Routing For Low-Earth-Orbit Satellite Delay Tolerant Networks

The spatial information network is a backbone communication network composed of many satellites and satellite constellations,which realizes the interconnection between terrestrial networks and spacecraft.The network architecture that can be applied to the space environment includes three types: the space IP protocol system,the CCSDS protocol system and the DTN protocol system.Because the spacecraft network has the characteristics of intermittent connection,long delay and high bit error rate,the DTN protocol system is more suitable for spacecraft network,thus forming spatial DTN network.The routing technology including multicast routing is the main research direction of the spatial DTN network and can realize the transmission and distribution of information in the airspace.As a key component of the spatial DTN network,the LEO satellite DTN network is also an important topic for researching its routing technology.Based on the predictable characteristics of time-varying network topology,this thesis proposes an MTD unicast routing algorithm when researching LEO satellite DTN network routing technology.Through this algorithm,the minimum temporal path from source node to destination node can be found.At the same time,a multicast version MBMTD algorithm is proposed based on the MTD algorithm.In addition,an MTBMTD routing algorithm is proposed from the point of view of fully utilizing the contact opportunities and reducing the number of message copies in the network.This thesis evaluates the performance of the MBMTD and MTBMTD routing algorithms based on the ONE simulation platform and compares the performance with the Epidemic algorithm.In order to satisfy the reality of the simulation scenario,LEO satellite DTN network models are established in the STK.Then,these routing algorithm performances are implemented by importing contact information in the ONE.The simulation results show that the three routing algorithms are similar in the success rate of message transmission,but the MTBMTD algorithm is much better than the MBMTD and Epidemic algorithm in the message replication ratio.The experiment results showed that when the nodes in the network are dense,the performance of the MTBMTD routing algorithm proposed by this thesis is improved more significantly.