基于LEO极轨道星座的卫星网络路由算法研究

发布时间：2018-04-30 13:43

本文选题：卫星网络 + 星座结构　；参考：《北京邮电大学》2014年博士论文

【摘要】：随着卫星通信技术的不断发展,星上设备具备了在轨信息处理、数据转发的能力,加上激光、微波等宽带星间链路技术的应用,使高带宽卫星网络系统成为现实。卫星网络相较于传统的地面网络,具有覆盖范围大、不受地理和自然条件限制、通信距离远、容量大的特点,逐渐成为未来网络发展的趋势。然而,卫星作为网络的骨干节点,在太空环境中高速绕地球转动,导致卫星网络的拓扑结构变化迅速,星间链路切换频繁等问题。同时,由于卫星特殊的工作环境,对星上设备的体积、性能也有严格的限制。因此,设计一套合理有效的路由算法是卫星网络所面临的一项技术挑战。本文以LEO极轨道星座的卫星网络系统为研究对象,对应用于此环境下的分布式路由算法进行了详细的研究,主要的研究成果如下： (1)提出了一种应用于极轨道星座的卫星网络的选径策略研究模型,得到在特定星座参数的情况下,网络中最短延迟路径一定属于最短跳路径的结论,从而证明以路径跳数作为路由代价的分布式路由算法同样能够得到最短延迟路径。在太空远距离通信的环境中,采取最短延迟策略的路由算法理应是最合理的。分布式路由算法避免了节点之间的链路状态信息交互,能够更好的应对频繁的拓扑变化,简化了算法实现的流程,但只能以短跳数作为路由代价。本文对最短延迟路径与最短跳路径的相互关系详细分析,得到了在特定星座参数下,最短延迟路径必定属于最短跳路径集合的结论。同时在理论分析的过程中,得到了路径的延迟与横向链路的纬度相关,为后文提出的基于横向传输优先级的分布式路由算法奠定了基础。通过仿真分析表明,在此模型基础上理论分析得到的星座参数、最短延迟路径和最短跳路径的关系,与星间链路的实际情况是一致的。 (2)提出了一种基于横向传输优先级的卫星网络分布式流量均衡路由算法,进一步简化了卫星网络分布式路由算法的复杂程度,克服了卫星网络中流量分布不均匀的问题。通过对LEO极轨道星座卫星网络选径策略的分析发现,路径的传输延迟与选择的横向路径卫星所在纬度有重要关系,而对经度信息并不敏感。本文在传统的曼哈顿网络结构基础上,提出了一种改进型的卫星网络拓扑模型,该模型将动态的卫星网络拓扑划分为一个静态的网络拓扑和一个动态的横向传输优先级表两种形式相结合。在此拓扑模型的基础上所提出的分布式路由算法,极大的简化了算法的复杂度。此外,针对卫星网络中,横向路径的流量会大量集中在高纬度区域的问题,在分布式路由算法的基础上,提出了基于横向传输优先级和基于横向转发概率的流量均衡策略,避免了大量集中的现象。仿真结果表明,当星座参数保证最短延迟路径属于最短跳路径时,本文提出的分布式路由算法与传统的集中式路由算法得到的路径相同；在最短延迟路径不属于最短跳路径的情况下,两种路由算法的结果差异细微。此外,仿真数据证明本文提出的两种流量均衡策略,均能够有效的改善横向传输流量集中在高纬度区域的问题。 (3)提出了一种基于卫星网络分布式路由算法的抗毁策略,克服了分布式路由算法在网络拓扑损坏后性能下降的问题。分布式路由算法通过避免交换链路状态信息来应对高速变化的网络拓扑结构,简化了算法的流程,更适合于星上设备执行。而另一方面,算法缺乏对网络拓扑未知损毁的应对策略。针对分布式路由算法在抗毁性方面的弱点,提出了一种结合分布式路由算法和动态路由算法的抗毁路由策略。考虑到动态路由算法泛洪信息对路由算法自身性能的影响,提出了自愈区域的概念,以限制泛洪信息传播范围。通过仿真结果证明,在卫星网络拓扑结构受到一定程度损坏时,该策略能够快速实现协议的收敛,保证路由算法的高效性。与传统的分布式路由算法相比较,应用了抗毁策略的分布式路由算法在网络拓扑受到损坏的情况下有明显的性能优势。
[Abstract]:With the continuous development of satellite communication technology, the satellite equipment has the ability of on orbit information processing, data forwarding, and the application of broadband intersatellite link technology such as laser and microwave, which makes the high bandwidth satellite network system become a reality. Compared with the traditional ground network, the satellite network has large coverage and is not restricted by geographical and natural conditions. However, as the backbone of the network, the satellite, as the backbone of the network, revolves around the earth at high speed in the space environment, which leads to the rapid change of the topology of the satellite network, the frequent switching of intersatellite links and so on. In the same time, the satellite equipment is due to the special working environment of the satellite. Therefore, the design of a reasonable and effective routing algorithm is a technical challenge facing the satellite network. This paper studies the satellite network system of the LEO polar orbit constellation, and studies the distributed routing algorithms applied in this environment. The main research results are as follows:
(1) a study model of the path selection strategy applied to the satellite network of polar orbit constellation is proposed. The conclusion is that the shortest delay path in the network must belong to the shortest hopping path in the case of the specific constellation parameters. Thus, it is proved that the distributed routing algorithm with the path hop as the routing cost can also get the shortest delay path. In space remote communication environment, the shortest delay strategy should be the most reasonable routing algorithm. The distributed routing algorithm avoids the link state information interaction between nodes. It can better cope with frequent topology changes and simplify the process of algorithm implementation, but it can only take the short hop number as the routing cost. This paper is the shortest delay. The relationship between the late path and the shortest hop path is analyzed in detail, and the conclusion is obtained that the shortest delay path must belong to the shortest hop path set under the specific constellation parameters. In the process of theoretical analysis, the delay of the path is related to the latitude of the lateral link, which is a distributed path based on the lateral transmission priority. The simulation analysis shows that the relationship between the parameters of the constellation, the shortest delay path and the shortest hop path, which is based on the model, is consistent with the actual situation of the inter satellite link.
(2) a satellite network distributed traffic equilibrium routing algorithm based on transversal transmission priority is proposed, which further simplifies the complexity of the distributed routing algorithm of satellite network and overcomes the problem of uneven distribution of traffic in the satellite network. Through the analysis of the path selection strategy of the satellite network of the LEO polar orbit constellation, the path transmission is found. In this paper, a modified satellite network topology model is proposed on the basis of the traditional Manhattan network structure. This model divides the dynamic satellite network topology into a static network topology and a dynamic lateral transmission. The distributed routing algorithm based on this topology model has greatly simplified the complexity of the algorithm. In addition, in the satellite network, the traffic of the lateral path will be concentrated in the high latitude region. Based on the algorithm, the distributed routing algorithm is based on the transversal transmission optimization. The first level and the traffic equilibrium strategy based on the lateral forwarding probability have avoided a large number of concentrated phenomena. The simulation results show that the distributed routing algorithm proposed in this paper is the same as that of the traditional centralized routing algorithm when the constellation parameters guarantee the shortest path, and the shortest path is not the shortest path. In the case of hopping path, the results of the two routing algorithms have little difference. In addition, the simulation data show that the two traffic equilibrium strategies proposed in this paper can effectively improve the problem of the horizontal transmission flow concentration in the high latitudes.
(3) an anti destruction strategy based on distributed routing algorithm based on satellite network is proposed to overcome the performance degradation of distributed routing algorithm after the network topology is damaged. The distributed routing algorithm avoids the exchange link state information to cope with the high speed changing network topology, simplifies the process of the algorithm and is more suitable for the satellite devices. On the other hand, the algorithm lacks the strategy to deal with the unknown damage of the network topology. Aiming at the weakness of the distributed routing algorithm in the aspect of destruction, this paper proposes a routing strategy which combines the distributed routing algorithm and the dynamic routing algorithm. Considering the impact of flood information on the performance of the routing algorithm, the dynamic routing algorithm is proposed. The concept of self healing region is presented to limit the spread of flood information. The simulation results show that the strategy can quickly achieve the convergence of the protocol and ensure the efficiency of the routing algorithm when the topology of the satellite network is damaged to a certain extent. Compared with the traditional distributed routing algorithm, the distributed routing of the anti destruction strategy is applied. The algorithm has obvious performance advantages when the network topology is damaged.

【学位授予单位】：北京邮电大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN927.2

【参考文献】