Effect of Variable Backoff Algorithms on Age of Information in Slotted ALOHA Networks

In this article, we analyze the effect of implementing variable backoff algorithms on the average peak age of information (PAoI) and the average age of information (AoI) in slotted ALOHA networks. To this end, we first analytically derive the average PAoI in exponential backoff slotted ALOHA when the number of backoff stages is finite. We also show that the reduction in average PAoI achieved by the exponential backoff algorithm can significantly increase the average AoI, which is not desirable. Then, we propose an age-based backoff algorithm and present the intuition behind it. In contrast to exponential backoff, our proposed age-based backoff algorithm reduces the average PAoI significantly, while changing the average AoI limitedly. The numerical results confirm our analytical results as well as the superiority of the proposed age-based backoff algorithm over exponential backoff.