Your Wi-Fi router has a secret superpower

Your Wi-Fi router can now do a headcount

A team of electrical engineers has come up with a method for counting the number of people in an area based solely on how the power requirements of a Wi-Fi network fluctuate, with many diverse applications.

The researchers, led by Yasamin Mostofi, put two Wi-Fi nodes at the opposite ends of a 70-square metre space and examined changes in the wireless signal. When people crossed the beam between the two nodes, the Wi-Fi signal dropped slightly, and when they were off to one side they scattered the beam.

By examining these two phenomena, the team was able to develop a probabilistic mathematical method for estimating the number of people moving around in the space - it's been tested successfully with up to nine people so far.

"This is about counting walking people, which is very challenging," said Mostofi. "Counting this many people in such a small area with only Wi-Fi power measurements of one link is a hard problem, and the main motivation for this work."

Given the ubiquity of Wi-Fi networks around the world, this discovery could be used in many fields. Smart heating and lighting systems could intelligently adjust their output based on the level of occupancy, while in search and rescue, a stricken office building could automatically report the number of inhabitants to disaster recovery teams.

In the latter scenario, Mostofi is hoping to combine this work with her lab's previous work on imaging stationary objects and humans through walls using Wi-Fi signals. The results were published in IEEE's Selected Areas in Communications journal.

Duncan Geere
Duncan Geere is TechRadar's science writer. Every day he finds the most interesting science news and explains why you should care. You can read more of his stories here, and you can find him on Twitter under the handle @duncangeere.
Latest in Wi-Fi & Broadband
Eero 7 mesh Wi-Fi system on a wooden table
I tested the affordable Eero 7 mesh Wi-Fi system, and as long as you don't need 6.0GHz Wi-Fi, it's great for bringing those dead spots back to life
Eero 7 on a nightstand
Amazon's new Eero 7 and Pro 7 complete a 'comprehensive lineup' for its customers – here's everything you need to know
A hacker wearing a hoodie sitting at a computer, his face hidden.
I just learned something awful about my home Wi-Fi setup thanks to iFixit’s ‘worst of CES 2025’ awards
Extendable WiFi 7 KV
Don't buy a router, buy a fast and secure ASUS WiFi 7 extendable router
Netgear Nighthawk router next to its box on a table
Netgear Nighthawk RS200 review: Netgear’s latest Wi-Fi 7 router is competitively priced – but makes compromises to get there
Netgear Orbi 770 router system resting on a table
Netgear Orbi 770 review: fast speeds, low Wi-Fi 7 prices
Latest in News
cheap Nintendo Switch game deals sales
Nintendo didn't anticipate that Mario Kart 8 Deluxe was 'going to be the juggernaut' for the Nintendo Switch when it was ported to the console, according to former employees
Three angles of the Apple MacBook Air 15-inch M4 laptop above a desk
Apple MacBook Air 15-inch (M4) review roundup – should you buy Apple's new lightweight laptop?
Witchbrook
Witchbrook, the life-sim I've been waiting years for, finally has a release window and it's sooner than you think
Amazon Echo Smart Speaker
Amazon is experimenting with renaming Echo speakers to Alexa speakers, and it's about time
Shigeru Miyamoto presents Nintendo Today app
Nintendo Today smartphone app is out now on iOS and Android devices – and here's what it does
Nintendo Virtual Game Card
Nintendo reveals the new Virtual Game Card feature, an easier way to manage your digital Switch games