Joint User Association and Passive Beamforming in Heterogeneous Networks With Reconfigurable Intelligent Surfaces

In this letter, the joint design of user association (UA) and passive beamforming (PBF) has been investigated for heterogeneous networks equipped with reconfigurable intelligent surfaces. Firstly, a closed-form lower bound of ergodic rate is derived using statistical channel state information and adopting the maximum ratio transmission precoding. After that, a joint UA and PBF problem is formulated to maximize the weighted sum-rate (WSR), which is then decomposed into UA and PBF subproblems and solved by our proposed priority-based swapping and fixed-point iteration algorithms. Simulation results demonstrate that our proposed scheme achieves significant WSR performance gain when compared to the state-of-the-art methods.