地空信道特性研究

地空信道为典型的变参信道,变参形成的根本原因是多径和遮挡,特别是在远距离低仰角通信时,多径等因素会直接影响传输质量。地空信道中引入的多径衰落情况、多径时延的分布、衰落速率、相干时间等参数以及地面站天线仰角等均会直接影响地空通信系统设计,为达到平稳传输效果,在系统设计之初,必须对相应的信道特征有比较明确的了解,以便采取相应的抗多径、抗遮挡措施。

Research on Characteristics of Air-ground Communication Channel

The air-ground channel is a typical channel with variable parameters, the basic reasons for which are multi-path and occlusion. The quality of transmission is directly affected by multi-path, especially, when the channel is far-distance. The design of air-ground communication can be affected by the elevation angle of antenna of ground station and the parameters including the condition of multi-path fading, distribution of multi-path delay, fading rate and coherence time etc. In order to get stationary transmission, it is necessary to understand the characteristics of corresponding channel definitely before designing so that the method for anti-multipath and anti-occlusion is acquired.