User association for massive MIMO cellular networks with small cell wireless backhaul

In this paper, we consider the heterogeneous network, where a macro base station equipped with massive multiple input multiple output (MIMO) antennas provides the wireless backhaul for small cell base stations (SBSs). In this scenario, because the capacity of the small cell is limited by the wireless link with the macro base station, the unbalanced user distribution among base stations might significantly degrade the performance of networks. We address this problem by jointly considering the user association problem and bandwidth allocation for wireless backhaul small cell. Since the problem is non-convex due to the coupling constraint at the small cells, we propose the effective algorithm to solve the problem. The simulation results verify the convergence and highlight the effectiveness of our algorithm.