MPOE based adaptive space-time multiuser detector for multipath CDMA channels

DS-CDMA is a popular multiple access technology for wireless communication. The performance of DS-CDMA is limited by multiple access interference and multipath distortion. Multiuser detection and space-time processing techniques are employed to improve the performance of DS-CDMA. An adaptive space-time multiuser detector based on the minimum probability of error (MPOE) criterion is proposed here for an asynchronous multipath DS-CDMA channel, with the receiver employing multiple antennas. The receiver structure is derived for gradient descent based adaptation. A blind version of the receiver is also proposed. It is seen that the MPOE receiver offers BER performance comparable to the optimal non-adaptive MMSE detector in steady state, however with much lower computational complexity and a faster convergence rate compared to other adaptive implementations of the MMSE detector (LMS, RLS).