Social-Aware Caching and Resource Sharing Maximized Video Delivery Capacity in 5G Ultra-Dense Networks

In 5G networks, a massive number of connections of high data rate services, e.g., video streaming services, certainly make the networks deteriorated because of extreme traffic congestion at the backhaul links of macro base stations (MBSs). Although ultra-dense networks (UDNs) have been considered as a promising architecture to stimulate the 5G networks, the congestion problem hampers the UDNs to provide mobile users (MUs), i.e., represented by device-to-device (D2D) pairs and shared downlink resource users (SUs), with high video delivery capacity. In this paper, we propose a social-aware caching and resource sharing (SCS) strategy for video streaming services in 5G UDNs. Particularly, we formulate the SCS problem by taking into account the social relationship of each D2D pair, the available storage of femtocell base stations (FBSs) and transmitters (TXs) of D2D pairs, the target signal to interference plus noise ratio (SINR) of SUs, and the popularity of videos. The SCS problem is then solved for 1) optimal number of caching copies of each video and optimal caching placements in the FBSs and 2) optimal resource sharing allocation between the SUs and the D2D pairs for D2D communications. This way, the workload at the backhaul links of the MBSs can be reduced. Simultaneously, an arbitrary MU can retrieve the videos alternately from the MBSs, FBSs, and TXs at high cache-hit ratio and maximum delivery capacity. Simulation results are analyzed to show the benefits of the proposed SCS strategy compared to other conventional schemes.