Design Of Satellite Network Routing Protocol

With the development of satellite communication technology and the improvement of satellite manufacturing technology,the LEO satellite is playing an increasingly important role in the satellite Internet,and the research of LEO satellite constellation has ushered in a fierce upsurge.As the core of LEO satellite network technology,satellite network routing is the key to improve network performance,and has always been a research hot spot.At present,most satellite network routing algorithms only focus on the problem of inter satellite routing forwarding,while considering the ground terminal access to the satellite network,few routing algorithms are proposed to deal with the problem of frequent inter satellite routing switching.Moreover,the existing algorithms have poor adaptability to inter satellite link failures.With that in mind,this paper studies the LEO satellite network routing algorithm in order to solve the problem of frequent inter satellite routing switching.Based on the research of LEO satellite constellation and the existing satellite network routing algorithms,this thesis proposes an adaptive survivable routing algorithm VN-ASR based on virtual nodes,completes the simulation of VN-ASR,and compares the performance of VNASR with the existing algorithms.First,the key technologies of satellite network are introduced,including satellite constellation technology and satellite network routing algorithms.The thesis analyzes the characteristics of satellite network routing,summarizes the shortcomings of existing satellite network routing algorithms,and provides the foundation for the following research of the thesis.Secondly,based on the special LEO satellite Walker Star constellation,considering frequent inter satellite routing switching when ground terminal access to satellite network,and the network congestion which caused by uneven traffic load,this paper proposes an adaptive survivable routing algorithm VNASR based on virtual nodes.VN-ASR includes routing table updating,link fault detection,multi-path routing and congestion avoidance mechanism.The updating of routing table occurs when the virtual nodes corresponding to actual satellite nodes change or the connections relationship between satellite nodes change.The link fault detection mechanism sends Hello packet to neighbor nodes periodically to detect link state,and starts UPDATE flood to trigger the updating of the routing table when the changes of link state are detected.The multi-path routing mechanism guarantees low packet loss performance from link failures occurring to routing table updating by switching the main and the alternative path.By judging the congestion information of the next-hop link and the busy state of the nexthop node,the congestion avoidance mechanism selects the appropriate next hop from the primary and alternative path to avoid network congestion.Then,the VN-ASR is implemented by STK and OPNET software,and the VN-ASR is modeled from network layer,node layer to processing layer.Finally,the scenario is set to verify the characteristics of VNASR,and then the performance of VN-ASR is evaluated by comparing with the classical DRA based on virtual nodes.After simulation analysis,VN-ASR can solve the problem of DRA performance degradation caused by multi-points fault.And in the simulation scenario close to the real earth traffic distribution,VN-ASR has lower packet loss rate and lower average delay than DRA.In terms of congestion avoidance,although VN-ASR can guarantee small packet loss rate,it will introduce long queuing delay and large routing overhead,we need to continue to optimize congestion processing in the future.