This paper considers an uplink Internet of Things system with synchronous periodic traffic, where multiple devices generate their status updates at the beginning of each global frame and attempt to send them to a common access point. To achieve a low network-wide age of information (AoI) in an easily implementable manner, we require each device to adopt an age-dependent random access protocol, i.e., to transmit with a certain probability only when its corresponding AoI reaches a certain threshold. We analyze the time-average expected AoI by a multi-layer Markov model where an external infinite-horizon Markov chain manages the jumps between the beginnings of frames, while two internal finite-horizon Markov chains manage the evolution during an arbitrary frame for different cases. Simulation results verify the accuracy of the modeling and the AoI advantage over age-independent schemes.

翻译：本文研究具有同步周期性流量的上行物联网系统，其中多个设备在每个全局帧开始时生成状态更新，并试图将其发送到公共接入点。为实现低网络年龄（Age of Information, AoI）且易于实施，我们要求每个设备采用年龄依赖的随机接入协议，即仅在其对应AoI达到特定阈值时以一定概率进行传输。我们通过多层马尔可夫模型分析时间平均期望AoI，其中外部无限时域马尔可夫链管理帧开始时刻的跳变，而两个内部有限时域马尔可夫链分别管理不同情况下任意帧内的演化过程。仿真结果验证了所建模型的准确性，并证实了该方案相较于年龄无关方案在AoI性能上的优势。