Making Sense of RF Sensing

What is RF Sensing?

RF Sensing uses radio frequency (RF) waves - like those your cell phone or Wi-Fi router emits - to find and identify objects and people in a space. Generally speaking, a transmitting device sends these RF waves out in all directions when it broadcasts a message to other devices. As the RF waves scatter around, they interact with everything from your furniture to the walls and the people in the room. This interaction helps RF sensing systems gather a wealth of useful information about the room or area. It’s a brilliantly discreet way to keep an eye on things and understand different environments without being invasive.

As we explore the world of RF sensing, we'll focus on its two primary approaches: device sensing and wireless network sensing.

• Device Sensing: Here, the idea is to capture the transmissions of specific devices in order to sense that a device is there. This can either be from the perspective of a static device (e.g. a router) detecting that mobile phones are transmitting nearby or from the perspective of a mobile device detecting that certain static devices (e.g. BLE anchors) are transmitting nearby. 

• Wireless Network Sensing: In contrast, this approach involves both the transmitter and receiver being stationary. They continuously analyze the RF waves to detect any changes or disruptions in the environment. This method is especially useful for monitoring fixed spaces, like securing a room or understanding the usage patterns in a home.

Each of these technology areas comes with its own set of fancy terms and applications - such as RTLS, 802.15.4 sensing, and WiFi sensing - each designed for specific needs. Getting the hang of these terms isn’t just about sounding smart, it’s key for avoiding confusion, understanding what they do, and where you can use them.

Our goal of this article is to demystify the world of RF sensing and empower you on your smart home journey. 

Now let's dig in!

Device Sensing

Defined simply, device sensing is the technology used to detect and track devices based on the RF signals they emit. This capability splits into two primary categories: Known and Unknown Device Sensing. They each serve a distinct purpose, allowing us to interact with and understand our technology-rich environment more effectively.

Known Device Sensing revolves around recognizing and/or tracking devices whose identities and characteristics are already known to the system. This includes things like RTLS (Real-Time Location Systems), Known Communication Sensing and Query & Search. Let's look at these a bit closer.

• RTLS (Real-Time Location Systems): These systems are the backbone of industries requiring precise location tracking, such as healthcare for monitoring patients or logistics for managing warehouse inventories.

• Known Communication Sensing: This involves recognizing devices by their unique communication patterns, like a phone’s specific way of connecting to Wi-Fi. Just as people have different ways of greeting each other, devices connect in distinct ways. By identifying these patterns, systems can efficiently manage and secure devices in environments like smart homes, corporate networks, or hospitals, whether it’s a phone, a smart speaker, or a medical device.

• Query and Response: This method is like a roll call for devices; the system sends out a signal (the query), and the devices respond, confirming their presence on the network. It’s widely used in settings where maintaining an accurate inventory of devices is critical.

Unknown Device Sensing on the other hand, deals with detecting devices that are not previously identified by the system. This category is particularly valuable for security and management in tech-dense spaces. Within this group, we have things like BLE Advertising, WiFi Probe Request and Other Radio Scanning.

• BLE Advertising: Devices that use Bluetooth Low Energy (BLE) broadcast their presence, which can be picked up by sensors designed to listen for such signals. This is often used in retail environments to interact with customers’ smartphones.

• WiFi Probe Request: When devices like smartphones search for available WiFi networks, they send out probe requests. Sensing these requests helps in understanding device density and movement patterns in spaces like shopping malls or airports.

• Other Radio Scanning: This involves scanning a spectrum of radio frequencies to detect any active transmissions within an area, useful for security measures in sensitive environments.

By leveraging both known and unknown device sensing, we can gain a comprehensive view of the digital and physical landscape around us, enhancing everything from user experience to security.

Wireless Network Sensing

A good way to envision Wireless Network Sensing is to picture it as the unseen guards of our spaces. Wireless Network Sensing uses fixed RF transmitters and receivers (WiFi routers, smart light bulbs, smart outlets, smart thermostats, etc.) to continuously monitor and analyze RF waves within an environment. This static surveillance helps detect any changes, painting a detailed picture of a space without any physical intrusion. It’s like having invisible security cameras that can see the airwaves instead of the visual spectrum, providing a discreet but powerful way to understand and interact with various environments. As a reminder, this sensing category senses people, not devices.Whether it’s turning the lights on as you enter a room or sounding an alarm when an intruder is detected, these technologies integrate seamlessly to enhance the security and convenience of a connected home. 

Let’s look at the three communication systems on which Wireless Network Sensing can be operated, each harnessing unique technologies to cater to specific scenarios:

Bluetooth Low Energy (BLE) Sensing

BLE-enabled devices are found throughout homes and businesses all over the world. Found in light bulbs, switches, outlets, and a host of other devices, the RF communications between these low-power chips can be leveraged to determine if there is activity in the space. While widely used as a communication technology, BLE is typically only used to commission an IoT device, rather than as a primary means of communicating with it. However, when a device can handle simultaneous BLE communications, BLE sensing can unlock new possibilities, turning what was once just a setup tool into a valuable feature - all with a simple OTA update.

802.15.4 (Thread or Zigbee) Sensing

The 802.15.4 standard is known for its low power usage and high reliability, perfect for environments where numerous devices need to communicate efficiently and reliably. Technologies such as Thread and Zigbee create mesh communication networks that can be used to create sensing areas. With Thread and Zigbee being mesh systems by nature, these systems are built for sending and receiving communications between devices in a network making them ideal for adding Wireless Network Sensing via OTA update.

802.11 (WiFi) Sensing

With billions of devices in homes, business, and other types of buildings worldwide, WiFi is the most prevalent RF standard on earth. Wireless Network Sensing technology can be used to turn common WiFi networks into advanced occupancy sensors, analyzing disruptions in the WiFi signals caused by any changes to the environment, people and objects interacting with the world around them. It’s particularly good at enhancing security systems, where it can detect an intruder based on the disturbance in Wi-Fi signal patterns, or in energy management systems to adjust heating and cooling based on occupancy detected via Wi-Fi signals. Central to this system are hubs and routers. They facilitate communication between connected devices and can use signal disruptions in the data traffic to sense objects or individuals along communication paths between hubs and connected devices.

Wireless Network Sensing not only strengthens our control over the environments we live and work in but also deepens our understanding of them. By getting familiar with these technologies, we unlock new possibilities to optimize and secure our spaces in ways we never thought possible.

Final Thoughts

As we end our exploration of RF Sensing, it’s clear that the power of this technology lies in its ubiquitous availability and thus scalability. It enables smarter living, enhances security, and fosters efficiency in ways we’re just beginning to explore. By demystifying these technologies and understanding their capabilities and applications, you’re not just keeping pace with technological advancements - you're stepping into a world where your interaction with technology is more intuitive, seamless, and impactful.

So, whether you're optimizing a smart home, boosting retail experiences, or securing sensitive environments, remember that the knowledge of RF sensing you've gained here is a powerful tool in your toolkit. Use it to make informed decisions, innovate responsibly, and shape a future where technology serves us with precision and care.

Ivani is a nationally recognized technology and intellectual property development company focusing on scalable sensing solutions. Ivani's primary technology offering, sensify®, is a patented suite of custom firmware and software that allows wireless communication systems to observe Radio Frequency (RF) disturbances without adding new hardware.  The custom firmware is loaded onto standard wireless communications hardware (smart switches, outlets, light bulbs, thermostats, etc), allowing integration of the technology into both new and legacy products. It analyzes these disturbances to detect human presence or absence in an area. For more information about sensify® and Ivani, please visit www.ivani.com