Fresh Field Mtc 004 Section 2

8/9/2019 Fresh Field Mtc 004 Section 2

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GSM SystemOptimisationSection Two

OMC Statistics


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2001 Freshfield Communications Limited.Company Confidential Slide 2

Raw Counters AvailableRaw Counters Available List of Statistics AvailableList of Statistics Available

Definition of StatisticsDefinition of Statistics

Application of Statistics in Network LifecycleApplication of Statistics in Network Lifecycle

Daily and Weekly Analysis of StatisticsDaily and Weekly Analysis of Statistics

Presentation of StatisticsPresentation of Statistics

Summary Summary

Presentation OutlinePresentation Outline


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At the end of this course, attendees will:At the end of this course, attendees will: Understand the various gradeUnderstand the various grade--ofof--service statisticsservice statistics

Understand the raw statistics used in computing the gradeUnderstand the raw statistics used in computing the grade--ofof--serviceservice

parametersparameters

Have an appreciation for methods of analysing OMC data for dailyHave an appreciation for methods of analysing OMC data for dailyoptimisationoptimisation

Have an appreciation of methods of presenting information toHave an appreciation of methods of presenting information to

Planning & Design DepartmentsPlanning & Design Departments

Understand the need for visual display of statistics and trendingUnderstand the need for visual display of statistics and trending

ObjectivesObjectives


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To assess and perform a quality health check on the networkTo assess and perform a quality health check on the networkon a weekly, monthly, quarterly, bion a weekly, monthly, quarterly, bi--annual and annual basisannual and annual basis

Key subscriber parameters such as Call Success Rate, HandoverKey subscriber parameters such as Call Success Rate, Handover

Success rate and RF Loss Rate are analysedSuccess rate and RF Loss Rate are analysed

To establish traffic projections for future growth of networkTo establish traffic projections for future growth of network For day For day--toto--day optimisation of the network to prevent customerday optimisation of the network to prevent customer

churn and migration to other networkschurn and migration to other networks

Why Compute GOS Statistics?Why Compute GOS Statistics?


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Raw counters available can be divided into:Raw counters available can be divided into:

Connection Establishment StatisticsConnection Establishment Statistics

Includes counters which are pegged when a signalling channel or traffic channelIncludes counters which are pegged when a signalling channel or traffic channel

is requiredis required

TCH Assignment StatisticsTCH Assignment Statistics

Includes counters which are pegged when a TCH assignment is requiredIncludes counters which are pegged when a TCH assignment is required

Handover StatisticsHandover Statistics

Includes counters which are pegged when an intra cell, intraIncludes counters which are pegged when an intra cell, intra--BSC or inter BSCBSC or inter BSC

handover is attempted whether successful or nothandover is attempted whether successful or not

Usage and Congestion StatisticsUsage and Congestion Statistics

Includes counters which are pegged to indicate cell usage and congestionIncludes counters which are pegged to indicate cell usage and congestion Call Clearing StatisticsCall Clearing Statistics

Includes counters that are pegged for normal and abnormal clearing of callsIncludes counters that are pegged for normal and abnormal clearing of calls

Raw Counters AvailableRaw Counters Available


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Connection Establishment StatisticsConnection Establishment Statistics

TCH Assignment StatisticsTCH Assignment Statistics


STATISTICS STATISTICS STA TISTICS

ACCESS_PER_AGCH CHAN_REQ_MS_BLK OK_ACC_PROC_IMSI_DET ACCESS_PER_PCH CONN_REFUSED OK_ACC_PROC_PAGE_RSP

ACCESS_PER_RACH CONN_REQ _TO_MSC OK_ACC_PROC_SUC_RACH

ALLOC_SDCCH OK_ACC_PROC_CM_REEST PAGE_REQ_FROM_MSC

ALLOC_SD CCH _FAIL OK_ACC _PROC _CM_SER V PAGE_REQ _FROM_MSC_FAIL

CHAN_REQ_MS_FAIL OK_ACC_PROC_LOC_UPD INV_EST_CAUSE_ON_RACH

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2001 Freshfield Communications Limited.

Company Confidential

Slide 8

Usage and Congestion StatisticsUsage and Congestion Statistics

Call Clearing StatisticsCall Clearing Statistics


STATISTICS STATISTICS

SDCCH_C

STI

TCH_USA

SMS_I

IT _

_SDC CH TCH_C

STI

USY_SDC CH SMS_I

IT _

_TCH

USY_TCH_MAX

STATISTICS STATISTICS

CALLS_QUEUED CLR_REQ_TO_MSC

CIPHER_MODE_FAIL RF_LOSSES_TCHRF_LOSSES_SDCCH


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Slide 9

General StatisticsGeneral Statistics

Call Volume (CV)Call Volume (CV)

Call Setup Success Rate (CSSR)Call Setup Success Rate (CSSR)

Call Drop Rate (CDR)Call Drop Rate (CDR)

Assignment Success Rate (ASR)Assignment Success Rate (ASR)

Handover Success Rate (HSR)Handover Success Rate (HSR)

Handover Failure Rate (HFR)Handover Failure Rate (HFR)

Congestion StatisticsCongestion Statistics

SDCCH Congestion Key (SD CONG)SDCCH Congestion Key (SD CONG)

TCH Congestion Key (TCH CONG)TCH Congestion Key (TCH CONG)

SUP Congestion (Setup Congestion)SUP Congestion (Setup Congestion)

Congestion AttemptsCongestion Attempts

List of Statistics AvailableList of Statistics Available


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Slide 10

RF Environment StatisticsRF Environment Statistics

TCH RF Loss Rate (RF_TCH_LOSS)TCH RF Loss Rate (RF_TCH_LOSS)

SDCCH RF Loss Rate (RF_SDCCH_LOSS)SDCCH RF Loss Rate (RF_SDCCH_LOSS)

Erlangs Handled (TCH_USAGE)Erlangs Handled (TCH_USAGE)

Maximum TCH Slots Used (MA _TCH_BUS )Maximum TCH Slots Used (MA _TCH_BUS )

Maximum TCH Slots Available (AVL_TCH)Maximum TCH Slots Available (AVL_TCH)

List of Statistics AvailableList of Statistics Available


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Slide 11

Sample StatisticsSample Statistics

Call volume of a cell by

cell basis Dropped Call Rate per cell 1 Hr Period of Measurement


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Slide 12

Call VolumeCall Volume

Represents the total number of call attempts to the cellRepresents the total number of call attempts to the cell

Computed on a cell by cell basisComputed on a cell by cell basis

Gives an indication of the total number of calls that can be billed byGives an indication of the total number of calls that can be billed by

the operatorthe operator

By trending this parameter, the optimisation engineer will have a clearBy trending this parameter, the optimisation engineer will have a clearindication of the suitability of this cell for serviceindication of the suitability of this cell for service

Very low call volume indicates that cell may be used in desert areas for coverageVery low call volume indicates that cell may be used in desert areas for coverage

only or, if located in urban areas, cell is not necessaryonly or, if located in urban areas, cell is not necessary

Progressive high call volume will trigger the need for more TR s or more sitesProgressive high call volume will trigger the need for more TR s or more sites



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Slide 13

Call Volume Per CellCall Volume Per Cell

Call volume of a cell by

cell basis

Note however that the largest call volume does not always

correspond with the largest number of TCH assignments

Also note that it does not always correspond with the largest

Erlang figure supported during this hour of measurement


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Slide 14

Call Setup Success RateCall Setup Success Rate

It is the probability of a subscriber being able to setup a call but notIt is the probability of a subscriber being able to setup a call but not

necessarily make a callnecessarily make a call

The call has to be assigned an SDCCH and then a voice channel orThe call has to be assigned an SDCCH and then a voice channel or

TCHTCH

The call setup success rate depends depends upon a counter which isThe call setup success rate depends depends upon a counter which is

incremented immediately after the network has successfully allocatedincremented immediately after the network has successfully allocated

an SDCCH and the ciphering and authentication processes have beenan SDCCH and the ciphering and authentication processes have been

successfully completed.successfully completed.

It does not measure call completion rate and is therefore alwaysIt does not measure call completion rate and is therefore always

higher than actual call success rate.higher than actual call success rate.


%100]SDCCH_ON_INIT_SMS+RSP_PAGE+REEST_CM+EMERG_REQ_SERV_CM+CALL_REQ_SERV_CM_PROC_ACC_OK

CALLS_TOTAL[=CSSR


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Slide 15

Call Drop RateCall Drop Rate

The dropped call rate defines the ratio of the number of calls whichThe dropped call rate defines the ratio of the number of calls which

are terminated from the network to the number of call attemptsare terminated from the network to the number of call attempts

This represents the most important parameter for optimisationThis represents the most important parameter for optimisation

It is not defined as the ratio of dropped calls to total TCH allocationIt is not defined as the ratio of dropped calls to total TCH allocation

attemptsattempts


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Slide 16

Call Drop RateCall Drop Rate

Call Drop Rate


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Slide 17

Assignment Success RateAssignment Success Rate

Defines the ratio of the number of TCH assignments made by a cell toDefines the ratio of the number of TCH assignments made by a cell to

the required number of TCH assignments at the start of calls andthe required number of TCH assignments at the start of calls and

during handoverduring handover



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Slide 18

Assignment Success RateAssignment Success Rate

Assignment Success Rate


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Slide 19

Handover Success RateHandover Success Rate

Represents the handovers that were successful as a percentage on aRepresents the handovers that were successful as a percentage on a

cell basiscell basis

It is the ratio between raw statistics of successful handovers due to anIt is the ratio between raw statistics of successful handovers due to an

intraintra--cell, intra BSC and inter BSC and the number of attempts forcell, intra BSC and inter BSC and the number of attempts for

each of these handovers that were peggedeach of these handovers that were pegged


%100]ATMPT_HO_SS_INTRA_O T+ATMPT_HO_CELL_INTRA+ATMPT_HO_SS_INTER_O T

S CC_HO_SS_INTRA_O T+S C_HO_CELL_INTRA+S C_HO_SS_INTER_O T[=HSR


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Slide 20

Handover Failure RateHandover Failure Rate

Indicates in percentage the handovers attempted but which failed on aIndicates in percentage the handovers attempted but which failed on a

destination cell and did not redestination cell and did not re--establish on the original cellestablish on the original cell

Counter is incremented on the destination cellCounter is incremented on the destination cell

It is the ratio between the raw statistics of handovers and the totalIt is the ratio between the raw statistics of handovers and the total

number of attempts that were made.number of attempts that were made.

WhereWhere

Note that HSR + HFRNote that HSR + HFR {{ 100% because some handovers attempts100% because some handovers attempts

result in dropped callsresult in dropped calls


%100]ATMPT_HO_SS_INTRA_O T+ATMPT_HO_CELL_INTRA+ATMPT_HO_SS_INTER_O T

DELTA-ATMPT_HO_SS_INTER_O T+MS_LOST_HO_SS_INTRA_O T+MS_LOST_HO_CELL_INTRA[=H R

RET RN_HO_SS_INTER_O T+S C_HO_SS_INTER_O T=DELTA


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Slide 21

SDCCH Congestion Key (SD CONG)SDCCH Congestion Key (SD CONG)

Represents in percentage the SDCCH congestion on a cell by cellRepresents in percentage the SDCCH congestion on a cell by cell

basisbasis

It is the ratio of the failures in allocating an SDCCH to the total numberIt is the ratio of the failures in allocating an SDCCH to the total number

of bids that was attemptedof bids that was attempted

This parameter will include congestion during handovers if an SDCCHThis parameter will include congestion during handovers if an SDCCHhandover is enabled for cellshandover is enabled for cells

The SDCCH congestion key is usually high in the LAC area borders.The SDCCH congestion key is usually high in the LAC area borders.

Cells at the border may therefore require additional signallingCells at the border may therefore require additional signalling

channels.channels.


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Slide 22

SDCCH UsageSDCCH Usage

Network

IMSI Attach and DetachIMSI Attach and Detach

Location updates during idle and dedicated modesLocation updates during idle and dedicated modes

LAC 1LAC 2


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Slide 23

Macro

Macro

Micro

Service

Handovers, if enabledHandovers, if enabled


handover


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Slide 24


EmergencyNumber Dialling

and Service

Supplementary Services

Call forward

Call barring

SMS

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Slide 26

TCH Congestion KeyTCH Congestion Key

TCH Congestion Key


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Slide 27

Cells may go into TCH congestion due to the following:Cells may go into TCH congestion due to the following:

Large increase in traffic due a festival or other event taking placeLarge increase in traffic due a festival or other event taking place

Hardware radio failure in same cellHardware radio failure in same cell

Hardware radio failure in adjacent cellHardware radio failure in adjacent cell

High SDCCH Congestion in same or adjacent cellHigh SDCCH Congestion in same or adjacent cell

Calls being established on or maintained on cells which are draggingCalls being established on or maintained on cells which are dragging



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Slide 28

Tracking ProblemsTracking Problems

If high TCH congestion exists, by examining the BUS _TCH_MAIf high TCH congestion exists, by examining the BUS _TCH_MA

counter, we can establish how many timeslots have been used.counter, we can establish how many timeslots have been used.

We can also examine the AVL_TCH counter to give an indication ofWe can also examine the AVL_TCH counter to give an indication of

how many timeslots are available.how many timeslots are available.

If BUS _TCH_MA is very much less than AVL_TCH, but congestionIf BUS _TCH_MA is very much less than AVL_TCH, but congestionis high, then there is a high probability of radio failureis high, then there is a high probability of radio failure

If SUP Congestion is low, but TCH congestion is high, then too manyIf SUP Congestion is low, but TCH congestion is high, then too many

handovers may be occuringhandovers may be occuring



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Slide 29

SUP Congestion (Setup Congestion)SUP Congestion (Setup Congestion)

SUP Congestion key is an indication of failure in the assignment ofSUP Congestion key is an indication of failure in the assignment of

TCH.TCH.

It provides customerIt provides customer--experienced congestion for traffic channelsexperienced congestion for traffic channels

because it is triggered every time a call is blocked after the call setupbecause it is triggered every time a call is blocked after the call setup

phase.phase. It can be used to monitor the diffference between handover blockingIt can be used to monitor the diffference between handover blocking

and starting calls blocking.and starting calls blocking.



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Slide 30

SUP Congestion KeySUP Congestion Key

SUP Congestion Key


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Slide 31

SDCCH RF Loss RateSDCCH RF Loss Rate

Ratio of terminations on the SDCCH because of radio link loss inRatio of terminations on the SDCCH because of radio link loss in

relation to transactions established on an SDCCHrelation to transactions established on an SDCCH


%100

EMERG_PROC_OK+

SMS_PROC_ACC_OK+DET_IMSI_PROC_ACC_OK+

UPD_LOC_PROC_ACC_OK+RSP_PAGE_PROC_ACC_OK+

REEST_CM_PROC_ACC_OK+SERV_CM_PROC_ACC_OK

SDCCH_LOSSES_RFG

(%)RateLOSS_RF_SDCCH


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Slide 32

TCH RF Loss Rate (RF_TCH_LOSS)TCH RF Loss Rate (RF_TCH_LOSS)

Indicates as a percentage the ratio of calls that were terminatedIndicates as a percentage the ratio of calls that were terminated

because of a radio link loss in relation to calls that have already beenbecause of a radio link loss in relation to calls that have already been

allocated a TCHallocated a TCH

Counters are incremented if the link is lost due to coverage deficiencyCounters are incremented if the link is lost due to coverage deficiency

or due to interferenceor due to interference

Counters are not incremented due to congestionCounters are not incremented due to congestion


%100]SUC_HO_BSS_I H TRA_I H+SUC_HO_BSS_I H TER_I H+CALLS_TOTAL

TCH_LOSSES_RF[

I

(%)RateLOSS_RF_TCH


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Fresh Field Mtc 004 Section 2