Wi-Fi signals can do rough head counts

Estimating the number of people present by looking at Wi-Fi signals could help make buildings more energy efficient

Researchers at the University of California, Santa Barbara have done experiments showing that Wi-Fi signals traveling between wheeled robots (front left) can be used to estimate the number of people in an area. The graph on the lower right shows the received Wi-Fi signal.

Researchers at the University of California, Santa Barbara have done experiments showing that Wi-Fi signals traveling between wheeled robots (front left) can be used to estimate the number of people in an area. The graph on the lower right shows the received Wi-Fi signal.

We're all walking around in a soup of Wi-Fi signals, but researchers say they can be put to another use -- counting people.

When people cross the path of a Wi-Fi signal, it weakens somewhat. That effect can be measured and provide a rough head count, according to researchers at the University of California, Santa Barbara (UCSB).

The technology could be used for applications such as making buildings more energy efficient by adjusting the temperature according to the number of people inside.

In a series of simple experiments, a Wi-Fi router and receiver on two Pioneer 3-AT wheeled robots were placed on either side of areas indoors and outdoors. A number of people walked around the area, weakening the Wi-Fi signals going from one robot to the other. The people didn't carry any communication equipment.

By analyzing the way the signal was changed -- either weakening or being scattered -- by the presence of the people, the researchers could estimate their number through a mathematical model.

The method was fairly accurate, usually being off by one or two people out of a group of up to nine, even when people crossed the path of the signal multiple times.

"For a lot of applications, an exact number may not be needed but rather a fairly accurate assessment could do the job," Yasamin Mostofi, a UCSB professor of electrical and computer engineering who has also experimented with Wi-Fi to give drones the ability to "see through" walls, said via email.

Mostofi believes the method could be scaled. Apart from smart buildings, it could help first responders by providing an estimate of the number of people in a disaster. Stores could also use it to better plan merchandise layouts.

Mostofi isn't sure of the maximum number of people that can be estimated, but she plans to expand the experiment to include a Wi-Fi network in a building and discover the fundamental limits of the method.

Tim Hornyak covers Japan and emerging technologies for The IDG News Service. Follow Tim on Twitter at @robotopia.

Join the PC World newsletter!

Error: Please check your email address.

Tags Internet-based applications and servicesroboticsSanta BarbaraUniversity of CaliforniaComponentsinternet

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Tim Hornyak

IDG News Service
Show Comments

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?