火星邻近空间进入、下降、着陆（EDL）段是决定火星探测任务成败的一个重要环节，在此过程中，着陆器要穿过火星大气，经历“黑障”现象，如何确保火星邻近空间EDL段信息传输的可靠性是一项非常重要和有意义的研究课题。目前我国还没有建立精确的火星邻近空间EDL段通信信道模型，而且现有的火星探测器采用的信道编码是固定速率码，性能受信道条件所限。鉴于此，本项目针对火星邻近空间EDL段可靠通信问题开展研究。分析火星大气特性和动态等离子鞘套特性对通信信号的影响，基于电磁波传播理论、散射理论、时域有限差分方法建立火星邻近空间通信信道模型；然后将无速率码引入到火星邻近空间通信中，根据火星EDL段信道特性，设计能确保火星邻近空间通信可靠性的无速率码。利用NI-USRP搭建火星邻近空间通信仿真实验平台，对设计的无速率码的性能进行测试和验证。项目组前期的研究工作为本项目的顺利开展奠定了很好的基础。

Entry, Descend and Landing (EDL) phase of Mars proximity space is an important part for determining the success or failure of Mars exploration mission. During the phase, a lander passes through the Martian atmosphere and experiences "blackout" phenomenon. It is a very significant and meaning research topic that how to ensure the reliability of information transmission during EDL phase of Mars proximity space. At present, an accurate EDL channel model for Mars proximity space communications has not been established. Moreover, the channel codes adopted by the existing Mars explorers are fixed rate codes, which are limited by channel conditions. Consequently, this project carries out researches on the reliable communication during EDL phase of Mars proximity space. The influences of Mars atmosphere and dynamic plasma sheath characteristics on communication signals are analyzed. A channel model for Mars proximity space communications is established based on electromagnetic wave propagation theory, scattering theory and finite difference time domain method. And then rateless codes are used to Mars proximity space communications. According to the Mars EDL channel characteristics, rateless codes are designed to ensure the reliability of Mars proximity Space communications. The simulation experiment platform for Mars proximity Space communications is built based on NI-USRP. And the performance of designed rateless codes is tested and validated using the built simulation experiment platform. Preliminary work has laied a good foundation for the smooth development of the project.