Direct multiuser symbol detector for space-time block coded MC-CDMA system with uniform linear array

Space-time coded multi-carrier code division multiple access (MC-CDMA) is a promising scheme for future multiuser wideband wireless communication systems, therefore the combination of space-time coding and MC-CDMA is studied in this paper in order to benefit from the diversity gain and achieve an enhanced performance wireless communication systems. We study the scheme exploiting not only the uniform linear array (ULA) at the base station of macrocellular systems, but a rate 1 space-time block code (STBC) as well. The proposed blind multiuser detection scheme includes two steps: at first, by dividing the ULA into two identical overlapping subarrays, a specific auxiliary matrix is constructed, and includes both symbol sequence and the directions-of-arrival (DOA) information of all active users. DOA can be estimated and the users with different impinging DOA are separated by an ESPRIT like algorithm; then a direct symbol sequence detector is developed for all active users within one macrocell without space-frequency channel estimation by exploiting the structure of the STBC and the singular value decomposition. In comparison with schemes based on channel estimation, our algorithm need not explicitly estimate the space-frequency channel for each active user, so it has lower computation complexity. Computer simulation results demonstrate the validity of this proposed scheme.