
9
10
Cell Plan Review
DESCRIPTIONS Cells might be more attractive compare to its neighbors. Cells can’t handover to its best neighbors. Utilization might be low bt TCH congestion is still present. This could be on Transcoder resource congestion. Faulty TRU – Hang up without alarms and rejecting traffic
High Timing Advance
Obstruction
7
Drop Call Problem
SOLUTION Parameters to check: 1. Power – BSPWRB, BSPWRT 2. Locating 1 or 3 Parameters 3. HCS Check coverage (TA) thru MRR – if applicable 1. Perform NCS if applicable 2. Perform Drivetest ,Frequency Scanning to locate for missing neighbours.
Balance FR/EFR, HR, Fr AMR resource.
Escalate to O&M
Perform an MRR analysis to review cells coverage and coverage scope. 1. High Antenna – down tilt, lowering location 2. High Antenna Gain – change out to lower gain antenna 3. High BTS power – power down 1. Consider antenna relocation 2. Consider site relocation 3. Consider site nomination
Drop Call is the abnormal termination of after the Call Establishment and before the message release or the disconnect message is received by the MS or the Network. 7.1
Drop Call Troubleshooting Process Flow
Dropped calls on TCH
High ICM?
YES
Check frequency plan, external interferers and/or filters
YES
Check site location & TALIM
YES
See Handover Analysis
YES
Limit Coverage Physical adjustments
YES
Swap & repair HW
F
Check locating parameters
NO
High timing Bad parameter setting?
YES
Correct parameter setting
advance? NO
Check lost handovers
NO
Check radio network features
Power regulation used properly?
Most dropped calls during handover? NO
Correct power regulation parameters NO
YES
Check Cell Plan Check output power Site covering too much? Power balance?
NO
Adjust output power NO
YES
DTX used?
Check BTS error log NO
Introduce DTX HW fault?
YES NO
Check dropped call reason
Check link quality YES
Bad quality?
See RXQUAL Troubleshooting
Transmission fault?
YES
Perform link investigation
NO
Add site
NO
Low signal strength?
See Low SS Troubleshooting
Best server exists?
YES
Missing neighbours suspected?
Run NCS/Check on Drivetest. Add Neighbors
Forward to Design Team for Site Nomination
Wait for Site to be Integrated F
Ensure Improvement
END
7.2 No. 1
Drop Call Problem Troubleshooting table
2
Power Regulation
3
Power Balance
DESCRIPTIONS The quality Parameters are too aggressive. The quality Parameters are too aggressive or too sloppy. Uplink and Downlink
4
DTX Feature
Optional Feature
5
Bad Quality
6
Low Signal Strength UL/ DL Missing Neighbours
Drop call due to bad quality Drop call due to Low Signal Strength (Ul/DL/BL) Undefined neighbours, calls dropped due after failure to handover after Interference on Uplink
7
PROBLEM Bad Parameter Settings
8
High ICM
10
High TA
Disconnection due to High Timing Advance
11
DCR due to Lost Handover
After handover the, the call was disconnected and the call was
12
Cell Plan
Site may be overshooting or serving on a wrong coverage
SOLUTION Locating Parameters: 1. Urgency Condition Parameters 2. Locating 1 or 3 Parameters Power Control Settings Review
Adjust BTS power (BSPWRB, BSPWRT) or MS power (MSTXPWR) Activate feature, this will minimize drop call due to an improved radio environment. See RXQUAL Analysis See Low Signal Strength Analysis
- Review neighbour relations; update the best neighbours to be defined. -If available, generate NCS and MRR - Conduct actual drivetest if necessary, do frequency scanning. -Check possible faulty TRU, check connection error count rate of each TRU. - Check possible internal and external interference. - check repeaters - See RXQUAL Analysis - Site must be overlapping, review coverage - Do physical adjustments: a. Downtilting b. Antenna Change-out - Power Down - Parameter adjustment – TALIM -Check HW faults: 1. Transmission Problem 2. TRU Faults, etc. -Review neighbours, delete unnecessary neighbours - Check Antenna Height, Direction Tilting, create changes if necessary - Check antenna specification – recommend change out if necessary
13
HW Fault
14
Link Failure
15
No Best Server
8
Intermittent signal strength or quality which results to drop call Transmission disturbance within 3 seconds or repeated with 10 seconds the call will be dropped. No dominant server, maybe the coverage is weak
Escalate to O&M: - Faulty TRU, Combiners, feeders, antenna and etc. - High Transmission SLIPs. Check MO SLIP2 counter (DIPS) increment rate, this shows the number of transmission dips.
See Low Signal Strength Analysis
Handover Problems 8.1
Handover Analysis Process Flow
E
Handover analysis
Select worst relation
External? Check successful handovers per cell
NO
YES
Start Inter-BSC/MSC analysis
NO
Next cell
NO
Success below x%?
YES
High ratio of High ratio of lost urgency handovers? handovers?
High ratio of retensions?
8.2
No or few Handover Attempts No or few handover attempts
Check neighbouring cell relations, use NCS if necessary
Unnecessary neighbouring cell relations?
YES
Remove unnecessary relations
NO
Check locating parameters
Unfortunate parameter setting?
YES
Rectify parameter setting
NO
Check BTS definition
BTS defined but not in service?
YES
Rectify parameter setting
NO
END
8.3
No or few Handover Attempts troubleshooting table
8.4
Unsuccessful Handovers Process Flow
Unsuccessful handovers
B
Delayed handover decision
Check congestion performance
YES
Check handover parameters
YES
Introduce unused features
YES
Improve coverage
YES
Reduce interference for potential candidate
NO
TCH congestion?
YES
Add TCH capacity
Check use of radio features
NO
Check SAE setting Are all radio features used? SW congestion?
YES
Increase SAE NO
NO
Check coverage
Check neighbouring cell definitions
Wrong cells defined?
YES
Check interference, run MRR and/or FAS; check ICM
Remove incorrect definitions
NO
Missing neighbours?
Perform drive test YES
Run NCS, add missing relation Timer expiry after MS is lost?
NO
Too many neighbours?
YES
Remove unnecessary relations
YES
NO
Too many measurement channels?
YES
Low SS on cell border?
Review and correct the defined MBCCHNO NO
NO
NO
Check Locating parameters
Bad quality?
Strange or corrupt parameter setting?
NO B
YES
Rectify parameters
C
C
Check BTS Error Log
HW fault?
YES
Swap & repair HW
YES
Improve transmission
YES
Change feeder
YES
Rectify tilting
YES
Change antenna position
YES
Rectify installation
NO
Check link quality
Transmission fault? NO
Perform site visit
Check antenna installation
Antenna connected to wrong feeder?
NO
Incorrect downtilt?
NO
Hidden antenna?
NO
Bad antenna installation?
NO
END
8.5
Unsuccessful Handovers Troubleshooting Table
8.6
Handover Reversions Troubleshooting Table
8.7
Ping Pong Handovers Troubleshooting Table
8.8
Inter MSC Handover Analysis
Inter MSC HO Analysis
Check parameter setting in either MSC or BSC
Check Software version
Check Exchange properties
Check Software File Congestion SAE 500 Block MHIC, MHOC,MHO & MHOAP
Check link performance : #7 Signalling Link Failure /Congestion
Check signalling Performance: MAP signalling performance
Check ratio of Handover Command to Handover Attempts
Check all address definitions in MSC
Check all BSC definitions in the MSC
Check all software route definitions in the MSC
Correct Problem
9
GPRS Throughput Analysis 9.1
GPRS Throughput Troubleshooting Process flow
throughput
Yes
packet loss
Yes
good?
blocking
No high?
high?
Yes buffer size traffic quality of links mobility
9.2 S.No
Yes BLER
voice traffic
concurrent TBFs
mobility
TBF drop rate
congestion
high?
many reconfigurations?
many?
high?
high?
high?
Yes
Yes
Yes
Yes
Yes
Yes
new frequency plan coverage plan
dimensioning
application behaviour: nothing to do!
cell reselection
frequency plan mobility voice traffic
timeslot dimensioning
GPRS Throughput Troubleshooting Table
Troubleshooting Steps 1 CHECK THE STATISTICS OF THE PROBLEMETIC CELL/AREA IF THERE ARE MANY GPRS USERS, INCREASE CAPACITY/ DEDICATE MORE 2 TIME SLOTS FOR GPRS 3 CHECK IF COVERAGE IS GOOD OR NOT CHECK RXQUAL IN THE AREA, AND IMPROVE THE RXQUAL, CHECK 4 FREQUENCY PLAN 5 CHECK TA CHECK CELL RESELECTION PARAMETERS (C31/C32 IF PBCCH DEFINED) 6 AND TUNE ACCORDINGLY 7 CHECK AND OPTIMIZE POWER CONTROL PARAMETERS CAREFULLY 8 CHECK RAC AND LAC PLAN CAREFULLY, AND OPTIMISE IT ACCORDINGLY CHECK GEOGRAPHICAL PLAN OF PCU, PROBLEM OCCURS IF THERE ARE 9 CELL RESELECTIONS IN CELLS WHICH ARE IN DIFFERENT PCU 10 CHECK THE CONGESTION ON Abis INTERFACE CHECK IF THE PCU HAS BEEN EQUIPPED WITH SUFFICIENT CAPACITY OR 11 NOT 12 CHECK IF THERE ARE ENOUGH RESOURCES AVAILABLE AT Gb INTERFACE
9.3
GPRS Parameters to Check for NON_DRX_TIMER
ACCESS_BURST_TYPE
PAN_INC, PAN_DEC, PAN_MAX
Access Type (One-Phase / Two-Phase)
Resource Allocation Methods
T3168
T3192
RLC BS_CV_MAX
MAC
Format of PACK_CTRL_ACK-Messages Network Control Order
Power control parameters like Alpha and Gamma should be checked.
