Special issue on age of information

Information freshness at the monitoring station is of fundamental importance in the dissemination of time-critical information. Applications that rely on information freshness include networked monitoring, situational awareness and automated control (e.g., tactical networks, sensor networks, airplane/vehicular control, and Cyber-Physical Systems) applications. Other commercial applications include data analytics (e.g., crowdsourcing, financial trading, social networks, and Internet of Things) applications. Age of Information (AoI) is a concept that has recently gained prominence as a performance metric for characterizing information freshness at the receiver. It is interesting to note that improving first-order metrics such as, providing high throughput and / or low delay, that lead to improved performance in traditional data networks, are inadequate when it comes to improving information freshness. Therefore, there is a critical need to re-examine existing metrics and develop new ones for current and future real-time applications.