  Information aging has gained prominence in characterizing communication
protocols for timely remote estimation and control applications. This work
proposes an Age of Information (AoI)-aware threshold-based dynamic frame
slotted ALOHA (T-DFSA) for contention resolution in random access machine-type
communication networks. Unlike conventional DFSA that maximizes the throughput
in each frame, the frame length and age-gain threshold in T-DFSA are determined
to minimize the normalized average AoI reduction of the network in each frame.
At the start of each frame in the proposed protocol, the common Access Point
(AP) stores an estimate of the age-gain distribution of a typical node.
Depending on the observed status of the slots, age-gains of successful nodes,
and maximum available AoI, the AP adjusts its estimation in each frame. The
maximum available AoI is exploited to derive the maximum possible age-gain at
each frame and thus, to avoid overestimating the age-gain threshold, which may
render T-DFSA unstable. Numerical results validate our theoretical analysis and
demonstrate the effectiveness of the proposed T-DFSA compared to the existing
optimal frame slotted ALOHA, threshold-ALOHA, and age-based thinning protocols
in a considerable range of update generation rates.
