On the Role of Age-of-Information in Internet of Things
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The success of many Internet of Things (IoT) applications relies on the ability of the network to deliver sensing measurements from the IoT devices to the destination nodes while they are still fresh. In this article, we provide an accessible introduction to the emerging idea of Age-of-Information (AoI) that quantifies freshness of information and explore its possible role in the efficient design of freshness-aware IoT. We start by summarizing the concept of AoI and its variants with emphasis on the differences between AoI and other well-known performance metrics in the literature, such as throughput and delay. Building on this, we explore freshness-aware IoT design for a network in which IoT devices sense potentially different physical processes and are supposed to frequently update the status of these processes at a destination node (such as a cellular base station). Inspired by the recent interest, we also assume that these IoT devices are powered by wireless energy transfer by the destination node. For this setting, we investigate the optimal sampling policy for IoT devices that minimizes long-term weighted sum-AoI. This policy jointly optimizes wireless energy transfer and scheduling of update packet transmissions from IoT devices. Using this, we also characterize the achievable AoI region and demonstrate a fundamental trade-off between achieving fairness among different processes and achieving the minimum sum-AoI. Multiple promising directions for future research and extensions for our proposed system setup are presented.
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