极化码在水声通信系统中的应用研究

Research on Application of Polar Code in Underwater Acoustic Communication System

水声信道由于其强多径效应、多普勒频移、噪声以及有限带宽等特点成为目前最复杂的信道类型之一。信道编码技术如卷积码可以有效提高水声通信的可靠性,而在2009年提出的极化码(Polar code)相较卷积码具有香农限可达性等优点且拥有较低的编解码复杂度,因此可以将极化码作为信道编码方案应用到水声正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)通信系统中。极化码构造方法采用巴氏参数界法,解码选择BP解码算法。仿真表明,在水声时不变信道中,信噪比为4dB时,码长512的极化码的误码率可以达到10-4。在水声时变信道中,信噪比为10dB时,极化码的误码率达到10-4至10-5,优于卷积码在水声信道的性能,性能提升约2dB左右。

Underwater acoustic(UWA)channel is one of the most complex channel types due to its strong mul-tipath effect,Doppler frequency shift,noise and limited bandwidth.Channel coding techniques such as convolutional codes can effectively improve the reliability of UWA communication.Compared with convolutional codes,Polar codes have the advantages of Shannon limited accessibility and lower coding and decoding complexityproposed in 2009.Therefore,the paper applied the polar codes as channel coding schemes to underwater acoustic orthogonal frequency division multiplexing(OFDM)communication system.The polar codes construction method adopts the Bhattacharyya parameter boundary method,and the decoding selects the BP decoding algorithm.The simulation shows that in the UWA time-invariant channel,when the signal-to-noise ratio is 4dB,the bit error rate(BER)of the polar codes with the code length of 512 can reach 10-4.In the UWA time-varying channel,when the signal-to-noise ratio is 10dB,the BER of the polar codes can reach 10-4 to 10-5,which is better than the performance of the convolutional code in the UWA channel.The performance increase is about 2dB.