Joint Access Selection and Resource Allocation in Cache-Enabled HCNs with D2D Communications

With the explosive increase of wireless data traffic, caching is regarded as a promising technology to combine with heterogeneous cellular networks (HCNs), which can offload cellular traffic and improve the system performance effectively. In this paper, we investigate the communication scenario about cache-enabled HCNs with device-to- device (D2D) communications. Both small cell base stations (SBSs) and D2D user equipments (DUEs) have the caching hardware that can store popular contents to serve users locally. With the caching technology introduced, heavy traffic load in the HCNs could be relieved and the request latency could be decreased, which results in better user experience. Meanwhile, due to the constraints of the limited resource, access selection of users and resource allocation are two significant problems that need to be carefully studied. Thus, we propose a novel scheme to study the access selection and resource allocation jointly. First, we formulate the access selection, spectrum allocation as a joint optimization problem to maximize the system capacity, where bandwidth resource is allocated flexibly and the quality of service (QoS) of users is satisfied. Since the original problem is a mixed combinatorial problem, which is a non-convex optimization, an efficient solution is proposed to transfer the original problem to a convex problem so as to reduce computational complexity. In the simulation, we compare our scheme with other three schemes. Simulation results are presented to validate the effectiveness of our proposed scheme.