多层卫星网络链路中断容忍路由策略设计

链路中断和接续对卫星网络路由有重要影响,该文针对多层卫星网络,设计了链路中断容忍路由策略,利用非均匀时间段内卫星网络拓扑结构的可预测性进行路由表计算,采取动态的拥塞控制机制和洪泛策略,解决由于卫星运动、通信设备故障引发链路中断情况下的路由问题。仿真结果表明,该路由策略具有较高的链路利用率,能够减少动态路由计算中时延信息收集和星上路由表生成给卫星节点带来的时空开销。     

多层卫星网络研究概述

随着空间信息系统的发展,多层卫星通信网络成为发展趋势之一。多层卫星网络能够利用各种轨道高度卫星星座的优点,发挥其在覆盖范围、星际链路、传输时延等方面的优势,满足各种业务的不同服务质量（Qos）要求,将成为未来卫星通信网络发展的一种理想组网模式。     

基于稳态化的卫星网络低时延路由策略

卫星网络动态拓扑被建模成在空间上延展、时间上连续的稳态图模型—时空连接图(Space-Time Connection Graph,STCG),且权重为数据在STCG的空间数据链路和虚拟时间链路的传输时延.通过对传统静态路由算法进行改进,使其可以应用到STCG中为卫星网络制定传输时延最短的路由;仿真结果表明,该路由策略可...     

宽带卫星网络边界路由技术研究

在中低轨道卫星星座中,利用星间链路组网是宽带卫星网络技术发展的一个主要方向。卫星网络中的边界路由主要解决卫星网络和地面网络之间在网络层的互操作性问题,实现网络层的互相融合,使端用户能够通过异构网络透明通信。在分析已有研究的基础上,结合地面网络使用的边界路由技术,本文给出了地面网络和卫星网络的互连模型,分析了具有星间链路的卫星网络中边界路由问题的实质,然后介绍了一种基于BGP-4协议的卫星网络边界路由机制,最后总结全文并指出后续的研究方向。     

面向6G通信的多层低轨卫星网络路由算法

在面向6G的移动通信网络中,低轨卫星网络（LEO, Low Earth Orbit）运行高度低、时延小,可大范围部署实现全球广域低时延通信。当前低轨卫星星座正朝着多层轨道面发展,多层轨道的跨层链路增加了数据传输路径,但跨层轨间链路的频繁通断,增大了多层LEO网络层间路由选择的难度。为此提出了一种面向6G移动通信的多层LEO卫星网络路由算法。首先建立跨层链路,面向端到端传输时延和可靠性需求,分析影响跨层轨间链路频繁通断的因素,基于LEO卫星网络虚拟位置思想,选择卫星节点对建立可靠跨层链路;然后实现路由选择,基于所建立的跨层星间链路,采用时空演化图模型刻画动态网络拓扑,设计最短路径算法计算最佳传输路径。最后,构建三层卫星网络场景对所提算法进行仿真验证。结果表明,相对于现有方法,所提算法在端到端时延和可靠性均有明显提升。     

多层卫星通信网络结构设计与星际链路分析

针对单层卫星网络时延高、网络阻塞概率大等问题,研究了多层卫星网络的系统结构及其特点.为解决单一轨道对卫星性能发挥的限制问题,结合不同轨道卫星特点,引入分层卫星网络结构,采用Walker和极轨星座覆盖带设计法,设计了多层卫星网络星座.针对“强连接”模型中星际链路冗余度过高的问题,采用“弱连接”模型作为星际链路建立的基本原...     

卫星移动通信系统星间链路设计

通过对现有的卫星移动通信系统星间链路的分析发现 ,不但卫星移动通信系统星间链路的指向具有周期性变化的特性 ,而且星间链路的相对距离也在周期性变化。这种星间链路指向的周期性规律变化 ,为星间通信链路的搜索建立以及星间通信设备的设计制造提供了研究的方向和理论依据。对星间链路的误码率的分析 ,主要探讨了由于卫星星体振动而引起的通信误码与振动的标准偏差 (幅度 )、通信所使用的光波波长、发射到接收的距离以及激光波束半径之间的关系 ,为实际星间链路的设计打下了坚实的理论基础。     

稀路由卫星通信系统

熊猫牌５５Ｂ００型稀路由卫星通信系统是南京无线电厂和南京通信工程学院、总参五十七所共同研制出的新一代卫星通信产品。本文介绍了该系统的技术特点、设备组成、网络监控管理的主要功能。     

一种优化的卫星通信星际路由算法设计

在分析传统的链路——状态算法的基础上，提出了一种优化的卫星通信星际路由算法。该算法能够找出任意两颗卫星间通信的最佳路径集合，同时能够在链路质量容许的情况下，尽量避免通信链路切换的发生，从而较大地提高了系统性能。     

无线传感器网络自适应并发多路由算法

无线传感器网络地理位置路由算法需要克服本地最小化现象.已有的算法均以"右手规则"为基础来克服这一现象,但是,"右手规则"会损失链路且难以在路由过程中动态调整所选路由,对自适应多路由选择不利.通过深入分析本地最小化现象,发现合理限定贪心算法的选路区域可以克服本地最小化现象,由此提出Clockwise Rule,该规则不损失链路,可动态调整所选路由,耗费低.在此基础上,提出了自适应并发多路由算法APMR(Adaptive Parallel Multi-path Routing).算法是分布式的,可在任意中继节点处动态调整路由策略,优化路由过程.仿真结果表明APMR算法对网络性能有很好的改善.     

多层卫星网络激光星间链路空间特性仿真

多层卫星网络结构由于其鲁棒性强,可实现无缝覆盖等特点而成为研究热点。针对高轨/中轨/低轨(GEO/MEO/LEO)多层卫星网络结构,研究了各个节点间的激光链路,推导出了不同轨道间两个卫星位置关系的坐标转换公式。对同层间激光链路(OISL)、异层间激光链路( OIOL) 俯仰角、方位角以及距离参数和GEO对LEO覆盖特性进行了仿真。结果表明,卫星光学终端俯仰指瞄范围完全可以满足目标星的移动要求,但水平指瞄范围和扫描速度是影响星间激光链路性能的主要因素。     

A novel QoS routing protocol for LEO and MEO satellite networks

The rapid advance of communication and satellite technology pushes broadband satellite networks to carry on multimedia traffic. However, the function of onboard routing cannot be provided in existing satellite networks with inter‐satellite links, and quality of service (QoS) of satellite networks cannot be reliably guaranteed because of great difficulties in processing of long distance‐dependent traffic. In this paper, a two‐layered low‐Earth orbit and medium‐Earth orbit satellite network (LMSN) is presented. A novel hierarchical and distributed QoS routing protocol (HDRP) is investigated, and an adaptive bandwidth‐constrained minimum‐delay path algorithm is developed to calculate routing tables efficiently using the QoS metric information composed of delays and bandwidth. The performance of LMSN and HDRP is also evaluated through simulations and theoretical analysis. Copyright © 2007 John Wiley & Sons, Ltd.     

部分全连接星际链路网络动态路由策略研究

本文在构造部分全连接星际链路网络的基础上,提出了用卫星网络的自适应状态判决路由策略（ＡＳＤＲ）。通过仿真研究,ＡＳＤＲ与常规的咱由策略进行了比较。结果表明ＡＳＤＲ策略端到端的阻塞概率性能（ＥＥＢＰ）较为优越,特别是在重负载的条件下较常规的路由策略有较大的改善。     

Priority‐based adaptive routing in NGEO satellite networks

In a non‐geostationary satellite constellation with inter satellite links (ISLs), there could be many shortest paths between two satellites in terms of hop count. An efficient routing algorithm should effectively use these paths in order to distribute traffic to ISLs in a balanced way and to improve the performance of the system. This paper presents and evaluates a novel priority‐based adaptive shortest path routing (PAR) scheme in order to achieve this goal. PAR sets the path towards the destination in a distributed manner, using a priority mechanism depending on the past utilization and buffering information of the ISLs. Moreover, to avoid unnecessary splitting of a flow and to achieve better utilization of ISLs, enhanced PAR (ePAR) scheme is proposed. This paper evaluates performance of the proposed techniques by employing an extensive set of simulations. Furthermore, since there are a number of ePAR parameters that should be adjusted depending on the network and traffic characteristics, a detailed analysis of ePAR scheme is provided to form a framework for setting the parameters. This paper also includes a method for adaptation of the proposed algorithms to minimum‐delay path routing. Copyright © 2006 John Wiley & Sons, Ltd.     

Load balancing routing for single-layered satellite networks

The varying population density leads to imbalanced utilization rate of satellites. To ensure an intelligent engineering of traffic over satellite networks, a distributed routing scheme for single-layered satellite network, load balancing routing protocol based on mobile agent (LBRP-MA) is proposed. For LBRP-MA, mobile agents explore route by migrating autonomously. Upon arriving at destination, mobile agents migrate back. On each intermediate satellite, mobile agents evaluate path cost considering satellite geographical position as well as inter-satellite link (ISL) cost, and finally take ISL congestion index into account to update routing tables. Through simulations on the Courier-like constellation, the proposed approach is shown to achieve guaranteed end-to-end delay bound and decrease packet loss ratio with better throughput, which is especially suitable for data transferring in case of high traffic load. Moreover, results of the complexity analysis demonstrate that LBRP-MA can have low onboard signaling, storage and computation requirements. Furthermore, issues of LBRP-MA such as ISL congestion index and cost modification factor are discussed.     

一种基于分时的LEO卫星网络无环路由算法

在分析传统卫星网络路由算法的基础上，提出一种基于分时的LEO卫星网络无环路由算法(DTRA)。针对卫星在各时间片之间进行路由表切换时可能出现的路由环问题，算法采用平滑路由表切换策略消除由于切换前后网络状态信息不一致而产生环路的可能性，保证分组在任何时刻都能够沿无环最短时延路径被转发。同时，DTRA也能够通过使用无环备份路径处理可能出现的链路拥塞、节点失败等突发情况。通过复杂性分析可知，算法只需较小的星上存储开销和星上处理开销，而无需星问通信开销。仿真实验结果也表明算法能够提供数据最优传送，具有较好的端到端时延性能。     

Adaptive power control for satellite to ground laser communication

We develop an adaptive power control algorithm to facilitate satellite to ground laser communication through turbulence fading channels. Adaptive control is a powerful tool that improves energetic gain of the satellite laser. We use discrete laser transmitter intensity levels in our control algorithm. A novel recursive technique defines optimal laser transmitting intensity levels so that the laser‐transmitted power is adapted according to instant changes of the signal‐to‐noise ratio caused by channel fading. The algorithm's performance is first investigated in a general form suitable for any channel fading statistics. Then it is specified for a typical lognormal fading channel. The results indicate an improvement of up to 10dB in energetic gain. Copyright © 2007 John Wiley & Sons, Ltd.     

卫星移动通信系统星间链路空间参数分析

通过对现有的卫星移动通信系统星间链路的分析发现,伴随着卫星座高度的增加,卫星移动通信系统星间链路指向的动态变化范围不断扩大,星间链路的相对距离也不断增大。由此引出对最优化的极轨道卫星移动通信系统星暗链路主要参数的模拟与分析,从中得到了一些规律性的结论,为星间链路的设计与建立提供了理论基础;同昱,卫星移动通信系统星间链路指向性的周期性变化,也为星间链路建立过程中最优化搜索算法的建立提供了探索的方向和     

QoS routing based on mobile agent for LEO satellite IP networks

Current quality of service (QoS) routing schemes for low earth orbit (LEO) satellites IP networks either neglect the varying population density or fail to guarantee end-to-end delay. As a remedy, QoS routing protocol based on mobile agent (QoSRP-MA) is proposed. QoSRP-MA is a source-based routing protocol. Once connection requests arrive, QoS mobile agents are dispatched from ingress satellite to explore routes, which migrate using satellite routing tables. Upon arriving in egress satellite, QoS mobile agents migrate back towards ingress satellite to reserve bandwidth. To construct satellite routing tables, load balancing routing algorithm based on mobile agent (LBRA-MA) is presented. In LBRP-MA, at regular intervals mobile agents launched on all satellites migrate autonomously to evaluate path cost and update routing tables. Moreover, path cost between source and destination is evaluated considering satellite geographical position as well as inter-satellite link (ISL) cost. Furthermore, ISL congestion index is considered to update routing table. Through simulations on a Courier-like constellation, it shows that QoSRP-MA can achieve guaranteed end-to-end delay bound with higher throughput, lower connection failing ratio and signaling overhead compared to high performance satellite routing (HPSR) scheme.