低轨卫星通信系统路由与流量均衡策略研究

发布时间：2018-01-22 00:46

本文关键词： 低轨卫星通信系统路由算法流量均衡算法 OPNET仿真平台　出处：《电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：作为移动通信的重要组成部分,低轨卫星通信系统正越来越受到人们关注。一方面原因是其可以弥补地面通信系统覆盖不足的缺点,另一方面是作为应急通信手段具有其它系统无法替代的优势。然而,虽然低轨卫星通信系统时延较低且电波传播损耗小,其依然存在一些问题:第一,卫星节点都处于高速运动的状态,路由算法不易设计。第二,由于星上处理能力有限以及卫星所处的太空环境较为恶劣,因此会出现星上网络数据拥塞或者卫星节点故障等问题,需要相应的方案来保证数据在规定时间内送达。目前,星间网络路由算法的主要思路之一是借助星座运行的周期性和规律性来确定网络拓扑,根据拓扑再来确定路由路径。值得注意的是,卫星网络的路由往往是考虑了多个网络指标的最优解,因此也会考虑到流量均衡或拥塞避免的问题。在上述背景下,本文首先搭建了基于OPNET的仿真平台,对整个端到端的通信流程进行模拟,并对系统的时延、吞吐量、误码率等指标以及系统对高动态用户的服务情况等方面进行仿真分析。其次在仿真平台上对低轨卫星通信系统的路由算法展开研究。针对时间虚拟化路由算法具有时延小、复杂度低等优点但对网络突发情况适应性差的问题,经过理论分析提出了一种具有动态监测思想的路由算法,该算法通过监测发送队列以及通信中的回传信息来确定网络是否发生拥塞并进行相应的路由策略调整,仿真表明该算法在继承时间虚拟化算法优点的同时可以改善网络拥塞带来的影响。最后在仿真平台上对流量均衡算法展开研究,不同于路由算法中流量均衡是数据在星上传递时工作的,本文从另外一个角度对流量均衡进行考虑,即在用户数据进入卫星网络之前采用接入多颗卫星的方式将用户的数据分发至多颗卫星,达到避免拥塞、减小时延的目的,仿真表明在相同网络条件下该算法能够比传统算法容纳更多的用户同时进行通信,具有较好的性能。
[Abstract]:As an important part of mobile communication, Leo satellite communication system is attracting more and more attention, on the one hand, it can make up for the shortcomings of inadequate coverage of terrestrial communication system. On the other hand, as a means of emergency communication, it has the advantage that other systems can not be replaced. However, although the delay of Leo satellite communication system is relatively low and the propagation loss of radio waves is small, there are still some problems: first. Satellite nodes are in the state of high-speed motion, routing algorithm is not easy to design. Second, because of the limited processing power on board and the space environment of the satellite is relatively bad. Therefore, there will be problems such as onboard network data congestion or satellite node failure and so on. The corresponding scheme is needed to ensure the data delivery within the specified time. At present. One of the main ideas of the inter-satellite network routing algorithm is to determine the network topology by means of the periodicity and regularity of constellation operation, and then to determine the routing path according to the topology. The routing of satellite networks often takes into account the optimal solution of multiple network metrics, so it also takes into account the problem of traffic equilibrium or congestion avoidance. This paper first builds a simulation platform based on OPNET to simulate the whole end-to-end communication process, and the delay and throughput of the system. The error rate and the service of high dynamic users are simulated and analyzed. Secondly, the routing algorithm of Leo satellite communication system is studied on the simulation platform. The time virtualization routing algorithm is provided. There's a small delay. With the advantages of low complexity but poor adaptability to network burst, a routing algorithm with the idea of dynamic monitoring is proposed through theoretical analysis. The algorithm determines whether congestion occurs in the network and adjusts the corresponding routing policy by monitoring the sending queue and the return information in the communication. Simulation results show that the algorithm not only inherits the advantages of time virtualization algorithm, but also improves the impact of network congestion. Finally, the traffic equalization algorithm is studied on the simulation platform. Different from traffic equalization in routing algorithm, traffic equalization is considered from another angle. In order to avoid congestion and reduce delay, the user's data is distributed at most of the satellite by accessing multiple satellites before the user data enters the satellite network. Simulation results show that the proposed algorithm can accommodate more users than the traditional algorithm in the same network conditions and has better performance.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN927.2

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