| Space-based Internet (SI) is a newly proposed notion in recent years, whose core is satellite communication networks. Low earth orbit (LEO) satellite system is chosen as the most suitable formation of SI due to its inherent advantages such as: high bandwidth, low delay between satellite and earth, small deterioration of links, global coverage and frequency multiplexing capability, and so on. As the foundation of reliable and effective information transmission, high performance routing is not only the key technology but also a challenging problem in the research of satellite communication networks. Because there are many distinct differences between terrestrial and satellite networks, it is necessary to develop new routing protocols, which are fit for satellite networks in consideration of their special characteristics: for instance, frequent changes of satellite network topology, large delay jitter between satellite and earth, etc.First of all, a series of conceptions are introduced in this thesis, including: LEO satellite communication networks, routing algorithms, model of satellite constellations and related definitions. Secondly, some typical routing algorithms which belong to different routing mechanisms are analyzed respectively, so are their features. Then a novel routing algorithm named Simple QoS-qualified Routing Algorithm (SQRA) is proposed. On the premise of not increasing computation complexity, two classical routing algorithms are combined in SQRA, aiming at sharing complementary advantages of each other and improving integrated performances. Simulation results demonstrate that SQRA can be implemented easily. It has acquired better performances, and has achieved the optimality to some extent. Besides, SQRA has realized the goal which is dedicated to satisfy different business data type A or B's different requirements for QoS performance. Finally, summary of the whole dissertation is given and the issues of SQRA that need to be studied further are also presented. |
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