Age of Information: Updates with Priority

Independent sources send their status updates to a server for delivery to a monitor. We analyze an age of information timeliness metric when sources are assigned different priorities. We consider two service facilities (a) there is no waiting room and an update in service is preempted on arrival of an equal or higher priority update, and (b) there is a waiting room for at most one update and preemption is allowed in waiting but not in service. We model the age process as a stochastic hybrid system.