Age of Information in Random Access Networks: A Spatiotemporal Study

TL;DR

This paper develops an analytical framework to evaluate the age-of-information in wireless random access networks, revealing complex behaviors and the impact of protocols like ALOHA on AoI under various network conditions.

Contribution

It introduces a novel analytical model for AoI in wireless networks that incorporates spatial and fading effects, providing insights into protocol impacts and non-monotonic AoI behaviors.

Findings

AoI may not decrease monotonically with packet arrival rates in dense networks.

ALOHA protocol reduces AoI at high packet arrival rates but not at low rates.

The model's accuracy is validated through simulations.

Abstract

We investigate the age-of-information (AoI) in the context of random access networks, in which transmitters need to send a sequence of information packets to intended receivers over shared spectrum. We establish an analytical framework that accounts for the key features of a wireless system, including the fading, path loss, network topology, as well as the spatial interactions amongst the queues. A closed-form expression is derived to quantify the network average AoI and its accuracy is verified via simulations. Our analysis unveils several unconventional behaviors of AoI in such a setting. For instance, even when the packet transmissions are scheduled in a last-come first-serve (LCFS) order whereby the newly incoming packets can replace the undelivered ones, the network average AoI may not monotonically decline with respect to the packet arrival rates, if the infrastructure is densely deployed. Moreover, the ALOHA protocol is shown to be instrumental in reducing the AoI when the packet arrival rates are high, yet it cannot contribute to decreasing the AoI in the regime of infrequent packet arrivals.