Basic Optimization Techniques
May 2008Prepared by: Muhammad Azim Riaz (LCC)
Key Performance Indicator’s (KPI)Key Performance Indicator’s (KPI)Key Performance Indicator s (KPI)Key Performance Indicator s (KPI)
CSSR (Call Setup Success Rate)CSSR (Call Setup Success Rate)
i. TCH Traffic/TCH Blocking
ii SDCCH Traffic/SDCCH Blockingii. SDCCH Traffic/SDCCH Blocking
iii. SDCCH Success Rate (SDR)
Drop Call Rate (DCR)Drop Call Rate (DCR)
HOFR (Handover Failure)
HOFR LOS (HO Failure due to lack of resource)
CSSR (Call Setup Success Rate)CSSR (Call Setup Success Rate)
CSSR Analysis:CSSR Analysis:
– High TCH Blocking Rate (low TCH Access Rate)
– High SDCCH Blocking Rate (low SD Access Rate)
– Low SDCCH Success Rate (high SDCCH Drop Rate)( g p )
Check for normal RF conditions
• BCCH
• Tilts etc.
Ch k f R t 166 h t i ht b th f l SDCCH t • Check from Report 166 what might be the causes for low SDCCH success rate
Shifting of SDCCH to BCCH TRX moving it from Hopping TRX.
TCH Traffic and TCH BlockingTCH Traffic and TCH Blocking
Inadequate SDCCH/AGCH channel capacity preventing TCH assignment.
Inadequate TCH resources resulting in channel assignment failure.
TCH Traffic and TCH Blocking
• TCH Traffic for MOC and MTC call
Traffic in erlang
• 1 erlang means 1 subscriber occupied 1 circuit for 1 hour
• 1 erl = 1 (sub) * occupy time (sec)/3600
• High Blocking rate => High Traffic , Low Availability
TCH Traffic and TCH Blocking RateTCH Traffic and TCH Blocking Rate
Traffic Distribution & possible solutionsTraffic Distribution & possible solutions
Case Study: TCH_RAW_BLKCase Study: TCH_RAW_BLK
DCS/GSM Traffic Balancing through parametersDCS/GSM Traffic Balancing through parametersCongested Cell
By Using Aggressive FRU/FRL SettingsBy Using Aggressive FRU/FRL Settings
Coverage Prediction using ASSET 3GCoverage Prediction using ASSET 3G
TCH_UNAVAIL Impacting CSSRTCH_UNAVAIL Impacting CSSRIf TCH_Unavail is high on site then we have
to resolve it on priority basis, for that purpose we need to raise it on Service Deskpurpose we need to raise it on Service Desk,
but 1st confirm that the issue is there for some time.
Solutions for Reducing TCH BlockingSolutions for Reducing TCH Blocking
Solution
Remove any TCH_UNAVAIL issue
Use aggressive FRU & FRL settings
Coverage Control (Down tilting, Reduce Antenna height)
Parameter (Traffic Sharing, Aggressive PBGT settings)
Increase Capacity (Add more TRX)
Plan new sites in that area for Traffic Sharing
SDCCH Traffic & SDCCH BlockingSDCCH Traffic & SDCCH Blocking
SDCCH Usage
SMSLocation UpdateIMSI Detach/AttachMOC&MTC CallSupplementary Service (Call waiting, call forwarding)High Blocking => High SD Traffic, low Availability
Solution
Increase Capacity (add more SDCCH Timeslot)Reduce unnecessary Location update
SDCCH Traffic & SDCCH Blocking RateSDCCH Traffic & SDCCH Blocking Rate
High SD_BLK Segment AnalysisHigh SD_BLK Segment AnalysisIf SD BLK is high and we already have defined max. SD’s on 900, then we can ,
define SD TS on DCS
SD BLK might be high due to high # of location updates/IMSI Attach & Detach or DR
HO attempts
Effect of SD_AVAIL on SD BLKEffect of SD_AVAIL on SD BLK
SD_BLK due to Location UpdatesSD_BLK due to Location Updates
Too many location updates on this segment we can use aggressive
“cellreselecthysterisis” settings to avoid too many cell reselection in
idle mode.
SD Utilization by IMSI Attach/DetachSD Utilization by IMSI Attach/Detach
SD DropsSD Drops
SD D RSD D RSD Drops Reason:SD Drops Reason:
Low Signal LevelInterferenceHardware Fault (BSC/BTS/TRX/TSL/Transmission)
SD Drops Analysis using report :: 166SD Drops Analysis using report :: 166
DROP CALL RATE (DCR)DROP CALL RATE (DCR)
Drop on Handover
Interference on target cellIncorrect serving cellIncorrect serving cell
Low Signal Level/Quality
RxLev/RxQual thresholds exceededMS enter high attenuation area (building/tunnel etc)
High Co - Adjacent and/or External Interference
Excessive interference on TCHsExcessive interference on TCHsExcessive interference on CCHs
Hardware degradation
DCR_USR from Optima StatsDCR_USR from Optima Stats
DCR Distribution from OptimaDCR Distribution from Optima
DCR Analysis using Report :: 163DCR Analysis using Report :: 163
196 :: Quality Report196 :: Quality Report
Interference due to CoInterference due to Co--BCCH / CoBCCH / Co--BSICBSIC
Analyzing Quality issue using TEMS LOGSAnalyzing Quality issue using TEMS LOGS
Impact of Interference on DCR & CSSRImpact of Interference on DCR & CSSR
TA Report 232TA Report 232
Per NBR Attempt Report :: 153Per NBR Attempt Report :: 153
Drop due to Non RF reason (TXN or NSS end)Drop due to Non RF reason (TXN or NSS end)
Call Drop due to Intracell HO FailureCall Drop due to Intracell HO Failure
Radio Link Timeout Expiry due to HO FailureRadio Link Timeout Expiry due to HO Failure
Radio Link Timeout Expiry due to Weak Coverage PatchRadio Link Timeout Expiry due to Weak Coverage Patch
Lack of Dominant ServerLack of Dominant Server
Handover Failure (HOFR)Handover Failure (HOFR)
Handover Failure Rate
Co-BSIC/BCCH problem
Freq Clash
Traffic from large TA’s
HW suspected issue
Missing neighbors of any neighbor siteg g y g
Low Signal level
Bad Quality
HOFR LOS = 100*HO Fail due to Neighbor Congested/Total HO request
HOFR LOS solution
Solve TCH Blocking of Target cell
Optimizing Neighbour ListsOptimizing Neighbour Lists
Effects of poor maintenance:Effects of poor maintenance:
Unwanted legacy neighboursg y g
Oversized neighbour lists
Co-channel neighbour definitions
Missing neighboursMissing neighbours
Unintentional 1-way neighbour definitions
Optimise by:Optimise by:
Analyze neighbour performance from statistics.
Utilize automated neighbour detection
Identify inconsistent neighbour profilesIdentify inconsistent neighbour profiles
Modify appropriate neighbour lists
Reports for HOSR/HOFR AnalysisReports for HOSR/HOFR Analysis
Adjacency discrepancies (060)Adjacency discrepancies (060)
Frequency check of adjacent cells (062)
Adjacent cell double frequencies (069)
Adjacent cells with the same NCC, BCC and frequency (076)
Cells having high HO failure ratio (150)
Adjacencies having high HO failure ratio (153)
Report :: 74 Report :: 74 -- ADJACENCIES OF CELLSADJACENCIES OF CELLS
Analyzing 074 Using MapInfo ToolsAnalyzing 074 Using MapInfo Tools
Report :: 150 Report :: 150 -- CELLS HAVING HIGH HO FAILURE RATIOCELLS HAVING HIGH HO FAILURE RATIO
Report :: 76 Report :: 76 -- ADJACENT CELLS WITH THE SAME NCC,BCC AND ADJACENT CELLS WITH THE SAME NCC,BCC AND FREQUENCYFREQUENCY
Report :: 60 Report :: 60 -- ADJACENCY DISCREPANCIESADJACENCY DISCREPANCIES
Routine Optimization Check PointsRoutine Optimization Check Points
Cluster definitions by investigating BSC borders, main cities, freeways, major roads.
Investigating customer distribution, customer habits (voice/data usage).g g ( g )
Running specific traces on Network to categorize problems.
Checking trouble ticket history for previous problems.g y p p
Checking any fault reports to limit possible hardware problems prior to test.