RSMA-Aided Iterative Max-Age Scheduling for Multi-Source Systems

In this work, we consider a multiple channel system composed of several Internet of Things (IoT) devices, each measuring an independent time-varying signal. In these systems, a crucial performance measure is the Age of Information (AoI) at the monitoring station, which is characterized as the elapsed time since the generation of the most recent update correctly received from each device. We employ a computationally efficient and near-optimal policy called Iterative Max-Age Scheduling (IMAS) to assign devices to the available channels, which reduces the AoI at the receiver. The devices transmit their measurements to the central monitoring station employing Rate-Splitting Multiple Access (RSMA). We compare the AoI obtained by the proposed approach with those using Orthogonal Multiple Access (OMA) or power-domain Non-Orthogonal Multiple Access (NOMA), showing that RSMA, thanks to its flexibility in terms of rate and power allocation, enables the connection of more simultaneous devices, positively impacting the AoI of all devices.