Multi-pulse/single-pulse design for maximizing SIR in partially equalized OFDM systems over highly dispersive channels

Signal transmission over mobile channels undergoes interferences coming from neighboring symbols in time and frequency. In this paper, we consider a mobile transmission by the OFDM/BFDM technique. Single pulse modulation (SPM) or multi pulse modulation (MPM) combined with a partial equalization of few neighboring pulses (for SPM) or co-located pulses (for MPM) at the receiver can be suited efficiently in the time-frequency lattice structure to optimize the overall system performance. In our design, we compare the Signal to Interference Ratio (SIR) for non equalized single pulse, to the ESIR (Equivalent SIR) of two-PM and three-PM. Then the ESIR is optimized for two-PM when ideal suppression of the interference coming from the first pulse is done. Next, residual interference (imperfect equalization) is considered in the optimization. Finally, we compare the gain brought by equalization as the number of co-located pulses is increased. The obtained simulation results show that SPM and MPM are almost equivalent when no equalization is considered. When partial equalization is considered, the higher is the number of co-located pulses, the better is the ESIR. Also, for imperfectly equalized two-PM, residual interference has low effect on the system performance when it goes higher than 1%.