A Research On The Routing Mechanism Of Small Satellite Network

Recently,with the development of space technology,the number of small satellites in the world is increasing rapidly.In a dynamic scenario,research on the dynamic routing algorithm of the small satellites needs to be introduced Ad-hoc routing technology because the small satellites network model is closer to the Ad-hoc network in structure.First of all,according to the networking requirements of small satellites in highly dy-namic and constantly changing topology,this thesis proposes a routing scheme for small satellite cluster networking,and establishes an inter-satellite self-organizing network ar-chitecture including the physical layer,the data link layer and the network layer.The main functions implemented by the physical layer are wireless data transmission and re-ception.And it can provide reliable wireless communication channels for upper-layer network communication.The data link layer can establish the clock synchronization of the whole networke and allocate channels reasonably by using time division multiplexing(TDMA).In order to use OLSR protocol in the scenario of small satellites networking,some optimizations have been made to the Optimized Link State Routing Protocol(OLSR)in the network layer of this architecture.The optimized OLSR protocol can reduce the sys-tem overhead and shorten the route convergence time significantly.OPNET simulation results show that the routing scheme this thesis proposed demonstrates excellent clock synchronization speed,low end-to-end delay,and fast route convergence.Secondly,in view of the frequent packet loss when using unreliable routes in high load and high dynamic scenarios,this thesis proposes an inter-satellite link-aware route destroy-resistant strategy called OLSR-LT based on OLSR,which uses received power,carrier frequency and other parameters of the received 2 consecutive HELLO messages to calculate the link lifetime of two adjacent nodes in the small satellite Ad-hoc network,and select a backup route according to the link lifetime and multipath routing technology.OLSR-LT can enable alternate route to ensure the reliability of the routing protocol when the main route is busy or queued.Simulation results using OPNET show that the OLSR-LT effectively improves the data packet arrival rate,reduces the end-to-end delay and packet queuing time,and improves the real-time performance of the small satellite network transmission compared with the traditional OLSR protocol.Finally,this thesis designs and implements a semi-physical simulation verification system using "FPGA+Linux" based on the small satellites network routing scheme.The system includes four small satellite self-organizing network nodes,each of which can realize basic functions like network access,networking with other nodes and wireless data communication.And the system performance can meet the requirements of efficient networking in high dynamic scenarios.