Research On Content Caching Strategy In Mobile Edge Networks

With the rapid development of mobile communication technology and the emergence of a large number of new internet services,the data traffic of mobile services is increasing explosively.Although cloud servers can meet users' demands for computing and storage resource,long distance transmission and access will cause the quality of user experience to decline.In order to tackle this problem,edge caching technology uses storage resources in the edge network to cache popular contents to the edge nodes in response to frequent content requests from user devices,thereby reducing the traffic load of the backhaul link and improve the efficiency of the communication system.Moreover,in order to effectively utilize the cache resources of the edge server and reduce the content download delay,it is quite important to consider diversified user request modes and design a reasonable content cache configuration strategy.In this thesis,the optimization method of content caching in the mobile edge network are studied.The main contents of this thesis are summarized as follows:Aiming at the problems of backhaul link congestion and end-to-end delay caused by the rapid growth of data traffic,this thesis proposes a multi-constrained edge content collaborative caching optimization scheme.The proposed scheme comprehensively considers the content popularity and file size,the location distribution of users and edge servers,and edge server cache capacity,formulates the edge content collaborative caching problem as a content average download delay minimization problem,and by applying the Mc Cormick equivalence principle,the original problem can be equivalently transformed into an integer linear programming problem.The tabu search algorithm model is proposed to iteratively optimize the deployment location of the content,and the multi-constraint based cache configuration strategy is selected for the content.The simulation results show that the proposed scheme is close to the optimal solution,and it achieves significant effects in improving the edge cache hit ratio and reducing the average content download delay.According to the results,the influence of the popularity change rate on the cache update cycle under different edge server cache capacities and popularity distributions is obtained.Under mobile edge network model,to solve the problem of user experience degradation caused by user mobility and the time-varying content popularity,this thesis proposes a mobility and popularity awareness based adaptive edge caching scheme.The proposed scheme comprehensively considers the global popularity and local popularity of the content,the user temporal and spatial transfer characteristics,and the edge server cache resource state.According to the global and local popularity of the content,the file size and the cache capacity constraints of the edge server,the scheme initializes the edge cache configuration of the content.According to the real-time change of content popularity,the spatiotemporal mobility of the user and the cache resource state of the edge servers,the scheme further determines the potential cache value of the content and adaptively updates the content cache configuration.The simulation results show that the proposed scheme can effectively improve the edge cache hit rate and reduce the content download delay.