Age- and Correlation-Aware Information Gathering

Age-of-information (AoI) is a metric that quantifies the freshness of gathered information. In this letter, we expand the concept of AoI by introducing a metric called correlation-aware AoI (CAAoI) to capture both the freshness and the degree of correlation in gathered information. The CAAoI of an information gathering system is evaluated when an unmanned aerial vehicle gathers information about a set of physical processes from a set of ground devices, such that each physical process is sensed by one or more devices. An optimization problem is formulated to minimize the normalized weighted sum of the time-average CAAoI in the considered information gathering system. An ant colony optimization algorithm is developed to solve the formulated problem. Simulation results illustrate that the proposed CAAoI captures both the freshness and diversity of the gathered information.