基于被动时间反转的差分循环移位扩频水声通信

Differential Cyclic Shift Keying Spread-Spectrum Underwater Acoustic Communication Based on Passive Time-Reversal

针对在时变的水声信道中系统的精确同步十分困难,而传统循环移位扩频系统在没有精确同步的条件下,很难准确判决的问题,提出一种差分循环移位扩频水声通信方法.该方法采用差分方式调制,能够在系统粗同步的条件下准确解调信息;在接收端采用被动时间反转方法解调,抑制多径效应产生的影响,并降低系统的复杂度.湖上试验结果表明:所提方法在1.8km的通信距离下实现无误传输;对试验数据附加噪声和同步误差处理后,在信噪比为-8dB、同步误差为5/4移位单元情况下的误码率达到10-5.

Accurate synchronization is more difficult in the time-variation channel. Conventional cyclic shift keying spread spectrum suffers performance impairment from timing errors in underwater acoustic communications. To solve this problem, a differential cyclic shift keying spread-spectrum underwater acoustic communication technique based on passive time-reversal was proposed. The proposed method requires only ＂coarse＂ synchronization at the symbol level. The passive time-reversal can suppress the inter-symbol in- terference caused by multipath. Lake experiment results show that the proposed method has no bit trans mitting error at 1.8 km range; After adding the noise collected at the test, the BER is at 10-4 when SNR is --8 dI3 with the 5/4 shift units time error.