Multi-Rate Probabilistic Caching Optimized Video Offloading in Dense D2D Networks

In this letter, we propose a multi-rate caching (MRC) scheme for video offloading in dense device-to-device (D2D) networks. The MRC scheme utilises homogeneous Poisson Point Process model, D2D underlay transmission mode, and features of videos encoded into multiple rates (or versions), to derive the cache and spectrum sharing hit probabilities and the cache-based achievable rate. This way, an MRC optimisation problem is formulated for optimal caching probability and encoding rate selection of each video. The MRC optimisation problem further considers the playback resolution and storage resource constraints of the mobile devices to serve the mobile users more efficiently. As a result, the MRC solution gains the highest video offloading playback quality while conserving the bandwidth and caching storage resources of dense D2D networks.