Realization Of Channel Equalization And Doppler Compensation In OFDM Underwater Acoustic Communication

As a focus on the researching of underwater acoustic communication, OFDM technology has advantages in high spectrum efficiency, strong ability in preventing multi-path and impulse noise, high-speed transmission under efficient bandwidth utilization, and simple implementation. But faced with limited bandwidth, strong multi-path interference and fast time-varying channel structure.The main task of this paper is to build an OFDM system with channel estimation, equalization and Doppler compensation modules in the signal processing platform of underwater acoustic communication system. The board uses a high-performance fixed-point DSP device, the TMS320C6455 as the main signal processing chip, and a FPGA chip, XC2V1000-5FG256 of Virtex-II series procuced by the Xilinx company is used for logic control. After getting through the digital and analog data streams of the board, OFDM system software structure is designed based on DSP/BIOS system, including the transmitting part and receiving part. It achieves real-time data processing. The paper focuses on theory and implementation of channel estimation and equalization, and shows the results.Because of real-time correlation and float-point operations, there is large amount of computation in the DSP chip. During software designing, the program flow and structure is thought over, meanwhile the CPU clock rate is very high(1-GHz), so the code is efficient and achieves the expected effect. In addition, the paper gives the system real-time performance analysis.