Evaluation of availability of initial-segments of video files in Device-to-Device (D2D) network

We propose a new caching concept in which wireless nodes in Device-to-Device (D2D) network can cache the initialsegments of the popular video files and may share to users in their proximity upon request. We term this approach as Bootstrapping-D2D (B-D2D) system. Our findings suggest that caching only initial-segments creates a large pool of popular files, thus improving the probability of availability of initial-segments within the vicinity of the requesting users. Our proposed B-D2D system is based on a popular clustering algorithm called density-based spatial clustering of applications with noise (DBSCAN), that groups the users into dense and arbitrary shape clusters based on two predefined thresholds. We then formulate an optimization problem to maximize the probability of availability of initialsegments within the transmission range of requesting wireless devices. The simulation results demonstrate that, caching the initial video segments could substantially improve the availability of segments within the proximity of users without requiring any extra hardware infrastructure cost, and D2D services could be utilized to deliver the video contents with lower startup delays in cellular networks.