Content-based Wake-up for Energy-efficient and Timely Top-k IoT Sensing Data Retrieval

TL;DR

The numerical results reveal the effectiveness of the CoWu approach, which is able to collect top-k data with higher energy efficiency while reducing k-QAoI when compared to round-robin scheduling, especially when the number of nodes is large and the required size of k is small.

Abstract

Energy efficiency and information freshness are key requirements for sensor nodes serving Industrial Internet of Things (IIoT) applications, where a sink node collects informative and fresh data before a deadline, e.g., to control an external actuator. Content-based wake-up (CoWu) activates a subset of nodes that hold data relevant for the sink's goal, thereby offering an energy-efficient way to attain objectives related to information freshness. This paper focuses on a scenario where the sink collects fresh information on top-k values, defined as data from the nodes observing the k highest readings at the deadline. We introduce a new metric called top-k Query Age of Information (k-QAoI), which allows us to characterize the performance of CoWu by considering the characteristics of the physical process. Further, we show how to select the CoWu parameters, such as its timing and threshold, to attain both information freshness and energy efficiency. The numerical results reveal the effectiveness of the CoWu approach, which is able to collect top-k data with higher energy efficiency while reducing k-QAoI when compared to round-robin scheduling, especially when the number of nodes is large and the required size of k is small.

Figures (11)

• Figure 1: An example of the top-$k$ query employing , where $k = 2$. (a): The sink transmits signal at the early time against the deadline. (b): The sink transmits signal at the late time against the deadline. (c) An example on how the timing and the threshold of signal affects the accuracy of a top-$k$ set at the deadline.
• Figure 2: An example of the evolution of , , and with linear age, where $k = 2$ and $\Omega_{k}=\{A, B\}$. (a): The sink receives fresh data from nodes $A$ and $B$ by the deadline. (b): The sink receives data from sensor node $A$ while it fails to collect data from the sensor node $B$.
• Figure 3: The achievable set of total energy consumption and for the different data collection methods (Linear age).
• Figure 4: of against $\zeta$, where $V_{\mathrm{th}} = 46$ and $V_{\mathrm{th}} = 48$ (Linear age).
• Figure 5: of against $\zeta$, where $V_{\mathrm{th}} = 46$ and $V_{\mathrm{th}} = 48$ (Exponential age with $\alpha = 0.02$).