浅海水声信道中的一种带循环均衡的Turbo译码结构

A Turbo decoding structure with iterative equalization for shallow water acoustic channels

针对浅海水声信道长时延、强多途干扰的特点,建立了一种新的带自适应循环判决反馈均衡的Turbo译码结构,并对其性能进行了仿真研究。该结构对典型的Turbo译码器进行了改进,使之不但能输出信息比特,同时又能输出校验比特,这些比特经硬判决、符号映射及信道交织后反馈回判决反馈均衡器,构成带自适应循环判决反馈均衡的Turbo译码结构。厦门港实测5途浅海水声信道仿真结果显示,该结构具有优良的抗多途性能,信噪比大于4dB时,误比特率小于10^(-5),比联合判决反馈均衡的Turbo译码结构提高了约2.5dB。

A new Turbo decoding structure with an iterative decision feedback equalizer （DFE） for shallow water acoustic channels was built based on the consideration of the channels＇ characteristics of long time-delay and strong multipath, and its perfomumces were simulated. In this new structure, the conventional Turbo decoder is modified to generate both information and parity bits, and these bits are first passed to the hard-decision, the symbol mapping, then channel interleaving, and then fed back to the DFE to implement the new Turbo decoding structure with the iterative DFE. The simulations show that the new structure can improve the anti-multipath performance of the system. When signal to noise ratio （SNR） is greater than 4 dB, the bit error rotes （BER） is less than 10^-5, and the gain in SNR achieved is 2.5 dB greater compared to the conventional structure of the Turbo decoder with DFE in five-path shallow water acoustic channel of the Xiamen harbor.