  Caching at mobile devices and leveraging device-to-device (D2D) communication
are two promising approaches to support massive content delivery over wireless
networks. Analysis of such D2D caching networks based on a physical
interference model is usually carried out by assuming uniformly distributed
devices. However, this approach does not capture the notion of device
clustering. In this regard, this paper proposes a joint communication and
caching optimization framework for clustered D2D networks. Devices are
spatially distributed into disjoint clusters and are assumed to have a surplus
memory that is utilized to proactively cache files, following a random
probabilistic caching scheme. The cache offloading gain is maximized by jointly
optimizing channel access and caching scheme. A closed-form caching solution is
obtained and bisection search method is adopted to heuristically obtain the
optimal channel access probability. Results show significant improvement in the
offloading gain reaching up to 10% compared to the Zipf caching baseline.
