Routing and Multicast Algorithms for LEO Satellite Networks

低地球轨道(LEO)卫星系统以较短的往返延迟提供全球覆盖。凭借这些特性，它们将在全球互联网中扮演关键角色，以支持实时和非实时应用。低轨卫星系统中的路由和组播是支持这些服务的关键问题。非实时应用的特点是延迟界限松散。他们对延迟的变化也不敏感。因此，可以使用基于数据报的路由方案来支持这种类型的流量。为支持低轨卫星网络的无连接路由，提出了半集中式数据报路由协议(SC-DRP)。SC-DRP的目标是在最小延迟路径上转发LEO卫星网络中的分组。SC-DRP利用LEO和MEO/GEO卫星计算路由表，这将提高卫星网络中数据流量承载在LEO卫星网络中的可靠性和时延性能。数据报多播协议(DMP)是为了支持无连接多播而提出的。DMP基于SC-DRP并创建最短路径树。实时应用程序要求严格的延迟限制，并且对延迟变化非常敏感。因此，面向连接的路由方案可以支持实时业务。卫星连通模式的变化会影响低轨卫星网络中已建立的路径。因此，确定稳定路径是非常重要的。针对LEO卫星网络中面向连接的路由问题，提出了时延耦合概率路由协议(DC-PRP)。DC-PRP计算符合连接的延迟和延迟抖动界限的路径。面向连接的组播协议LEOCOM(Connection-Oriented Multicast Protocol)被提出用于面向连接的组播，它创建延迟受限的组播树。使用贪婪搜索算法来优化组播树长度。

Low Earth Orbit (LEO) satellite systems provide global coverage with short round trip delays. With these properties they will play a crucial role in the global Internet to support real-time and non-real-time applications. Routing and multicasting in LEO satellite systems are the key issues to support these services. Non-real-time applications are characterized by relaxed delay bounds. They are also insensitive to the variations in delay. Thus, datagram-based routing schemes can be used to support this type of traffic. the Semi-Centralized Datagram Routing Protocol (SC-DRP) is proposed to support connectionless routing in LEO satellite networks. The SC-DRP aims to foward the packets in the LEO satellite network on minimum delay paths. SC-DRP utilized LEO and MEO/GEO satellites to calculate routing tables, which will increase the reliability and delay performance of datagram traffic in satellite networks, where the data traffic is carried in the LEO satellite network. The Datagram Multicast Protocol (DMP) is proposed to support connectionless multicasting. DMP is based on the SC-DRP and creates shortest path trees. Real-time applications impose strict delay bounds and are sensitive to delay varations. Thus, real-time traffic can be supported by connection-oriented routing schemes. The changing connectivity pattern of satellites affects the estbalished paths in LEO satellite networks. Thus, determining stable paths is very important. The Delay-Coupled Probabilistic Routing Protocol (DC-PRP) is proposed for connection-oriented routing in LEO satellite networks. DC-PRP computes paths conforming to the delay and delay jitter bounds of the connections. The Connection-Oriented Multicast Protocol (LEOCOM) is proposed for the connection-oriented multicasting, which creates delay-constrained multicast trees. The multicast tree length is optimized using a greedy search algorithm.