DOA-matrix decoder for STBC-MC-CDMA systems over frequency-selective channel

A space-time block coded multicarrier (MC)-CDMA system, equipped with a uniform linear array (ULA) at the base station, over a frequency-selective channel is studied. A blind decoder providing closed-form solutions of the transmitted symbol sequences for all active users in one macrocell is developed. The decoder employs the DOA-matrix method to obtain a set of signal subspaces. From them, the information-bearing symbol sequences of multiple users are estimated by exploiting the structure of space-time block coding (STBC). The performance and computational complexity of the proposed decoder are evaluated by simulation.