Average age of information in a multi-source M/M/1 queueing model with LCFS prioritized packet management

In this paper, we consider an M/M/1 status update system consisting of two independent sources, one server, and one sink. We consider the following last-come first-served (LCFS) prioritized packet management policy. When the system is empty, any arriving packet immediately enters the server; when the server is busy, a packet of a source waiting in the queue is replaced if a new packet of the same source arrives and the fresh packet goes at the head of the queue. We derive the average age of information (AoI) of the considered M/M/1 queueing model by using the stochastic hybrid systems (SHS) technique. Numerical results illustrate the effectiveness of the proposed packet management policy compared to several baseline policies.