gsm rf planning-ptt

7/29/2019 GSM Rf Planning-PTT

http://slidepdf.com/reader/full/gsm-rf-planning-ptt 1/20

RF Network Design

& Planning



Introduction

The high level life cycle of the RF network planning process can besummarised as follows :-

• To help the operator to identify their RFdesign requirement

• Optional

• Discuss and agree RFdesign parameters,assumptions andobjectives with thecustomer

• Coverage requirement•Traffic requirement

• Various level of design(ROM to detail RFdesign)

• Issuing of search ring• Cand. assessment• Site survey, design,approval

• Drive test (optional)

• Frequency plan• Neighbour list• RF OMC data• Optimisation

Comparative Analysis

RF Designrequirement

RF Design

SiteRealisation

RF Design

Implementation



Comparative Analysis

This is an optional step

This is intended to :-

• Help an existing operator in building/expanding their network

• Help a new operator in identifying their RF network requirement, e.g.

where their network should be built

For the comparative analysis, we would need to :-

• Identify all network that are competitors to the customer

• Design drive routes that take in the high density traffic areas of interest

• Include areas where the customer has no or poor service and the

competitors have service



Coverage Design Inputs by BSNL

• Coverage Thresholds

– Indoor Coverage : Signal Level measured at street better than –65

dBm. Indoor coverage to be provided in commercial complexes,

hotels,technology parks etc.

– In Car Coverage: Signal Level measured at street better than –75 dBm.

In Car coverage to be provided in residential areas, highways, tourist

spots etc.

– Outdoor Coverage : Signal level measured at street better than –85

dBm. All remaining areas to be covered with Outdoor coverage.

– These are general guidelines for planning , specific areas not provided.



Capacity Design Inputs by BSNL

• Frequency spectrum available 6.2 MHz (31 channels).

• Average traffic per sub for RF design : 50 mErlang.

• Synthesizer frequency hopping can be used.

• GOS: 2%

• Existing network Database

– Total No. of sites with configuration

– Site details eg location(Lat-Long), Antenna height ,azimuth,



50mE = 3600* 50 * 10-3 = 180seconds = 3 min = Average

Voice call holding time (urban)Rural = 1.5min = 25mErlangs

1 Erlang of network traffic(TCHs)

= 20 no. of users with 50mEindividual traffic (call holding)



RF Network Design

There are 2 parts to the RF network design to meet the :-

• Capacity requirement• Coverage requirement

For the RF Coverage Design

RF

Coverage

Design

Link

Budget

Propagation

Model

Digitised

DatabasesCW DriveTesting

Customer Requirements



CW Drive Testing

CW drive test can be used for the following purposes :-

• Propagation model tuning• Assessment of the suitability of candidate sites, from both coverage and

interference aspect

CW drive test process can be broken down to :-

TestPreparation

Propagation

Test

Data

Processing

• Equipment required

• BTS antenna selection

• Channel selection

• Power setting

• Drive route planning

• Test site selection

• Transmitter setup

• Receiver setup

• Drive test

• Transmitter dismantle

• Measurement averaging

• Report generation



CW Drive Testing - Propagation Test

Scanning Receiver Setup - HP 7475A Receiver Example

HP 7475A Receiver



Propagation Model

Standard Macrocell Model for Asset

Lp (dB) = K1 + K2 log(d) + K3 Hm + K4 log(Hm) + K5 log(Heff)+ K6 log(Heff) log(d) + K7 Diffraction + Clutter factor

where Lp, Diffraction, Clutter factor are in dBd, Hm, Heff are in m

•It is based on the Okumura-Hata empirical model, with a number of additional features to enhance its flexibility

• Known to be valid for frequencies from 150MHz to 2GHz

• Applies in condition :-

– Base station height : 30 - 200 m – Mobile height : 1 - 10 m – Distance : 1 - 20 km

• An optional second intercept and slope (K1, K2) for the creation of a two-piece model with the slope changing at the specified breakpoint distance.



Link Budget

Link Budget Element of a GSM Network

BTS Antenna Gain Max. Path Loss Fade Margin

LNA

(optional)

Feeder Loss

Diversity

Gain

BTS ReceiverSensitivity

ACE

Loss

BTS TransmitPower

Penetration Loss

MS Antenna Gain,

Body and Cable Loss

Mobile Transmit

Power

Mobile Receiver

Sensitivity



Link Budget

BTS Transmit Power • Maximum transmit power • GSM900 and 1800 networks use radios with 46dBm maximum transmit

power

ACE Loss• Includes all diplexers, combiners and connectors.• Depends on the ACE configuration• The ACE configuration depends on the number of TRXs and combiners

used

No of TRXs

Network ACE Configuration Downlink ACELoss (dB)

1 or 2 GSM900 2 antennas per cell, diplexer 1.0

1 or 2 GSM1800 2 antennas per cell, diplexer 1.2

3 or 4 GSM900 2 antennas per cell, diplexer + hybrid combiner 4.43 or 4 GSM1800 2 antennas per cell, diplexer + hybrid combiner 4.4



Link Budget

Penetration Loss

• Penetration loss depends on the building structure and material• Penetration loss is included for in-building link budget

• Typical value used for Asia-Pacific environment (if country specificinformation is not available) :-

– Dense Urban : 20 dB – Urban : 18 dB – Suburban : 15 dB – Rural : 9 dB

Body Loss

• Typical value of 2dB body loss is used

MS Antenna Gain

• A typical mobile antenna gain of 2.2 dBi is used



Link Budget

Link Budget Example (GSM900)

UPLINK DOWNLINKMS Transmit Power 33 dBm BTS Transmit Power 46 dBm

Cable Loss 0 dB ACE Loss ZMS Antenna Gain 2.2 dBi Feeder Loss 2 dB

Body Loss 2 dB LNA Gain 0 dBPenetration Loss W BTS Antenna Gain 18 dBi

Slow Fade Margin X Max. Path Loss YMax. Path Loss Y Slow Fade Margin XBTS Antenna Gain 18 dBi Penetration Loss WLNA Gain 0 dB Body Loss 2 dB

Feeder Loss 2 dB MS Antenna Gain 2.2 dBi

ACE Loss 0 dB Cable Loss 0 dB

Diversity Gain 4 dB Diversity Gain 0 dB

BTS Receiver Sensitivity -107 dBm MS Receiver Sensitivity -102 dBm



Site Realisation

Candidate Assessment Report-Site Survey Forms

• Site survey Forms for all suitable candidates for the search ring• For each candidates :-

– Location (latitude/longitude)

– Location map showing the relative location of the candidates and also

the search ring

– Candidate information (height, owner etc)

– Photographs (360º set, rooftop, access, building)

– Possible antenna orientations

– Possible base station equipment location

– Information for any existing antennas

– Planning reports/comments (restrictions, possibilities of approval etc.)



Site Realisation-Site Survey Form

Final RF Configuration Form

• Base Station configuration

– Azimuth

– Antenna height

– Antenna type

– Down tilt

– Antenna location

– Feeder type and length

– BTS type

– Transmit power

– Transceiver configuration

Date

BSNL Circle

CITY / SSA

Site ID

Site Name

Owner Name

Address & Contact No.

Construction

Tower Type Bldg. Hgt

Tower Hgt Antenna Ht

Coordinate LAT N LONG E

GSM ANTENNA:

AZ M -TILT

SECTOR 1 85° +1.9 Spheroid:

SECTOR 2 185° +0.7

SECTOR 3 307° +1.3

Candidate No.

Assess: Priority

Morphology/Clutter

Site Blockage if Any

Remark

Name: Name:

Signature: Signature:

BSNL/ NBSNL

20 m.

GBT / Rooftop 10 m.

6 m.

TECHNICAL SITE SURVEY FORM

June 12, 2004

BHPAT-09

Bihar

Container/Room

BSNL Survey Team RepresentativeNokia Representative

Accept/ Reject

85° 48 ' 31.2"

AP909014-2

AP909014-2

Patna 09

26° 21' 25.9"

TYPE

AP909014-2



Traffic Engineering

Spectrum

AvailableReuse factor

Maximum number of

TRX per cell

No of TCH

availableTraffic offered

Traffic

Requirement

Subscriber

supported

Channel

loading



Traffic Engineering

•Traffic Requirement

•The Erlang per subscriber

•Grade of Service (GoS)

• GoS is expressed as the percentage of call attempts that are blocked

during peak traffic

• Most cellular systems are designed to a blocking rate of 1% to 5% duringbusy hour



Traffic Engineering

After determining the number of TCH available and the trafficrequirements, the traffic offered is calculated using the Erlang B table

• For example, for a 2% GoS and 3 TRX configuration, the traffic offered is14 Erlang

• If the traffic per subscriber is 50mE/subscriber, then the total subscriberssupported per sector = 280

For a uniform traffic distribution network, the number of sites requiredfor the traffic requirement is :-

site per supportedSubscriber

ssubscriber Total sitesTotal



Traffic Engineering

Erlang B Table

N 1% 1.20% 1.50% 2% 3% 5% 7% 10% 15% 20% 30% 40% 50%1 0.01 0.01 0.02 0 .02 0.03 0.05 0.1 0.11 0.18 0.25 0.43 0.67 1

2 0.15 0.17 0.19 0.22 0.28 0.38 0.5 0.6 0.8 1 1.45 2 2.73

3 0.46 0.49 0.54 0.6 0.72 0.9 1.1 1.27 1.6 1 .93 2.63 3.48 4.59

4 0.87 0.92 0.99 1.09 1.26 1.52 1.8 2.05 2.5 2.95 3.89 5.02 6.5

5 1.36 1.43 1.52 1.66 1.88 2.22 2.5 2.88 3.45 4.01 5.19 6.6 8.44

6 1.91 2 2.11 2 .28 2.54 2.96 3.3 3.76 4.44 5.11 6.51 8.19 10.4

7 2.5 2.6 2.74 2.94 3.25 3.74 4.1 4.67 5.46 6.23 7.86 9.8 12.4

8 3.13 3.25 3.4 3.63 3.99 4.54 5 5.6 6.5 7.37 9.21 11.4 14.3

9 3.78 3.92 4.09 4.34 4.75 5.37 5.9 6.55 7.55 8.52 10.6 13 16.3

10 4.46 4.61 4.81 5.08 5.53 6.22 6.8 7.51 8.62 9.68 12 14.7 18.3

11 5.16 5.32 5.54 5.84 6.33 7.08 7.7 8.49 9.69 10.9 13.3 16.3 20.3

12 5.88 6.05 6.29 6 .61 7.14 7.95 8.6 9.47 10.8 12 14.7 18 22.2

13 6.61 6.8 7.05 7.4 7.97 8.83 9.5 10.5 11.9 13.2 16.1 19.6 24.2

14 7.35 7.56 7.82 8.2 8.8 9.73 10.5 11.5 13 14.4 17.5 21.2 26.2

15 8.11 8.33 8.61 9.01 9.65 10.6 11.4 12.5 14.1 15.6 18.9 22.9 28.2

16 8.88 9.11 9.41 9.83 10.5 11.5 12.4 13.5 15.2 16.8 20.3 24.5 30.2

17 9.65 9.89 10.2 10.7 11.4 12.5 13.4 14.5 16.3 18 21.7 26.2 32.2

18 10.4 10.7 11 11.5 12.2 13.4 14.3 15.5 17.4 19.2 23.1 27.8 34.2

19 11.2 11.5 11.8 12.3 13.1 14.3 15.3 16.6 18.5 20.4 24.5 29.5 36.2

20 12 12.3 12.7 13.2 14.0 15.2 16.3 17.6 19.6 21.6 25.9 31.2 38.2

21 12.8 13.1 13.5 14 14.9 16.2 17.3 18.7 20.8 22.8 27.3 32.8 40.2

22 13.7 14 14.3 14.9 15.8 17.1 18.2 19.7 21.9 24.1 28.7 34.5 42.1

23 14.5 14.8 15.2 15.8 16.7 18.1 19.2 20.7 23 25.3 30.1 36.1 44.1

gsm rf planning-ptt

Documents