Doppler Compensation of Underwater Acoustic OFDM Based on Parallel Search in Time and Frequency Domain and FPGA Implementation

摘要

Since the performance of orthogonal frequency division multiplexing (OFDM) system is severely limited by Doppler shifts over underwater acoustic (UWA) channels., an algorithm of two dimensional parallel search in time and frequency domain is proposed. In order to facilitate the realtime implementation of the algorithm on FPGA, the simplified design of transmitted signal and Doppler compensation algorithm is carried out. In the transmitted signal., the M sequence and the OFDM symbol are mixed in a certain mode. Doppler estimation algorithm uses the M sequence for correlation processing., which is suitable for real-time receiver processing over time-varying underwater acoustic channels, excellent performance results are obtained by block-by-block processing, without buffering the whole packet.