适合于稀疏水声信道的低复杂度联合迭代均衡译码

Low Complexity Joint Iterative Equalization and Decoding Scheme for Sparse Underwater Communication Channel

浅海远程水声通信面临严重多径扩展、衰落以及低信噪比的挑战,为克服传统内嵌二阶锁相环的判决反馈均衡器结构在中低信噪比条件下性能较差的缺点,提高水声通信系统的可靠性,该文提出一种适合于稀疏水声信道的低复杂度联合迭代均衡译码方法.该方法以内嵌的二阶数字锁相环补偿Doppler造成的相位偏移,利用水声信道的稀疏特性进行均衡器系数更新,补偿多途效应产生的码间串扰,通过均衡器和译码器之间多次联合迭代交换软信息提高系统的BER性能.基于实测湖试信道条件进行了仿真,结果表明LC-JIED方法对于浅海远程稀疏水声信道十分有效,通过编码器与均衡器之间多次迭代交换软信息可大幅提高系统性能,适合于中低信噪比应用场合,具有广泛的应用前景.

Long-range communications in shallow water faces great challenges of severe multipath interference,fading,and low SNR.The traditional second-order digital phase lock loop（DPLL） embedded decision feedback equalizer can only work at high SNR,serious error propagation may occur at low and moderate SNR.In order to improve reliability of long-range shallow water communications,a low complexity joint iterative equalization and decoding（LC-JIED） scheme is proposed for sparse underwater communication channel.The method compensates for Doppler shifts using an embedded second-order DPLL,and updates the equalizer coefficients by taking into account sparsity of the channel.System performance is greatly improved by iteratively exchanging soft information between the equalizer and decoder.Simulations based on real lake channel profiles show that the proposed method is effective for sparse underwater channel.It can significantly improve reliability of long-range shallow water acoustic communications by exchanging soft information between equalizer and decoder at low to moderate SNR.