3RD-GENERATION MOBILE NETWORK ARCHITECTURES FOR THE UNIVERSAL MOBILE TELECOMMUNICATIONS SYSTEM (UMTS)

Mobile telecommunications is the fastest growing sector of the telecom munications industry, with second-generation systems being implemented with great success all over the world. Spectrum limitations and vario us technical limitations of second-generation systems have led some re gions to develop concepts for a third-generation mobile system. Planne d to begin operation at the start of the next millennium, third-genera tion systems are currently the subject of research and development and standardization by the International Telecommunication Union (ITU) an d regional standards bodies. This paper addresses the market for third -generation services and several technical issues of network architect ures for the Universal Mobile Telecommunications System (UMTS). We pla ce particular emphasis on the collaborative research activity conducte d in Europe since 1988, funded by the European Commission. One of thei r major research projects is Radio Independent Broadband on Wireless ( RAINBOW), which is investigating the feasibility of a UMTS network inf rastructure based on the concept of radio dependence/independence. Thi s UMTS network infrastructure can support both second-and third-genera tion multiple air interface standards. Lucent is a major partner in th is collaborative research effort, providing the Global System for Mobi le Communications (GSM) radio interconnection to the asynchronous tran sfer mode (ATM)-based network infrastructure of the RAINBOW demonstrat or.