Research On Content Caching And Collaborative Distribution In Cellular And D2D Hybrid Networks

With the explosive growth of mobile data traffic and the number of mobile terminals, traditional cellular communication systems are facing unprecedented challenges in achieving low-latency and high-throughput during content distribution. The traditional cellular network cannot guarantee the service quality effectively because of the load capacity of the base station and the limitation of spectral resources and backhaul chain resources. The combination of cellular and device-to-device (D2D) hybrid networks can improve the efficiency of spectrum resource utilization,balance network load and enhance user experience. In addition, with the growing popularity of content services, more and more demands of content sharing among users posed many problems such as content transmission redundancy, network load imbalance and so on.Introducing the content caching mechanism in the hybrid network of cellular and D2D can effectively improve the network capacity and reduce the content transmission redundancy. However, how to consider cache-related factors to improve system utility and reduce the energy consumption of content distribution is worth considering when designing content caching scheme and content distribution strategy. In this paper, we studied the above problems and the main work is as follows.Firstly, a content caching scheme based on cache capacity restriction is proposed, which aims to utilize D2D communication and content caching to efficiently share content among users and improve the global utility of the system. First of all, the system model of content caching in cellular and D2D hybrid network is described. Content popularity and content cache mode selection in mixed network are analyzed. Next, an optimization problem based on system utility maximization is proposed. This problem takes into account the necessary factors such as the content size, the terminal cache capacity and the D2D communication range, and can optimize the system utility by calculating the content cache probabilities. Finally, a discrete binary search algorithm (DBSA) with low complexity is proposed to solve the proposed problem. Finally, the validity of the scheme is validated by simulation.Secondly, a collaborative content distribution strategy is proposed,which aims to effectively achieve content sharing and reduce content distribution in hybrid networks. First of all, the system model of content-based collaborative distribution in cellular and D2D hybrid network is described. Next, a content collaboration strategy is proposed, which aims at minimizing the total energy consumption of the network. The network energy consumption includes the energy consumption of the cluster head node caching content and the content forwarding energy consumption.Thirdly, cooperative game theory model is used to model the collaborative distribution problem in cellular and D2D hybrid networks. A distributed clustering algorithm (DCA) is proposed to solve the proposed problem.Finally, the simulation results show that the proposed algorithm can effectively reduce the network energy consumption and improve the network throughput.