Abstract
The collaboration between communication and sensing has emerged as an important technology for sixth-generation (6G) wireless communication networks. In this paper, we investigate the beamforming for the collaborative system of communication and sensing via the collaboration between reconfigurable intelligent surfaces (RIS) and multiple-input single-output (MISO) base stations (BS) in multi-user MISO systems. In order to promote the sum communication rate for all users while ensuring the radar sensing performance, we formulate a non-convex optimization problem to maximize the sum rate for all users under the constraints of the radar signal-to-noise ratio (SNR). To address the non-convex optimization, we propose a hybrid approach combining fractional programming and the alternating direction method of multipliers (ADMM) to optimize acceptance filter coefficients, the beamforming and the RIS reflection coefficients matrix. The simulation results indicate that the proposed scheme is able to enhance the communication capability while ensuring the radar performance. Furthermore, compared to the scheme without RIS collaboration, our scheme achieves more accurate alignment with target directions for sensing, while also providing good communication performance.