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Omnitele Ltd. 20031

Testing of GSM

[email protected]

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Contents GSM network quality audit

Network quality benchmarking Optimisation

Statistics / Operation & Maintenancemeasurements

Field measurements

GPRS measurements Testing of special features

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GSMRadio Network Quality Audit

and Optimisation

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Background On what basis does the customer rate GSM operators quality ?

_ Prices

_ Coverage area_ Call blocking/dropping_ Speech quality_ Customer service

_ Else?

The user experienced service quality in GSM links directly to theperformance of the radio network

Differentiation from competitors

Radio networkquality related!

Radio networkquality related!

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Optimisation outcome ? Network optimisation is a tradeoff between quality,

traffic/revenues and investments.

Without fine-tuned network the customer complaints are increa work load is increased and marketing becomes inefficient

Do you know how your network is performing ?

Direct impact on customer satisfaction !

GSMnetworkindicators ofEuropeanoperatorcustomer

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Network quality benchmarking

How does your networks quality matchagainst the competitors ?

and against the world standard ?

Quality Survey /

Urban area

Call

success

rate

Handover

success

rate

DL

signal

quality

DL signal

power level

MS TX

power class

900

MS TX

power class

1800

Handovers/

call

SQI

MTC 95,70 % 97,90 % 0,4 -67.1 dBm 9,6 5,0 3,6 28,1

Competitor 96,80 % 99,00 % 0,4 -61.6 dBm 5,5 3,5 3,5 28,8

Operator 1 (+1m) 97,90 % 99,20 % 0,2 - 8,7 1,8 2,5 29,1

Operator 2 (+1m) 96,90 % 95,50 % 0,5 - 7,2 1,5 1,4 28,2Operator 3 (< MTC) 95,40 % 96,10 % 0,6 - 7,8 N/A 3,1 27,3

Operator 4 (< MTC) 95,20 % 95,00 % 0,3 - 8,7 N/A 1,7 28,9

Operator 5 (< MTC) 95,20 % 99,10 % 0,5 - 7,3 1,4 2,4 28,8

Examplebenchmarkingstatistics

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Field measurements

Benchmarking Troubleshooting

_ statistics, customer complaints Base station start-up

Testing equipment_ Testing software e.g. TEMS Ericsson in a laptop_ Test mobile phones (one or more)

_ Indoor/outdoor antenna_ Cables + battery chargers

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Field measurements

Testing route_ Roads, train

_ Hot spot, pedestrian_ Urban, suburban, rural

Test setup_ Idle mode_ Continuous call_ Call sequence (90s calls / 15s idle)

Tested frequencies: 900/900E/1800

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Example _ Call Success Rate

93,0 %

94,0 %

95,0 %

96,0 %

97,0 %

98,0 %

99,0 %

Call success rate

GSM1800 large European

GSM900/1800 large

European

GSM900/1800 largeEuropean

GSM900 small Middle East


GSM900/1800 large

European

GSM900/1800 large

European

GSM900 very small

European

GSM900 small European

GSM900/1800 very small

Middle East

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Example _ SQI

0

5

10

15

20

25

30

35

SQI (max 30)

GSM1800 large European


GSM900/1800 large

EuropeanGSM900 small Middle East



GSM900/1800 large

European

GSM900 very smallEuropean

GSM900 small European

GSM900/1800 very smallMiddle East

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Network quality benchmarking Could there be an indicator that shows your network is

underperforming ?

Independent benchmark needed What kind of action should be taken to improve the

situation ?

Correctly targeted networkoptimisationQuality Survey /Urban area Callsuccess

rate

Handover

success

rate

DL

signal

quality

DL signal

power level

MS TX

power class

900

MS TX

power class

1800

Handovers/

call

SQI

MTC 95,70 % 97,90 % 0,4 -67.1 dBm 9,6 5,0 3,6 28,1

Competitor 96,80 % 99,00 % 0,4 -61.6 dBm 5,5 3,5 3,5 28,8

Operator 1 (+1m) 97,90 % 99,20 % 0,2 - 8,7 1,8 2,5 29,1

Operator 2 (+1m) 96,90 % 95,50 % 0,5 - 7,2 1,5 1,4 28,2

Operator 3 (< MTC) 95,40 % 96,10 % 0,6 - 7,8 N/A 3,1 27,3

Operator 4 (< MTC) 95,20 % 95,00 % 0,3 - 8,7 N/A 1,7 28,9

Operator 5 (< MTC) 95,20 % 99,10 % 0,5 - 7,3 1,4 2,4 28,8

Examplebenchmarkingstatistics

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Network optimisation process

Customer

Feedback

Field measurements

and performance

evaluations

Operation &

Maintenance

Measurements

Postprocessing

INPUTSMANAGEMENT

MARKETING

CUSTOMER

SERVICE

NETWORK

PLANNING

Continuous process!

Benchmarking

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Optimisation targets

Satisfied customers

Maximum utilisationof hardware

Effective andeconomic use

of network !

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Troubleshooting

Handover problems

Quality problems Coverage problems & New site location identification Network layers fine-tuning Capacity problematics LAC optimisation New feature implementation (software and hardware) Micro cells introduction

Indoor coverage fine-tuning BSS parameter fine-tuning

Omniteles engineers are experienced to encountethe major issues effecting the quality of GSM netw

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Dual Band considerationsDual Band Strategy

Spectrum requirements

Network evolution

from traffic hot spots to seamless coverage

900/1800 spectrum for indoor / outdoor,

interference reduction, data

Capacity gain calculations for different scenarios

Planning and Implementation

Planning methods

BSS parameters

Site suitability criteria Sharing of RF components

Planning / measurement tool requirements

Planning and Implementation

Planning methods

BSS parameters

Site suitability criteria Sharing of RF components

Planning / measurement tool requirements

Utilisation Traffic steering between

900/1800 layers

Parameter optimisation Coverage/capacity GPRS strategy

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Interference check perchannel_ Evaluation of the

significance of the residualinterference

_ HO/Cell selection marginshould be included in theanalysis

_ C/Ic (and C/Ia) statistics perchannel

Interference per network_ On the dominance area_ C/Ic (and C/Ia) statistics

_ Shows the overallinterference picture

Interference analysis_ Used by turns with the

allocation in order to

validate (and optimize, ifnecessary) the frequency(reuse) plan

Frequency planning & interference analysis

Frequency planning objectives_QoS objectives

_Overall C/Ic and C/Ia requirements_Cell-to-cell C/Irequirements

13,1

6,13

5,13

13,8

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n er erence re uc on

means Antenna redirection the most predictable

coverage is in danger

Antenna tilting ideally very useful: steepens

the slope

in practice difficult to predict

should be always measured useful for large clearence

angles

Power reduction UL/DL interference power

balance is lost coverage is lost

not recommended

All interference reduction meansmay generate problems in other

frequencies

Optimising is done frequency by frequency

Reducing interferenceImproves network quality!

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Optimising adjacencies & LAC Missing neighbours very often result in unnecessary

dropped calls and bad quality

Correct neighbour relations can be determined by

analysing measurement results

Unnecessary LAC updatescan easily increase the

singalling load significantl

Increased signallingreduces the room for payloa

Are your adjacenciesand LACs optimised ?

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Optimising parameters

newconclusions

measure the performance andcompare to the ref. performance

+

change the cell parametersunder optimisation

-

apply the changes permanentlyin the network/service area

happy with theresults ?

select the set of performanceparameters and test cells

study theoretically the impactof the intended change

measure with a test MS

happy with theresults ?

-

+

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ase per ormanceparameters

QOS as well as RF and capacity planning parameters assessedper cell, per BSC and per network QOS parameters_ Dropped call rate_ Dropped call rate due to radio_ Cumulative UL/DL quality

statistics_ TCH BH blocking rate_ SDCCH BH blocking rate

_ (Call setup success rate)_ (Handover success rate)

RF planning parameters_Number of calls_TCH RF loss rate

_SDCCH RF loss rate_TCH mean holding time_Handovers per call_Cumulative UL/DL level statistics

_Idle channel UL interference_Power balance

Capacity planning parameters_TCH BH traffic (e.g. weekly and average of daily BH traffics)

_BH activity per subscriber (segment)_Total TCH time (per subscriber)_SDCCH weekly BH traffic_BH paging load

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Example _ BH traffic

20 June: 290 000 subs 17 mErl/subscriberMean holding time ? -> BHCA/subscriber

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Conclusion The GSM network optimisation process consists of

complex technical measurements and analysis Every network is individually planned and thus have

individual problems which decrease the quality Professionally performed optimisation will increase

customer satisfaction GSMnetworkindicators ofEuropeanoperator

customer

How to increase the quality and capacitywith minimum investments ?

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How can Omnitele assist you?

Radio network quality auditand optimisation

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How often?How often? Regularly, e.g. once a year

Where?Where? Predefined areas

How?How?

Performing the quality audit

Why?Why? To observe and follow thequality of the network

With measurementsBy comparing

Who?Who? Independent from theoperator and vendor

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Complete analysis of the qualityperceived by subscribers

Location of interference, inadequatesignal strength and quality, congestion

On-the-job training for Operators ownstaff

Proposal for corrective actions in bothshort and long term

Comparison to the competitors and

world class standard

Network quality audit

-- Objectives --

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Network quality audit-- Area definition --

The most important cities, roads, suburbs

Same basic area every time, expanded with

possible new coverage areas

Areas representing different kind of coverage,different subscriber density etc.

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ca. 1/3 of the # of cells in thearea

30 min. of driving for each

covering the whole sub-servicearea

distinction of areas with different

required coverage probabilities following the foreseen traffic

distribution

all HO pairs tested

closing loops & major highways

marketing should be consulted

emphasis on the city

the most important roads the most important suburbs

the areas with foreseendifficulties

Measurement route definition

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In addition to complete quality audit weekly

measurements are recommended


-- Regularity --

Once a year if the network is quite stable

More often if the network is still under

construction

N k li di

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--The auditor --Should be independent from the OperatorsTechnical Department and the Vendor

Because, then ...

The comparison will be objective

Should have experience from other networks

The Operator gets the information what is t

performance level of the network comparedthe other networks

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Quality audit-- Comparison --

Comparison with previous quality auditsComparison with competitors

By Quality Index

Predefined criteria the network should fulfill

Quality Index (measured indicators)

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Long and extensive experience on radio network planning_ Dimensioning and nominal planning_ Site planning_ Parameter planning_ Network tuning and optimisation

Experience from several equipment suppliers

Projects:

GSM planning in Finland_ Radiolinja project (worlds first GSM network)_ GSM1800 city networks_ Ongoing Finnish 2G project (3rd Finnish operator)

GSM planning abroad_ Italy Czech republic_ Netherlands Brazil

Why Omnitele ?

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GSM network dimensioning/nominal planning for start-up operators_ Tanzania_ Jordan_ Pakistan

Network audits and optimisation projects_ Finland

Radiolinja City networks

Finnish 2G_ Abroad:

Greece Ivory Coast Kuwait Togo Jersey Czech Republic

Guernsey Faroe Islands Cyprus Andorra Bahrain

Why Omnitele ?

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GPRS Optimisation ingeneral

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Optimisation Process

Input

The business strategy for GPRS

Existing and desired quality of the

network (field measurements & OMC

studies):

Congestion

QoS of the existing network

InterferenceDifferent vendor solutions

Required services and expected

usage

Input

The business strategy for GPRS

Existing and desired quality of the

network (field measurements & OMCstudies):

Congestion

QoS of the existing network

InterferenceDifferent vendor solutions

Required services and expected

usage

Output

Optimal parameter settings:

Dedicated/dynamic radio

capacity allocation

Traffic steering between the

radio layers

Coding scheme adaptation

Different timers

Optimal hardware configurationProtocol optimisation

Key performance indicator

definition and measurements

Future plan winner strategy

Output

Optimal parameter settings:

Dedicated/dynamic radio

capacity allocation

Traffic steering between theradio layers

Coding scheme adaptation

Different timers

Optimal hardware configuration

Protocol optimisation

Key performance indicator

definition and measurements

Future plan winner strategy

Best quality with minimum investment

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Measurement System Set-upEnd-to-End data performance

GPRS layer data performance

RF performance

Data at

application layer

Data at

RLC/LLC layer

Air-interface

Data at

application layer

Data at

RLC/LLC layer

Air-interface

GPRS Mobile Server

End-to-End data performance

GPRS layer data performance

RF performance

Data at

application layer

Data at

RLC/LLC layer

Air-interface

Data at

application layer

Data at

RLC/LLC layer

Air-interface

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Monitored Key Performance Indicators

(KPI) C/I of the measured channels

Average RLC throughput (kbit/s) Average LLC throughput (kbit/s)

Average number of timeslots used by a single user

CS usage (% of time in the CS1/CS2 *)

Average cell reselect time Network response time (RTT)

RLC bit error rate

*) Available only in networks with dynamic CS adaptation

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GPRS Parameter Planning (1) Goals: To handle GPRS in cells with high CS (speech)

traffic To steer the GPRS traffic to wanted cells

Adequate definition of GPRS timers

Radio interface capacity division between CS/PS Optimise the performance of specific service

Optimised end-user experience !

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GPRS Parameter Planning (2) Omnitele has profound hands-on experience with Alcatel GPRS parameters

Ericsson GPRS parameters Nokia GPRS parameters

Daily planning &Optimising

Drive tests

Troubleshooting

Measuring GPRS network performance

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Measuring GPRS network performance

Number of timeslots used permobile

Coding scheme

usage

Data flowbehaviour

Re-

transmissions Cell re-

selections, RA

updates etc.

RLC and LLC

Throughput

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GPRS Networkperformance

benchmarking

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Why benchmark the network

performance ?

Performance of the GPRS networks vary significantly

between the operators

The QoS status of operators GPRS network is best

determined by benchmarking the network performance against competitors performance and/or world class operators

operating in different markets

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Benchmarking Results

Examples

33.331.3

33.231.3

34.7

32.4

15.0

20.0

25.0

30.0

35.0

X Y Z

Throughput DL [kbit/s]

RLC Throughput [kbit/s]

LLC Throughput [kbit/s]

1.5

1.8

1.1

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

X Y Z

Network response time (s)

Network response

time (s)

Example country:

Three nation-wide GPRS operators

Same drive routes in the benchmarking

Significant differences in KPIs of the three operators

I i h P f f

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Improving the Performance of

Your Network

After benchmarking the GPRS performance, theproblem areas will be identified

Recommendations for improvements are given

Service optimisation plan will be made

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BSC Measurements

In addition to end-to-end field measurements, BSC measurements

can be performed from the BSC of the benchmarked operator

Better overall picture of the problem cells: Suggestions to

improvements

Some of the key issues that can be identified from BSC are:

Overall GPRS traffic

Blocking of GPRS calls

Retransmissions

PCU loading

Note: The BSC measurements can only be benchmarked against

Omnitele archive since there is no access to competitors BSC

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How can Omniteleassist you ?

Example of Omnitele s GPRS Projects

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Example of Omnitele s GPRS ProjectsNetwork acceptance and optimisation

1 Int roduc tion

2 Descript ion of field measurements2.1 GPRS measurement model2.1.1 Application layer performance measurements2.1.2 GPRS layer performance measurements2.1.3 RF performance measurements2.2 Monitored Key Performance Indicators2.2.1 Carrier t o Interference rat io for t he measured channels (dB)

2.2.2 Coding scheme usage (%)2.2.3 RLC/LLC throughput (kbit/s)2.2.4 Cell reselection t ime (s)2.2.5 Routing area update time (s)2.2.6 Network response time (s)

3 Findings during the Installat ion3.1 Alcatel acceptance tests

3.1.1 MFS acceptance tests3.1.2 Core acceptance tests3 .2 Detect ed problems3.2.1 MFS3.2.2 Core

4 Integrat ion t est ing4.1 Carrier to Interference rat io4 .2 Coding scheme usage4.3 Throughput4.3.1 Normal cell load t hroughput measurements4.3.2 High cell load throughput measurements4 .4 Cell reselec tion4 .5 rou ting area update time4.6 Network response t ime4.6.1 Pinging with Windows Command prompt4.6.2 Pinging with different int ervals between the pings

5 GPRS Parameter fine-tuning5.1 Further routing area update testing5.2 Optimisation of the coding scheme usage

5.2.1 CS_Lev parameter5.2.2 CS_Qual_1_2 / CS_Qual_2_15.2.3 TBF_CS_Period1 / TBF_CS_Period25.3 Congestion control5.4 network response time optimisation5.5 Other investigated issues5.5.1 Frequency scans in the east coast5.5.2 Missing adjacencies

6 Comparison of finnish GPRS operators networkPerformance indicators6.1 Throughput6.2 Cell Reselection time (s)7 comparison of different vendors GPRS features7.1 Automatic Link adaptation (ALA)7.2 Congestion control7.3 Multiplexing users into the Timeslots7.4 TRX preference

8 suggestions for GPRS network development8.1 Alcatel GPRS core rel2 and BSS software B78.2 Traffic monitoring8.3 Air-Interface compression software9 Conclusion

H C O it l A i t Y ?

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How Can Omnitele Assist You?

Contract negotiations:

Assistance in definition of the technical framework to the systemspecifications: How should the GPRS system perform?

Hands-on experience: Alcatel, Ericsson and Nokia GPRS systems

Implementation:

Verification of the system performance: Specification of the operatoracceptance tests and system integration tests

Parameter planning, parameter fine-tuning and optimisation of the GPRS

network Service optimisation:

WAP&Web: Parameters&timers

Content optimisation: Performance Enhancement Proxy selection process

MMS: Radio capacity optimisation

GPRS performance benchmarking

Comparison of your GPRS networks performance to your competitors

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Please visit our web sitewww.omnitele.fi

for more information

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