Performance of new adaptive combined space-time receiver for multiuser interference rejection in multipath slow fading CDMA channels

A new adaptive combined array and multiuser detector (spatial and temporal) structure for direct sequence code division multiple access (DS-CDMA) has been proposed by Legnain, Falconer and Sheikh (see CCECE'98) to combat cochannel interference and increase the capacity for cellular CDMA. The structure uses a L-sensor (element) linear array. Each element is followed by a chip matched filter (CMF) and a fractionally spaced adaptive equalizer. The proposed structures combine the multipath component as well as suppressing interference. It outperforms the conventional receiver and the structures proposed by Abdulrahman, Sheikh and Falconer (IEEE JSAC, vol.12, no.4, p.698-706, 1994) and by Miller (see IEEE Tran. Comm., vol.43, no.2/3/4, p.1746-55, 1995) in-terms of capacity, near far resistance, multipath combining. The proposed structure can also operate in heavy traffic channels with many users having the same angle of arrival (AOA) as the desired user when the conventional array can not. The focus in this paper is the cochannel interference rejection and multipath combined capabilities of this structure. Analysis of the optimum tap weights and the minimum mean square error in multipath fading channels are provided, and comparison between this structure and the structures propose by Abdulrahman et al. and by Miller is also provided.