Information Freshness and Packet Drop Rate Interplay in a Two-User Multi-Access Channel

Emmanouil Fountoulakis, Themistoklis Charalambous, Nikolaos Nomikos, Anthony Ephremides, Nikolaos Pappas



Abstract :In this work, we combine the two notions of timely delivery of information to study their interplay; namely, deadlineconstrained packet delivery due to latency constraints and freshness of information. More specifically, we consider a twouser multiple access setup with random access, in which user 1 is a wireless device with a buffer and has external bursty traffic which is deadline-constrained, while user 2 monitors a sensor and transmits status updates to the destination. We provide analytical expressions for the throughput and drop probability of user 1. For user 2, we derive in closed form the age of information distribution, the average age of information (AoI), and the probability the AoI to be larger than a certain value for each time slot. The relations reveal a trade-off between the average AoI of user 2 and the drop rate of user 1: the lower the average AoI, the higher the drop rate, and vice versa. Simulations corroborate the validity of our theoretical results. 

Index terms :Age of information, deadline-constrained traffic, multi-access channel, random access.