A complexity-reduced joint detector scheme for OFDM-CDM systems

Orthogonal frequency division multiplexing code division multiplexing (OFDM-CDM) is one of the major transmission technologies for future mobile communications. The OFDM-CDM can achieve an additional diversity gain and has an advantage of inter-interference suppression by spreading the data in the frequency domain. The performance of OFDM-CDM systems can be improved by employing a joint detection scheme such as the maximum likelihood (ML) method. However, the complexity of the ML detection scheme increases exponentially as the number of codes increases. In this paper, we propose a complexity-reduced ML algorithm that uses a modified Euclidean distance as the soft metric for decoding, providing near optimum ML performance. Finally, the performance of the proposed scheme is verified by computer simulation