Wi-Fi is watching you: the future of presence detection

Your Wi-Fi router could soon know when you’re at home, which rooms you use – even how you move. For telecom operators, it promises smarter homes and more data insights. But for users, will any place be truly private?

Xfinity, part of US-based telco Comcast, has recently launched a new home internet feature that has some customers reaching for their tin-foil hats – Wi-Fi-powered motion tracking:

The feature allows users to turn their router into a sensor to monitor movement within their homes at no extra cost.

WiFi Motion detects movement between the user’s Xfinity Gateway router and up to three Wi-Fi enabled devices (e.g. smart appliances, though not smartphones). When motion is detected, the signal between the two is disrupted, and a notification is sent to the user’s app.

This method can detect even the smallest of movements, and can even be calibrated to ignore pets, though it cannot accurately triangulate the location of movements, or identify what is being detected.

WiFi Motion only works in areas with a strong signal, and its quality is affected by room layout, building materials, and placement of the Gateway.

Recent developments in AI have only now made it practical to interpret signal variations, filter out noise and identify patterns. Given the resources still needed to process the data, it's unlikely the Gateway itself will analyse signal strength fluctuations, meaning at least some data is likely being sent to Comcast.

But the technology has been with us for a while; in a 2022 study, researchers at Carnegie Mellon University demonstrated a method for tracking bodies through walls using Wi-Fi via a computer vision system developed by Facebook that maps pixels to a 3D model of a human body:

Back in 2015, a team at the University of California, Santa Barbara found a way to count a crowd of up to nine people using two Wi-Fi cards placed at either end of an indoor or outdoor area.

Meanwhile, the idea of – and concerns over – surveillance via radio signals is even older, as this scene from 2008’s The Dark Knight highlights:

In residential and commercial environments, detecting the presence of people opens a range of possibilities, from energy-saving automations to enhanced security and occupancy analytics. Wi-Fi can offer several advantages for this type of monitoring:

• Non-intrusive: Unlike cameras, Wi-Fi sensing does not capture visual images, offering a less invasive form of surveillance.
• Ubiquity: Wi-Fi can penetrate walls and cover multiple rooms with a single, extant access point or mesh setup, reducing the need for new hardware.
• Device-free: Unlike Bluetooth or RFID-based solutions, users do not need to wear or carry any devices.

Furthermore, emerging wireless standards, such as Wi-Fi 7, are expected to bring improved signal resolution and reduced latency, which could enhance the reliability of presence detection systems.

Ethical and privacy concerns

Many are concerned that WiFi Motion turns routers into low-resolution cameras with “the ability to see through walls.”

This new feature has also resulted in conversations about privacy and security. Comcast states that it may “disclose information generated by your WiFi Motion to third parties without further notice to you in connection with any law enforcement investigation or proceeding, any dispute to which Comcast is a party, or pursuant to a court order or subpoena.”

Likewise, some are concerned that this data could be passed along to law enforcement agencies to pinpoint exactly when users were at home. In December, the FTC ruled against Venntel, accused of selling the locations of millions of people to Immigration and Customs Enforcement (ICE) agents, as the organisation has significantly stepped up raids against undocumented citizens.

Telecom providers and systems integrators must therefore address the ethical implications of passive presence detection, including how this data is integrated with BSS/OSS solutions:

• Users often aren't fully aware that this kind of sensing is happening, particularly in public settings.
• Even without video, patterns of presence and motion can reveal intimate behaviours. Presence detection systems should avoid collecting more data than necessary (e.g. storing only occupancy status without logging detailed movements), and users must be clearly informed about what is being detected, stored, and analysed.
• If misused, data could fuel capitalist-style social scoring (e.g. insurance pricing based on in-home activity) or intrusive employee productivity monitoring.
• When presence data is stored or transmitted, it must be encrypted and protected against unauthorised access.

Telcos are well-positioned to provide occupancy sensing as a value-added service by offering secure, ethical and intelligent sensing solutions. Integrating presence data into BSS/OSS platforms can enable new service models while demanding strong data governance. Key applications include:

• Security and intrusion detection
  Continuous presence verification adds an extra layer of protection in sensitive areas; unusual movements can trigger alerts.
• Smart home
  Smart home services could integrate occupancy analytics dashboards and contextual or presence-based automation (e.g. adjusting lighting and temperature, or turning off appliances).
• Elderly care and fall detection
  Passive presence data helps detect falls, inactivity or unusual behaviour in elderly care, enabling non-intrusive health monitoring.
• Retail analytics
  Monetisation via anonymised footfall data (with consent) could open new revenue streams in retail planning, with the potential to integrate usage analytics into billing and CRM systems. Presence detection can inform customer flow patterns and optimise staffing or store layout, and spatial data could inform ad placement or push notifications based on customer behaviour.
• Smart cities
  At scale, anonymised spatial data could help model urban mobility and transport demand, inform energy efficiency programmes or green initiatives, and enable smart city partnerships. For example, Alphabet’s Sidewalk Labs has rolled out Wi-Fi kiosks in New York to measure traffic congestion and monitor air quality.

Wi-Fi sensing could quietly transform everyday connectivity into a new layer of spatial intelligence for detecting presence, movement and behavioural patterns, without needing cameras or wearables, opening up opportunities for telcos to offer smarter homes, more personalised services, and even new revenue models.

As networks become ambient observers, the distinction between convenience and surveillance begins to blur, and, if deployed without transparency or consent, risks eroding user trust and privacy. Telecoms and tech companies must lead with design principles that prioritise privacy, user agency, and minimal data collection. Anonymisation, clear opt-in models, and strong governance will be essential to maintaining trust.

Wi-Fi sensing can create safer, smarter environments, but only if we commit to building them with integrity, including ensuring that BSS/OSS solutions handling this data maintain the highest privacy and security standards.

Update [25/07/2025]: Researchers from La Sapienza University of Rome have taken Wi-Fi tracking one step further by developing a system which can generate a unique biometric identifier based on how a person’s body interacts with surrounding Wi-Fi signals.