dic Mobile Telephone (NMT) in Nordic countries To solve this problem, in 1982 the Conference of European Posts and Telecommunications (CEPT) formed the Groupe Spécial Mobile (GSM) to develop a pan-European mobile cellular radio system (the acronym later became Global System for Mobile communications). The goal of the GSM study group was to standardize systems to provide Improved spectrum efficiency International roaming Low-cost mobile sets and base stations High-quality speech Compatibility with Integrated Services Digital Network (ISDN) and other telephone company services Support for new services The existing cellular systems were developed on analog technology. How- ever, GSM was developed using digital technology. Benchmarks in GSM Table 1-1 shows many of the important events in the rollout of the GSM system; other events were introduced, but had less significant impact on the overall systems. Commercial service was introduced in mid-1991. By 1993, 36 GSM net- works were already operating in 22 countries. Today, you can be instantly reached on your mobile phone in over 171 countries worldwide and on 400 networks (operators). Over 550 million people were subscribers to GSM Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Introduction to GSM Chapter 1 Table 1-1 Events Major Events in CEPT establishes a GSM group in order to develop the standards for a pan- European cellular mobile system. A list of recommendations to be generated by the group is accepted. Field tests are performed to test the different radio techniques proposed for the air interface. Time Division Multiple Access (TDMA) is chosen as access method (with Fre- quency Division Multiple Access [FDMA]). The initial Memorandum of Under- standing (MoU) is signed by telecommunication operators representing 12 countries. GSM system is validated. The responsibility of the GSM specifi