Noncoherent sequence detection of differential space-frequency modulation MIMO-OFDM

In a multiple-antenna broadband system, differential space- frequency modulation (DSFM) MIMO-OFDM in conjunction with noncoherent detection, which avoids channel state information (CSI) estimation, is attractive for time- and frequency- selective channels for its reduced complexity. However, a long power-delay profile (PDP), which we encounter frequently in broadband systems, will deteriorate the performance rapidly. In this paper, a noncoherent sequence detection of DSFM MIMO-OFDM is proposed, which exploits the correlation among subcarriers and utilizes the past several symbols to detect the current one and it can be used to alleviate the performance degradation introduced by long PDPs. We also present an analytical approximation of the symbol-error rate (SER) for DSFM, which enables quick and accurate performance evaluations. Simulation results confirm the efficacy of our approach and it is more flexible than the fixed window multiple-symbols detection under variable numbers of subcarriers.