or coordinate global telecom networks and services. The ITU-T is one of the three sectors of ITU and produces the quality standards covering all the fields of telecommunications. ETSI (European Telecommunication Standard Institute): This body was primarily re- sponsible for the development of the specifications for the GSM. Owing to the technical and commercial success of the GSM, this body will also play an important role in the development of third-generation mobile systems. ETSI mainly develops the telecommu- nication standards throughout Europe and beyond. ARIB (Alliance of Radio Industries and Business): This body is predominant in the Aus- tralasian region and is playing an important role in the development of third-generation mobile systems. ARIB basically serves as a standards developing organisation for radio technology. ANSI (American National Standards Institute): ANSI currently provides a forum for over 270 ANSI-accredited standards developers representing approximately 200 distinct organisations in the private and public sectors. This body has been responsible for the standards development for the American networks. 3GPP (Third Generation Partnership Project): This body was created to maintain overall control of the specification design and process for third-generation networks. The result of the 3GPP work is a complete set of specifications that will maintain the global nature of the 3G networks. 1.2 MOBILE NETWORK EVOLUTION Mobile network evolution has been categorised into 'generations' as shown in Figure 1.1. A brief overview on each generation is given below. Future! 4th Generation ?? 3rd Generation GSM+EDGE GSM+GPRS GSM+VAS 2nd Generation (digital) 1st Generation (analogue) Figure 1.1 Evolution of mobile networks MOBILE NETWORK EVOLUTION 1.2.1 The First-generation System (Analogue) The first-generation mobile system started in the 1980s was based on analogue transmission techniques. At that time, there was no worldwide (or even Europe-wide) coordination for the development of technical standard