Price-Based Resource Allocation in Massive MIMO H-CRANs with Limited Fronthaul Capacity

In this paper, we study the frequency and power allocation problem in remote radio head cluster (RRHC)-based millimeter wave (mmWave) massive MIMO heterogeneous cloud radio access networks (H-CRANs) with limited fronthaul capacity. The coordinated multipoint (CoMP) transmission is applied in each RRHC for cancelling the intra-cluster interference. To avoid the inter-tier interference, different frequencies are used by the macro base station (MBS) and RRHs. Following this, we formulate a joint frequency and power allocation optimization problem to maximize the downlink weighted sum rate of the system subject to per-RRHC power and fronthaul capacity constraints, which is a non-convex optimization problem and is diffcult to directly solve. Next, we fix the frequency allocation and the original problem can be divided into two independent optimization problems, i.e., the weighted sum rate maximization problems of MUs and RRH users (RUs), respectively. For the former, the convex optimization technique can be used to solve it. As for the latter, we propose a two-layer iterative algorithm to deal with it. Specifically, we use the price-based outer iteration to control the fronthaul capacity constraints and the minimum mean square error (MMSE)-based inner iteration to obtain the power allocation. To this end, one-dimension search method is adopted to find the optimal frequency allocation. Finally, numerical results are conducted to verify the effectiveness of the proposed algorithms under different parameters.