A Game-Theoretic Approach for Optimal Distributed Cooperative Hybrid Caching in D2D Networks

The distributed cooperative hybrid caching problem based on content-awareness in device-to-device networks is studied in this letter. Besides caching from the base station, nodes also can cache files from nearby nodes. We also consider the content similarity between caching nodes, which would reduce the cost further through caching similar traffic from one source cooperatively. We model the cost reducing problem as a local cooperative game, and prove it to be an exact potential game, which has at least one pure Nash equilibrium (NE). Fortunately, the potential function is just the aggregate cost of the network, which means the NE point minimizes the total cost. We modified the log-linear learning algorithm and designed a half-fixed action to reduce the strategy space, and with random action to pursue better performance. The simulation results show that the modified log-linear learning algorithm achieves better performance compared with other algorithms, and the content-aware hybrid caching reduces the cost.