Leveraging Reconfigurable Intelligent Surface to Minimize Age of Information in Wireless Networks

In this paper, we consider a wireless network consisting of a base station (BS) that is serving multiple realtime traffic streams forwarding information updates to their destinations in order to sustain the freshness of information. Since the wireless channels may be unreliable due to the impurities of the propagation environments, such as deep fading, blockages, etc., we integrate a reconfigurable intelligent surface (RIS) to the wireless system in order to mitigate the propagation-induced impairments, enhance the quality of the wireless links, and ensure that the required freshness of information is achieved for these real time applications. For this network set-up, we investigate the joint optimization of the traffic streams scheduling and the RIS phase-shift matrix with the goal of minimizing the sum Age of Information (AoI). In order to solve this optimization problem, we propose an efficient algorithm based on a change-of-variables with semi-definite relaxation (SDR). Finally, we perform extensive simulations to verify the effectiveness of our proposed method against other baseline schemes.