performance monitoring & kpi improvement workflows
TRANSCRIPT
Performance Monitoring & KPI Improvement Workflows
LEO.AJ
Performance Management….
• Performance management is the process and procedures involved in ensuring that a network operates at maximum efficiency and to the defined Quality of Service (QoS) levels throughout its lifetime. In order to carryout this function a number of tools have been designed to assist both network managers and network engineers.
• The Key Functionalities of Performance management are:-• Ongoing process to monitor network performance• Sustains network quality throughout its lifecycle by proactive maintenance• Reduces risk of network degradation• Improve network performance through optimisation techniques• Support business interests of the network operator
• Poor maintenance procedures lead to network performance degradation resulting in:
• Reactive fault rectification• More complaints from customers• Customer churn• Reduced profit margins• Weakening of operator’s business position
Performance Management….
• PERFORMANCE DATA SOURCES:
• Performance Data can be obtained from a number of sources including:
– Drive Tests
– Statistical Measurements:
– MSC data
– Databases (HLR/VLR)
– BSS data (BTS/BSC)
– Customer Complaints
– Field Engineer Reports
KPI’s
• KPI’s: KEY PERFORMANCE INDICATOR DEFINITION’S
– CSSR: This is defined as the ratio of successful calls to attempted calls. This formula calculates the proportion of mobiles which successfully access a TCH.
• CSSR % = (Succ TCH Seizures / Attempted TCH Seizures) X 100
– TCH Blocking: TCH Blocking is the ratio of blocked TCH Seizure attempts to that of all attempted TCH Seizures.
• TCH Blocking % = ( Blocked TCH Seizures attempts/Attempted TCH Seizures) X 100
– SDCCH BLOCKING: SDCCH Blocking is the ratio of blocked SDCCH Seizure attempts to that of all attempted SDCCH Seizures.
• SDCCH Blocking % = ( Blocked SDCCH Seizures attempts/Attempted SDCCH Seizures) X 100
– TCH Assignment Failure Rate (excluding blocking) is the rate of TCH seizure failed (system + radio) during normal assignment procedure over the total no of TCH requests for normal assignment procedure. It is mostly expressed as a %ge.
• TCH Assignment Failure Rate = ( Failed TCH Seizures / TCH Assignment Requests) X 100
KPI’ s Cont….
– DCR: Drop Call Rate calculates the proportion of mobiles which, having successfully accessed the TCH, subsequently suffer an abnormal release, caused by loss of the radio link. This figure is comprised of RF Losses on the TCH plus losses during handover.
• DCR % = ( Total Abnormal Release/ (Successful TCH Seizures + Intra cell HO + Inter cell HO) X 100
– CSR: Call Success Rate Single overall figure for network quality from a subscriber’s perspective which represents the proportion of calls which complete successfully i.e. Set-Up successfully and do not suffer an RF loss before user termination or successful hand out.
• CSR % = CSSR %ge * (1- DROP CALL RATE)
– HSR: The HANDOVER SUCCESS RATE statistic tracks the percent of handovers that were attempted from the source cell (cell for which the statistic is presented) that succeeded in making it to the destination cell.
• HSR % = (succ Outgoing Internal Inter Cell HO / att Outgoing Internal Inter Cell HO ) X 100
INTRODUCTION TO KPI MONITORING
In KPI Monitoring following points are important:-•KPI definitions must be accurate and audited for usage•KPI Trends must be prepared on a weekly, Monthly and daily basis•KPI data collection should be made for suitable duration to identify issues
Performance Monitoring:
• Daily:
– Daily Performance Monitoring focuses on assessing and identifying issues that need immediate attention.
• Weekly:
– Weekly reporting should be done for a weekly performance evaluation of the network.
• Monthly:
– Monthly reporting should be done for generating KPI trending and strategically implementing Network changes or expansions
• All KPI reports need to be monitored at the following different levels:
– Cell Level
– BSC Level
– Network Level
Performance Monitoring Data Inputs:
• Performance data can be collected from the following different sources. Following KPI’s need to be given special attention:
» Call Setup Success Rate
» Assignment Failure Rate
» Drop Call Rate- TCH & SDCCH
» Handover Success Rate- Intra & Inter
» TCH & SDCCH Blocking
• These stats can be collected from the following different sources:-
» KPI Statistics
» Drive Test Field Report and Post Processing data
» Customer Complaints
» Performance tools in OMCR in Uplink, Downlink and call trace data
KPI Analysis Phase:• The Purpose of the analysis phase is to identify all the prevalent issues in
the network that need attention. This phase consists of the following different checks to identify the cause of poor performance on the cells:-
– Consistency Checks
– Parameter Verification
– Drive tests log analysis
– Physical Site Audits
– Feature Verification
– Depending on the analysis several recommendations may be done to improve network stats like:
– Mechanical tuning
– Frequency Plan changes
– Neibour Plan Changes
– Hardware changes
– Feature enabling &
– Parameter changes
Dropped calls on TCH
Check dropped call reason
Bad quality?
Low signal strength?
Most dropped calls during handover?
Check lost handovers
Perform interference analysis with MRR
and/or FAS
Perform low signal strength analysis
Perform handover analysis
Swap & repair HW
Check site position
Site covering too much?
Check MS fleet
Best server exists?
Check radio network features
Power regulation
used properly?
DTX used?
Check output power
Check locating parameters
Bad parameter setting?
Check antenna installation
Perform site survey
Check BTS error log
HW fault?
Transmission fault?
Check link quality
Power balance? Adjust output power
Introduce DTX
Correct parameter setting
Frequency hopping used?
Remove site or change frequency
Perform link investigation
Activate frequency hopping
Add site
Perform MTR/CTR/MRR etc. recordings
Perform drive tests
High timing
advance?
END
F
F
Check site location & TALIM
NO
Correct power regulation parameters
YES
NO
YES
YES
NO
NO
YES
YES
NO
NO
YES
YES
NO
YES
NO
YES
NO
NO
YES
NO
YES
YES
NO
NO
YES
Missing neighbours suspected?
Run NCS YES
NO
iInterference? Check frequency plan,
external interferers and/or filters
YES
NO
Drop Call Rate:Optimisation Flowchart
Check TCH congestion
Low TCH assignment success rate
Congestion
on TCH?
Check output power, check if cell reachestoo far by TA distribution with MRR
Low output power? Check output power
parameters
Wrong parameter
setting?
Check signal strength of
BCCH and TCH
Low SS for call
access?
Check BTS Error Log
HW fault?
NO
YES
END
Rectify parameters
Contact NMC toswap & repair HW
Check coverage plots
Perform drive tests
Dominant
server exists?
YES
NO
YES
Add BTS NO
Add transceivers and/ortune Assignment to other
cell and CLS.
YES
NO
YES
YES
NO
Adjust TCH output
power
NO
Check interference withICM, FAS and/or MRR
Disturbance
on SDCCH or
target TCH?
Improve & adjust
frequency plan
NO
YES
Improving TCH Assignment Success rate
Collect statistics
Change parameter value
Update parameter recommendations, write report
if required
More parameter values to be tested?
Parameter differs from par. rec. and/or par. log?
Evaluate statisticsCompare with the pre-analisis
result
Recommended value(s) to be changed?
Yes
Yes
No
No
No
Update parameter logYes
FINISH
PRE-ANALYSIS
Parameter Tuning Workflow
Feature enabling workflow:
2. Proposal
no yes
5. Field Trial
7. Activation
8. Follow-up
9. Documentation
6. Go
ahead?
noyes
3. Field
trial?
1. Select
Feature
SDCCH
congestion
Check site position
Location area border?
Change locationarea border
Check andincrease CRH
Check TCH traffic
TCH Congestion?
Check SMS activity
Many SMSmessages?
Check channel configuration
Same for allcells in area?
Check traffic trend
Short termtraffic growth?
Check SDCCH dimensioning
D
D
Underdimensioned
SDCCH?
Check SDCCH mean holding time
Long meanholding time?
Check periodic registration
Too frequentregistrations?
Is cellbroadcast
used?
Check HWavailabilty
Low availability?
See TCH & SDCCH
availability
Avoid cell broadcastif possible
Change channelconfiguration
Add TCHcapacity and/orAssignment to
other cell or CLS
Consider changingregistration interval
timers
No activity
Check HW and number
of false accesses
RedimensionSDCCH
END
YES
NO
NO
NO
NO
NO
YES
NO
NO
NO
NO
YES
YES
RedimensionSDCCH
1
YES
YES
YES
NO
YES
YES
YES
YES
SDCCH Congestion Improvement Plan.
NO
END
SDCCH & TCH
availability
Transmission problem?
Missing SW correction?
Contact NMC toload correct SW
HW fault?
Capacity problem?
Perform more investigations
NO
NO
YES
NO
NO
YES
YES
YES
Cell basebandhopping?
Check transmission
Check loaded SWAdd transmission
capacity
Change or repairtransmission equipment
Check that NUMREQBPCis set to SYSDEF and thatnumber of frequencies is
correct
YES
HW problems? YES
Check BTS Error log
Replace & repair faulty HW
YESCell synth hopping?
Check NUMREQBPC(RLBDP), set to number
of channels
NO
NO
Improving TCH & SDCCH Availability
High RACH FAILURE
Check BSIC allocation
Check frequency plan
Access burst from another co-channel cell
Check cell parameter setting
MAXTA too low?
Check SAE
Software file congestion?
Check ICM, run FAS if needed
High noise floor?
END
Reduce interference
Increase SAE
Increase MAXTA
Change BSIC or frequency plan
Check if unknown access code
YES
NO
NO
YES
NO
YES
NO
YES
Check site location
High located site? Consider tilting or
lowering site
NO
YES
Improving RACH Success Rate
Handover
analysis
Check successful handovers per cell
Success below x%?
Check handover activity
More than x
handovers
performed?
Check handover flow
Check site location
Important cell?
Uneven flow?
Difference in
performance in out-
and incoming?
Focus on bad direction
E
Check if K or L locating is used
E
Select worst relation
External?Start Inter-BSC/MSC
analysis
High ratio of
urgency
handovers?
High ratio of lost
handovers?
YES
YES
YES
YES
YES
NO
NO
YES
Check if many ping-pong
handovers
Check if assignment handovers
are used
END
Check if cell has HW problems
Check if congested target cell
Perform measures to
improve performance
Check SAE
Check handover related parameters such as relations,
missing relations (using NCS), BA-list, BSIC,
hysteresis, offsets, etc.
NO
NO
NO
Next cell
High ratio of
retensions?
NO NO
Check up- and down link interference with
MRR, FAS ICM, TEMS
Check frequency plan
YES YES
Improving Handover Success Rate
CSSRCSSR might be affected and degraded due to followingissues:
– Due to radio interface congestion.– Due to lack of radio resources allocation (for instance: SDCCH).– Increase in radio traffic in inbound network.– Faulty BSS Hardware.– Access network Transmission limitations (For instance: abis expansion restrictions)
Analysis & Findings:Following methods are used to diagnose CSSR degradations as well as improvements– Radio link Congestion statistics monitored using radio counter measurement. – Drive Test Reports. Customer complaints related to block calls have been reviewed.
Improvement Methodologies:Following measures significantly improve the CSSR in live network:
– Radio Resources enhancement (Parameter modification/changes in BSS/OMCR) such as • half rate, • traffic load sharing and • direct retry parameters implementation.
– Transmission media Expansion to enhance hardware additions (such as TRX).– Faulty Hardware Replacement (such as TRX) in order to ensure the resources availability
in live network.
THANK YOU!!