Iterative receivers for multiuser space-time coding systems

摘要

Space-time coding (STC) techniques, which combine antenna arraynsignal processing and channel coding techniques, are very promisingnapproaches to substantial capacity increase in wireless channels.nMultiuser detection techniques are powerful signal processingnmethodologies for interference suppression in CDMA systems. In thisnpaper, by drawing analogies between a synchronous CDMA system and an STCnmultiuser system, we study the applications of some multiuser detectionnmethods to STC multiuser systems. Specifically, we show that thenso-called “turbo multiuser detection” technique, whichnperforms soft interference cancellation and decoding iteratively, can benapplied to STC multiuser systems in flat-fading channels. An iterativenmultiuser receiver and its projection-based variants are developed fornboth the space-time block coding (STBC) system and the space-timentrellis coding (STTC) system. During iterations, extrinsic informationnis computed and exchanged between a soft multiuser demodulator and anbank of MAP decoders, to achieve successively refined estimates of thenusers' signals. Computer simulations demonstrate that the proposedniterative receiver techniques provide significant performancenimprovement over conventional noniterative methods in both single-usernand multiuser STC systems. Furthermore, the performance of the proposedniterative multiuser receiver approaches that of the iterativensingle-user receiver in both STBC and STTC systems