Joint Social-Aware and Mobility-Aware Caching in Cooperative D2D

The cooperative D2D content sharing mode is that multiple users can share content with each in a cooperative way. In this mode, we can improve the transmission efficiency and transmission stability of communication. Although there are many literatures on cooperative D2D, the mobility problem in this transmission mode has been ignored by many people. Moreover, traditional D2D communication is a one-to-one transmission mode, but cooperative D2D is a many-to-one transmission mode. There is a big difference of link establishment and content transmission between these two modes. And the impact of mobility on network topology is also very different. Therefore, the existing caching scheme and retransmission mechanism for D2D can not be applied to cooperative D2D. Meanwhile, whether in D2D or cooperative D2D, the success of the user requesting content is closely related to the social relationship between users, due to the social selfishness of D2D users. Therefore, in order to improve the performance of cooperative D2D content sharing, we exploit user interest similarity and mobility and propose a social-and-mobility-aware caching strategy for collaborative D2D scenarios. Not only that, we model the retransmission problem as a Knapsack problem and design the retransmission mechanism when the transmission link is interrupted to ensure the reliability of content sharing with the greedy algorithm. Finally, our simulation results show that our proposed caching placement scheme and retransmission scheme can improve the performance of cooperative D2D content sharing. In addition, we achieve a valuable caching guideline in cooperative D2D scenarios.