基于最小PDOP准则的星间链路拓扑方案

星间链路是卫星导航系统实现自主运行的一项关键技术.研究了一种 Walker(24/3/2) 星座,通过对卫星间可见性以及星间链路相关约束条件的分析,计算并确定了同轨卫星的A,B类排列方案,探索了建立位置精度因子(PDOP,Position Dilution Of Precision)值最小,即测距精度最高的星间链路拓扑结构的方法,并在此基础上利用Dijkstra算法计算出卫星之间以及卫星与地面站之间的最优路径.通过对星间数据传输时间延迟和星座网络卫星节点数据流量的统计,表明这种链路生成方案切实可行,能够满足预先设定的技术指标要求.同时对最短路径、最小跳数和网络流量均衡3种不同的计算策略进行了仿真,验证了这3种策略所造成的结果差异. 

Inter-satellite links topology scenario based on minimum PDOP criterion

Inter-satellite link is a critical technology for the satellite navigation system to realize its independent running. On the base of Walker(24/3/2) constellation, the visibilities between satellites and relative constraints of inter-satellite links were analyzed. After computing and determining the arrange scheme of satellites on the same orbit, the method to establish inter-satellite link topology with the minimal position dilution of precision(PDOP) value, that means the ranging precision is highest, was probed. On this basis the optimal paths between satellites and between satellites and ground stations were computed using Dijkstra algorithm. The statistics of time-delay in inter-satellite data transmission and data flow of satellite nodes show this link generation method can fulfill the pre-defined technological requirements and is practicable. Meanwhile simulate on three different strategies that are shortest path, minimal hop and balanced flow to verify the different results of the strategies.