蒸发波导超视距信道建模及容量估计

为衡量海上蒸发波导环境下的超视距通信系统性能，提出了一种超视距信道建模方法及容量估计方案. 基于蒸发波导折射率模型和抛物方程（parabolic equation, PE）模型研究电波沿海面蒸发波导信道传播的大尺度衰落特性，结合统计性模型研究其小尺度衰落特性，形成基于电磁仿真和统计规律的混合蒸发波导信道模型，并由此推导出系统信道容量的估算方案. 对实际海面传播环境进行电磁建模，计算了蒸发波导环境中的路径损耗分布和多天线系统的信道容量，量化了使用多输入多输出（multiple-input multiple-output, MIMO）技术带来的超视距传播性能提升. 仿真结果表明，在蒸发波导环境中采用MIMO技术能够有效地提升信道容量，实现较好的超视距传播效果. 本文结果对海上超视距通信系统的应用及性能评估具有重要意义.

Modeling and capacity estimation of BLoS channel in evaporation duct

In order to measure the beyond-line-of-sight (BLoS) communication and radar detection performance of a multiple-input multiple-output (MIMO) system in maritime environment with an evaporation duct, a scheme for estimating the capacity of BLoS channel based on the parabolic equation (PE) theory is presented. Based on the two-dimensional scalar wave equation, a two-dimensional PE theory is derived, and the Feit-Fleck PE is solved by combining the split-step Fourier transform (SSFT) algorithm to predict the fading characteristics of the wave propagation in the evaporation duct channel. The corresponding MIMO channel model is established with related statistical laws, then the calculation scheme of channel capacity is deduced. Firstly, the propagation loss distribution in the evaporation duct is simulated, and the path loss in the duct layer and the signal blind area at the same distance is calculated and compared with it in a free space. The feasibility and advantages of BLoS propagation in evaporation duct are verified. In addition, the channel capacity of the system corresponding to different antenna numbers is simulated to quantify the performance improvement of BLoS propagation brought by using MIMO. The results show that the MIMO system in an evaporative duct can effectively improve the channel capacity and achieve better BLoS propagation effect. The results of this paper are of great significance for the application and performance evaluation of MIMO technology in the field of BLoS maritime communication.