正交频分复用循环移位扩频水声通信

针对常规直接序列扩频水声通信数据传输速率低及M元扩频水声通信接收机复杂度高的问题,提出了一种正交频分复用(orthogonal frequency division multiplexing， OFDM)技术和循环移位键控(cyclic shift keying, CSK)技术相结合的调制方式,该调制能很大程度地提高系统的带宽使用率。从理论上对该方法在高斯白噪声信道条件下的误码率进行了分析。同时,采用Chu序列作为扩频序列,通过理论推导得出其峰均功率比(peak to average power ratio,PAPR)的上限为3dB。利用实际湖试测量得到的多径信道模型,与DSSS-OFDM方法进行了误码率性能的分析比较。结果表明，新提出的方法具有很好的抗多径性能,且具有带宽利用率高、复杂度低的特点,适用于中、远程及多用户水声通信。

OFDM cyclic shift keying spread spectrum underwater acoustic communication

Aiming at solving the problems of low data transmission rate of direct sequence spread spectrum underwater acoustic communication and high complexity of the receiver design of M-ary spread spectrum underwater acoustic communication, an orthogonal frequency division multiplexing cyclic shift keying spread spectrum(CSK-OFDM)method is proposed to improve bandwidth efficiency. The bit error rate performance is analyzed under the additive white Gaussian noise channel condition in theory. The peak to the average power ratio(PAPR)of the CSK-OFDM system is theoretically proved to be upper bounded by 3 dB using Chu sequences as spreading codes. Further simulation comparison to DSSS-OFDM is provided with the multi-path channel model based on lake trial data. Simulation results show that the CSK-OFDM method has excellent anti-multipath capability， low complexity as well as high bandwidth efficiency. Consequently, the proposed method is suitable for long-range and multi-users underwater acoustic communication.