A Time-Reversal-Based Transmission Using Predistortion for Intersymbol Interference Alignment

A time-reversal (TR)-based transmission using pre-distortion of the transmitted waveforms for intersymbol interference (ISI) alignment is proposed. This scheme differs from the previous TR-based pre-filtering schemes in that it uses distinctively designed pre-distorted waveforms that are based on the transmitted symbol information. In the proposed pre-distortion scheme, the successively received waveforms carrying adjacent transmitted symbols are aligned so that the received symbol power can be intensified. Since the overlapped portions of the successively transmitted waveforms from the proposed pre-distortion scheme are correlated, the power of the overall transmitted signal that is formed by time-shifting and adding the pre-distorted waveforms becomes larger than the sum of the individual pre-distorted waveform powers. In order to adjust the pre-distorted waveform power without measuring the actual power of the overall transmitted signal, an upper bound on the average power of the overall transmitted signal was derived analytically under a low SNR assumption. Simulation showed that the proposed pre-distortion scheme outperformed both conventional TR and the minimum mean square error (MMSE)-based pre-filtering when the ISI was serious with a high transmission rate.