Wireless Technology
Wi-Fi sensing: A useful disturbance in the electromagnetic force
By Hristo Stefanov of the prpl Foundation D
igital devices have become essential components in homes and industrial facilities across the globe. The benefits of Internet-of-Things (IoT)
technologies are clear-cut, but as the number of devices found within a single location increases, so does the amount of clutter. McKinsey estimates that 25 per cent of ‘smart’ homes feature three or more such gadgets, each managed via a different interface. Few are connected together, resulting in a lot of pain for the user before they get to the convenience promised by device developers. With this in mind, the next big trend within the digital home may be simplification.
What if one technology could do two things at the same time - communicate and sense movement? This is precisely the idea behind Wi-Fi sensing. Imagine wireless connectivity as a layer of electronic waves flowing around your home: These waves carry elements to your device, but their electromagnetic nature means they are affected by physical movements - a veritable ‘disturbance in the force’. The receiving device measures the variations in the depletion of received radio fibre (RF) waves, then uses statistical models to detect presence and gestures. This method will be enhanced continually by modern machine learning (ML) algorithms to increase precision and robustness.
Most current sensing is done through infrared sensors. These require both a wired connection and a line of sight, which leads to careful planning and positioning of devices around the home or industrial facility. They work relatively well for a specific purpose - perimeter security. Other technologies such as Bluetooth and Radio Frequency Identification (RFID) offer limited coverage and accuracy, with the latter requiring a fixed target in order to mark precise positioning. On the other hand, 5G and ultra wide band (UWB) provides greater accuracy, but necessitates the installation of costly radios. Ultrasound holds promise, but questions remain over its long- term safety to pets as well as humans.
42 July/August 2023
A new standard for Wi-Fi All of these technologies require dedicated devices, which can be a problem if a homeowner or business has limited space. By contrast, with a few key enhancements in the firmware of your Wi-Fi router or access point, it can quickly become a sensing mode capable of interpreting physical movements within the surrounding space.
We are already seeing signs that this concept is maturing quickly. Within the last ten years, various approaches to Wi-Fi sensing have been proposed and researched in academia. As these efforts advanced, a glaring need for standardisation emerged. This would unlock faster innovation through better vendor interoperability, technology awareness and industry collaboration. In 2020, the 802.11 Working Group at IEEE initiated activities for a new standard called 802.11bf, or ‘WLAN Sensing’. The first draft was released for the first time in January 2023, with final approval slated for March
Components in Electronics
2025. WLAN Sensing will be compatible with previous 802.11.xx Wi-Fi standards, and represents a major step forward for organisations involved with in-home and industrial applications.
Even before the standard comes to fruition, the most promising initial use cases for this technology have started to emerge. The key one is ‘room occupancy’; knowing if someone is in a room, and the changes within the room over time. This feature makes home automation systems smarter and more intuitive, able to follow occupants throughout the house. It can also be used to supplement existing security monitoring applications. As a result of this development, the monitoring of elderly people has become easier, with concerned users now able to get reliable statistics relating to the physical activity and sleeping cycles of their friends or relatives, alongside enhanced wandering alarms and fall detection notifications.
A collaborative market ecosystem is working hard to make Wi-Fi sensing not just a reality, but commonplace in homes and businesses across the globe. Chipset makers are participating in the IEEE Work Group to ensure there is sufficient processing capacity for the technology, while exchanging specifications with software vendors whose applications will communicate with the chips. Customer Premises Equipment (CPE) vendors will be responsible for integrating the technology to respond to the needs of the service providers and their customers. Some of the more prominent early proponents all have offerings within the market, and are actively testing this exciting technology with their customers. Open-source standards organisations like the prpl Foundation are helping to foster this collaboration between developers, vendors and adopters, providing an essential forum for members to communicate and work together to accelerate interoperability and functionality.
www.cieonline.co.uk.uk
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