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扩频水声通信能够抗信道衰落、多径干扰,具有传输距离远、可靠性高、被截获性低的优点。然而,水声通信可用带宽很窄,导致其数据率低。文章在伪随机序列扩频水声通信和OFDM水声通信研究及湖上成功实验的基础上,提出了一种基于M元伪随机序列组和OFDM技术的新型扩频OFDM(MSS-OFDM)水声通信方法。该方法能使得扩频水声通信数据率提高2.(log2M).(log2Q)倍。从理论上分析了M元扩频OFDM在高斯白噪声信道(AWGN)下的误码率性能,并通过仿真验证了其较强的稳健性。利用湖试测量得到的多径信道参数模型,分析比较了OFDM、SS-OFDM以及MSS-OFDM的水声通信误码率性能,结果表明:M元扩频OFDM具有双重抗多径干扰的优点,即使在没有保护间隔的情况下,也能获得较好的通信效果;由于采用了伪随机序列组,该方法也可用于水声网络通信。
Spread-spectrum underwater acoustic communication can resist channel fading and multipath interference, and has the advantages of long transmission distance, high reliability and low interception. However, the available bandwidth for underwater acoustic communications is low, resulting in low data rates. Based on the research of pseudo-random sequence spread spectrum underwater acoustic communication and OFDM underwater acoustic communication and the successful experiment on the lake, a new type of spread spectrum OFDM (MSS-OFDM) underwater acoustic based on M-ary pseudo-random sequence group and OFDM Communication method. This method can improve the data rate of spread spectrum underwater acoustic communication by 2. (log2M). (Log2Q) times. The bit error rate performance of M-ary spread-spectrum OFDM in Gaussian white noise channel (AWGN) is analyzed theoretically, and its robustness is verified through simulation. The BER performance of underwater acoustic communication of OFDM, SS-OFDM and MSS-OFDM is analyzed by using the multi-path channel parameter model measured by lake test. The results show that M-ary spread OFDM has the advantage of dual anti-multipath interference, Even without the protection of the interval case, but also to obtain better communication effect; due to the use of pseudo-random sequence group, the method can also be used for underwater acoustic network communications.