Waveform Design With Interference Pre-cancellation Beyond Time-Reversal Systems
In wideband communication systems, the time-reversal (TR) technique can boost the signal-to-noise ratio (SNR) at the receiver with simple single-tap detection. It has been shown that conventional waveform design can significantly improve the system performance of TR systems. However, when the symbol rate is very high, the severe intersymbol interference still limits the performance at high-power region. In this work, we study a new waveform design with interference pre-cancellation by exploiting the message information to further improve the performance. In the proposed design, the causal interference is subtracted by interference compensation, and the anticausal interference can be further suppressed by conventional waveform design by virtue of the more abundant degrees of freedom. The transmitter utilizes the information of previous symbols to enhance the signal quality while the receiver structure remains simple. In the multiuser scenario, both the interuser interference and intersymbol interference can be similarly categorized by the causality, and then be tackled accordingly by the proposed waveform design with interference pre-cancellation. The resulting multiuser waveform design is a nonconvex optimization problem, for which two iterative algorithms are proposed and both are guaranteed to converge to suboptimal solutions. Simulation results validate the convergence behavior and demonstrate the remarkable performance improvement over the conventional waveform design in the previous work.