This paper considers a  Q -ary orthogonal direct-sequence code-division multiple-access (DS-CDMA) system with high-rate space-time linear dispersion codes (LDCs) in time-varying Rayleigh fading multiple-input-multiple-output (MIMO) channels. We propose a joint multiuser detection, LDC decoding,  Q -ary demodulation, and channel-decoding algorithm and apply the turbo processing principle to improve system performance in an iterative fashion. The proposed iterative scheme demonstrates faster convergence and superior performance compared with the V-BLAST-based DS-CDMA system and is shown to approach the single-user performance bound. We also show that the CDMA system is able to exploit the time diversity offered by the LDCs in rapid-fading channels.
['Pei Xiao', 'Jinsong Wu', 'Mathini Sellathurai', 'Tharmalingam Ratnarajah', 'Erik G. Ström']
Iterative Multiuser Detection and Decoding for DS-CDMA System With Space-Time Linear Dispersion