Age of Information in Multi-Source Systems

In this work, we consider a system with multiple sensors, each measuring a different time-varying signal. The sensors report their measurements to a central monitoring station via multiple orthogonal communication channels. An important performance metric in such systems is the age of information at the monitoring station, defined as the amount of time that has elapsed since the recent most update from each sensor. We propose two scheduling policies and prove their optimality with respect to this metric. Another key objective in such systems is to minimize the energy consumption of the sensors. Motivated by this, we propose energy- efficient variants of the two scheduling policies and show that close to optimal performance can be achieved with significant reductions in the energy consumption of the sensors. We provide numerical results to validate our theoretical guarantees.