performance monitoring & kpi improvement workflows
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Performance Monitoring & KPI Improvement WorkflowsLEO.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 operators 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
KPIs KPIs: KEY PERFORMANCE INDICATOR DEFINITIONS 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 subscribers 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 KPIs 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 TCHF
Check frequency plan, external interferers and/or filters
Check locating parameters
Drop Call Rate: Optimisation Flowchart
High timing Bad parameter setting?NO YES
Correct parameter setting
Check site location & TALIM
Check lost handovers
Check radio network features Most dropped calls during handover?NO YES
Power regulation used properly?YES
Perform handover analysis
Correct power regulation parametersNO
Check site position
Check output power Site covering too much? Power balance?YES NO
Remove site or change frequency
Adjust output powerNO
Check BTS error logNO
Introduce DTX HW fault? Activate frequency hoppingNO YES
Swap & repair HW
Frequency hopping used?YES
Check link quality
Check dropped call reason
Transmission fault? Perform interference analysis with MRR and/or FAS
Perform link investigation
Best server exists? Perform low signal strength analysis
Low signal strength?
Check MS fleetNO
Perform drive tests Missing neighbours suspected?NO F YES
Perform MTR/CTR/MRR etc. recordings Perform site survey Check antenna installation END
Low TCH assignment success rate
Check TCH congestion
Improving TCH Assignment Success rateYES
Congestion on TCH?NO
Add transceivers and/or tune Assignment to other cell and CLS.
Check output power, check if cell reaches too far by TA distribution with MRR
Low output power?
Check output power parameters
Wrong parameter setting?
Check BTS Error Log
Check signal strength of BCCH and TCHNO
Contact NMC to swap & repair HW
Low SS for call access?
Check coverage plots Adjust TCH output power Perform drive tests
Dominant server exists?
Check interference with ICM, FAS and/or MRR
Disturbance on SDCCH or target TCH?
Improve & adjust frequency plan
Parameter Tuning WorkflowPRE-ANALYSIS
Change parameter value
Parameter differs from par. rec. and/or par. log?
Update parameter log
No Evaluate statistics Compare with the pre-analisis result
More parameter values to be tested?
No Recommended value(s) No be changed? to Update parameter recommendations, write report if required
Feature enabling workflow:1. Select Feature 2. Proposal
3. Field trial?
5. Field Trial
yes 6. Go ahead? 7. Activation
Check channel configuration
SDCCH Congestion Improvement Plan.Change channel configuration
Check HW availabilty Low availability?NO
Same for all cells in area? See TCH & SDCCHYES
availabilityIs cell broadcast used?YES
Avoid cell broadcast if possible
Check site position Check and increase CRH
Location area border?
Check traffic trend
Change location area border
Short term traffic growth?
Check TCH traffic TCH Congestion?NO
Add TCH capacity and/or Assignment to other cell or CLS
Check SDCCH mean holding time
Check SMS activity
Long mean holding time?
Check HW and number
of false accesses
Many SMS messages?NO
Redimension 1 SDCCH
Check SDCCH dimensioning
Check periodic registration
Too frequent registrations?
Consider changing registration interval timers
SDCCH & TCH availability
Cell synth hopping?NO
Check NUMREQBPC (RLBDP), set to number of channels
Improving TCH & SDCCH Availability
Cell baseband hopping?NO
Check that NUMREQBPC is set to SYSDEF and that number of frequencies is