Age-Efficient Random Access With Load Adaptation

The lightweight and energy-efficient Frame Slotted Aloha (FSA) protocol has become a promising MAC protocol in large-scale IoT systems. Existing work on minimizing the age of information (AoI) of FSA protocol cannot significantly benefit from frequent packet generations when the packet generation rate <inline-formula><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> exceeds its throughput <inline-formula><tex-math notation="LaTeX">$e^{-1}$</tex-math></inline-formula>. To fill this gap, this paper proposes two age threshold-based algorithms to reduce the AoI of FSA systems for <inline-formula><tex-math notation="LaTeX">$\lambda &gt; e^{-1}$</tex-math></inline-formula>, namely TF and TF+. Their core ideas are to only allow the nodes with age gain over the configured thresholds to send their packets so that the FSA systems are slimmed to a stable one with <inline-formula><tex-math notation="LaTeX">$\lambda &lt; e^{-1}$</tex-math></inline-formula> and a polling system, respectively. Technically, we design the threshold configuration rules for the two algorithms and characterize the normalized average AoI. We also conduct simulation and the results show that TF and TF+ achieve lower AoI than the prior works.