BS-RIS-User Association and Beamforming Designs for RIS-aided Cellular Networks

TL;DR

This paper proposes a joint BS-RIS-user association and beamforming design for RIS-aided cellular networks to maximize downlink sum-rate, using iterative and exhaustive search algorithms, demonstrating significant performance gains.

Contribution

It introduces a novel joint association and beamforming framework specifically addressing RIS frequency selectivity and dynamic user association in cellular networks.

Findings

Significant sum-rate improvement over baseline methods

Effective user association via dynamic access algorithm

Enhanced beamforming through iterative optimization

Abstract

Reconfigurable intelligent surface (RIS) has been regarded as a revolutionary and promising technology owing to its powerful feature of adaptively shaping wireless propagation environment. However, as a frequency-selective device, the RIS can only effectively provide tunable phase-shifts for signals within a certain frequency band. Thus, base-station (BS)-RIS-user association is an important issue to maximize the efficiency and ability of the RIS in cellular networks. In this paper, we consider a RIS-aided cellular network and aim to maximize the sum-rate of downlink transmissions by designing BS-RIS-user association as well as the active and passive beamforming of BSs and RIS, respectively. A dynamically successive access algorithm is developed to design the user association. During the dynamical access process, an iterative algorithm is proposed to alternatively obtain the active and passive beamforming. Finally, the optimal BS-RIS association is obtained by an exhaustive search method. Simulation results illustrate the significant performance improvement of the proposed BS-RIS-user association and beamforming design algorithm.