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2G Tuning Activity Process Flow
Drivetest Analysis
2G Tuning Activity Process Flow
Drivetest Analysis
NTS NETWORK INDONESIA
Table of Contents
1 Low Signal strength Problem ................................................................... 3 1.1 Design and Acceptance Signal Strength Criteria for NTS 2G. ................ 3 1.2 Low Signal Strength Troubleshooting Process Flow: .............................. 4 1.3 Low Signal Strength Troubleshooting Solution Table ............................. 4 2 RXQUAL Problem .................................................................................... 5 2.1 Acceptance RXQUAL level for NTS 2G................................................... 5 2.2 RxQual Troubleshooting Solution Table .................................................. 6 2.3 RxQual Troubleshooting Process Flow: .................................................. 7 3 Call Setup Success Rate Problem ........................................................... 8 3.1 Call-Set-Up Success Troubleshooting Process Flow: ........................... 10 3.2 Call-Set-Up Success Troubleshooting Solution Table .......................... 11 4 SDCCH Congestion Problem ................................................................. 12 4.1 SDCCH Congestion Troubleshooting Process Flow ............................. 12 4.2 SDCCH Cong Problem Troubleshooting Solution Table ....................... 13 5 SDCCH Drop Problem ........................................................................... 15 5.1 SDCCH Drop Troubleshooting Process Flow ........................................ 15 5.2 SDCCH Drop Problem Troubleshooting Solution Table ....................... 15 6 TCH Congestion problem....................................................................... 17 6.1 TCH Congestion Troubleshooting Process Flow .................................. 17 6.2 TCH Congestion Troubleshooting Solution Table ................................. 19 7 Drop Call Problem .................................................................................. 19 7.1 Drop Call Troubleshooting Process Flow .............................................. 20 7.2 Drop Call Problem Troubleshooting table .............................................. 21 8 Handover Problems................................................................................ 22 8.1 Handover Analysis Process Flow .......................................................... 22 8.2 No or few Handover Attempts ................................................................ 24 8.3 No or few Handover Attempts troubleshooting table ............................. 24 8.4 Unsuccessful Handovers Process Flow ................................................ 25 8.5 Unsuccessful Handovers Troubleshooting Table .................................. 28 8.6 Handover Reversions Troubleshooting Table ....................................... 29 8.7 Ping Pong Handovers Troubleshooting Table ....................................... 29 8.8 Inter MSC Handover Analysis ................................................................ 30 9 GPRS Throughput Analysis ................................................................... 32 9.1 GPRS Throughput Troubleshooting Process flow ................................. 32 9.2 GPRS Throughput Troubleshooting Table ............................................ 32 9.3 GPRS Parameters to Check for ............................................................. 33 10 Contributers ............................................. Error! Bookmark not defined. 10.1 Members .................................................. Error! Bookmark not defined.
1 Low Signal strength Problem
1.1 Design and Acceptance Signal Strength Criteria for NTS 2G.
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
Environment Acceptance
Level Additional dBm Drive test acceptance level for Signal Strength
CBD -71dBm -6dBm -77dBm
Dense Urban -73dBm -6dBm -79dBm
Urban -75dBm -6dBm -81dBm
Suburban -78dBm -6dBm -84dBm
Rural -84dBm -3dBm -87dBm
Open(Hwy) -88dBm -3dBm -91dBm
2G Coverage – Design Levels
CBD Dense Urban
Urban Suburban Rural Open [Hwy.]
Environment Bins >=
95% Bins >=
95% Bins >=
95% Bins >=
95% Bins >=
95% Bins >= 95%
RSSI [dBm] -64.0 dBm
-66.0 dBm -70.0 dBm -75.0 dBm -80.0 dBm -85.0 dBm
2G Coverage – Acceptance Levels
CBD Dense Urban
Urban Suburban Rural Open [Hwy.]
Environment Bins >=
95% Bins >=
95% Bins >=
95% Bins >=
95% Bins >=
95% Bins >= 95%
RSSI [dBm] -71.0 dBm
-73.0 dBm -75.0 dBm -78.0 dBm -84.0 dBm -88.0 dBm
1.2 Low Signal Strength Troubleshooting Process Flow:
RXLEV problem
Parameter Setting
Correct?
Check neighbour
parameter
Rivert issue to cell
plan
Installation
Istallation error?
Coverage Performance
Antenna
Check for possible swap feeder ect.
Check parameter as
in CDD and defined.
A
YES
NO
NO
NO
YES
NO
YES
Site Location
Check antenna
placement
Check coverage objective
Antenna Location
Island Site?
Coverage Issue?
Check hardware
Parameter
Neighbour
Missing neighbours
suspected?
YES
NO
NO
YES
YES
NO
NO
YES
A
Alarm occurred?
YES
Alarm
Perform troubleshooting
Server
No dominant server?
End
1.3 Low Signal Strength Troubleshooting Solution Table
Possible Reason
ANTENNA 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).
ANTENNA TILT - Tilting of the antenna or changing antenna
type may also decrease the coverage area.
SITE LOCATION CHECK COVERAGE OBJECTIVE – The main purpose the site
were constructed at the area.
COVERAGE
PERFORMANCE
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.
PARAMETER
SETTING 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.
NEIGHBOUR
CHECK NEIGHBOUR PARAMETER – Check for the correct
setting.
MBCCH IDLE/ACTIVE – Frequency define same as the
neighboring frequency.
INSTALLATION SWAPPED CELL
SWAPPED TX/RX
SWAPPED TRU
SWAPPED FEEDER – Feeder from different sector been
connected to wrong sector.
ALARM RX DIVERSITY LOST
VSWR – From BSC alarms ( Threshold value = 1.3)
TRANSMISSION
NO DOMINANT
SERVER If no dominant cell or similar signal strengths of a few cells found
during drive test, it is recommended to add BTS.
2 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 Acceptance
Level (design)
Acceptance level (DT)
RXQUAL Value
CBD -71dBm -77dBm > 3
Dense Urban -73dBm -79dBm > 3
Urban -75dBm -81dBm > 3
Suburban -78dBm -84dBm > 3
Rural -84dBm -87dBm > 3
Open(Hwy) -88dBm -91dBm > 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
Possible Reason
FREQUENCY PLAN
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.
COVERAGE
PERFORMANCE 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.
NEIGHBOUR 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 RE-LOOK STRATEGY – Plan hopping channel group again with
more frequencies, include more frequencies in BCCH group.
Improve frequency plan with additional spectrum.
UN-USE FEATURES
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
Parameter Setting
Correct?
Alarm
troubleshooting
Congestion
Pure congestion
Neighbour
Frequency
Upgrade capacity
Check parameter as
in CDD and defined.
A
YES
NO
NO
NO
YES
YES
Coverage
Check frequency
Check antenna location, tilt?
Frequency issue
Coverage Performance?
Neighbour issue? Check neighbour parameter ect
Parameter
Alarm
Alarm exist?
YES
NO
NO
YES
YES
NO
NO
YES
A
External downlink?
External frequency
Scan frequency
Re-look frequency
planning strategy
End
Un-use features IRC, BCCH type re-use
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:
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)
- 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(MOC) X 100 % No. of Call Attempts (MOC) – x (MOC)
CSSR (%) = No. of Successful Call Establishments X 100 % No. of Call Attempts – x
- 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.
CSSR (%) = No. of Successful Call Establishments(MTC) X 100 % No. of Call Attempts (MOC) – x (MOC)
3.2 Call-Set-Up Success Troubleshooting Solution Table
Low CSSR
RXQUAL RXLEV
Problem?
SDCCH congestion
?
SDCCH Drop?
TCH Congestion
?
See 1. RXQUAL Problem Troubleshooting. 2. Low Signal Strength Troubleshooting
HW Problem?
See SDCCH Congestion
Troubleshooting
See SDCCH Drop Troubleshooting
See TCH Congestion
Troubleshooting
Y
N
Y
N
Y
N
Y
N
Escalate to O&M Y
N
End
No. PROBLEM DESCRIPTIONS SOLUTION
1 Interference
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.
See RXQUAL or Low
signal Strength
Troubleshooting
2
SDCCH
Congestion
-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.
See SDCCH Congestion
Troubleshooting
3 SDCCH Drop
Rate
MS while establishing connection on
SDCCH, SDCCH drop its connection.
(See SDCCH Drop
Troubleshooting)
4 TCH
Congestion
Call establishment failed due to no TCH
resource can be allocated
(See TCH Congestion
Troubleshooting)
5 Hardware
Problems
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.
Escalate to O&M:
- Faulty TRU,
Combiners, feeders,
antenna and etc.
- High Transmission
SLIPs.
4 SDCCH Congestion Problem
4.1 SDCCH Congestion Troubleshooting Process Flow
4.2 SDCCH Cong Problem Troubleshooting Solution Table
Check Parameter Settings
Settings Ok?
LAC Border
Cell?
SDCCH Congestion
Radio Network Features
ACLC Activated?
Adjust Hysteresis
Adjust Parameters
Activate Feature
Increase SDCCH Active?
Activate Feature Upgrade
TRU
Upgrade SDCCH
SDCCH Maximum?
Improved? End
Y
N
Y
N
Y
N
Y
N
Y
N
Improved?
END
Y
N
No. Item Remarks Descriptions
1 Parameter
Adjustments
SDCCH
Measurement Filters
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
Cell might be more
attractive than other
cells
Check parameters: CRO, PT, TO, ACCMIN
etc
2 Border Cell
Cell caters more
traffic than normal,
such as locations
updates
Check parameter: CRH
3
Activate
Adaptive
Configuration
of Logical
Channels
Dynamic allocation of
SDCCH Resource Activate feature
4
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.
5 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
5.2 SDCCH Drop Problem Troubleshooting Solution Table
No. PROBLEM DESCRIPTIONS SOLUTION
Check Parameter Settings
Parameter Settings Ok?
Weak Coverage?
SDCCH Drop
See low Signal Strength Problem Troubleshooting
Adjust Parameters
Interfered? See RXQUAL Problem Troubleshooting
HW Problem?
Escalate to O&M
Cell Plan Review End
Y
N
Y
N
Y
N
Y
N
1 Parameter
Adjustments
SDCCH
Measurement Filters
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
2 Interference
MS is experiencing
interference despite of
good coverage.
See RXQUAL Problem Troubleshooting
3 Weak coverage
No dominant Server,
area is obstructed or
far from sites
See Low signal Strength Problem
Troubleshooting
4 Hardware
Problems
SDCCH connections
is disrupted, quality
and coverage is
intermittent.
Escalate to O&M:
- Faulty TRU, Combiners, feeders, antenna
and etc.
- High Transmission SLIPs.
5 Cell Coverage
Review
High Timing
Advance
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
Obstruction
1. Consider antenna relocation
2. Consider site relocation
3. Consider site nomination
6 TCH Congestion problem
6.1 TCH Congestion Troubleshooting Process Flow
Check Parameter Settings
Settings Ok?
Missing
Neighbours?
TCH Congestion
Radio Network Features
HR/FR Activated?
Dynamic Mode Adaptation
Active?
Add
Neighbours
Adjust Parameters
Activate Feature
Activate Feature
CLS Active?
Activate Feature
Thresholds so High?
Monitor KPI TRU Upgrade
N
Y Y
N
Y
N
Y
N
Y
N
Y
N
Compute for TCH Utilization
Check Transcoder Utilization/Congestion
GOS > 5% Imbalance?
Y
N
Review HW Alarms
Redimension Transcoder Resource
Cell Plan Review
Improved?
Y N
6.2 TCH Congestion Troubleshooting Solution Table
No. PROBLEM DESCRIPTIONS SOLUTION
1
Parameter
Settings
Review
Cells might be more
attractive compare
to its neighbors.
Parameters to check:
1. Power – BSPWRB, BSPWRT
2. Locating 1 or 3 Parameters
3. HCS
Check coverage (TA) thru MRR – if applicable
2 Missing
Neighbors
Cells can’t handover
to its best
neighbors.
1. Perform NCS if applicable
2. Perform Drivetest ,Frequency Scanning to
locate for missing neighbours.
3 Compute
Utilization
Utilization might be
low bt TCH
congestion is still
present. This could
be on Transcoder
resource
congestion.
Balance FR/EFR, HR, Fr AMR resource.
4 Hardware
Problem
Faulty TRU – Hang
up without alarms
and rejecting traffic
Escalate to O&M
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)
9 TRU Upgrade
Current traffic is
beyond its capacity
and traffic balancing
is optimum
TRU upgrade
Reassess DYMA, CLS and HR/FR resources
10 Cell Plan
Review
High Timing
Advance
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
Obstruction
1. Consider antenna relocation
2. Consider site relocation
3. Consider site nomination
7 Drop Call Problem
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
Check dropped call reason
Bad quality?
Low signal strength?
Most dropped calls during handover?
Check lost handovers
See RXQUAL
Troubleshooting
See Low SS
Troubleshooting
See Handover
Analysis
Swap & repair HW
Check Cell Plan
Site covering too much?
Best server exists?
Check radio network features
Power regulation
used properly?
DTX used?
Check output power
Check locating parameters
Bad parameter setting?
Ensure Improvement
Wait for Site to be
Integrated
Forward to Design Team
for Site Nomination
Check BTS error log
HW fault?
Transmission fault?
Check link quality
Power balance? Adjust output power
Introduce DTX
Correct parameter setting
Limit Coverage
Physical adjustments
Perform link investigation
Add site
High timing
advance?
END
F
F
Check site location & TALIM
NO
Correct power regulation parameters
YES
NO
YES
YES
NO
NO
YES
YES
YES
NO
YES
NO
NO
YES
NO
YES
YES
NO
NO
YES
Missing neighbours suspected?
Run NCS/Check on Drivetest. Add
Neighbors
High ICM? Check frequency plan,
external interferers and/or filters
YES
NO
7.2 Drop Call Problem Troubleshooting table
No. PROBLEM DESCRIPTIONS SOLUTION
1 Bad Parameter
Settings
The quality
Parameters are too
aggressive.
Locating Parameters:
1. Urgency Condition Parameters
2. Locating 1 or 3 Parameters
2 Power
Regulation
The quality
Parameters are too
aggressive or too
sloppy.
Power Control Settings Review
3 Power Balance Uplink and Downlink Adjust BTS power (BSPWRB, BSPWRT) or
MS power (MSTXPWR)
4 DTX Feature Optional Feature Activate feature, this will minimize drop call
due to an improved radio environment.
5 Bad Quality Drop call due to bad
quality
See RXQUAL Analysis
6
Low Signal
Strength UL/
DL
Drop call due to Low
Signal Strength
(Ul/DL/BL)
See Low Signal Strength Analysis
7 Missing
Neighbours
Undefined
neighbours, calls
dropped due after
failure to handover
after
- Review neighbour relations; update the best
neighbours to be defined.
-If available, generate NCS and MRR
- Conduct actual drivetest if necessary, do
frequency scanning.
8 High ICM Interference on
Uplink
-Check possible faulty TRU, check
connection error count rate of each TRU.
- Check possible internal and external
interference.
- check repeaters
- See RXQUAL Analysis
10 High TA Disconnection due to
High Timing
Advance
- Site must be overlapping, review coverage
- Do physical adjustments:
a. Downtilting
b. Antenna Change-out
- Power Down
- Parameter adjustment – TALIM
11 DCR due to
Lost Handover
After handover the,
the call was
disconnected and the
call was
-Check HW faults:
1. Transmission Problem
2. TRU Faults, etc.
-Review neighbours, delete unnecessary
neighbours
12 Cell Plan Site may be
overshooting or
serving on a wrong
coverage
- Check Antenna Height, Direction Tilting,
create changes if necessary
- Check antenna specification – recommend
change out if necessary
13 HW Fault Intermittent signal
strength or quality
which results to drop
call
Escalate to O&M:
- Faulty TRU, Combiners, feeders, antenna
and etc.
- High Transmission SLIPs.
14 Link Failure Transmission
disturbance within 3
seconds or repeated
with 10 seconds the
call will be dropped.
Check MO SLIP2 counter (DIPS) increment
rate, this shows the number of transmission
dips.
15 No Best Server No dominant server,
maybe the coverage is
weak
See Low Signal Strength Analysis
8 Handover Problems
8.1 Handover Analysis Process Flow
Handover analysis
Check successful handovers per cell
Success below x%?
E
Select worst relation
External? Start Inter-BSC/MSC analysis
High ratio of urgency
handovers? High ratio of lost
handovers?
YES
YES
NO
Next cell High ratio of retensions?
NO NO
YES YES
8.2 No or few Handover Attempts
No or few handover attempts
Unnecessary
neighbouring cell
relations?
Unfortunate
parameter setting?
Remove unnecessary
relations
Rectify parameter
setting
BTS defined but
not in service?
Rectify parameter
setting
YES
YES
YES
NO
NO
Check neighbouring cell relations,use NCS if necessary
Check locating parameters
END
Check BTS definition
NO
8.3 No or few Handover Attempts troubleshooting table
8.4 Unsuccessful Handovers Process Flow
Unsuccessful
handovers
Check congestion
performance
TCH congestion?
Check SAE setting
NO
SW congestion?
Check Locating parameters
Check neighbouring cell definitions
Wrong cells
defined?
Missing
neighbours?
Too many
neighbours?
Too many
measurement
channels?
Strange or corrupt
parameter setting?
NO
NO
NO
NO
NO
Check use of radio
features
Add TCH capacity YES
Increase SAE YES
Remove incorrect
definitions YES
Run NCS, addmissing relation YES
Remove unnecessary
relations YES
Review and correct the
defined MBCCHNO YES
B
NO
Rectify parameters YES
B
NO
Are all radio
features used? YES
Check coverage
NO
Low SS on cell
border?
Perform drive test
YES Improve coverage
Check interference, run MRRand/or FAS; check ICM
YES
Bad quality? Reduce interference for
potential candidate YES
Delayed handover
decision
Check handover
parameters YES
Introduce unused
features
Timer expiry after
MS is lost?
NO
C
NO
C
Check BTS Error Log
HW fault?
Check link quality
Transmission fault?
Swap & repair HW YES
NO
Improve transmission YES
Perform site visit
NO
Check antenna installation
Antenna connected to wrong feeder?
Incorrect downtilt?
Hidden antenna?
Bad antenna installation?
NO
NO
NO
Change feeder YES
Rectify tilting YES
Change antenna position
YES
Rectify installation YES
END
NO
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 Exchange properties
Check Software version
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 toHandover 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
good?
congestion
blocking
high?
BLER voice traffic concurrent TBFs mobility
Yes
No
high? many
reconfigurations?many? high? high?
new frequency plan
coverage plan
Yes
dimensioningtimeslot
dimensioning
application
behaviour:
nothing to do!cell reselection
Yes Yes Yes Yes
TBF drop rate
high?
frequency plan
mobility
voice traffic
Yes
packet loss
high?
buffer size
traffic
quality of links
mobility
Yes
Yes
Yes
9.2 GPRS Throughput Troubleshooting Table
S.No Troubleshooting Steps
1 CHECK THE STATISTICS OF THE PROBLEMETIC CELL/AREA
2
IF THERE ARE MANY GPRS USERS, INCREASE CAPACITY/ DEDICATE MORE
TIME SLOTS FOR GPRS
3 CHECK IF COVERAGE IS GOOD OR NOT
4
CHECK RXQUAL IN THE AREA, AND IMPROVE THE RXQUAL, CHECK
FREQUENCY PLAN
5 CHECK TA
6
CHECK CELL RESELECTION PARAMETERS (C31/C32 IF PBCCH DEFINED)
AND TUNE ACCORDINGLY
7 CHECK AND OPTIMIZE POWER CONTROL PARAMETERS CAREFULLY
8 CHECK RAC AND LAC PLAN CAREFULLY, AND OPTIMISE IT ACCORDINGLY
9
CHECK GEOGRAPHICAL PLAN OF PCU, PROBLEM OCCURS IF THERE ARE
CELL RESELECTIONS IN CELLS WHICH ARE IN DIFFERENT PCU
10 CHECK THE CONGESTION ON Abis INTERFACE
11
CHECK IF THE PCU HAS BEEN EQUIPPED WITH SUFFICIENT CAPACITY OR
NOT
12 CHECK IF THERE ARE ENOUGH RESOURCES AVAILABLE AT Gb INTERFACE
9.3 GPRS Parameters to Check for
NON_DRX_TIMER
Resource Allocation Methods
T3168
T3192Network Control Order
Format of
PACK_CTRL_ACK-Messages
BS_CV_MAX
Access Type
(One-Phase / Two-Phase)
ACCESS_BURST_TYPE
PAN_INC, PAN_DEC,
PAN_MAX
RLC
MAC
NON_DRX_TIMER
Resource Allocation Methods
T3168
T3192Network Control Order
Format of
PACK_CTRL_ACK-Messages
BS_CV_MAX
Access Type
(One-Phase / Two-Phase)
ACCESS_BURST_TYPE
PAN_INC, PAN_DEC,
PAN_MAX
RLC
MAC
Power control parameters like Alpha and Gamma should be checked.