中文摘要：

本文从平均谱效率的角度分析并讨论了基于正交频分复用（Orthogonal Frequency Division Multiplex,OFDM）技术的水声自适应通信系统的通信性能。在两种典型的水声统计信道假设下,根据信道状态信息的不同精确程度,针对不同的调制方式,对水声自适应通信系统的平均谱效率进行了理论推导,并给出了部分性能函数的解析形式,而后从多个角度给出了较为全面的数值仿真分析结果。仿真结果显示：当目标误码率为10-3时,水声自适应通信系统可以在相同发射功率下,显著地改善通信性能（约3 bit/s/Hz）;在同样的目标误码率下,如果维持传输性能不变,自适应通信系统可以显著节省发射功率（约10 dB）。在信道状态信息不确知的情况下,当信道估计误差大于-15 dB,或多普勒补偿后信道的扩展因子大于0.03时,自适应系统的性能才会显著劣化。此外,在统计意义上,自适应通信方法对于系统性能的改善程度随通信距离的增加而增大。

英文摘要：

In this paper,the performance of adaptive acoustic communication system based on OFDM（Orthogonal Frequency Division Multiplexing） is analyzed.With the assumption of two types of typical statistical acoustic channel models at various CSI（Channel State Information） precision conditions,two types of modulation scheme are considered to show the adaptive system performance in terms of the average spectral efficiency,by theoretical derivation and numerical simulation.It is shown that,with the accurate CSI,the adaptive acoustic communication system can improve the performance of systems significantly,specifically,either to increase the average spectral efficiency by about 3 bit/s/Hz,or to save the emitted power by about 10 dB,where the average target BER（Bit Error Rate） is set to 10-3.With imperfect CSI,based on the same target BER,only when the MSE of channel estimation is greater than -15 dB or the extend factor of channel after Doppler compensation is still greater than 0.03,the system performance will be significantly deteriorated.Moreover,statistically,the performance of the underwater system according to adaptive communication is improved with the increase of the communication range.