RF PLANNING IN GSM NETWORK

E.Christo Eljin Raj,II ME (AE),Reg. No-91009531007,PSNA CET,Dindigul.

Guided by:

Asst Prof:Mrs.K.Meena@Jeyanthi M.E

GSM-900 (125 Channels, operating band 900Mhz carrier spacing 200khz spacing 45Mhz)

GSM -1800 (374 Channels, spacing 95Mhz)

Types of GSM network

Frequency bandUplink 890 - 915 MHzDownlink 935 - 960MHz

Duplex Frequency Spacing 45MHz Carrier separation 200KHz Frequency Channels 124 Time Slots /Frame(Full Rate) 8 Voice Coder Bit Rate 13Kbps Modulation GMSK Access method FDMA/TDMA

GSM-900 System specifications

GSM is already used worldwide with over 450 million subscribers compared to CDMA’s 80 million.

International roaming permits.

GSM is mature, having started in the mid-80s. This maturity means a more stable network with robust features. CDMA is still building its network.

GSM’s maturity means engineers cut their teeth on the technology, creating unconscious preference.

The availability of Subscriber Identity Modules, which are smart cards that provide secure data encryption give GSM M-Commerce advantages.

GSM Advantages

GSM - Network StructureMS

MS

BTS

BTS

BTS

BSC

BSC

MSC

MSC

VLR

VLR

GMSC

HLR

PSTN

EIR

AuC

Um

Abis

AbisA

A

OMC Server

Um

GSM System Architecture

PSTN

Data Terminal

HLR/VLR

MSCBSC

OMC(Operation & Maintenance

Center)

OperationTerminal

BTS

HandsetA

X.25

A-bis SS7

Network sub-system PSTNRadio

sub-systemMobilestation

UM

SIMcard

RF PLANNING

Use of radio frequency bands is regulated by governments.

ITU works on standards for frequency allocation.

DEFINITION

Capacity Requirements- Spectrum- GOS (Grade Of Service)- Erlang / Subscriber- Projected Subscribers

Tools Required- RF Dimensioner or RF Planning tools i.e. Asset- Terrain / Clutter Database

Coverage Requirements- GSM900 or GSM1800- Area Requiring coverage- Coverage Area Probability i.e. 80%, 90%.- Coverage Type i.e. in-building, in-car, etc.- Coverage level i.e. in-building

Requirements

RF Design Process

RF Design -Implement

Gather Coverage and Capacity

Requirements

High Level RF Design

DriveTest

Site Survey

• Network Planning Tool• CW Propagation Tool• Traffic Modeling Tool• Project Management Tool

TOOLS USED FOR RF PLANNING

PRELIMINARY WORK

INITIAL SURVEY

INITIAL DESIGN

SELECTION OF SITES

RF PLANNING PROCEDURE

BSNL, Rajiv Gandhi Memorial Telecom Training Centre, Chennai.

Roger L. Freeman,” Fundamentals of Telecommunications”, Published by John Wiley & Sons.

Chang Yu; Subramaniau, S.”Advanced frequency planning techniques for TDMA and GSM networks”, The Bridge to Global Integration. IEEE Volume: 2, Publication Year: 1998.

References

THANK YOU