Age of information (AoI) was introduced in the early 2010s as a notion to characterize the freshness of the knowledge a system has about a process observed remotely. AoI was shown to be a fundamentally novel metric of timeliness, significantly different, to existing ones such as delay and latency. The importance of such a tool is paramount, especially in contexts other than transport of information, since communication takes place also to control, or to compute, or to infer, and not just to reproduce messages of a source. This volume comes to present and discuss the first body of works on AoI and discuss future directions that could yield more challenging and interesting research.
In an increasingly networked world in which information is becoming increasingly actual, how can a system know with certainty just how fresh the information on a remote system is? Much work has been done on delay or latency in systems, but only recently has the concept of the freshness of information in or about a system become quantifiable. This is termed the Age of Information.
Age of Information provides a whole new set of metrics and tools that can be used to characterize the freshness of information in communications, control and, indeed, information systems. In its early development, this monograph provides the reader with an easy-to-read tutorial-like introduction into this novel approach of dealing with information within systems. A critical summary of the work to date details the concept for the reader. A description of the fundamentals of the performance metrics is then presented before showing how the approach can be used as a tool in improving metrics in other contexts.
The survey and tutorial nature of this monograph will save any researcher or student considerable time in understanding the basics of Age of Information, which is destined to become an important research topic in networked systems.