Joint demodulation in DS/CDMA systems exploiting the space and time diversity of the mobile radio channel

A demodulation algorithm for a base station receiver in a direct sequence (DS) spread spectrum code division multiple access (CDMA) communication system is proposed which performs joint multiuser detection and estimation using the output signals of an antenna array in the absence of a tight power control. The scheme is a combination of a multistage (MS) detector for data recovery and a space-alternating generalized expectation maximization (SAGE) algorithm for channel parameter estimation. Monte-Carlo simulations show that the scheme is able to overcome the near-far problem while simultaneously combining the signal energy spread over time and space in a nearly optimum fashion