Your WiFi router is watching you. Not through a camera—it doesn’t need one. Using radio waves that already permeate your home, office, and public spaces, WiFi sensing technology can detect your presence, track your movements, identify you by your gait, and even monitor your breathing rate through walls. And unlike cameras or microphones, you can’t cover it up, turn it off, or even know when it’s happening.
A recent discussion on Hacker News garnering 392 upvotes brought renewed attention to research warning that WiFi could become an invisible mass surveillance system. The implications are profound: the same infrastructure that provides internet connectivity could simultaneously serve as an always-on, ubiquitous surveillance network—and there’s almost nothing you can do to stop it.
What Is WiFi Sensing?
WiFi sensing, also known as WLAN sensing, is a technology that uses existing WiFi signals to detect events and changes in an environment. Originally developed for legitimate applications like smart home automation, elderly care monitoring, and gesture recognition, the technology leverages the fact that radio waves are affected by objects and people in their path.
According to research published in IEEE Communications Surveys and Tutorials, mobile networks are evolving from communication-only systems toward “perceptive mobile networks” with joint communication and radar/radio sensing (JCAS) capabilities. This integration allows sensing to share the majority of system modules and the same transmitted signals used for data communication.
The technology operates across standard WiFi frequency bands—2.4 GHz, 5 GHz, and the newer 6 GHz—using the physical layer (PHY) measurements of WiFi signals to detect features in the local physical environment. The key measurement is Channel State Information (CSI), which contains detailed information about how radio signals propagate between transmitter and receiver.
The Four Domains of WiFi Sensing
WiFi sensing capabilities fall into four broad categories:
- Detection – Binary classification tasks like presence detection, intruder detection, and fall detection
- Localization – Determining where motion occurs in a space
- Recognition – Multi-class classification including gesture recognition, gait analysis, human/pet differentiation, and activity recognition
- Estimation – Quantitative measurements like breathing rate, heart rate, people counting, and distance estimation
Current commercial applications focus primarily on motion detection and localization, but research demonstrates far more invasive capabilities.
How It Works: The Technical Foundation
WiFi sensing exploits the way radio waves interact with objects and people in an environment. When a WiFi signal travels from your router to your laptop, it bounces off walls, furniture, and yes—human bodies. These reflections create a unique “channel” that can be measured and analyzed.
The IEEE 802.11bf standard, approved in September 2020, formalizes WLAN sensing protocols, defining how devices generate and provide low-level channel measurements. This standardization ensures interoperability across devices from different manufacturers—and also means the surveillance capabilities are built into the specification itself.
From Communication to Surveillance
Here’s what makes WiFi sensing particularly concerning from a privacy perspective:
It works through walls. WiFi signals at sub-7 GHz frequencies can penetrate drywall, wood, and other common building materials. Research from MIT demonstrated the ability to “see through walls with WiFi” as early as 2013.
It requires no cooperation from the target. Unlike Bluetooth beacons or GPS that require your device to actively transmit, WiFi sensing works passively. You don’t need to be carrying a phone or any device at all.
It can identify individuals. Multiple research papers have demonstrated person identification using WiFi signals. A 2016 paper titled “FreeSense: Indoor Human Identification with WiFi Signals” showed that unique body shapes and movement patterns create distinguishable WiFi signatures.
It can track vital signs. Systems like “Wital” can monitor breathing and heart rate using commercial off-the-shelf WiFi devices, without any wearable sensors or cameras—raising particular concerns for privacy in bedrooms and bathrooms.
The Privacy Implications Are Staggering
The convergence of several trends makes WiFi sensing a uniquely powerful surveillance technology:
Ubiquitous Infrastructure
WiFi routers are everywhere—homes, offices, coffee shops, airports, hotels, and public spaces. According to the Wireless Broadband Alliance, WiFi sensing can “utilize conventional WiFi transceiver hardware” already deployed worldwide. There’s no need to install new cameras or sensors; the surveillance network is already built.
No Visible Indicators
Unlike cameras (which may have recording lights) or microphones (which can be detected), WiFi sensing leaves no trace. You cannot look around a room and identify whether WiFi sensing is active. The router in the corner that provides your internet could simultaneously be tracking every movement in the building.
Difficult to Defend Against
Traditional privacy protections fail against WiFi sensing:
- You can’t block it – WiFi signals must pass through your space for you to have internet connectivity
- You can’t detect it – There’s no consumer technology to identify when WiFi sensing is active
- You can’t opt out – In public spaces, you have no control over the WiFi infrastructure
Potential for Abuse
While the technology has legitimate applications—elderly fall detection, smart home automation, building security—the potential for misuse is significant:
- Employers could monitor employee movements throughout buildings
- Landlords could track tenants without consent
- Retailers could analyze customer behavior with unprecedented detail
- Governments could deploy mass surveillance without visible cameras
- Abusers could monitor victims’ presence and activities remotely
A 2023 paper titled “Caveat (IoT) Emptor: Towards Transparency of IoT Device Presence” warned that “hidden IoT devices can snoop (via sensing) on nearby unsuspecting users” without their awareness.
Who’s Developing This Technology?
The development of WiFi sensing involves both academic researchers and commercial entities:
Academic Research
Major universities including MIT, Carnegie Mellon, and others have published extensively on WiFi sensing capabilities. Papers demonstrate increasingly sophisticated applications:
- “DensePose From WiFi” (2023) – reconstructing detailed human body poses
- “Breaking Coordinate Overfitting” (2026) – 3D pose estimation across different environments
- “AM-FM: A Foundation Model for Ambient Intelligence” (2026) – comprehensive human sensing using WiFi infrastructure
Commercial Development
The Wireless Broadband Alliance (WBA), an industry association promoting wireless broadband integration, established a dedicated WiFi Sensing Work Group. Major technology companies participate in developing standards and applications.
The IEEE 802.11bf Task Group is actively standardizing WiFi sensing protocols, ensuring that surveillance capabilities will be built into future WiFi devices by default.
Defense Strategies: What Can You Do?
Protecting yourself from WiFi sensing is challenging, but some strategies can help:
MAC Address Randomization
Modern operating systems including iOS, Android, macOS, Windows, and Linux support MAC address randomization. This prevents tracking via your device’s hardware address, though it doesn’t protect against device-free WiFi sensing that tracks your body directly.
According to Wikipedia, Apple announced in June 2014 that iOS would randomize MAC addresses for all WiFi connections. Windows has supported it since Windows 10, and Linux kernel support arrived in March 2015.
Physical Barriers
Radio frequency shielding materials (like those used in Faraday cages) can block WiFi signals, but this also blocks internet connectivity. This may be appropriate for sensitive spaces like bedrooms or meeting rooms, but is impractical for general use.
Minimize WiFi Exposure
- Use wired ethernet connections where possible
- Turn off WiFi routers when not needed
- Limit time spent in public spaces with dense WiFi coverage
Demand Transparency and Regulation
Consumer pressure can drive change:
- Ask venues about their WiFi sensing policies
- Support legislation requiring disclosure of sensing capabilities
- Advocate for “WiFi sensing off” options in devices
The Regulatory Landscape
As of 2026, specific regulation addressing WiFi sensing surveillance remains limited. The technology falls into regulatory gaps:
- Privacy laws often focus on data collection, not sensing
- Surveillance regulations typically address cameras and audio recording
- Consumer protection frameworks don’t cover passive RF sensing
However, growing awareness is prompting action. Privacy advocates at organizations like the Electronic Frontier Foundation (EFF) have long highlighted locational privacy concerns. The EFF’s Surveillance Self-Defense guide provides resources for protecting against various forms of monitoring.
What Regulation Should Address
Effective regulation of WiFi sensing should include:
- Mandatory disclosure – Devices with sensing capabilities must clearly indicate this to users
- Consent requirements – Sensing in private spaces should require explicit consent
- Data retention limits – Sensing data should be deleted promptly
- Access controls – Sensing data should be encrypted and access-controlled
- Opt-out mechanisms – Users should be able to disable sensing while maintaining connectivity
The Path Forward
WiFi sensing represents a fundamental tension between beneficial technology and privacy rights. The same capabilities that could save elderly lives through fall detection could enable unprecedented surveillance.
The technical reality is stark: once WiFi sensing becomes widely deployed in commercial routers, we will have created an invisible surveillance network more pervasive than any camera system in human history. And unlike cameras—which can be avoided, detected, and regulated—WiFi sensing operates in a regulatory and perceptual blind spot.
The time to establish privacy protections is now, before the technology becomes ubiquitous. Once every WiFi router is also a surveillance device, the network effects make regulation far more difficult. We must demand transparency, consent, and control over sensing capabilities in the devices that surround us.
Your WiFi router is watching. The question is: who’s watching the watchers?
References and Further Reading
- Zhang, J. Andrew, et al. “Enabling Joint Communication and Radar Sensing in Mobile Networks – A Survey.” IEEE Communications Surveys and Tutorials, 2021. arXiv.07559
- “Wi-Fi Sensing.” Wikipedia, retrieved February 2026.
- “MAC Spoofing.” Wikipedia, retrieved February 2026.
- Adib, Fadel, and Dina Katabi. “See through walls with WiFi!” ACM SIGCOMM 2013.
- Zhu, Guozhen, et al. “AM-FM: A Foundation Model for Ambient Intelligence Through WiFi.” arXiv, 2026.
- Halperin, Daniel, et al. “Tool release: gathering 802.11n traces with channel state information.” ACM SIGCOMM Computer Communication Review, 2011.
- Geng, Jiaqi, et al. “DensePose From WiFi.” arXiv, 2023.
- Xin, Tong, et al. “FreeSense: Indoor Human Identification with WiFi Signals.” arXiv, 2016.
- Zhang, Xiang, et al. “Wital: A COTS WiFi Devices Based Vital Signs Monitoring System Using NLOS Sensing Model.” arXiv, 2023.
- Jakkamsetti, Sashidhar, et al. “Caveat (IoT) Emptor: Towards Transparency of IoT Device Presence.” arXiv, 2023.
- Liu, Jianwei, et al. “A Framework for Behavior Privacy Preserving in Radio Frequency Signal.” arXiv, 2020.
- Yang, Jianfei, et al. “MM-Fi: Multi-Modal Non-Intrusive 4D Human Dataset for Versatile Wireless Sensing.” arXiv, 2023.
- Ji, Sijie, et al. “SiFall: Practical Online Fall Detection with RF Sensing.” arXiv, 2023.
- Wireless Broadband Alliance. “Wi-Fi Sensing: A New Technology Emerges.” White Paper, October 2019.
- IEEE Standards Association. IEEE 802.11bf Project Authorization Request, 2020.
- Electronic Frontier Foundation. “Locational Privacy.” eff.org/issues/locational-privacy