Downlink cellular radio capacity of a joint detection CDMA mobile radio system

Abstract

The standardization of third generation mobile radio systems is approaching. It is beyond question that third generation mobile radio systems are going to be evolutions of the second generation, in particular time division multiple access (TDMA) based systems such as GSM and its derivative DCS 1800/1900. Today, GSM is on its way to a being a worldwide standard for mobile communications because of its attractive capacity feature. However, code division multiple access (CDMA) has attracted much attention due to its beneficial flexibility which is to be a major requirement for the third generation systems. A proposed enhancement for TDMA based mobile radio systems which uses CDMA, termed joint detection (JD)-CDMA, combining both the flexibility advantage of CDMA and the capacity advantage of TDMA, is considered. In particular, the downlink cellular radio capacity is presented allowing comparisons with already published results concerning the uplink. It is shown that the cellular radio capacity is remarkably high for both the uplink and the downlink, respectively, exceeding the values obtained for GSM. Special features of the JD-CDMA mobile radio system are the use of coherent receiver antenna diversity as well as the elimination of multiple access interference from intracell interferers.