Research On Multi-layered Satellite Network Routing Strategy

With the rapid development of space technology, space resource for each country’s strategic position has become increasingly important. Thus, the competition for the space is increasingly violent, and they are trying to build spatial information network of great strategic significance. Spatial information network is a highly dynamic multi- layer heterogeneous network system based on space platforms(such as geostationary satellites or the lower orbit satellites, stratospheric balloons and drones, etc.) as the carrier, made up of a plurality of satellites and ground stations responsible for a variety of tasks such as real- time acquisition, transmission and processing of spatial information. Thus, the research on multi- layer satellite network has great significance. Compared to single- layerd satellite network, multi- layered satellite network has good survivability, network capacity, flexibility. However, the complexity of the multi- layerd satellite network is high, it also has large number of nodes and links. Because the satellite nodes are in constant motion, the entire network topology is dynamic and changes fast, so the routing technology of multi- layer satellite network is also more complex.This paper focused on the routing strategy of multi- layered satellite networks. Firstly, the advantages and disadvantages between single- layerd satellite network and multi- layered satellite network are compared, the necessity of research on multi- layered satellite network is analyzed. According to the characteristics of multi- layered satellite network, the significance of multi- layered satellite network routing technology is identified. The domestic and foreign research status of multi- layered satellite network routing technology is analyzed, the key technical problems at present are pointed out. Next, several typical multi- layered satellite networks are introduced, 3GEO + 66 LEO double-layerd satellite constellation is designed, and the connection characteristics and coverage characteristics of the constellation were analyzed. Then, a low-cost routing strategy based on optimization of the slot is proposed. This strategy included the following three aspects to improve: an optimal time slice division method is proposed, which reduces the number of routing updates within the satellite operating cycle; a satellite grouping management method based on the "clustering + grouping" is proposed; a flow balancing method through contolling the limit on the number of hops and links is proposed, which can solve the network congestion problem from both congestion avoidance and congestion relief. Simulation results verify that SORA has less inter- layer link connection, lower communication load and higher packet arrival rate. After that, mainly considered of the characteristic that polar-orbiting satellites’ s links are temporarily closed in polar regional, a new routing optimization strategy based on location forecast is proposed. Simulation results verify that LFRA can reduce the loss rate of the network and enhance the system’s reliability. Finally, the combination of STK and MATLAB co-simulation platform based on OPNET is designed and implemented.