Research On Routing Of LEO Satellite Network By OPNET Simulation

LEO(Low Earth Orbit) satellite system can produce truly global coverage and networking, with strong anti-destroying ability, short end-to-end delay, and large capacity, it has a broad application prospect in communication field. Routing protocol design is one of the essential technical challenging the LEO satellite network. Establishing a practical system for satellite network technology research costs too much, thus a simulation model for technical assessment is an economic and effective solution.In this dissertation, the research background is introduced firstly. The superiority of LEO satellite network is demonstrated; the existing satellite routing algorithms are summarized and classified, and the research trend is also pointed out. Then the characteristics of satellite motion,coverage and constellation are analyzed theoretically. Following research is mainly focused on the OPNET software modeling method, especially the simulation process, simulation mechanism and modeling technique in OPNET Modeler.Regarding to the load imbalance characteristics of satellite network, multipath routing and QoS(quality of service) of different packet scheduling algorithms are analyzed, a novel congestion control routing algorithm applicable to satellite network with multi-service is proposed. The algorithm integrates the scheduling strategy and alternate path strategy. First of all, it ensures the request of real-time traffic bandwidth based on the point of differentiated service, then let the non-real-time traffic to share remaining resources relatively fair; when congestion occurs, part of the low priority business will be guided to free paths.Finally, a simulation platform of satellite network is established in OPNET to verify the algorithm. Through the simulation, it can be found that new strategy not only ensure delay and bandwidth indicators of real-time traffic, but also ensure the relative fairness competition for resources of non real-time traffic, solve the problem that low priority traffic to be “starve” in resource competition. When congestion happens, the alternate path strategy is adopted to guide forward the non-real-time traffic to idle satellite nodes, which not only can ensure the timeliness of real-time traffic, but also can reduce the packet loss ration of non real-time service, improve the performance of network resources utilization.