根据激光星间链路的技术特点,并考虑导航卫星星间链路需兼顾通信、高精度测量与自主定轨的多重要求,研究了全球导航卫星系统(GNSS)激光星间链路拓扑的动态优化问题。采用有限状态自动机(FSA)思想建立了一种导航卫星激光星间链路的链路周期表。综合卫星平台、轨道动力学、激光终端捕获跟踪性能等工程约束条件,以网络时延和链路空间位置精度因子(PDOP)作为通信性能和高精度测量的量化指标,建立拓扑的多目标优化模型。提出一种基于多目标模拟退火算法(MOSA)的改进算法,求解全局最优拓扑结构,并在某卫星或某条激光链路不可用时进行动态优化。此外,还设计了一种避免冲突的链路交叉算法,改进了多源最小时延路由算法。仿真结果表明:在包括24颗MEO和3颗IGSO卫星的GNSS中,经该算法优化的拓扑结构具有良好的通信和测量性能,能够有效改善网络时延、PDOP值;当个别卫星或个别激光链路不可用时,改进算法计算出的拓扑结构仍能较好地兼顾高速通信与高精度测量性能。

The topology dynamic optimization problem for inter-satellite laser links of global navigation satellite system (GNSS) is studied according to the technical characteristics of inter-satellite laser links. The requirements of communication, high-accuracy measurement and autonomous orbit determination for navigation satellite crosslink are also considered. The periodic tables of inter-satellite laser links for navigation satellite are established via the finite state automation (FSA), and a multi-objective optimization model of topology is set up considering the three engineering constraints as follows: satellite platform, orbit dynamics, acquisition and tracking performance of laser terminal. The two quantitative indices of networks delay and position dilution of precision (PDOP) are used to evaluate the performance of communication and high-accuracy measurement. An improved algorithm based on multi-objective simulated annealing (MOSA) is proposed and used to solve the global optimization topology structure. Dynamic optimizations can be performed especially when some satellites or inter-satellite laser links are unavailable. Meanwhile, a link exchange method with conflict avoidance is applied, as well as an improved multi-sources minimum delay routing algorithm. Finally, simulation results show that the optimized topology has good communication and measurement performance and effectively improves networks delay and PDOP in GNSS which is comprised of 24 mesospheric earth orbit (MEO) and 3 inclined geo-synchronization orbit satellite (IGSO) satellites, and the requirements of both high-speed data and high-accuracy measurement are achieved even if individual satellites or inter-satellite laser links are unavailable.