水声通信中后验符号概率密度分布及概率成形容量分析

考虑到实际水声信道复杂特性对水声通信的影响,对系统的通信容量进行计算分析,并研究了一种适用于水声信道的容量评估算法。文中通过对不同条件下的均衡器输出的后验符号特性进行统计分析,提出了一种基于后验高斯分布的符号方差分段转移函数模型。在此基础上,采用Maxwell-Boltzmann分布来改变均衡器输出符号的成形分布,即引入概率成形技术对实际的水声通信系统容量进行评估分析。最后通过对水池和湖试多径信道数据的处理,获得了不同调制方式下的通信容量。结果显示,在特定的信噪比区间内,概率成形技术比传统的等概率映射的容量提升最大可达0.5 bits/symbol。 

The probability density distribution of the a posteriori symbols and probabilistic shaping capacity analysis in underwater acoustic communication

Considering the effects of underwater acoustic channel on underwater acoustic communications,the capacity of underwater acoustic communication system is analyzed,and an underwater acoustic channel capacity assessment algorithm is studied.A piecewise symbol-variance transfer function model based on the a posteriori Gaussian distribution is proposed via the statistical analysis of the a posteriori symbols which are the output of equalizers under different conditions.The Maxwell-Boltzmann distributions are used to perform probabilistic shaping on the output symbol of equalizer.Probabilistic shaping technology is introduced to analyze and assess capacity of the actual underwater acoustic communication system.Finally,the capacities with different modulation modes are obtained by analyzing the multi-path channel data of pool and lake experiments.The results show that the maximum improvement of the channel capacity by using probabilistic shaping technology over the conventional equiprobability mapping is 0.5 bits/symbol,in the specific Signal-to-Noise Ratio(SNR) region.