Main BSS oriented KPIs
• PCH success: helps in dimensionning CCCH resources, may affect MS pageability
• RACH success: helps in dimensionning CCCH resources, may affect MS access to the
network
• AGCH success: helps in the dimensionning CCCH resources, may affect MS access to
the network
• SDCCH traffic: helps in dimensionning signalling resources
• SDCCH availability: informs about available SDCCH resources
• SDCCH load: helps in anticipating SDCCH upgrade and shows efficiency of the use of
signalling resources
• SDCCH blocking: lack of SDCCH resources, directly affects call setup failure, billing has
not started, action needed urgently
• SDCCH congestion
• SDCCH access probability: 1-SDCCH blocking
• SDCCH drop rate: may affect call setup failure, action needed
• SDCCH success ratio
• TCH traffic: helps in dimensionning TCH resources, traffic is money
• TCH usage
• TCH holding time
• TCH availability: informs about TCH resources available
• TCH load: helps in anticipating TCH upgrade and shows efficiency of the use of traffic
resources
• TCH blocking: directly affects call setup failure, billing has not started, action needed
urgently
• TCH congestion
• TCH denied for call request
• TCH drop rate: directly affects dropped call rate, billing has stopped, action needed
• TCH success ratio after assignment
• RxQuality: directly linked to Bit Error Rate, may affect call quality in the case that the
system does not succeed in correcting the erroneous bits
• DL/UL Cumulative Quality < 5
• Frame Erasure Rate: affect call quality, directly perceived by the end-user
• Frequency Load: together with quality indicators (FER and dropped call rate) shows the
efficiency of the spectrum usage
• Ho distribution
• Ho failure per adjacency
• Ho success rate
Segment/Cell/Sector/BTS monitoring (Bad cell)
• Paging deleted
• Paging buffer
• RACH load
• SDCCH blocking rate
• SDCCH failure rate
• TCH blocking rate
• TCH failure rate
• Handover failure rate
• Handover cause UL quality/interference
• Handover cause DL quality interference
• Drop of number of SDCCH requests
• Drop of TCH traffic
• Few incoming handovers
• Few normal calls
TRX (Bad TRX)
• Bad RxQuality UL 0
• Bad RxQuality DL 0
• Bad RxQuality UL 7
• Bad RxQuality DL 7
• Idle UL interference out of band 1
• High RxLevUL – RxLevDL
• High RxLevDL – RxLevUL
Adjacencies (Bad Adj)
• High handover failures per adjacency basis
• High handover blocking per adjacency basis
• No or few handovers per adjacency basis
SDCCH failure analysis example
• Can be taken out from Network Doctor report 166
• Sorted by SDCCH drop total rate
• Filtered by SDCCH bids (seizures) > 100
OR
• Sorted by SDCCH drop radio rate
• Filtered by SDCCH bids (seizures) > 100
• Formula : SDCCH success ratio, SDCCH Drop ratio
• Target value : SDCCH drop total < 10%
SDCCH drop radio < 3%
Ghost SDCCH
• Double-Access /Multiple reservations due to co-Bsic, co-BCCH. Check and improve
frequency plan.
• RACH retransmissions/Multiple reservations due to bad coverage or interference and high
numberOfRachRetransmissions. Lower RACH retransmission parameter value. Check and
improve frequency plan and/or downtilt.
• RACH retransmissions/Multiple reservations due to mass paging deleted. During festivals/
holidays/ concerts many subscribers are located at the same LAC, paging and rach load
increases considerably. Consider LAC optimization, Abis expansion, paging group
optimization, reduce paging repeat & rach retransmission times during busy hour.
Radio Fails
• Check alarms and RxQuality report to verify whether there is a badly functioning TRX. Fix
hardware problem. Check antenna line.
• Coverage. Verify TA report and planning tool.
• Interference. Check Frequency Plan. Solution e.g. add sites, downtilt antennas, increase
RxLevAccessMin.
• Extended coverage of cells in location area borders. Check LU parameters and/or downtilt
• 100% ABIS Fails
• Failure in BTS software (BCSU reset in BSC).
• 100% AIF Fails
• BTS connected to other BSC or BTS is not declared in MSC.
TCH blocking
• Can be taken out from Network Doctor report 182
• Sort descending by blocking in Busy hour
• Formula : TCH denied for call request ratio, TCH call blocking
• Target value : < 2% (could be anticipated by traffic consideration)
TCH availability
• Check alarms (are TRXs & TSLs in Working State? ), check availability report and RxQuality
report to verify whether there is a badly functioning TRX. Make Loop Tests on TRX. Fix
hardware problem.
TCH capacity
• Bad TCH capacity dimensioning. Check number of TRXs.
TCH traffic
• Cell is covering a region greater than planned. Verify TA statistics. Change DMAX, or downtilt.
• High traffic in some cells. Solution .eg.:
Quality degradation
Add Macrocells no
Add Microcells no
Add TRXs with new freq no
Add TRXs without new freq no/yes (IUO, FH)
Activate Directed Retry no/yes
Activate Queuing no
Activate HR yes
Activate AMR-HR no
Activate DADL/B no/yes
Activate AMH no/yes
Activate C2 parameter yes
Modify hoMarginPBGT yes
TCH drop
• Can be taken out from Network Doctor report 163
• Sorted by TCH drop total rate
• Filtered by TCH norm seizures > 100
OR
• Sorted by TCH drops absolute number
• Filtered by TCH drop rate > 3 %
• Formula : TCH drop call ratio (w/o re-est.), TCH dropped conv. (after TCH ass)
• Target value : TCH drop total < 2 %
Radio Fails
• Check alarms and RxQuality report to verify whether there is a badly functioning TRX. Fix
hardware problem. Check antenna line.
• Coverage. Verify TA report and planning tool.
• Interference. Check Frequency Plan. Solution e.g. add sites, downtilt antennas, increase
RxLevAccessMin.
• Lack of neighbours
• Bad neighbour declaration
• Transcoder Failure
• Due to synchronisation problem. Synchronisation source set in BTS clock. Change to BSC.
• AIF Failure:
• Interface failures: problem with ET cards. Solution: block the circuits connected to this card and
then change ET card when available.
Rx Quality
• Can be taken out from Network Doctor report 196, 197 and 204
• Sorted reports and 197 ascending by UL/DL cumulative quality
• Formula : UL/DL cumulative quality/level ratio
• Target value : UL/DL cumulative quality < 5 = 100 %
Rx Quality Rx Quality x Rx Level
• Coverage Problem
• Bad Quality is due to weak signal. Check TA statistics. Add sites.
• Interference Problem
• Internal interference. Check if interference profile follows increases in traffic profile. Check
frequency plan and TA statistics. Modify frequency to verify if problem is solved.
• External interference. Check if interference is independent of traffic profile.
• Due to synchronisation problem. Synchronisation source set in BTS clock. Change to BSC.
• HW Problem
• Bad quality in all RxLevel classes of ONE TRX. Check alarms to verify whether there is a badly
functioning TRX. Fix hardware problem. Check antenna line.
• Swap frequency. If problem persists on the same TRX, fix HW problem.
• Bad quality in all RxLevel classes of TWO TRX. Verify combiner or common parts connected to
both TRX
• High share of traffic far from the BTS
• Internal Interference Problem:
High drop call rate in a certain area. Rx Quality statistics indicates an internal
interference problem. With planning tool evaluate sites with the same frequency -
interfering candidates. TA statistics will show traffic distance of interfering cells.
Downtilt is needed.
• No neighbours in area:
High drop call rate. As this cell is covering na unexpected region, there will be no
close neighbours declared and HO will not happen. Downtilt is needed
Link Balance
• If high Drop Call rates are observed, check Link Balance Statistics.
• DL > UL: It will be necessary to add a MHA in BTS in order to increase BTS
sensitivity and balance the situation. Another solution can be to decrease cell size
and reduce BTS power.
• UL > DL: In this case a Booster can be used to increase DL coverage or to improve
indoor levels.
Network Doctor : Worst Cells Detection
• ND134:
• This report gives information about the RACH performance per cell
• ND163:
• This report gives information about the dropped TCH rate per cell as well as where the TCH
dropped
• ND166:
• This report gives information about the dropped SDCCH rate per cell as well as where the
SDCCH dropped
• ND182:
• This report gives information about TCH traffic and TCH blocking per cell as well as about
SDCCH traffic and SDCCH blocking per cell
• ND186:
• This report gives information about the paging performance per cell
• ND202:
• This report gives information about the Access Grant performance per cell
Network Doctor: Cell Level Performance
• Benchmarking Reports: used to orient analysis and solution of the detected problem, output of the
worst cell detection process
• ND204
• RACH performance
• PCH performance
• AGCH performance
• blocking SDCCH
• drop SDCCH per cause
• blocking TCH
• drop TCH per cause
• Handover distribution
• Handover failure causes
• Idle UL interference
• RxQuality/RxLev distribution
• FER distribution
• Availability SDCCH, TCH, GPRS
• ND213: Cell Doctor
• ND216: Cell Analyzer
Network Doctor: Other useful reports
• ND181: TCH Traffic profile
• ND190: Interference Idle UL profile
• ND153: Handover per relation
• ND196: RxQuality distribution per TRX
• ND197: RxQuality distribution per TRX
• ND244: RxQuality distribution per AMR codec per TRX
• ND245: FER distribution per AMR codec per TRX
• ND195: Link Balance per TRX
• ND232: TA distribution
• ND229: GPRS related KPIs
