中文摘要：

为良好水声信道条件设计的通信方案在恶劣信道条件下无法工作,而为恶劣水声信道条件设计的通信方案在良好信道条件下虽然可以有效工作,但是系统频谱利用率极低;为提高系统的频带利用率,通常的手段是提高调制星座的阶数,然而大量实践研究工作表明高阶的调制星座很难在水声信道有效工作。针对以上问题,本文提出一种联合超Nyquist信号发射技术和速率兼容打孔编码技术的自适应迭代接收技术;在低阶星座条件下通过超Nyquist信号发射技术可提高系统的频带利用率,采用速率兼容打孔卷积码编码技术可适应信道变化提高系统的稳健性。仿真研究表明本文提出的方案的频谱利用率在较高信噪比的加性高斯白噪声信道条件下可以超过QPSK调制的信道容量。湖上高速（最高6 kn）走航试验表明：在浅水时变的多途信道条件下,本文提出的超Nyquist发射方案可是实现无误码率数据传输,其频谱利用率为1.8 bit/（s·Hz）。

英文摘要：

The underwater acoustic communication systems designed for good channel conditions do not work well in harsh channel conditions,and although those designed for harsh channel conditions can work effectively in good channel conditions,the spectral utilization efficiency of these communication systems is very low; while increasing the order of the modulation constellation is an effective way to improve the bandwidth efficiency of these systems,empirical studies show that a high-order modulation constellation works with difficulty in underwater acoustic channels. This paper proposes an adaptive iterative receiver,based on the super-Nyquist and rate-compatible punctured coding techniques. The super-Nyquist technique can improve the bandwidth efficiency of the system with a low-order modulation constellation,and the rate-compatible punctured coding technique can adaptively adjust to changes in the channel. Simulation results show that the spectral efficiency of the proposed receiver can exceed the channel capacity of QPSK modulation in the additive white Gaussian noise channel with a high SNR. Experimental results from a high-speed（ up to 6 knots） sailing trial show that the proposed receiver can achieve data transmission with an error-free bit rate and a spectral efficiency of 1. 8 bit /（ s · Hz） in shallow water channels with rich multipath spread and time-variance characteristics.