on this blog i will share how to analysis bad Qual due to Missing Neighbor & Late Handover
Analysis base on the Drive Test
Bad Qual due to missing neighbor :
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| BEFORE |
Analysis :
Bad Qual on snapshot above due to missing neighbor from Sites 132286_ISATTAMANPUSPA sec-1 to Sites 130809_XLJATI sec-3
Recommendation :
Create adjacencies from 132286_ISATTAMANPUSPA sec-1 to
130809_XLJATI sec-3
Status :
Quality slightly improved after optimization, can see the snapshot below
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| AFTER |
Note : mengapa saya meng analysis qual jelek karena missing neighbor base on hasil drive test di tems Serving + Neighbors tidak menunjukan Cell lain yang serving. dan untuk memastikan lagi kita bisa lihat dari data DAM
Bad Qual due late handover :
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| Before |
Analysis :
Bad Qual on snapshot above due to serving by sites 130010_NGAGLIKGENTENG sec-1. Bad Qual occur due late handover to sites 130014_KARANGGAYAMTBS sec-3 (better cell)
Bad Qual on snapshot above due to serving by sites 130010_NGAGLIKGENTENG sec-1. Bad Qual occur due late handover to sites 130014_KARANGGAYAMTBS sec-3 (better cell)
Recommendation :
Adjust Handover parameter from 130010_NGAGLIKGENTENG sec-1 to 130014_KARANGGAYAMTBS sec-3
Status :
Quality slightly improved after optimization Rxlevmin from 13 to 10, HOM from 4 to 0, can see the snapshot below
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| After |
Note : mengapa saya meng analysis qual jelek karena telat handovre, base on hasil drive test di tems Serving + Neighbors Site A sudah memiliki level yang jlek, dibandingkan Level Site B dan lokasi MS sudah dekat dengan Site B tapi Site A belum juga Ho ke Site B.
Analysis base on the Data OSS :
HOSR Analysis
Probable Reasons of Bad Handover Performance
Neighboring Cell Relation
Action: Add neighbor cell relation.
Action: Add neighbor cell relation.
Missed measurement frequencies in BA-list
Action: Check measurement frequencies list.
Permitted Network Color Code problem
Action: Check NCC Permitted
HW faults.
Action: Check BTS error log.
Blocking on Target Cell
Action: Remove Blocking on Tager Cell
Congestion
A high congestion might lead to dragged calls (handover performed at a not intended location) and a lot of unsuccessful handovers.
Action: Check TCH congestion.
Timer Expire After MS is Lost
The MS never answers the base station.
Action: Check coverage. Check interference.
Link Connection or HW Failure
Action: Check BTS error log. Perform site visit. Perform link performance measurements.
Bad Antenna Installation
Action: Perform site survey and check antenna installation. Check antenna cabling.
Many Neighbors Defined
Many defined measurement frequencies defined (>16) will decrease the accuracy of the mobile measurements to locate the best six servers. Many measurement frequencies mean few samples per frequency and problem for mobiles to decode the BSIC.
Action: Check number of definitions.
---Delayed Handover Decision
A delayed handover decision can be due to congestion in the target cell.
Action: Check handover parameters.
---Wrong Locating Parameter Setting
Action: Check locating parameters.
---Bad Radio Coverage
Action: Check coverage plots.
---High Interference, Co-Channel or Adjacent
The potential handover candidate is disturbed by interference. Outgoing handover due to bad uplink quality may indicate interference from co-channel another MS. On the border, the quality may be rather bad and the signal strength low. Bad downlink quality may indicate interference from another co-channel base station.
Action: Check interference. Check if many handovers are performed due to downlink or uplink bad quality.
---Receiver Antenna Problem or RBS HW problems (in candidate cell)
Action: Check antenna installation. Check RBS HW and Error log of the target cell
---Poor Inter-MSC/BSC Handover Performance
For outer or external cell, wrong definitions in either MSC or BSC may be reason for the problem.
Action: Check inter-MSC/BSC handover performance.
---Incorrect Down Tilt
Action: Perform site survey and check antenna installation.
Solution: Correct antenna tilting.
HOSR Analysis-Tips on Nokia system-1
Possibilities :
Co or Adjacent BCCH
High TCH Blocking on target cell
Wrong TSC setting regarding BSIC allocation
Bad Neighbor Relation
HW faulty or Unbalance TRX power among a sector
Others ( Inter BSC-Inter MSC)
Preparation Data :
BCCH, BSIC planning, ND report 072
Cell Stat or TQM of HO distribution and ND report 153
Alarm (ZEOH & ZEOL) and site visit
Timing Advance 232
Adjacent Consistency Check ND060, 62 or 69
ND Report 73 to check Undefined Neighbor.
HOSR Analysis -Tips on Nokia system-2
Problem Analysis
1. Check possibility Co. or Adj. Interference then change BCCH frequency.
2. Check neighbor traffic & TCH blocking, check possibility for traffic sharing or directed retry.
3. TSC value should be same with BCC, check performance HO out and incoming.
4. Parameter setting ADJE to make delay on worst target cell or faster HO on best target, focused on High HO Fail. Relate parameter FMT or AUCL.
5. Check TRX alarm (mostly 7745 together with 7743 or 7746). Check TRX configuration.
6. Optimize coverage from TA distribution or update missing Neighbor from ND 73.
7. Check the highest handover cause: by interference, quality, level, power budget, GPRS, etc. Check for the highest HO failure: by Blocked, Conn. Fail., Return to Old, End of HO,etc. The highest value is possible as the highest contribution of HO fail.
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regards,
Slems
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