非静止轨道卫星系统考虑通信中断的服务质量分析

基于Globalstar和Odyssey两个Walker delta星座,建立星间链路网络,重点分析网络中的不同轨道间星间链的动态特性,特别是与星上跟瞄系统密切相关的俯仰角、方位角和链路长度变化,为卫星网络路由提供依据.对传统的卫星路由策略作了改进,利用卫星系统的冗余覆盖的特性,选择不同策略下的最优路径.针对用户不能忍受通信中断的情况,提出考虑消除中断的路由策略,进行服务质量的分析比较.同时也比较在消除中断的路由策略下,LEO同MEO网络差异之处.消除通信中断是以其它QoS性能下降为代价.

Analysis of Termination-concerned QoS Performance in Nongeostationary Orbit Satellite Communication Systems

Based on the Globalstar and Odyssey systems,which are two well-known Walker delta type constellations,inter satellite link(ISL) networks are constructed and dynamic characteristics of inter orbit links are analyzed.Pointing,acquisition and tracking(PAT) subsystem on-board has close relationship with azimuth angle,elevation angle and ISL length whose variance is important to transponder's power control system.Multi-coverage of satellite system gives users more choices for accessing,and depending on different accessing,routing and handover strategies,optimized path is picked up.Unlike traditional routing schemes,termination-concerned routing schemes pay more attention to termination avoidance and routing simulations running on the Globalstar and Odyssey systems show that different schemes have different influence on QoS performances,as well as on different systems.Avoidance of communication termination only needs little decrease of some QoS performance.