Improved performance analysis for maximal ratio combining in asynchronous CDMA channels

Abstract

Direct Sequence Code Division Multiple Access (DS-CDMA) receivers typically use Maximal Ratio Combining (MRC) to favorably combine the energies of distinct multipath components from diversity branches. In previous research, compromising assumptions have been made to simplify the analysis, including a Gaussian approximation for interference or constant equal cross correlations. However, these assumptions corrupt the analysis especially in certain operating conditions such as a relatively small number of users, which is particularly relevant for modern CDMA systems that carry data. The contribution of this paper is to provide a general framework for accurately analyzing the performance of the diversity receiver in CDMA systems without these compromising approximations. From the analytical and numerical results, it is shown that the developed framework provides higher accuracy than previous approaches.