| The development trend of satellite network is to integrate with terrestrial networks and Internet businesses will increasingly flood into satellite network.In order to meet the QoS(Quality of Service)requirements of different types of businesses,at the same time,solve the problems of frequent changes in the topology,prolonged link propagation,and uneven distribution of ground traffic,efficient routing strategies need to be designed.According to the deep understanding of the research status,satellite network routing technology has a high degree of dependence on the network structure,high computational complexity of nodes,and large amount of storage on the satellite.Moreover,the satellite network resources are not efficiently utilized while satisfying various types of QoS,and the routing algorithm has less consideration of the survivability under the node failure.In this thesis,the satellite network routing problem based on QoS guarantee are studied.It includes the following four aspects:(1)Overview of satellite network routing technology.Based on the research of the satellite network structure and the comparative analysis of various satellite network routing algorithms proposed in recent years,the key problems at the current stage are pointed out.(2)Satellite network structure modeling and simulation.A dual-layer satellite network architecture based on coverage domain partitioning is designed for the purpose of global coverage,simple management and autonomous operation.It consists of 66 LEO(Low Earth Orbit)satellites and 12 MEO(Medium Earth Orbit)satellites.The satellites of the two orbital heights are connected by non-permanent inter-layer links.Constellation model building,orbital data generation,coverage analysis and visibility analysis are performed by satellite simulation tool.After obtaining the connection relationship data between each LEO satellite and the MEO layer,the domain management switching strategy is used to calculate the pre-stored information in the satellite node.(3)Satellite network routing optimization based on QoS guarantee.For the different businesses requirements,four QoS levels are defined.Then a routing algorithm based on QoS guarantee is proposed,and the following three aspects are improved:(1)A multi-queue scheduling algorithm combining priority queue and weighted round-robin queue is designed to meet the delay requirement of high-priority businesses,while ensuring that low-priority businesses also have the opportunity to use bandwidth resources.(2)A dynamic bandwidth adaptive routing algorithm based on link state is proposed to provide bandwidth guarantee for the third type of businesses while solving the congestion problem on the shortest path.The algorithm makes full use of the structural advantages of the LEO/MEO dual-layer satellite network for global state perception and routing calculation.(3)A multi-path strategy for different businesses is designed.The first two types of businesses lookup shortest-delay routing table,the third type of businesses look for the bandwidth adaptive routing table,and the last type of businesses are forwarded by the MEO layer.The experimental results show that the proposed algorithm can meet the QoS requirements of four types of businesses,and is also superior to the existing algorithms in terms of average end-to-end delay,throughput and packet loss rate.(4)Satellite network survivability routing algorithm.In this thesis,the factors affecting the survivability of satellite network are analyzed,and the concept of node coverage is proposed.The satellite network survivability routing strategy is designed,and it is enhanced by accessing satellite handover,failure state sensing and MEO rerouting.The performance of the algorithm is evaluated in the single-node and multi-node failure scenarios.The simulation results show that the proposed survivability routing strategy can cope with the failure of nodes within a certain proportion,and can restore the service transmission of the network in time while maintaining QoS well. |
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