Global System for Mobile Communication

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Mobile Communications Chapter 4: Wireless Telecommunication Systems slides by Jochen Schiller with modifications by Emmanuel Agu

Market q GSM
q
q

Overview q Services q Sub-systems q Components
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 4.1

Mobile phone subscribers worldwide
1600

approx. 1.7 bn

1400

1200

Subscribers [million]

GSM total TDMA total CDMA total 800 PDC total Analogue total 600 W-CDMA Total wireless Prediction (1998) 400

1000

200

0 1996 1997 1998 1999 2000 2001 2002 2003 2004 year

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

MC SS05

4.2

GSM: Overview
GSM
q q q q

q q q q

formerly: Groupe Spéciale Mobile (founded 1982) now: Global System for Mobile Communication Pan-European standard (ETSI, European Telecommunications Standardisation Institute) simultaneous introduction of essential services in three phases (1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2) è seamless roaming within Europe possible today many providers all over the world use GSM (more than 200 countries in Asia, Africa, Europe, Australia, America) more than 1.2 billion subscribers in more than 630 networks more than 75% of all digital mobile phones use GSM (74% total) over 200 million SMS per month in Germany, > 550 billion/year worldwide (> 10% of the revenues for many operators) [be aware: these are only rough numbers…]

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

MC SS05

4.3

Performance characteristics of GSM (wrt. analog sys.)
Communication
q

mobile, wireless communication; voice and data services international access, chip-card enables use of access points of different providers one number, the network handles localization better frequency efficiency, smaller cells, more customers per cell high audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g., from cars, trains) access control, authentication via chip-card and PIN

Total mobility
q

Worldwide connectivity
q

High capacity
q

High transmission quality
q

Security functions
q

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

MC SS05

4.4

Disadvantages of GSM
There is no perfect system!! q no end-to-end encryption of user data q no full ISDN bandwidth of 64 kbit/s to the user, no transparent Bchannel q q

reduced concentration while driving electromagnetic radiation abuse of private data possible roaming profiles accessible high complexity of the system several incompatibilities within the GSM standards

q q

q q

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

MC SS05

4.5

GSM: Mobile Services
GSM offers
q q

several types of connections
l

voice connections, data connections, short message service

multi-service options (combination of basic services)

Three service domains
q

Bearer Services q Telematic Services q Supplementary Services bearer services MS TE R, S MT Um GSM-PLMN transit network (PSTN, ISDN) tele services source/ destination network TE (U, S, R)

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

MC SS05

4.6

Bearer Services
q q q

Telecommunication services to transfer data between access points Specification of services up to the terminal interface (OSI layers 1-3) Different data rates for voice and data (original standard) q

data service (circuit switched)
l

synchronous: 2.4, 4.8 or 9.6 kbit/s l asynchronous: 300 - 1200 bit/s q

data service (packet switched)
l

synchronous: 2.4, 4.8 or 9.6 kbit/s l asynchronous: 300 - 9600 bit/s

Today: data rates of approx. 50 kbit/s possible – will be covered later!

Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

MC SS05

4.7

Tele Services I
q q q

Telecommunication services that enable voice communication via mobile phones All these basic services have to obey cellular...
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