Techniques to increase the capacity of a DS-CDMA system

The capacity or maximum number of users within a direct sequence code division multiple access (DS-CDMA) system is determined by the amount of noise or interference each user contributes to the overall system. DS-CDMA system design is thus the expertise of producing a spectrum that provides the smallest amount of interference to the other users. The paper first introduces two distinct system architectures; cellular and private mobile radio (PMR), and discusses how their system requirements differ. It also introduces the parameters by which DS-CDMA systems are measured, comparing the requirements of a classical CDMA system with those of the cellular and PMR multi-user schemes. It contains a discussion of which appropriate system value should be used to gauge the gain provided by the various capacity increasing techniques. It continues with an investigation of the various techniques that have been proposed for the cellular environment and the complexities concerned with their efficient usage. It provides an analysis of the gains provided against overall system complexity and other implementation considerations. The paper is concluded with a summary of the further methods that require research and the benefits they may provide.<>