Average information staleness (AIS) as a system measure of performance

This paper introduces and defines the average information staleness (AIS) as a new measure of communication systems striving to optimize most recent reliability while operating over networks subject to delays and errors. In such settings a dynamic source needs to provide updated information at a given report rate to a number of destinations. Relevant applications include stock market report services and military command and control center situation awareness. The AIS parameter depends on the following: (1) the source report rate, (2) the report completion rate, and (3) the average and the variance of the delay. In addition, this paper shows that to optimize AIS, by minimizing its value, some counter-intuitive tradeoffs between delay and completion rate must be made. Finally, results are presented for an example system that was analyzed by simulation, which showed explicitly the tradeoffs that need to be realized when attempting to optimize the AIS measure.