On ISI cancellation in MIMO-ML detection using FBMC/QAM modulation

In this paper, the filter-bank multicarrier (FBMC) system is considered, and we deal with the presence of the inherent intersymbol interference (ISI). Indeed, the transmitted data symbols in FBMC are OQAM (Offset QAM) modulated, and the received data symbols are corrupted by inherent interference terms which complicate the detection in a maximum likelihood (ML) sense in the spatial multiplexing scheme. Detection schemes with ISI estimation and cancellation are not always effective due to the error propagation. We propose in this paper to modify the conventional FBMC system by transmitting QAM data symbols instead of OQAM ones in order to reduce the inherent interference. Then, we propose a receiver based on ISI estimation and cancellation. A simple tentative detector is first used to attempt to cancel the ISI before applying the ML detection. We show by simulation that with the proposed FBMC/QAM system, the ISI cancellation is effective and the performance converges to the optimum one.