BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)
GUIDELINE
RECOMMENDATIONS
Copyright
?Ericsson AB2005,2006
Disclaimer
The contents of this document are subject to revision without notice due to continued progress in methodology,design and manufacturing.
Ericsson shall have no liability for any error or damages of any kind resulting from the use of this document.
Contents Contents
1Introduction1 1.1Purpose1 1.2Scope of the Radio Network KPIs1 1.3Structure of This Document1 1.4Status of the KPIs2 1.5Comments on the formulas2
2Circuit Switched KPIs5 2.1Introduction5 2.2Overview of the Circuit Switched KPIs5 2.3Accessibility6 2.4Retainability9 2.5Integrity12 2.6Inter System Operability16 2.7Traffic Level17
3GPRS KPIs in BSS19 3.1Introduction19 3.2Overview of GPRS KPIs20 3.3General GPRS KPIs22 3.4Best Effort Service KPIs(Traffic Class Background and
Interactive)26 3.5Streaming KPI30 3.6Dual Transfer Mode KPIs(R11and Onwards)31 3.7IP User Data Volume32
4Appendix A35
Glossary37
Reference List39
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
Introduction 1Introduction
1.1Purpose
The purpose of this guideline is to specify a standard set of BSS radio network
KPIs covering both the circuit and packet switched domains in order to align
the metrics used on the Ericsson BSS.The document describes the high level
KPIs,description on second level measurements can be found in Reference[1].
The Radio Network KPIs for BSS used within Ericsson are being aligned within
Ericsson,for example NetQB(see Reference[2])will gradually adapt to the
formulas in this document.To include new KPIs in NetQB will though require
that the feature a KPI is based on will have certain penetration in the customer
networks.
1.2Scope of the Radio Network KPIs
The following apply to the scope of the proposed radio network KPIs:
?The KPIs reflect the end-user perception of the performance of BSS as
far as possible rather than the system view.The KPIs are though only
based on what can be measured in BSS,for GPRS end-to-end KPIs on
service level need other types of measurements and are described e.g.by
GETEP see Reference[5].
?The KPIs are possible to collect from STS statistics and are formulated
on counter level.
?The KPI definitions in this version of the document are valid for the R10,
R11,R12,06A,06B,07A and07B BSS releases,respectively..If a
particular formula differs between releases,alternativ formulas are given
for different releases and the applicable release(s)is indicated.
?The KPIs are formulated on cell level;they can though of course be
aggregated on BSC or system level.It has been commented per KPI if a
simpler version of the formula can be used if applied on BSC or system
level.
1.3Structure of This Document
The KPI definitions are described in two separate chapters,one for circuit
switched(CS)and one for packet switched(PS)KPIs.
Appendix A lists the object types that must be collected to create the KPIs.
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
To limit the size of this document it does not contain a description of all included
counters.Descriptions of all counters in the BSC can be found in Reference
[10].
1.4Status of the KPIs
The work to define and improve the BSS KPIs is continuous.New KPIs are
added as new features or services are introduced,other KPIs are improved
after being evaluated in live networks.
1.5Comments on the formulas
?Formulas have been written for R10,R11,R12and06B if they differ.No updates to formulas were introduced in the BSS07releases.
?PERLEN stands for measurement period length in STS(minutes),and is available as a parameter in STS.
?NB_CELLS means number of cells for one BSC
Formulas that include handovers have considered handovers both to BSC
internal and external neighbors.If data is only collected from one BSC it is
not possible to obtain the incoming handovers from external cells,so then all
handovers for external cells could be omitted.
For formulas handling handovers user defined summation counter have been
used.The summation counters are not part of the BSC STS counters,but
should created on cell level in a post-processing tool.The summation counters
for both internal and external cell relations are available in the NWS database
and report generator in OSS,see Reference[7].The counters are also
described in Reference[3].
Note:The names used in NWS for the summation counters have been used in
this document and are described in BSDDB(Reference[7]).
The STS object types that contain counters for BSC internal cell relations are
NCELLREL and NICELASS,and for BSC external cell relations NECELLREL
and NECELASS.
The following formulas show how the summation counters are calculated
as a sum over all internal or external cell relations:
ATT=HOVERCNT
SUCC=HOVERSUC
REV=HORTTOCH
LOST=HOVERCNT-HOVERSUC-HORTTOCH
Introduction
ABSUCC=HOSUCBCL
AWSUCC=HOSUCWCL
The following summation counters are used for every cell in the BSC as the sum over all internal or external cell relations:
SUMOHOSUCC Sum of Successful Internal Handovers(Outgoing Handover) SUMOHOSUCC=NCELLREL.HOVERSUC
SUMOABSUCC Sum of Successful Internal Assignment Handovers to Better Cell(Outgoing Handover)
SUMOABSUCC=NICELASS.HOSUCBCL
SUMOAWSUCC Sum of Successful Internal Assignment Handovers to Worse Cell(Outgoing Handover)
SUMOAWSUCC=NICELASS.HOSUCWCL
SUMIHOSUCC Sum of Successful Internal Handovers(Incoming Handover) SUMIHOSUCC=NCELLREL.HOVERSUC
SUMIABSUCC Sum of Successful Internal Assignment Handovers to Better Cell(Incoming Handover)
SUMIABSUCC=NICELASS.HOSUCBCL
SUMIAWSUCC Sum of Successful Internal Assignment Handovers to Worse Cell(Incoming Handover)
SUMIAWSUCC=NICELASS.HOSUCWCL
SUMEIHOSUCC Sum of Successful External Handovers(Incoming Handover) SUMEIHOSUCC=NECELLREL.HOVERSUC
SUMEIABSUCC Sum of Successful External Assignment Handovers to Better Cell(Incoming Handover)
SUMEIABSUCC=NECELASS.HOSUCBCL
SUMEIAWSUCC Sum of Successful External Assignment Handovers to Worse Cell(Incoming Handover)
SUMEIAWSUCC=NECELASS.HOSUCWCL
SUMEOHOSUCC Sum of Successful External Handovers(Outgoing Handover) SUMEOHOSUCC=NECELLREL.HOVERSUC
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
SUMEOABSUCC Sum of Successful External Assignment Handovers to Better
Cell(Outgoing Handover)
SUMEOABSUCC=NECELASS.HOSUCBCL
SUMEOAWSUCC Sum of Successful External Assignment Handovers to
Worse Cell(Outgoing Handover)
SUMEOAWSUCC=NECELASS.HOSUCWCL
SUMOHOATT Sum of Internal Handover Attempts(Outgoing Handover)
SUMOHOATT=NCELLREL.HOVERCNT
SUMEOHOATT Sum of External handover Attempts(Outgoing Handover)
SUMEOHOATT=NECELLREL.HOVERCNT
SUMOHOLOST Sum of MS Lost Internal Handovers(Outgoing Handover)
SUMOHOLOST=NCELLREL.HOVERCNT-NCELLREL.HORTTOCH-
NCELLREL.HOVERSUC
SUMEOHOLOST Sum of MS Lost External Handovers(Outgoing Handover)
SUMEOHOLOST=NECELLREL.HOVERCNT-NECELLREL.HORTTOCH
-NECELLREL.HOVERSUC
For GSM to UTRAN handovers similar summation counters are created on cell
level,all counters are located in the object type NUCELLREL:
SUMHOVERCNTUTRAN Sum of the counter HOVERCNTUTRAN over all
GSM to UTRAN cell relations(outgoing handover)
SUMHOVERCNTUTRAN=NUCELLREL.HOVERCNT
SUMHOVERSUCUTRAN Sum of the counter HOVERSUCUTRAN over all
GSM to UTRAN cell relations(outgoing handover)
SUMHOVERSUCUTRAN=NUCELLREL.HOVERSUC
SUMHOLOSTUTRAN Sum of HOVERCNTUTRAN-HOVERSUCUTRAN-
HORTTOCHUTRAN over all GSM to UTRAN cell relations(outgoing handover)
SUMHOLOSTUTRAN=NUCELLREL.HOVERCNT-NUCELLREL.HORTTOC
H-NUCELLREL.HOVERSUC
Circuit Switched KPIs 2Circuit Switched KPIs
2.1Introduction
The circuit switched KPIs are grouped in the areas accessibility,retainability
and integrity as defined by ITU,see Reference[4].
Paging performance has not been included,as it primarily should be monitored
with MSC counters since one location area might span more than one BSC.
2.2Overview of the Circuit Switched KPIs
Page5below gives an overview of the circuit switched KPIs.
Table1Overview of CS KPIs.
Accessibility
Random access success rate SDCCH time congestion
SDCCH Drop rate TCH Assignment success rate
Retainability
TCH Drop rate Call minutes per drop
Handover success rate Handover lost rate
Integrity
Speech quality good(UL)Speech quality acceptable(UL)Speech quality
bad(UL) Integrity(R12and onwards)
Speech quality good(DL)Speech quality acceptable(DL)inserted:Speech
quality bad(DL) Inter system operability
GSM to UTRAN Handover
success rate
GSM to UTRAN Handover lost rate
Traffic level
TCH Traffic SDCCH Traffic
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
2.3Accessibility
2.3.1General
For setting up a signalling connection the mobile might try several times for
each call setup.Thereby building up a combined total metric for accessibility
success rate is not recommended,as one access failure seen from the
subscribers will be seen as several access failures in the system.Each step in
the call set-up process should thus be accounted for separately and for SDCCH
availability time congestion is a better measure than success rate.
2.3.2Random Access Success Rate
Formula
Table2Random Access Success Rate
Description
A failed random access burst does not mean a failure to access the system,as
the mobile may send many random access bursts each time it tries to access
the network.E.g.bad BSIC planning,too high TA,parameter settings(e.g.
MAXRET)or interference might cause a high number of random access failures.
The KPI covers random accesses over RACH both for CS and PS connections,
but not over PRACH(when using a MPDCH).Only failures related to the
random access as such are considered,rejects due to load regulation are not
included and can be monitored by separate counters.
2.3.3SDCCH Time Congestion
Formula
Table3SDCCH Time Congestion
Description
Circuit Switched KPIs Congestion on SDCCH might not lead to a call set-up failure as the mobile may
retry several times to set-up an SDCCH in case of congestion(controlled by the
MAXRET parameter).Also if immediate assignment on TCH is allowed the call
set-up may proceed on a TCH even if there is SDCCH congestion.SDCCH
time congestion starts incrementing when all channels are occupied,even if
there are no rejected accesses.
If there is an SDCCH in both the OL and the UL subcell the KPI will over
estimate the congestion as there might be available channels in one subcell
even if the other is congested.Note though that some mobiles may not be
capable or able to access both subcells.
The systems are normally dimensioned to have a certain SDCCH GoS,so the
KPI should be compared to the GoS that the system was planned for.The
system should normally be dimensioned with low SDCCH congestion,as a rule
of thumb the SDCCH Grade of Service(GOS)should be dimensioned for no
more than1/4of the TCH GOS.Even if the SDCCH congestion is normally
very low it is important to monitor it as it can rise sharply due to subscriber
behaviour,e.g.through heavy usage of SMS or positioning using AGPS.
If the feature Adaptive configuration of logical channels is used SDCCH
congestion is prevented by allowing on-demand SDCCHs to be allocated in
case of congestion,and monitoring the SDCCH congestion is less critical.
2.3.4SDCCH Drop Rate
Formula
Table4SDCCH Drop Rate
Description
A drop on SDCCH does not mean a failed call set-up since it can be used for
procedures that only require an SDCCH like a location area update or SMS.
In fact as the SDCCH holding time for call set-up is just under3seconds and
about twice as long for SMS,drops for SMS should be over represented.
The KPI does not include released SDCCH connection due to TCH or
transcoder congestion(i.e.the CNRELCONG counter),as it is seen in the
TCH assignment success rate KPI.The drop rate is related to all SDCCH
establishments in the cell;no compensation has been done for SDCCH
handovers,but as the mobiles normally camp on the SDCCH a short time
SDCCH handover occur seldom.
A high SDCCH drop rate may be due to:
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
?Poor coverage
?Interference
?Equipment faults(e.g.BTS or mobile related)
?Subscriber behaviour(sending frequent large SMS,using AGPS positioning or causing sudden loss e.g.entering an elevator)
2.3.5TCH Assignment Success Rate
Formula
Table5TCH Assignment Success Rate
Description
The assignment success rate covers both change from SDCCH to TCH or
changed channel mode on TCH from signalling to speech.
It should be noted that during the assignment procedure there may be several
attempts to allocate a channel in different cells,but the attempts counter in this
formula(TASSALL)will only be incremented once,if an attempt succeeds
or if all attempts have failed.
A low TCH assignment success rate would normally be due to TCH congestion.
The KPI shows the subscriber perceived TCH availability at call setup and is
impacted by parameter settings e.g.for the assignment time-out(TASSREQ)
and assignment to worse or better cell(e.g.AWOFFSET).The systems are
dimensioned to have a certain TCH GoS,so the KPI must be compared to the
TCH GoS the system was planned for.Note that congestion at hand-over is
not included in this KPI,or any other KPI,as there is no way to determine
the subscriber impact due to a hand-over that could not be executed due to
congestion.As a second level measurement the channel availability in the cells
should be monitored in terms if congestion time,this is though not a KPI as it
does not directly translate into a subscriber impact(with features like OL/UL
Circuit Switched KPIs subcells,Hierarchical Cell Structures,assignment to worse cell and dynamic
mode adaptation subscriber impact due to lack of channels is prevented).
The KPI does not only show failures due TCH congestion,but also includes
other reasons for failures to establish a TCH like transcoder congestion,CLEAR
COMMAND,RESET or RESET CURCUIT received from the MSC,Ater RESET
or Ater RESET CURCUIT received from the TRC,MS lost,link connection or
HW failure during the assignment process.
The TCASSALL and TASSALL counters in the formula are for successful
assignments are stepped in the target cell;if the assignment fails the TASSALL
counter is stepped in the serving cell(the cell where the MS was tuned in
for signalling).To show how many mobiles that tuned in for signalling in the
cell that managed to establish a TCH outgoing assignment handovers are
added(they managed to get a TCH in an other cell)and incoming assignment
handovers are subtracted(they tuned in to signalling in an other cell)from both
the numerator and the denominator.
2.4Retainability
2.4.1TCH Drop Rate
Formula
Table6TCH Drop Rate
Description
To capture the subscriber perceived drops in a cell the number of calls
terminated in the cell are considered,https://www.doczj.com/doc/a72363336.html,pensation is done for incoming
and outgoing hand-overs for all internal and external cell relations.
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
It is important to note that the TCH drop counters are stepped as soon as
a TCH is established even if there has yet not been any B-answer,this is
also applies when TCH is used for signalling.If the TCH is dropped before
the B-answer the subscriber will experience it as a failed call set-up rather
than a dropped call.If TCHs are used extensively for signalling one reason
for increased TCH drops could be transcoder congestion,it can be seen
in the counters THNRELCONG,THNRELCONGSUB,TFNRELCONG and
TFNRELCONGSUB.TCH connections that are lost are during handovers are
also seen as TCH drops in the counters.
If Adaptive Multi Rate(AMR)is used the subscriber will experience better
speech quality and is more likely to hold on to the call until it drops rather than
disconnecting the call due to poor speech quality,thus the drop rate might
increase slightly when AMR is introduced.There are separate dropped call
counters for AMR,which allows drops for AMR connections to be monitored
separately.
As HOVERSUC includes successful SDCCH hand-overs,the drop rate on cell
level can be skewed if there are a large number of SDCCH hand-overs.The
mobile though camps on the on the SDCCH only a short period of time and
number of SDCCH hand overs is normally small compared to the total number
of TCH assignment,typically less than one percent.
A high TCH drop rate may be due to:
?Poor coverage
?Interference
?Hardware faults(e.g.transcoder,BTS or mobile related)
?Subscriber behaviour(e.g.causing sudden loss by entering an elevator or pulling out the battery)
?Handover failure
?Too high timing advance(TA)
2.4.2Call Minutes Between Drops
Formula
Table7Call Minutes Between Drops
Description
Circuit Switched KPIs This KPI complements the TCH drop rate KPI as the call holding time may
be differ in different networks or in different parts of one network,which may
impact the TCH drop rate.
2.4.3Handover Success Rate
Formula
Table8Handover Success Rate
Description
The KPI does not only cover TCH handover but also handovers during
assignment and SDCCH handovers.
A low handover success rate may be due to not optimized cell plan,parameters
or neighbor relations.
The handovers that are not successful or not lost(see Section2.4.4on page
11)revert to the old cell.A high rate of reverted Handovers could indicate that
there exists two cells with the same BSIC-BCCH combination,and both of them
are defined as neighbors.Other reasons are that the handover is attempted
before the uplink in the new cell works,and the old cell is sufficiently good for
allowing a reversion.The failure in the new cell can be too aggressive settings
for HO,or an indication of a faulty RX in the target cell with lower sensitivity.
Note that Handover reversions do occur in any network even at good conditions
-normally the rate is around1%.The reason fir this is likely temporary dips,
collisions in the air interface etc.The Handover failure is not perceived by the
subscriber,but could lead to a subsequent drop due to penalties in locating and
handovers to other cells that are not good candidates.
2.4.4Handover Lost Rate
Formula
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
Table9Handover Lost Rate
Description
The KPI does not only cover TCH handover but also handovers during
assignment and SDCCH handovers.
The KPI shows the subscriber perceived impact due to failed handovers,as
it shows the percentage of handover that resulted in a lost call.This KPI is
important to correlate to the TCH drop rate since a lost handover for a TCH will
also bee seen in the TCH drop KPI.
2.5Integrity
2.5.1General
The Integrity KPIs are based on the Speech Quality Supervision function,which
is a method to measure and monitor the speech quality in the network based on
radio quality information.The speech quality is determined by monitoring the
radio conditions for each ongoing call in the network.The radio conditions are
converted to a Speech Quality Index(SQI)which corresponds to a subjective
speech quality,for more details see Reference[9].
SQI is in R10and R11is available on the uplink,in R12with the features EMR
and SQS enhancements SQI on the downlink will be available for EMR capable
mobiles.In R11STS counters for RXQUAL uplink and downlink are introduced.
The RXQUAL distribution for different hopping networks(or different network
configurations)will not truly reflect the difference in subjective speech quality of
the networks.The RXQUAL measure can thus not be used for benchmarking,
and should therefore not be used as a KPI.However,RXQUAL is still interesting
when comparing between cells within one network.
Note:Please note that packet ABIS influence on speech quality will not be
visible in the SQI values UL and DL,respectively.
2.5.2Speech Quality on the Uplink
Formulae
Circuit Switched KPIs Table10SQI UL
2.5.3Speech Quality on the Downlink(R12and Onwards)
Using the R12features“Enhanced Measurement Reporting"(EMR)and
“Speech Quality Supervision Enhancements”it is also possible to obtain SQI
statistics on the downlink for EMR capable mobiles.EMR introduces a new
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
measurement report,replacing the existing MR for EMR capable mobiles.
The EMR message itself provides improved downlink transmission quality
information for a specific MS can be used as basic input to statistics,power
control and enhanced drop call handling.
R12Formulae
Table11SQI DL
Circuit Switched KPIs
BSS RADIO NETWORK KEY PERFORMANCE INDICATOR(KPI)GUIDELINE
2.6Inter System Operability
A UTRAN cell is considered as a candidate for handover in the GSM system if
the signal quality in the target cell is good enough.When prioritizing between
UTRAN or GSM the traffic load of the GSM cell is also used as a criterion for
handover towards UTRAN.The handover between GSM to UTRAN can be
controlled by a several parameters,more details can be found in Reference[8].
Only outgoing handovers from GSM cells to UTRAN cells are counted in BSS.
Similar counter exist in the UTRAN system that cover handovers from UMTS
to GSM.
GPRS Cell Reselections to UMTS are not counted in BSS since the BSC is not
aware if a mobile moves to another GSM BSC or to the UTRAN network.
2.6.1GSM to UTRAN Handover Success Rate
Formula
Table12GSM to UTRAN Handover Success Rate
Description
The KPI covers SDCCH and TCH handovers to UTRAN,no handovers during
assignment are done to UTRAN.
The handovers to UTRAN are not seen in the general retainability KPIs for
handover success rate and handover lost rate,see Section2.4.3on page11
and Section2.4.4on page11.Generally the handovers to UTRAN are only
seen in the UTRAN specific handover counter in BSS,except for the SDCCH
hand over counters on cell level where they are included.
2.6.2GSM to UTRAN Handover Lost Rate
Formula