Probing for Better Age of Information in Energy-Harvesting Random Access Networks

TL;DR

This paper analyzes how channel probing and reservation strategies affect the Age of Information in energy-harvesting random access networks, revealing that all-active contention can reduce AoI.

Contribution

It introduces and compares three probing schemes, deriving closed-form AoI expressions and demonstrating the effectiveness of all-active contention in energy-harvesting networks.

Findings

All-active contention (AUC) achieves the lowest AoI.

Probing-based access outperforms direct transmission in energy-constrained regimes.

Allowing more contention can reduce AoI despite collision risks.

Abstract

In this paper, we investigate the impact of channel probing and reservation on the Age of Information (AoI) in energy-harvesting (EH) random access networks, where each source relies solely on harvested energy for status updating. To mitigate collisions, each node may expend a small amount of energy to send a probing signal before transmission, and a successful probe reserves the channel in the current slot. If probing fails, the node can either remain silent, termed strict avoid free competition (SAFC), attempt data transmission with a certain probability, termed reserved nodes competition (RUC), or adopt all-active nodes competition (AUC), where all energy-sufficient nodes may contend regardless of whether they probed. We derive closed-form expressions for the network-average AoI under these three schemes and validate them via simulations. The results show that AUC consistently achieves the lowest AoI by shortening the waiting time to convert harvested energy into successful updates. This finding challenges the conventional wisdom that strict collision avoidance is always optimal in energy-constrained systems, since allowing additional contention can effectively amortize probing overhead across more transmission opportunities. Comparisons with EH-enabled slotted ALOHA further show that probing-based access significantly outperforms direct transmission in energy-constrained regimes, highlighting channel probing as an effective approach to improving freshness.