Reliability Enhancement for Multimedia Delivery in Caching-Assisted MmWave HetNets

growth of bandwidth-intensive multimedia applications may impose a heavy traffic burden on wireless links of heterogeneous networks (HetNets), which also requires substantial energy consumption. Edge caching is emerging to reduce the service latency and relieve the huge burden on the backhaul links in HetNets. Moreover, millimeter wave (mmWave) spectrum with huge available bandwidth has been regarded as a promising technology to satisfy the high capacity demands in future HetNets. However, the high directionality coupled with harsh propagation environment makes mmWave communication vulnerable to blockage, which makes link establishment and maintenance challenging. In this paper, we propose a joint maximum distance separable (MDS) coded caching and transmission problem for a mmWave HetNet, aiming at minimizing the backhaul energy consumption while satisfying users' quality of service (QoS) requirements on high data rate. The formulated mixed integer non-linear programming (MINLP) problem is solved by decomposing it into two stages of subproblems. In the first stage, the convex optimization technique is applied to tackle the coded caching subproblem. Subsequently, we propose two efficient algorithms based on matching in the second stage to deal with the transmission subproblem. Simulation results demonstrate that the proposed schemes can effectively maximize the backhaul energy saving and enhance the download rate with the benchmark scheme.