planning part_1- gsm standardisation and technology

7/31/2019 Planning Part_1- GSM Standardisation and Technology

1/28

Soc Classification level

/1 Nokia Siemens Networks

GSMGSMStandardisationStandardisation

and Technologyand Technology


2/28



Module objectives

DESCRIBE GSM ARCHITECTURE AND MAIN

ELEMENTS

LIST RADIO ACCESS TECHNOLOGIES

DESCRIBE THE PRINCIPLES OF GMSK MODULATION

At the end of this module you will be able to


3/28



Content TECHNOLOGIES

GSM OVERVIEW RADIO ACCESS

MODULATION


4/28



Introduction

TECHNOLOGIES

GSM OVERVIEW

RADIO ACCESS

MODULATION


5/28



GSM Evolutionary Steps


6/28



System architecture - GSM, GPRS and UMTS

BTS

RNC

BSCBTS

SGSN

GGSN @GPRS

infrastructure

UMTS infrastructure

MSC


7/28



Introduction

TECHNOLOGIES

GSM OVERVIEW

RADIO ACCESS

MODULATION


8/28



StandardisationETSI

European Telecommunications Standards Institute

Financed by EU

Co-operation of suppliers and operators

Specification of European telecommunications standards

ETSI- standards :

Cellular GSM 900/1800 - GPRS - UMTS Cordless DECT

Paging ERMES

Trunked radio TETRA


9/28



GSM Bandwidth & Main Parameters900 MHz & 1800 MHz

GSM 900 :

GSM 1800 :

Channel spacing 200kHz

Usual bandwidth values (GSM900):5 ..8 MHz per operator in one or more sub-bands

1710 1785 1805 1880

duplex distance: 95 MHz

890 915 935 960


Operator A Operator B Op. BOp. Anot allocated


10/28



GSM 1900 :

2 x 60 MHz at channel spacing 200kHz ~300 channels

Band divided into sub-bands A..F

sub-bands A, B, C : 2 x 15 MHz spectrum

sub-bands D, E, F : 2 x 5 MHz

1850 1910 1930 1990


Operator A Operator DOp. B Op. EOperator C Op. F

GSM Bandwidth & Main Parameters1900 MHz


11/28



E-GSM :

E-GSM band: 880-890 MHz & 925-935 MHz

880 890 925 935


GSM Bandwidth & Main ParametersE-GSM


12/28


13/28



NMS

NSSBSS

GSM Architecture & Interfaces

BSC HLR/AC/EIR

TCSM

MSC/VLR

BTS

AbisInterface

AterInterface

AInterface

AirInterface

TC

AterInterface

O&MInterface


14/28



Introduction TECHNOLOGIES

GSM OVERVIEW

RADIO ACCESS

MODULATION


15/28



Multiple Access TechnologiesBasics

Multiple accessschemes are used to allow many mobile users toshare simultaneously a finite amount of radio spectrum

Multiple access enhances the capacityof the link

Multiple access technologies can be grouped as narrowbandandwidebandsystems, depending on how the available bandwidth isallocated to the users

ffc


16/28



200

100

50

Bandwidth Conventional

radio systemsFDMA

Multiple Access TechnologiesFDMA

Frequency DivisionMultiple Access

Individual radio channels are allocated

to individual users on demandfor thetime of transaction

Each radio resource is identified withthe carrier frequency and the relative

bandwidthAmplifiers and combiners may introduceintermodulationeffects


17/28



Multiple Access TechnologiesTDMA

Time Division Multiple Access

The resource (time slot) is available only to a user for the time of transaction

High synchronization overhead & adaptive equalization are required

TDMA is mainly used in digital systems

T = Allocated time

t

Slot for user 1

Slot for user 2

Slot for user 3

Slot for user 5

Slot for user 7

Slot for user 8

Slot for user 4

Slot for user 6


18/28



Ti

0 1 0 0 1 x 0 1 1 1 0 0 1 0

1 1 0 1 1 1 0 0 1 1 0 0x=0

0 0 1 0 0 0 1 1 0 0 1 1x=1

Tc 1 chip

user information

W d i = 1 / Ti

each data bit is codedwith a chips code sequence

Tc Ti/n B 1/Tc n * W

W = modulation bandwidth before expansionB = modulation bandwidth after expansion

B >> W spread spectrumG = processing gain = bandwidth expansion factor (n = B/W)

Multiple Access TechnologiesCDMA

Code Division Multiple Access

Against near-farproblem, power controlis used

Unlike FDMA and TDMA, CDMA has a softcapacity limit


19/28



Multiple Access TechnologiesSDMA & PR

Space Division MultipleAccess

The radiated energy for each user iscontrolled in space

Normal application: sectorizedantennas

Future application: adaptiveantennas

Packet Radio

The access to the radio channel isuncoordinated

Burst of data

Low spectral efficiency and delays

ALOHA algorithm is used forcontentions


20/28



Time

Frequency

UL

DL

Time

Frequency

UL

DL

Duplex TechnologiesFDD & TDD

Frequency DivisionDuplex

UL & DL are divided in Frequency

Time Division Duplex UL & DL are divided in Time


21/28



Channel Types

A to B

B to A

f1f2f3f4

FDMA: e.g. walkie-talkie

A to B B to A A to B B to A

X to Y Y to X X to Y Y to X

C to D D to C C to D D to C

M to N N to M N to M M to N

f1f2f3f4

FDMA/TDD: e.g. CT2-system

f1f2f3f4

1 2 3 4 5 6 ... 1 2 3 4 5 6

TDMA/TDD : e.g. DECT

Multiple access and Duplex combination

f1f2f3

f4

.. 1 2 3 4 5 6 ... 1 2 3 4 5

3 4 5 6 ... 1 2 3 4 5 6 .. 1

FDMA/TDMA/FDD: e.g. GSM


22/28



Difference Between Multiple Access and Duplex

Multiple accessallows several users to share simultaneously a partof the radio spectrum

(full)Duplex allows the user to use Uplink and Downlinksimultaneously

To avoid interference between Uplink and Downlink, Duplex distanceis needed e.g. GSM 900 Duplex distance is 45 MHz


23/28



Introduction TECHNOLOGIES

GSM OVERVIEW

RADIO ACCESS

MODULATION


24/28



Modulationis the process of encoding information from a messagesource in a manner suitable for transmission

Modulatingsignal = baseband signal Modulatedsignal = bandpass

signal

Demodulationis the process of extracting the baseband messagefrom the modulated carrier

Modulation TechnologiesBasics

Modulation

fc

bandpass

f0

baseband


25/28


26/28


27/28



Exercises / Questions

Why is duplex distance needed?

List the GSM interfaces.

Which radio access technology is used in GSM?


28/28



References

1. W.C.Y. Lee, Mobile Communications Design Fundamentals,John Wiley & Sons, 1993.

2. W.C.Y. Lee, Mobile Cellular Telecommunication Systems,McGraw-Hill Book Company, 1990.

3. J. Lempiinen, M. Manninen, Radio Interface System Planning

for GSM/GPRS/UMTS, Kluwer Academic Publishers 2001.

planning part_1- gsm standardisation and technology

Documents