Low complexity space-frequency MLSE for multi-user COFDM

The possibility of multi-user detection with receiver diversity has gotten a lot of attention lately. In this paper we show how this technique can be realized using OFDM together with bit interleaved coded modulation (BICM) as coding scheme. We present an optimum MLSE based metric for the decoding in such systems. Since the optimum metric proves to be rather complex we develop an alternative approach based on the ML estimation of the transmission symbols. Following this approach, with very little additional receiver-complexity, a true multi-user detection of bandwidth efficient QAM schemes in extremely selective environments becomes possible.