Future-generation wireless networks

Starting with today's 3G :standards, future-generation wireless networks are discussed. Two complementing major trends are identified: seamless roaming between different air interfaces, leading to the Always Best Connected concept, and the continuous development of the current third-generation standards. The evolution of WCDMA toward high-speed downlink packet access, aiming for peak rates in the order of 8-10 Mb/s, is dmcribed as an example of air-interface evolution. Fourth-generation technologies such as ad hoc networking and multihop networks, still at the research level, are discussed and their impact on wireless communication systems addressed. he growth of mobile comniu-nication is explosive and a t the end of 2000 the number of subscribers exceeded 700 million. So far mostly speech services have been offered, but with the introduction of packet-switched radio systems (GPRS) and third-generation (3G) systems starting in 2001, users will be able to select from a vast menu of mobile data services. The addition of mobility to data communication enables new services not meaningful in a fixed network, e.g., positioning-based services. However , the development of mobile services has only started and in the future we will see new application areas opening up. In this article, future-generation systems are discussed, starting with a description of current trends and a brief overview of the cellular systems of today. The focus of the article is on the access networks. We consider the evolution of current systems, exemplified by a description of possible improvements in the packet-data support in wideband CDMA (WCDMA), end more long-term 4G research such as ad hoc and multi!iop networking. Clearly, due to its nature a description csf the long-term research on 4G is less detailed than the sections covering the evolution of the 3G systems. A growing portion of cellular traffic is data traffic, and we can see the first signs of a mobile Internet. More than 8 billion SMS messages being sent during the single month of June 2000, and the fact that Mobitex grew more in 1999 than in all previous years combined, are just two examples of this trend. In Japan the i-mode service had approximately 17 million subscribers at the end of 2000, with an increase of more than 1 million subscribers per month. The number of WAP-enabled terminals in circulation exceeds 50 million, and more then 10000 WAP sites are available in 95 countries. These are just a few examples of the increasing popularity of data …