By Sumantri Pramudiyanto (+6281703544310)Jakarta, April 7th , 2009

GSM Cell Planning and OptimizationStudy Case : Sragen Area

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ContentCell Planning ProcessIdle Mode OperationBSS ParameterRF Optimization flow chartStudy Cases of RF Optimization

Cell Planning Process

Cell planning can be described briefly as all the activities involved in determining which sites will be used for the radio equipment, which equipment will be used and how the equipment will be configured

Traffic and coverage AnalysisCollecting required dataMaking discussion with the client to know their

demand.Analyzing traffic and coverageRequired 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%

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 into

smaller cluster, then classify the subdistrict into cluster depend 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 be covered :

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

Pt = 65629

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

nrPoPt )1(

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 on traffic.

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 use configuration 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)

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

Link Budget

Nominal Cell Plan - Result

Sragen Utara

Sragen Timur

Sragen Tengah

Sragen Barat

CW Test / Model TuningIn order to find out

appropriate propagation model, RF Engineer should 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.

SurveySurvey 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 photo around 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.

Detail PlanningAll of nominal coordinates must be fixed in detail

planning phase.Scope of works in Detail Planning :

Frequency PlanningParameter 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.

Detail Planning – Frequencies 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 of required 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%

Detail Planning – Frequencies Allocation

MAIO = 0 8 16

MAIO Step = 2

SFH Allocation untill configuration 5/5/5

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 same MAList.

We can choose best pairs HSN to reduce collision frequencies between server and adjacent.

Detail Planning – Coverage Result

Coverage Prediction Sragen Kota

Coverage Prediction Sragen Utara

Coverage Prediction Sragen Timur

Coverage Prediction Sragen Barat

NCC = 4,5

NCC = 2,3

NCC = 0,1

NCC = 5,6

Detail Planning – Interference Prediction

C/I Sragen KotaC/I Sragen Barat

C/I Sragen TimurC/I Sragen Utara

Installation and System TuningAfter Installation done, the installation team

need to conduct commisioning (VSWR Measurement, check hardware 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.

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 = msTxPowerMaxCCHMax.

Tx power level an MS may

use when accessing the

system

Cell ReselectionC1 + cellReselectOffset - temporaryOffset*H(penaltyTime-T) T < = penaltyTime

C2 =C1 + cellReselectOffset …………………………………………. T > penaltyTime

1 when T < = penaltyTime H(x) =

0 when T > penaltyTime

Cell Reselection Histerysis

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 dual

band network (GSM<>DCS) RACHBT (RACH Busy Threshold) (0-127) defines a threshold for the signal level on the

RACH 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/uplink for power increase UPTLEVU/D (0-63) defines the upper threshold of the received signal level on the

uplink/downlink for power reduction LOWTQUAD/U (0-7) the lower threshold of the received signal quality on the downlink

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

uplink for 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 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 LEVHOM parameter 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 Optimization Flow ChartStart

Identify KPI Formula

Identify the problems

SDSR Problems ?

Check TRX

Quality

Check Alarm

Check Interference

Check all others cause (Radio link

Failure, T200, Transcoder) from

statisticsHOSR

Problems ?

Check SDCCH Blocking

Check TCH

Blocking

Check Alarm

Check co-channel and

co-BSIC

Check Interference

Check Neighbor Relation

Check Handover Failure Per

Cause

Check Handover Parameter

DCR Problems

Check TRX

Quality

Check Alarm

Check co-channel and

co-BSIC

Check TA

Check Interference

problems

Check Malist, MAIO and

HSN

Check measurement from statistics

Take Action list

Y

Y

Conclusion Every New Network need good plan for

avoid problems 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 KPIPre Launch Optimization is done for new

sites on air or expansion sites.