Cooperative Transmission and Probabilistic Caching for Clustered D2D Networks

In this paper, we aim at maximizing the offloading gain for a clustered cache-enabled device-to-device (D2D) network whose devices adopt probabilistic caching and cooperative transmission. Devices with surplus memory probabilistically cache a content from a known library. A requested content is either brought from the device's local cache, cooperatively transmitted from catering devices, or downloaded from the network. For this network, we derive a closed-form expression for the offloading gain and formulate the offloading maximization problem. In order to simplify the objective function and obtain a tractable expression, we derive a lower bound on the offloading gain, for which a suboptimal solution is obtained when considering a special case. Results reveal that the obtained suboptimal solution can achieve up to 12% increase in the offloading gain compared to the Zipf's caching technique.