Research Of Routing In Space-based Networks

With the rapid development and application of spaceflight technology, the space's strategic role is becoming more and more important in the political, military and economic fields, etc. Obtaining predominance in space turns into the foremost task for the development of spaceflight military power for all the countries in the world. The space-based network is a type of wireless network system in space in which various satellite nodes are inter-connected by inter-satellite links. As the main part of the future integrated space-ground information framework, the space-based network will be applied widely in many military environments, such as strategic presentiment, information supply in territorial battle, tactical command and control, and battlefield management, etc.Routing technology has special meaning for increasing the delay performance and reliability performance of data traffic transmission. Despite that the routing problem has been resolved effectively in terrestrial networks, many new challenges exit for routing in space-based network due to highly dynamic topology, very limited on-board processing capabilities, large propagation delay of inter-satellite links and unbalanced traffic load carried in the network. Routing is the basic problem in the design of space-based networks, and is one of the research focuses nowadays. Based on the analysis of the technology challenges for routing in space-based network and the limitation of related work, this dissertation focuses on resolving the problem of routing algorithms designing for space-based networks in different evolution phases and with different networking architectures.The major contributions of the dissertation include:Firstly, considering the very limited on-board processing capabilities of the low earth orbit (LEO) satellites during the initial stage of the space-based network, by introducing the idea of "off-line" routing computation, this dissertation proposes a Discrete Time based Routing Algorithm (DTRA) for LEO satellite networks, the main idea of which is that the system cycle is divided into n time segments by selecting some special time points satisfying given conditions, through analyzing the dynamic regularity of the changing network topology. In DTRA, the network topology can be described as pre-computed virtual graph over each time segment. The length and state of the inter-satellite links are considered only changing at the time of segments boundary. Consequently, the dynamic network topology will be modeled as a series of static topologies. By using the loop-free secondary routes and the routing table compressing mechanism, the algorithm has several advantages comparing with traditional "off-line" routing algorithms, such as higher adaptive capabilities to variable network traffic load and less on-board overhead.Secondly, supporting dynamic adaptive routing based on on-board routing computation is one of the key characteristics of the advanced phases of the space-based network. To realize dynamic routing based on on-board computation in space-based networks, the dissertation...