  As the most well-known application of the Internet of Things (IoT), remote
monitoring is now pervasive. In these monitoring applications, information
usually has a higher value when it is fresher. A new metric, termed the age of
information (AoI), has recently been proposed to quantify the information
freshness in various IoT applications. This paper concentrates on the design
and analysis of age-oriented random access for massive IoT networks.
Specifically, we devise a new stationary threshold-based age-dependent random
access (ADRA) protocol, in which each IoT device accesses the channel with a
certain probability only when its instantaneous AoI exceeds a predetermined
threshold. We manage to evaluate the average AoI of the proposed ADRA protocol
mathematically by decoupling the tangled AoI evolution of multiple IoT devices
and modeling the decoupled AoI evolution of each device as a Discrete-Time
Markov Chain. Simulation results validate our theoretical analysis and affirm
the superior age performance of the proposed ADRA protocol over the
state-of-the-art age-oriented random access schemes.
