Research on Time–Frequency Joint Equalization Algorithm for Underwater Acoustic FBMC/OQAM Systems

This study focuses on the equalization problem of the filter bank multicarrier system based on offset quadrature amplitude modulation (FBMC/OQAM) in underwater acoustics and proposes an innovative joint time–frequency-domain equalization (JTFDE) algorithm. The algorithm combines frequency-domain Minimum Mean Square Error (MMSE) equalization with time-domain adaptive decision feedback equalization, effectively addressing the shortcomings of traditional single-domain equalization methods in terms of multipath interference suppression and time-varying channel tracking. By first using frequency-domain linear equalization to preliminarily eliminate multipath interference, and then combining it with time-domain Recursive Least Squares (RLS) adaptive decision feedback to further suppress residual interference, the system performance is significantly improved. The experimental results show that compared with existing single-domain equalization methods, this scheme reduces the bit error rate at the system receiver and enhances the system’s interference resistance.