A novel parallel interference cancellation scheme for OFDM in time-varying underwater acoustic channels

Orthogonal frequency division multiplexing (OFDM) systems are sensitive to channel variations caused by motility, which introduce inter-carrier interference (ICI). In this paper, a novel parallel interference cancellation (PIC) scheme is proposed to deal with ICI for OFDM in time-varying underwater acoustic channels (UWAC). The key idea is to estimate and remove ICI from the received signal before equalization in each iterative process. Meanwhile, ICI estimation, is achieved via time-varying channel estimation based on a piece-wise linear model where time-variations information is extracted from adjacent symbols. Moreover, PIC method is introduced to further refine the performance of channel estimation and equalization. Avoiding inversion of channel gain matrix, the proposed scheme has the best performance-complexity tradeoff compared with the existing methods. Simulation results demonstrate its good performances of ICI mitigation, bit error rate (BER), and robustness against UWAC.