Fundamental limits on latency in cloud- and cache-aided HetNets

Hybrid architectures are generally composed of a cyber cloud with additional support of edge caching. By utilizing the benefits associated with cloud computing and caching, powerful enhanced interference management techniques can be readily utilized — that among others — also results in low-latency transmission. In this paper, we study the impact of cloud and edge processing on the latency for a heterogenous network (HetNet) consisting of two users and two transmitters. We define an information-theoretic metric, the delivery time per bit (DTB), that captures the delivery latency. We establish bounds on the DTB as a function of cache size, backhaul capacity and wireless channel parameters. We show the optimality on the DTB for various channel regimes.