Lower-complexity direct symbol detector for multiuser MC-CDMA system using antenna array without vector channel estimation

This paper investigates the multicarrier code-division multiple access (MC-CDMA) system with the uniform linear array (ULA) at the base station, and a lower-complexity direct symbol detector is derived for multiple users within one macrocell without uplink space-frequency vector channel estimation. Being the byproduct, direction-of-arrivals (DOAs) of multiple users are also estimated. By segmenting the ULA into two overlapping subarrays, we construct an auxiliary matrix, which includes both symbol sequences and DOAs information of multiple users. Performing the eigen decomposition on the auxiliary matrix, we can obtain the closed-form solution of symbols and DOAs for multiple users. In comparison with schemes based on channel estimation, our algorithm need not explicitly estimate uplink space-frequency vector channels for multiple users, so it has a lower computation complexity. Simulations demonstrate the performance of our proposed algorithm.