中低轨卫星跨层激光链路二次同步切换方法  

A Two-Step Synchronous Handover Scheme of Optical Inter-Orbit Links in LEO and MEO Satellite Network

作　　者：李勇军[1] 吴继礼 赵尚弘[1] 邓博于 缪新萍[1] 

机构地区：[1]空军工程大学信息与导航学院,陕西西安710077 [2]空军西安飞行学院,陕西西安710306

出　　处：《电子学报》2017年第3期762-768,共7页Acta Electronica Sinica

基　　金：国家自然科学基金(No.6231012);陕西省自然科学基础研究计划(No.2015JM6360)

摘　　要：中低轨卫星之间跨层激光链路的无缝切换直接决定了双层卫星光网络的稳定性.异步切换方法会导致网络拓扑频繁重构,而集中同步切换将造成两层间连接中断,网络运行状态失控.为此,本文提出了中低轨卫星星座激光链路的二次同步切换方法,在保证中低轨道卫星连通的基础上,可降低网络拓扑重构频率.研究了整数周期比的中轨道和低轨道卫星空间位置特性,建立了中低轨卫星星座构形二阶非球摄动模型,确定了中低轨道之间轨道周期比为3的双层卫星星座构形.按连接和切换顺序将该星座构形中跨层激光链路分为两组,以相对周期的1/4为基准,每次令其中一组同步切换,通过交替完成切换.研究结果表明,二次同步切换方法使得网络拓扑重构频率降低到链路切换频率的1/7,比集中切换方法在网络平均时延方面降低了30ms.In optical double-layer satellite network, the stability of network is determined by the OIOLs （ Optical In- ter-Orbit Links） seamless handover directly. Asynchronous handover method often results in frequent topology reconfigu- ration. However, synchronously centralized handover leads to cutoff of connection between two layers, and thus network operation condition gets out of control. A two-step synchronous handover scheme of MEO （Medium Earth Orbit） satellite and LEO （Low Earth Orbit） satellite constellation is proposed. Connection between LEO satellites and MEO satellites is guaranteed and topology reconstructing frequency is decreased. When orbit period of MEO satellite is integer multiple of LEO satellite, space position relation between LEO and MEO satellites is investigated. The second-order aspberic perturba- tion model of LEO satellite and MEO satellite constellation is built up. The orbit period ratio between MEO and LEO satel- lite is calculated as 3. The double-layer satellite network is designed. The laser links between the two layers in the elabo- rately configured LEO/MEO constellation pattern are divided into two groups based on connection and handover se- quence. 1/4 relative periods of the MEO satellite is considered as the handover criterion. In each 1/4 relative period, one group of inter-layer laser links switches synchronously. Research results show topology reconstructing frequency is reduced to 1/7 of link handover frequency. The average network time delay is decreased by 30ms compared with synchronously centralized handover method.

关 键 词：卫星光网络 跨层激光链路 无缝切换 同步切换 

分 类 号：TN929.1[电子电信—通信与信息系统]