N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 9 - Wireless Systems and Technologies                                                                                 Slide 26 of 80                                                                                                    ________________

Global System for Mobile (GSM)

                                    A European Standard 

                                    GSM Types

                                    Time Division Multiple Access (TDMA)

                                    Speed and Transmission Rates

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GSM is a digital system and is designed to handle data communications. It supports both digital voice and data transmission. GSM is a widely deployed digital cellular telephone standard. It is used in networks all over the world. The frequency band is typically 890 and 915 M Hz. The standard was developed in Europe by Groupe Special Mobile. Now the development work is looked after by the European Telecommunications Standards Institute (ETSI).

The frequency spectrum allocated for the service is divided into 200 K Hz blocks. Each block is capable of transmitting at 270,833 bps supporting 8 simultaneous conversations. It uses the TDMA technique to allow users to access the network. GSM is capable of supporting 16 simultaneous conversations with lower-bit-rate voice digitizers.

GSM Types:    - GSM-900 operates at 890 - 915 M Hz and 935 - 960 M Hz
                    - E-GSM (GSM protocol applied to extended frequency range operating at 800 - 915 M Hz and
                      925 - 960 M Hz
                    - DCS - 1800 operates at 1710 - 1910 M Hz and 1930 - 1990 M Hz

GSM supports voice, data, text messaging and cross-border roaming.