不同调制方式下高斯信道容量的计算

摘要

Calculating the channel capacity with different modulation schemes has important theoretical sig-nificance on the design of practical communication systems. In this paper,according to Shannon informa-tion theory,the definition of the capacity of continuous channel and additive white Gaussian noise( AWGN) channel is introduced. Then by revealing the relationship between mutual information and differential en-tropy,the closed expressions of calculating Gaussian channel capacity with different modulation schemes are derived. By modeling the electric satellite channel as the Gaussian channel, the satellite communication employing rateless code with different modulation schemes is simulated. The numerical results show that the proposed expressions of calculating Gaussian channel capacity provide a good guidance for selecting the coding rate and the starting condition of decoding for the practical satellite communications.%计算不同调制方式下的信道容量对实际通信系统的信道编译码设计具有重要的理论意义。首先从Shannon信息论出发，介绍了平稳无记忆连续信道与加性白高斯噪声信道容量的定义。接着利用互信息与微分熵的相互关系，推导了几种常用的不同调制方式下高斯信道的容量，并给出了相应的信道容量闭合计算表达式。通过将电力卫星通信信道模拟为高斯信道，对采用无速率信道编码联合不同调制方式的卫星通信进行了数值仿真。仿真结果显示，通过推导得到的闭合表达式计算信道容量，能对实际卫星通信的编码速率、译码启动条件的确定起到很好的理论指导作用。