Research On D2D Caching Content Distribution Technology Based On Network Coding

With the rapid growth of network intelligent mobile devices and the continuous emergence of various new mobile application services,mobile data traffic has shown a trend of rapid increase in massive amounts.The servers in the traditional centralized network architecture bear heavy communication pressure.Mobile Edge Caching has become a core technology to effectively alleviate server load through smart devices deployed at the edge of the network and caching popular content.Encoding cache utilizes wireless edge cache information,and simultaneously meets the content needs of multiple users through multicast transmission,which can effectively increase network throughput.The D2 D caching system not only stores popular files in the base station,but also uses the storage capacity of smart devices(nodes)to cache files in edge smart devices.Compared with storing files directly in the base station,it can effectively increase the throughput per unit time and reduce Base station load,reduce backhaul link and communication energy consumption.However,in order to achieve the best network adaptability,the encoding cache and edge cache network must face system parameters such as file size,cache size,user preference for files within the coverage of different edge base stations,and heterogeneous number of users.Mass data and edge device cache capacity are difficult to match and merge.At the same time,the cache capacity of smart devices is limited,and the node cannot cache all the files required by the user.A single node can only cache some of the current popular files,reducing the system throughput per unit time;and the energy of the node is limited,and it is impossible to continuously perform D2 D with the maximum transmission power.Link transmission.Therefore,how to design a reasonable cache strategy and power allocation to improve the throughput of the system is a problem that needs to be solved urgently.In response to the above problems,this article discusses the impact of coded and uncoded caches on backhaul load,service time,and network throughput.With the goal of increasing the maximum throughput of the network system,the study of the cache technology based on network coding in the D2 D edge cache network Adaptability issues.The main research contents are summarized as follows:The basic theories related to network coding and coding caching are introduced in detail to lay the foundation for specific scheme design and performance analysis in actual application scenarios.A detailed analysis of the base station-user joint buffering system model and the upper and lower bounds of the memory-rate trade-off,and comparing the coded buffering scheme with the uncoded buffering scheme through simulation,it is found that the coded cache can effectively reduce the backhaul load of the server compared with the uncoded cache.Furthermore,the fountain code is introduced as a coding caching scheme into the base station-user joint caching system model,and the fountain code is used for content placement on the user side.It is proved by simulation that the fountain code as a content placement scheme requires more backhaul load than the uncoded content placement scheme.Small,achieve higher performance gains.A D2D-base station cooperative coding and caching network model is established,an edge caching network with base station and D2 D joint caching is constructed,and a random caching network and a multi-cluster mathematically easy-to-handle throughput expression based on the fountain code caching network is derived.And when the buffer capacity and network power are limited,an optimization problem to maximize throughput is established.In the random buffering scheme,the optimal solution is obtained by transforming the optimization problem into a concave problem,and the buffering strategy and power allocation optimization algorithm are designed in the fountain code buffering scheme,and the approximate optimal solution is obtained.Compared with the random buffering scheme,the simulation proves that the throughput of the fountain code scheme is higher,and the optimization algorithm of the buffering strategy and power allocation can further improve the system throughput.Further discuss the impact of different caching methods on the average service time of the system.A network and caching model of edge base station-D2 D user collaborative caching is established,and the average service time expression of this model is derived.Finally,the impact of different values of transmission parameters on the average service time of the system is analyzed through simulation,and then the encoding cache is compared with other traditional content placement schemes that are not cached,which proves that the application of the encoding cache in the edge base station-user collaborative cache network is reducing The transmission delay brings benefits.