Coded Caching in Wireless Device-to-Device Networks Using a Hypercube Approach

We consider a novel hypercube approach to design wireless device- to-device (D2D) caching networks with single-hop transmissions. Previous work has demonstrated that caching is an effective method to significantly increase per-user throughput. However, the state-of- the-art schemes are generally impractical because content files must be partitioned into an exponential number of packets with respect to the number of users. This paper addresses this issue by proposing a novel cache placement and coded multicasting scheme based on a hypercube approach. In particular, each lattice point on the hypercube represents a specific set of packets and each packet is from a distinct file. Each user caches all the lattice points of a "hyperplane" on this hypercube and the intersections of orthogonal "hyperplanes" lead to multicast codewords. We demonstrate that the hypercube approach achieves a rate that is almost identical to that of the state-of-the-art schemes, especially for a large number of users. More importantly, the required number of file partitions is exponentially less compared to the state-of-the-art schemes. Moreover, we also investigate the use of spatial reuse, which further increases the per-user throughput and reduces the required number of file partitions.