Research On Caching Strategy Of Satellite-terrestrial Backhaul Network

In recent years,with the development of mobile terminal technology,mobile communication service is expanding rapidly,especially the amount of data generated by multimedia service is growing explosively.5G mobile communication network will be deployed and operated in 2020 to provide people with a more rapid and convenient network life.At the same time,with the development of satellite communication technology and the increase of users' demand for access network,the cooperative transmission between satellite and terrestrial communication network will be the trend of mobile communication in the future.Satellite mobile communication system has the characteristics of wide coverage,no geographical restriction,wide communication bandwidth and large transmission capacity.Therefore,it is an indispensable part of the next generation mobile communication system.The combination of 5G mobile communication network and the satellite will bring more convenient and comprehensive network life for people with the greater challenges:The transmission of repeated data between satellite and terrestrial backhaul network will take up limited bandwidth resources and cause low utilization of wireless resources.In the terrestrial communication network,such as Internet,caching has been proved an effective way to improve network performance,and research on cache in terrestrial communication has been mature.Therefore,this paper applies caching technology to the combination of terrestrial-satellite backhaul network.Based on that,we propose an optimized cache allocation and replacement strategy,which can solve the problem of low utilization rate of wireless links between satellite and terrestrial and the delay of users' request during data transmission.First of all,this paper gives a general overview of satellite backhaul network,network architecture and key technologies of 5G,and caching technology based on ICN architecture.Then,we analyze the data transmission problem in the 5G-satellite backhaul network,and introduce applying caching strategy can satisfy the high capacity and flexible expansion service needs in future 5G network.It provides a theoretical support for the proposed 5G-satellite backhaul architecture and the optimized caching strategy.Aiming at the problem of low transmission efficiency and large delay in 5G-satellite backhaul network,this paper firstly proposed an architecture of 5G-satellite backhaul network for data transmission.The architecture integrates satellite and terrestrial related network from the perspective of core network and content server.It adopts the way of sharing core network between the satellite and the terrestrial network to communicate,and the content server is configured to realize the cache of the content data.Secondly,this paper analyzes the cooperation between 5G base stations and satellite to complete the process of modeling the problem of satellite-terrestrial collaboration caching.Then we propose a cooperative cache allocation algorithm based on Simulated Annealing algorithm to minimize the average delay by optimizing the category of caching content.Through the simulation experiment,it is proved that the proposed scheme can achieve the target of minimizing the average delay of users.In addition,considering the multi-level cache architecture of 5G-satellite backhaul network and the dynamic change of file popularity over a period of time,this paper proposes a multi-level cache replacement strategy based on LRU.Through the theoretical analysis and the simulation experiment,results verify that the proposed scheme has significantly improved the performance of saving wireless resource consumption,such as reducing request delay and raising requests hit rate.