Research On D2D Caching Strategy In 5G Wireless Network

The advent of 5G communication technology will promote the rapid development of multimedia technology.Wireless video services have gradually become the mainstream services of the mobile Internet,which will be the main force in the explosion of wireless data traffic.Faced with the explosive growth of data traffic and the scarcity of spectrum resources,the existing cellular system can no longer meet the needs of mobile users.Applying D2 D caching technology to the mobile network,make full use of the storage space of the mobile terminal,and design a caching strategy to cache hot files in the mobile terminal in advance during off-peak communications.When a user requests a file,he can directly obtain it in the local cache or obtain it from a user who has the file in the cache and is close to its physical location through D2 D communication,which can greatly increase the data transmission rate,shorten the data transmission delay and reduce the workload of the base station.At present,in order to solve the problem of user selfishness in D2 D caching strategy,some scholars have studied incentive caching strategy.They design reward mechanism to encourage users to participate in content sharing.However,they ignore the trust between users and the security of data storage,which may lead to the requester rejecting the content or malicious transmission of unsafe content.Therefore,this paper proposes an incentive caching strategy based on blockchain.Taking into account the user's mobility,the current mobility-aware caching strategies assume that the user can transmit complete content in one contact and ignore that the physical link state will affect the mobile user's communication connection,which does not conform to the realistic scenario;Moreover,these studies did not consider the lack of user interest similarity.Users will encounter other users with similar interests while moving.If the user's needs can be known in advance,this can bring a qualitative improvement in the performance of the caching strategy.Aiming at the above shortcomings,this paper proposes a coding caching strategy that combines user interest and mobile awareness.Committed to studying the optimization algorithm of content caching strategy in D2 D caching network,the specific research content of this article is as follows:(1)Proposing an incentive caching strategy based on blockchain to maximize the total profit of the system.Applying blockchain to the D2 D cache network to encourage more content sharing between mobile terminals.The base station can use "Mining" revenue to reward mobile terminals,where the "Mining" profit depends on the size of the shared data.In order to maximize profits,this chapter formulates the cache placement problem and obtains the best cache solution.Finally,the problem of sharing cache content by studying multi-user matching is further studied,and the Nash stable solution is obtained by designing a hierarchical structure and DU-pairing algorithm,and then the optimal user cache allocation strategy in this optimal matching scenario is obtained.Finally,experiments are conducted to verify that the proposed algorithm can maximize the total profit of the system.(2)A coding caching strategy combining user interest and mobile awareness is proposed to maximize the cache hit rate.From the perspective of coding cache,this chapter proposes a coding caching strategy which combines user interest and mobile awareness,and models the maximization of cache hit ratio as an optimization problem.It is an NP-hard problem,and then proves that the problem is monotonic.For the sub-modal problem,the approximate optimal solution is finally obtained through the greedy algorithm.The simulation results prove that the caching strategy proposed in this chapter has a higher cache hit ratio than the most popular caching strategy and the equal probability random caching strategy.