154461060 GSM Cell Planning and Optimization

8/12/2019 154461060 GSM Cell Planning and Optimization

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By Sumantri Pramudiyanto (+6281703544310)

Jakarta, April 7th, 2009

GSM Cell Planning and Optimization

Study Case : Sragen Area

Materi berikut merupakan open content, bersifat free utk didistribusikan


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Content

Cell Planning Process

Idle Mode Operation

BSS Parameter

RF Optimization flow chart Study Cases of RF Optimization


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Cell Planning Process

Cell planning can be described briefly as all the activities involved indetermining which sites will be used for the radio equipment, which

equipment will be used and how the equipment will be configured


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Traffic and coverage Analysis Collecting required data

Making discussion with the client to know their demand.Analyzing traffic and coverage

Required data :

Geography data

Demography data Data of around network

Available frequency

Number of customer which

wish to cover

Customer demand :

GOS 2%

95 % Indoor coverage

(C/I > 12 db) > 95%


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Nominal Cell Plan - Dimensioning (1)

Geography and Demography data taken from sragen.go.id

Table 1 Geographic +Demographic data Table 2 Demographic data per years

Wide of area which will be covered

Target subscriber

After the data available, we need to divided the region intosmaller cluster, then classify the subdistrict into clusterdepend on traffic, contour area, and etc.

From the demographic data (Table 2) , we able to calculate% growth of population.

573333 = 437556 x (1+r)6

r = 0.046

Assume that, in 2010 the operator want to cover 10 %subscriber in the region, so the number of subscribers to becovered :

Pt = 10 % x 57333 x (1+0.046)3

Pt = 65629

If traffic allocation per subscriber equal to 60mE then totaltraffic in Sragen area = 65629 x 60 mE = 3937.74 E

nrPoPt )1(


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Nominal Cell Plan - Dimensioning (2) From the geographic data we can determine Erlang distribution by

density in each cluster.

The next step, we can calculate the number of required sites depend ontraffic.

Using erlang B table we can count number of sites for cluster sragen tengah(GOS 2%, 1585.85 Erlang)1586 TS ~ 227 TRX

Sragen tengah locate in center of town and has high traffic we useconfiguration 5/5/5 so the number of sites required in this cluster :

227/15 TRX = 15 Sites

With the same way we can calculate number of sites for the others cluster:Sragen Timur = 9 sites (Config 4/4/4)

Sragen Barat = 12 sites (Config 4/4/4)

Sragen Utara = 9 sites (Config 4/4/4)


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Nominal Cell Plan Link Budget Link Budget Calculation is required to achieve system balance between

uplink and downlink signal.

Output from system balance is a cell size in every sites. We can calculate coverage area per sites in suburban and rural cluster by

equation L = k x R2

Lsite suburban = 1.95 x (1.865)2= 6.78 km2

L site rural = 1.95 x (2.67)2 = 13.90 km2

The next step, calculating number of sites related to coverage.

Choose the biggest one


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Nominal Cell Plan - Result

Sragen Utara

Sragen Timur

Sragen Tengah

Sragen Barat


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CW Test / Model Tuning In order to find out appropriate

propagation model, RF Engineershould perform CW Test.

Drivetesting should be performed

encircle the route and represent

all of azimuth. Input all of drivetesting result to

the planning tools then

conducting calibration to get

appropriate propagation model.


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Survey

Survey is required to ensure whether the nominal cell

position can be realized or not ? In general, The RF Team should give alternative

nominal or informed SAR ( 300m) to survey team, in

case the nominal cannot be realized.

The survey team should take the panoramic photoaround the nominal (0-360 degree), and report to the

RF team if appear obstacle around the nominal.

Panoramic photo used to determine coverage

target/azimuth

Survey team also need to survey : road to nominal,

electricity, space for equipment.


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Detail Planning All of nominal coordinates must be fixed in detail

planning phase.

Scope of works in Detail Planning : Frequency Planning

Parameter Planning (BSIC, MAList, MAIO, HSN, etc) Adjacency planning

The main key in conducting frequency planning is

avoiding co-channel and adjacent interference.

For TCH Frequency planning, we able to apply SFH or

Baseband hopping in order to reduce the interference.


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Allocation

SFH Pattern 1x1 will be applied in this implementation

Number of Malist frequencies can be calculated by using

equation :

Maximum configuration for the sites 5/5/5, so that number ofrequired frequencies :

Nfreqs/site= (12 3 ) x 2 + 3.2 = 24 Frequencies

FL =

NTRX

# HoppersX 100%

3 sectors with 24 hopping frequencies :

-TCH = 3 TRXs FL = (3/24)*100% = 12,5%

-TCH = 4 TRXs FL = (4/24)*100% = 16,67%


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Detail Planning Frequencies Allocation

MAIO = 0 8 16

MAIO Step = 2

SFH Allocation untill configuration 5/5/5


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Detail Planning HSN Planning

Drivetest for QOD Program.ppt / 24.04.2008 /

VS

HSN used to the parameter that differentiates the

hopping algorithm between two cells having the sameMAList.

We can choose best pairs HSN to reduce collision

frequencies between server and adjacent.


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Detail Planning Coverage Result

NCC = 4,5

NCC = 2,3

NCC = 0,1

NCC = 5,6

D t il Pl i I t f P di ti


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Detail Planning Interference Prediction


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Installation and System Tuning

After Installation done, the installation team need to

conduct commisioning (VSWR Measurement, checkhardware installation )

The Drive test team also need to verify whether the

BTS serving target correctly or not

Then, Acceptance Test Procedure is conducted to

check how well the KPI meets the demand.

Pre Launch Optimization performed to achieve the KPI

Target for new site or TRX expansion.


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IDLE MODE OPERATIONNormal Cell Selection

Search all the RF channels , take samples during 3-5 s and

calculate averages. And put them in ascending order with respect to

signal level. Then tune to the strongest RF channel.

Search for the frequency correction burst in that

carrier in order to varify if it is a BCCH carrier

Camp on the cell

Try to synchronize to the carrier and read

the BCCH data.

Is it a BCCH

carrier?

Is it a correct

PLMN ?

Is the cell barred?

Is C1>0

Tune to the next highest

RF channel which is not

tried before

No

No

NoNo

Yes

Yes

Yes

Yes

C1 = (A - Max(B,0))

A = Received Level Average -

p1

B = p2 - Maximum RF Output

Power of the Mobile Station

p1 = rxLevelAccessMin

Min. received level at the

MS required for access to

the system

p2 = msTxPowerMaxCCH Max.

Tx power level an MS may

use when accessing the

system


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Cell Reselection

C1 + cellReselectOffset - temporaryOffset*H(penaltyTime-T) T < = penaltyTime

C2 =

C1 + cellReselectOffset . T > penaltyTime1 when T < = penaltyTime

H(x) =

0 when T > penaltyTime


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Cell Reselection Histerysis

BSS P t


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BSS ParameterBTS Parameter

RxLevAMI (0-63)Minimum signal strength for access the BTS in idle mode.

CRESOFF (Cell Reselection Offset) (0-25)used for C2 Calculation, normally used in dualband network (GSMDCS)

RACHBT (RACH Busy Threshold) (0-127)defines a threshold for the signal level on theRACH

HRACTT1 (0-100)Half Rate Activation Threshold

T3212 (0-255)Parameter LUP Periodically

MAXRETR (1,2,4,7)Maximum Retransmission on RACH

SDCCHCONGTH (0-100)SDCCH Congestion threshold

RDLNKTO (0-15)Timer for Radiolink timeout

Power Control Parameter

LOWTLEVD/U (0-63)the lower threshold of the received signal level on the downlink/uplinkfor power increase

UPTLEVU/D (0-63)defines the upper threshold of the received signal level on theuplink/downlink for power reduction

LOWTQUAD/U(0-7) the lower threshold of the received signal quality on the downlink forpower increase

UPTQUAU/D (0-7)defines the upper threshold of the received signal quality on the uplinkfor power reduction

PWRINCSS (DB 2,4,6)defines the step size used when increasing the MS transmit power

PWREDSS (DB 2,4)defines the step size used when reducing the MS transmit power

BSS P (2)


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BSS Parameter (2)Handover Parameter

HOLTHLVDL/UL (0-63) defines the receive signal level threshold on the downlink

/uplink for inter-cell level handover decision.

HOLTHQUDL/UL (0-7) defines the receive signal quality threshold on the

downlink/uplink for inter-cell quality handover decision

Adjacent Parameter

RXLEVMIN the minimum received signal level the adjacent cell must provide to be

regarded as a suitable target cell for handover

HOM Handover margin for better cell

LEVHOMparameter defines the handover margin for handovers due to uplink level or

downlink level

QUALLEVHOM this parameter defines the handover margin for handovers due to

uplink quality or downlink quality

RF O ti i ti Fl Ch t


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RF Optimization Flow Chart

Start

Identify KPIFormula

Identify the problems

SDSRProblems ?

CheckTRX

Quality

CheckAlarm

CheckInterference

Check all otherscause (Radio link

Failure, T200,Transcoder) from

statisticsHOSR

Problems ?

CheckSDCCHBlocking

CheckTCH

Blocking

Check Alarm

Check co-channel and

co-BSIC

CheckInterference

CheckNeighborRelation

CheckHandover

Failure PerCause

Check

HandoverParameter

DCR Problems

CheckTRX

Quality

Check Alarm

Check co-channel and

co-BSIC

Check TA

Check

Interferenceproblems

Check Malist,MAIO and

HSN

Checkmeasurementfrom statistics

Take Actionlist

Y

Y


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Conclusion

Every New Network need good plan for avoidproblems that will be arise.

Commonly there are six step in conducting

planning.

The most critical problems in performing cell

planning process is interference.

the New Sites onair need to be optimized to

achieve the KPI Pre Launch Optimization is done for new sites on

air or expansion sites.

154461060 GSM Cell Planning and Optimization

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