LAUSR

In this paper, we propose a femto base station cluster (FBSC)-based fog radio access network (F-RAN) structure, where multiple femto base stations (FBSs) coordinately serve users in each FBSC with the millimeter wave band. In addition, the FBS head (FBSH) in each FBSC receives data from the central processor (CP) via fronthaul link with the microwave band. Based on this, we formulate a transmission delay minimization problem by optimizing coordinated hybrid analog/digital precoding under transmit power constraints of each FBS in the FBSCs and the base station (BS) in the CP. Then, we propose a coordinated analog precoding scheme for multiple FBSs within the same FBSC. Meanwhile, we equivalently divide the original problem into two independent optimization problems, and propose an effective iterative algorithm to solve them. Simulation results show the effectiveness of our proposed algorithms.