20 - Other wireless communications systems

Abstract

This chapter discusses various wireless communications systems. Most mobile and cellular systems go through a continuous development of the underlying technology. They also continuously develop the features, services, and performance supported. The direction of development is from the baseline “narrowband” systems of the 1990s supporting mainly voice services to today's “wideband” systems. These target a much wider set of services, including broadband wireless data. Developments have been madefor various technologies in the IMT-2000 family and also for several non-IMT-2000 technologies, including the WiMAX and MBWA standards. This chapter provides an overview of these technologies and provides a high-level description of some of the solutions chosen in their ongoing evolution. The various technologies are developed in different standardization bodies, but all show a lot of commonalities. The reason is that they target the same type of application and operate under similar conditions and scenarios. The fundamental constraints for achieving high data rates, good quality of service, and system performance require a set of efficient tools applied to reach those targets. Moreover, a closer look at many of the evolved wireless communication systems show that they often combine multiple techniques from previous steps and are built on a mix of time division multiple access (TDMA), Orthogonal Frequency Division Multiplex (OFDM), and spread spectrum components.