Wireless Communications

In Time Division Multiple Access (TDMA), within a given time frame a particular user is allowed to transmit within a given time slot. This technique is used in most of the second-generation digital mobile communication systems. In Europe the system is known as GSM, in USA as DAMPS and in Japan as MPT. In Code Division Multiple Access (CDMA) every user is using a distinct code so that it can occupy the same frequency bandwidth at the same time with other users and still can be separated on the basis of low correlation between the codes. These systems like IS-95 in the USA are also developed and standardized within the second generation of the mobile communication systems. CDMA systems within a cellular network can provide higher capacity and for this reason they become more and more attractive. At this moment it seems that both TDMA and CDMA remain viable candidates for application in future systems. This book provides enough information for correct understanding of the arguments in favour of one or other multiple access technique.The final decision about which of the two techniques should be employed will depend not only on technical arguments but also on the amount of new investments needed and compatibility with previous systems and their infrastructures. The book comprises a collection of specially written contributions from some prominent specialists in wireless communications and presents the major, up to date, issues in this field. The material is grouped into four chapters: communication theory, covering coding and modulation; wireless communications; antenna and propagation; and advanced systems and technology. The book describes clearly the issues and presents the information in such a way that informed decisions about third generation wireless systems can be taken.