With the continued development of smart homes and wearable devices, artificial intelligence is gradually moving from the front of the screen to operating in the background. The entire industry is shifting from visible interfaces to technologies that can quietly integrate into our living and working spaces. As Network World magazine points out, this shift is giving rise to what many call “ambient intelligence.” This represents a way for devices to perceive their surroundings without our direct interaction.
Systems no longer rely on apps or voice commands, but instead perceive their environment by capturing motion, gestures, and patterns. They respond passively to us — by sensing our location and behavior. However, while cameras have long been the default tool for this perception, they also have some serious drawbacks. They raise privacy concerns, perform poorly in low light, have blind spots, and often require significant network bandwidth. Cameras also increase the cost of devices, especially with heavy use.
Therefore, many researchers and engineers are exploring new ways to perceive the world using our existing tools, such as Wi-Fi, radar, and sound. Wireless technologies combined with edge computing can detect movement and the presence of people in a space. They achieve this without capturing images or recording audio. As smart devices become increasingly prevalent in homes, businesses, and built environments, our goal is to make our surroundings smarter. This applies not just to a single device, but integrated into the space itself.
Using Wi-Fi to Sense Motion
Wi-Fi sensing is one of the most promising areas. It uses wireless signals that power internet connections to detect motion and activity without adding any new hardware. Wi-Fi access points emit radio waves that reflect off various objects such as walls, furniture, people, and pets. Receivers in other devices, such as smart light bulbs or routers, pick up some of these reflected signals.
The system captures information known as Channel State Information (CSI). It shows how the signal changes as the radio waves travel through space. When someone or an object moves, the system measures these changes. Over time, the system learns the “normal” state of the space. It alerts when any changes occur. These subtle changes can tell us a lot — such as someone walking, standing, or even breathing.
This method works without light, and walls or furniture do not obstruct it.This approach remains private and passive, and it uses devices that many people already have.Recent research shows that, with the help of intelligent software, Wi-Fi systems can detect motion with over 90% accuracy in large home networks. Therefore, millions of routers and light bulbs can work together to form a sensing layer.
Some systems are even intelligent enough to distinguish between people and pets. They use details such as walking speed and movement patterns to determine whether the movement is by a person, a dog, or a robot vacuum. This perceptive ability makes it possible to build smart homes that can respond effectively.
Radar Sensing in Smart Homes
Engineers are introducing radar as another tool in smart homes. Its basic principle is simple: emit a signal and then measure its reflection. Car parking and security systems have long used radar technology, and engineers now apply similar technologies indoors.
These devices use several radar technologies:
Ultra-wideband (UWB) radar emits short, low-energy signals, making it easy to measure distance and detect motion. It works well indoors and can even penetrate walls, often used for tasks such as fall detection and breathing monitoring. UWB radar offers high accuracy and energy efficiency.
Millimeter-wave (mmWave) radar operates at extremely high frequencies and can detect subtle movements, such as gestures or breathing. It can also distinguish multiple moving people. However, millimeter-wave sensors can be power-intensive, expensive, and difficult to penetrate walls. As a result, designers typically use them in small spaces such as cars or studios.
Ultrasonic radar uses high-frequency sound waves instead of radio waves. These sensors are so sensitive and silent that the human eye can barely detect them. They measure distance and detect motion with high precision. Although inexpensive and power-efficient, airflow or physical obstructions can significantly reduce their effectiveness. Devices such as smart speakers and thermostats sometimes use ultrasound to detect the presence of people nearby.
Creating smarter spaces, not just smarter devices
The goal of these systems is to create living spaces that automatically adjust to people’s behavior. Imagine lights automatically turning on when you move. Heating systems adjusting based on location. Health monitors tracking your breathing while you sleep — all without cameras or human intervention.
When developers combine artificial intelligence with wireless sensing technology, these systems can operate silently in the background. Users do not need to see, touch, or speak to them.And because they don’t collect personal data like images or recordings, they are easier to trust.
However, the devices still face many challenges depending on the home, layout, and lifestyle. Sensors must be accurate and reliable. The industry needs standards to ensure interoperability between different devices and brands. One standard currently under development is IEEE 802.11bf. It aims to extend Channel State Information (CSI)-based sensing technology to the mainstream application of Wi-Fi devices.
Next Step: Signal Fusion
One of the most promising ideas is integrating different types of sensors into a single system. For example, by fusing Wi-Fi data with audio or temperature readings, artificial intelligence can build a more complete picture of events. This approach, known as multimodal sensing, allows systems to learn not only when events occur, but also why and what they mean.
Voice assistants like Alexa are already experimenting with this concept. Features like “Intuition” leverage behavioral patterns to automatically take action. They dim lights at night or adjust the thermostat when you typically leave a room. The more signals these systems have access to, the smarter they become.
But with more data comes greater responsibility. The increasing prevalence of wearable devices equipped with always-on microphones or cameras builds deeper contextual awareness when they interact with smart home devices. At the same time, they also raise more privacy concerns. As these systems become increasingly aware of our presence, habits, and actions, how to use this information becomes more crucial than ever.
Background-Running Technologies
Passive wireless sensing technology holds great promise, providing systems with the necessary contextual information without requiring monitoring or listening. It is efficient, scalable, and better aligned with privacy-first design principles.
Whether for elderly care, energy-efficient HVAC systems, or hands-free control in augmented reality (AR), these sensing methods lay the foundation for smarter homes and spaces. The systems require no user attention — they simply monitor silently. This all happens without causing disruption.
As homes become increasingly intelligent, the smartest parts may well be those technologies you’ll never see.