# Time Management in Wireless Sensor Networks for Industrial Process Control
## 1 Introduction
Our proposal is to include control loop capabilities directly into the underlying IEEE 802.15.4-2020 standard, as including this in the application layers of wireless protocols means additional processing overhead in the  
Figure 1: Evolution of wireless control: (**a**) a classic control loop using wired connections between the controller and the process; (**b**) using wireless communication to send the setpoint, while the process control is performed locally, near the process; (**c**) our proposal: use wireless communication to send the command to the process, as computed by the controller, and send back the feedback from the process to the controller. data frames. This will allow the control of fast processes over wireless, not just slow ones, as presented in the literature. Two case studies immediately benefit from this new concept: an industrial process in which the controller and process are at a significant distance from each other, and inside a satellite where one of the methods of reducing production costs and sending it into space is to reduce the number of wires between the equipment. Replacing wired control with wireless is not an easy task, considering the industrial process requirements that need to be followed. One of the most important and critical of these requirements is the management of wireless network time, which is the focus of this article. Wireless sensor networks (WSNs) have been extensively studied for industrial applications, with a growing focus on synchronization and energy efficiency. Ref. [9] provided early insights into the requirements for control-oriented WSNs, highlighting reliability and timing as key barriers to broader adoption. Recent surveys and implementations have reinforced these priorities. For instance, [PERSON] et al. [10] showed how IEEE 802.15.4 can support robust industrial monitoring, while [PERSON] and [PERSON] [11] proposed hybrid synchronization schemes scalable to large sensor fields. Moreover, [PERSON] et al. [12] explored architectural trade-offs in synchronization algorithms, including distributed and hybrid approaches, which informed the design choices behind our low-drift, COTS-compatible system. This article follows a more pragmatic and practical approach by using COTS components and development boards to simulate a time-synchronized control loop between two wireless nodes, with one being the controller and the other being the process. The starting point was the implementation of the IEEE 802.15.4-2020 standard in Time-Slotted Channel-Hopping (TSCH) mode which we slightly extended to allow the proper time management of the wireless control network. Promising results have been obtained that point out what is still needed to achieve better time management and allow control over wireless for even faster and more critical processes. The remainder of this article is structured as follows: Section 2 describes the research starting points--the IEEE 802.15.4-2020 standard, the hardware setup, and the development environment. Section 3 presents the obtained results which include the development of a hardware abstraction later to separate the physical layer from the upper layer in the software implementation, the developed transceiver driver, the time management algorithm, and the testing and validation of our proposed solution. Section 4 discusses the results obtained compared to existing work and future improvements and Section 5 concludes this article with a brief conclusion and future work directions.