Traffic Statistic
Problem Cause Analysis Guideline
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
Decision Tree The objective of this flow chart is to simplify the problem and trouble-shooting suspicious fault and assist to analyze the problem. For problem analysis , this document had been written from the experience. In the real optimization task is nothing can be generic, therefore these routes just only shows the main root cause of problem. It can used to find out the root cause of problem and trouble-shoot more deep investigation . In the brief version, only main KPI will be addressed. Term of agreement : The transmission is cover for A-bis, Asub interface.
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Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
Call Setup Success Rate
See SDCCH Congestion
SDCCH Congest --> Fix problem SDCCH congestion
1
CSSR
2
See SDCCH DROP
SDCCH Drop --> Fix problem SDCCH drop
3
See TCH Access Fail
TCH Access Failure --> Fix problem TCH failure rate
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
SDCCH Assignment BCCH or BSIC --> Correct
TR Link & site config
Site Configuration Parameter incorrect
BER:Bit Error Rate
Link up and down --> Fix TR link
Poor Coverage --> low RxLev (-110dbm), Low Rxqual
Improper Ant --> Antenna point to wrong direction orientation
lack of Radio calibration (parameters)
Coverage Problem
Radio Problem
Overshooting --> Adjust azimuth(direction)& down tilt (Mechanic or Electric) co-Channel Frequency
SDCCH Drop Interference Problem
Adjacent Frequency
Freq planning (bad frequency planning) --> Request RF to change new Frequency Large coverage
Freq planning Problem
External Source --> US Army, British Army or other operator
Cross Feeder (DL/UL) -->Correct
Ant Sys Problem
Ant, Connector, Feeder and Combiner DEGRADATION or FAULTY!
Hardware Problem
TRX Problem --> Check "BSS_SDCCH_ALLOCATION" -->High SDCCH failure rate -->Replace with new TRX
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
SDCCH Congestion
SDCCH time slot always busy (All SDCCH busy time(second) --> Check
Wrong resource allocation
SDCCH Congestion
between signaling and Traffic Channel (SDCCH/8;SDCCH+CBCH;combine BCCH...)
Lost of SDCCH resource
Hardware or SDCCH reconfiguration(delete SDCCH TS) problem --> Fix faulty TRX (no need to add more SDCCH TS)
Not Enough SDCCH resource -->add more SDCCH Bad SDCCH Dynamics setting --> Check configuration of Dynamic SD
Improper Parameter setting
Bad cell_reselect_hysteresis setting Bad Directed retry and Queue Setting
Too much SDCCH traffic (abnormal case)
Hot sopt area near the site or Special event (many subscribers)
Cell is over shoot(large coverage)
Improper Ant direction --> Change the direction
Output power in Radio equipment (high output power)
Surrounding cell OOS(Out of Service =site down) --> Fix (put the site on air ASAP)
Bad Planning
Prepared by: Chum HUOT, BSS TS,Suly Iraq
Too much Location Update --> Check with RF planning team
25-April-2007
TCH Call Drop: Poor Coverage (low RxLev,Rxqual) --> Normal case
Coverage Problem Improper Ant direction lack of Radio calibration
Radio Problem
Overshooting
Co-Channel Frequency
Freq planning Problem -->Request
RF to change new frequency
Large coverage
Adjacent Frequency
Interference Problem
Freq planning Problem
External Source --> From US Army or other operator
Check neighbor relationship in Mapinfo Target cell Congestion
See TCH Access Block (high)
Missing neighboring cells Wrong HO relation declaration
Unable to HO to target cell
Problem at Target cell Problem at Target Cell
TCH Drop
TCH Drop due to TR link & HO
See High Incoming HO Failure
Low outgoing HSR
See Incoming Handover Failure (high) at Target
Wrong Parameter setting
Duplicate BCCH, BSIC
Parameter Problem Wrong HO relation declaration
Improper Parameter setting
TR link rpoblem BER: link up and down --> Request TR team to check&fix
Cross Feeder (DL/UL) --> Correct ASAP
Ant Sys Problem
Hardware Problem Hardware mal-function -->Check "BSS_TCH_ALLOCATION" TRX Problem "Radio Link Alarm" --> Foruth Level reset --> delete/add -->Replace new TRX
VSWR alarm: TX/RX cable,CDU,SCU,connector -->Alarm,historical alarm.
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
TCH Seizure Failure Rate: Site Configuration
BCCH or BSIC incrrect
Parameter Problem Parameter incorrect
Improper Parameter Setting
Improper Parameter setting Poor Coverage
Improper Ant orientation
Coverage Problem
lack of Radio calibration
Radio Problem
Overshooting Freq planning Problem
co-Channel Frequency
Overshooting
TCH Seizure Failure
Adjacent Frequency
Interference Problem
Freq planning Problem
External Source TRX Degradation(mal-function)
TRX Problem Tx (D/L)Power Problem TRX Faulty Abis /Transmission Problem
Clock Loss of Sync (Bit Error Rate)
Cross Feeder (DL/UL)
Hardware Problem Ant Sys Problem Wrong DB( Equip page) Eg. - Redandant path not set properly. - Cross Feeder
Prepared by: Chum HUOT, BSS TS,Suly Iraq
Ant, Connector, Feeder and Combiner DEGRADATION or FAULTY!
25-April-2007
TCH Blocking Rate(congestion rate)
TCH time slot always busy(All TDCCH busy time(second)
TCH blocking
Wrong resource allocation between signaling and Traffic Channel -->Check TCH TS configuration. Hardware problem(TRX faulty) -->Replace new TRX
Lost of TCH resource Not Enough TCH -->Activate Dynamic TCH -->expansion (add TRX) -->add new site Capacity Too low threshold for incoming HO
Wrong Parameter setting
Too high threshold for outgoing HO
Large coverage area
Wrong Directed retry, Half rate, Queue, and CR Setting
Hot sopt area near the site or Special event
Too much TCH traffic (abnormal case)
Improper Ant Orientation -->Adjust direction o down tilt
Cell is over shoot(large coverage) Output power in Radio equipment (Over Coverage)
Neighbour Congestion Missing Neighbour Calls cannot Hand-Off
Prepared by: Chum HUOT, BSS TS,Suly Iraq
See Outgoing Handover Failure
25-April-2007
Abnormal Traffic Have Assignment Traffic but No Handover Traffic
Hardware problem
Reset TRX TRX Faulty!
Statistic problem
Replace faulty TRX
stats is not reliable(wrong)
HO stats is disable Cell barred For Test (CBA=disable)
Enable "CBA=Yes"
Abnormal Traffic
Wrong parameter setting
No Assignment Traffic but Have Handover Traffic(CSSR=0)
Hardware problem
TCH Lock or OOS
TRX Faulty!
SDCCH Lock or OOS
Statistic problem
wrong Missing neighbor cell Low HO incoming statistic per relation
Inconsistency database
No Assignment and No Handover Traffic (Sleeping Cell)
Wrong parameter Setting
Hardware problem
Site on air but BCCH TRX not working --> no signal on mobile handset (zero bar) Replace sleeping TRX
Statistic problem
stats is not reliable
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
Low Mean Holding Time (average holding time) High Drop Call See High Drop Call
Low Mean Holding Time
Bad HO (Pingpong HO)
See Quality HO
See Intra-cell HO
See Level HO Cross Feeder (DL/UL)
Ant Sys Problem Hardware Problem Ant, Connector, Feeder and Combiner DEGRADATION or FAULTY!
TRX Problem
Poor Coverage Improper Ant orientation
Coverage Problem
lack of Radio calibration
Overshooting
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
Idle Interference
TRX Faulty Feeder and Connector Faulty
Hardware Problem
Idle Interference
Combiner Faulty
Internal Interference
Investigate using Spectrum Analyser/ scanning drivetest tool
External Interference
Identify the Spectrum affected and locate the source of the interference
Frequency Retune
Raise the problem to External Affairs team
Cross feeder (UL/DL)
Wrong Configuration Overshooting
Improper Ant orientation
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
Outgoing Handover Failure Rate: Cross Feeder (DL/UL)
Ant Sys Problem Hardware Problem Ant, Connector, Feeder and Combiner DEGRADATION or FAULTY! TRX Problem
Clock Problem
Site Configuration Discrepancy
HO parameter setting Discrepancy BCCH or BSIC Discrepancy
Outgoing HO Failures
Neighbour Declaration Discrepancy
Improper Parameter setting
Power Control parameter Discrepancy Improper HO Parameter
Wrong HO relationship declaration
Improper Power Control Parameter Incorrect Database for Neighbour Relationship (Both Int/Ext)
Wrong Neighbour Relationship
Freq Planning Problem Duplicate BCCH, BSIC Poor Coverage
Coverage Problem Improper Ant orientation lack of Radio calibration
Radio Problem
Overshooting
co-Channel Frequency
Interference Problem
Freq planning Problem Overshooting
Adjacent Frequency
Freq planning Problem
External Source
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007
Incoming Handover Failure Rate: Cross Feeder (DL/UL)
Ant Sys Problem Hardware Problem Ant, Connector, Feeder and Combiner DEGRADATION or FAULTY!
TRX Problem
Clock Problem
Site Configuration
HO parameter setting Discrepancy BCCH or BSIC Discrepancy
Incoming HO Failures
Neighbour Declaration Discrepancy
Improper Parameter setting
Power Control parameter Discrepancy
Improper HO Parameter
Improper Power Control Parameter
Wrong HO relationship declaration
Incorrect Database for Neighbour Relationship (Both Int/Ext)
Wrong Neighbour Relationship
Freq Planning Problem Duplicate BCCH, BSIC Poor Coverage
Coverage Problem Improper Ant orientation lack of Radio calibration
Radio Problem
Overshooting
co-Channel Frequency
Interference Problem
Freq planning Problem Overshooting
Adjacent Frequency
Freq planning Problem
External Source
Prepared by: Chum HUOT, BSS TS,Suly Iraq
25-April-2007