| J | Sadler D. and Manikas A. MMSE Multiuser Detection for Array Multicarrier DS-CDMA in Fading Channels IEEE Transactions on Signal Processing, accepted for publication, 2004. |
Reception of asynchronous, multicarrier DS-CDMA in time-varying, multipath radio channels with use of a receiving antenna array is investigated. Interference reducing MMSE receivers are discussed, and by considering the time-variation of the channel, a modified structure is derived which is efficient for channels experiencing small-scale fading. A blind implementation of this receiver is then proposed. Subspace concepts are applied to formulate a tracking, composite channel vector estimator which operates effectively in fading situations, even when high levels of interference are present. Both the modified MMSE weight matrix and diversity combining weights are generated from these channel estimates. Simulations of the proposed receiver show it to have superior performance over a standard MMSE receiver which is periodically re-evaluated to permit it to follow the channel variations due to small-scale fading. Furthermore, a hybrid MMSE receiver is proposed which applies different processing methods depending on each transmitters mobility, resulting in improved performance.