Design And Simulated Implementation Of Reliability Routing Algorithm Based On Topology Reconfiguration In Deep Space Optical Communication Network(DSOCN)

Deep space communication system,as core infrastructure of space information network construction plan,undertakes the important role of information transmission and exchange in deep space detection work.In recent years,with the rise of worldwide deep space exploration,the traffic of deep space communication presents the obvious growth trend.Due to the inherent defects,for example,the high delay,low SNR,limited transmission rate and poor confidentiality,the conventional microwave communication system could not effectively support deep space communication tasks which have long distance transmission and high bandwidth demand.In face of the challenges of traditional microwave communication system in deep space environment,both academic and industrial communities begin to focus on the deep space optical communication technology which has wide prospect of development.Compared with the traditional microwave communication system,space optical communication system has large capacity of transmission,strong anti-interference ability and good secrecy.It not only reduces the design size and weight of communication terminal,but also effectively saves the system power consumption.On the other hand,because of the thin air(or vacuum)in deep space environment,the influence of atmospheric turbulence is small for spatial optical signal transmission.Thus,it is advantageous for the long distance transmission of spatial optical signal.The technological merits of space optical communication and the superior transmission condition of deep space environment provide a favorable research opportunity for deep space optical communication.At present,the research organizations and institutes from many countries in the world are investing a lot of human and material resources to carry out the related research work of deep space optical communication.The ShenZhou-10 Spacecraft launched in 2013 by China successfully implemented the transmission task of real-time video of space teaching through space optical link for 45 minutes.This significant technological breakthrough further arouses the enthusiasm of academic and industrial communities for deep space optical communication research.However,the current researches of deep space optical communication are mainly concentrated in the point-to-point signal transmission,the key technology of topology structure and network routing optimization are often neglected.This cannot meet the urgent needs of mass traffic in future deep space optical communication.At the same time,due to the differences of network structure and transmission characteristics,the related technology in traditional microwave communication satellite network and ground free space optical network cannot be directly applied to Deep Space Optical Communication Network(DSOCN),which has long transmission distance,highly dynamic topology,large bandwidth demand and high reliability requirement.Therefore,the research of key technology for topology structure and routing optimization in DSOCN has important strategic significance for carrying out comprehensive exploration tasks of deep space and building high-speed information channel in the future.This thesis focuses on the research of key techniques of topology structure and routing optimization in DSOCN.Combined with the intrinsic characteristics of DSOCN,for example,long transmission distance,highly dynamic topology,large bandwidth demand and high reliability requirement,the reliability routing algorithm based on topology reconfiguration is studied in order to provide necessary theoretical guidance and technical reference for the future construction and development of DSOCN.First of all,according to the characteristics of highly dynamic and complicated network environment in DSOCN,this thesis researches the robust topology structure based on algebraic connectivity in DSOCN.We fully consider the influence of deep space environment factors,transmission wavelength and transmission distance on the link reliability and topology robustness,and then propose the Robust Topology Initial Structure(RTIS)algorithm.At the same time,considering the time-varying link outage goes against the robustness of network topology,we further propose the Robust Topology Reconfigured Structure(RTRS)algorithm to solve the topology optimization problem of minimizing the number of reconfigured links.Then,for the high reliability transmission requirement in DSOCN,we research the end-to-end reliability cooperative routing algorithm and propose the end-to-end reliability estimation model.We fully consider the relationship between the topology changes and routing reliability,then analyze the influence of the link outage on reliability,and finally propose the Cooperative Reliability Routing(CRR)algorithm and Local Reliability Rerouting(LRR)algorithm.In the CRC algorithm,we mainly consider how to improve the end-to-end reliability with minimal cooperation link.In the LRR algorithm,we mainly consider the influence of topology changes on routing reliability,the routing reliability in the process of topology reconstruction is maintained by local rerouting mechanism to minimize the cost of rerouting on the premise of ensuring the end-to-end reliability.The VC++ 6.0 software is employed to develop the simulation platform of DSOCN in order to evaluate the performance of proposed algorithms.A comparative analysis is made between the proposed algorithms.Simulation results demonstrate that the proposed RTIS and RTRS algorithms gain the obvious advantages in improving the network topology robustness and adapting to time-varying link-state,and the proposed CRR and LRR algorithms gain the obvious advantages in providing continuously reliable routing in the case of highly dynamic network topology.