Resource allocation and user-centric clustering in ultra-dense networks with wireless backhaul

In this paper, we consider the joint optimization of resource allocation in wireless backhaul links and user-centric clustering in the access links. The objective is to maximize the weighted sum rate (WSR) of all users under the backhaul resource constraints. To solve this intractable problem, we adopt the ℓ₁-norm approximation approach to convert the non-convex backhaul constraints into the solvable forms. We then reformulate the objective function as a set of second-order cone constraints based on the successive parametric convex approximation method. An iterative algorithm is proposed to solve the transformed problem based on its special property. Simulation results show that the proposed algorithm outperforms other existing schemes under different network settings.