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Slow Wi-Fi? FM Radio Might Help With That


If you live in an apartment building or another densely populated area and your Wi-Fi is slow, your neighbors bingeing on Netflix may be to blame.

Your and your neighbors' Wi-Fi networks have a limited number of wireless frequency channels to move your data. And when things get crowded and busy, Wi-Fi networks can overlap and bump into each other and slow down your Internet connection.

"I'm doing something, you're doing something, but none of us have a reference point about when the other party will do something or not," says Aleksandar Kuzmanovic, associate professor of electrical engineering and computer science at Northwestern University, describing how Wi-Fi devices might operate.

"There's no sense of timing, no sense of coordination. And hence, I listen a little bit, I don't hear, I send something. This may create trouble to you because you just sent something. And then we both back off. There could be time wasted before somebody grabs the airtime," he says.

Looking for a way to organize this common discord, Kuzmanovic and his colleagues Marcel Flores and Uri Klarman have found an interesting aide: FM radio.

It's not a simple app to install on your phone, but the researchers say they've developed the first system for Wi-Fi devices to coordinate for everyone's benefit without explicit communication or human involvement. And it comes over FM — strong enough to reliably travel through walls and ubiquitous enough that many devices are already geared to receive it.

Knowing that Wi-Fi devices already hear each other over Wi-Fi frequencies, the scientists looked for a way to help the devices harmonize.

That's where FM radio comes in.

When you're listening to the radio, say, in your car, your display may show the name of the artist and song playing on the station, or sometimes traffic and weather alerts. That information arrives over a digital signal, called the Radio Data System or RDS, which travels right beside the broadcast signal.

RDS data, Kuzmanovic explains, have a signal structure that delivers bits of information in a series that constantly repeats itself.

So if Wi-Fi networks can converge on the same RDS (by scanning the FM dial for the lowest-frequency radio station with a strong enough signal), they can use it to harmonize their time-telling.

"Devices are able to detect that there is this particular repeating structure and hence they are all able to independently come to the conclusion that hey, this must be the beginning of this particular RDS signal sequence that's repeating in time," Kuzmanovic tells All Tech.

"And then once they come to that particular point ... they divide the time into particular time slots and then they listen to how others are behaving relative to these time slots and that further determines their own behavior — when will they send data, when they will not send data," he says.

Put simply, the RDS signal acts as a clock for Wi-Fi devices to time the quietest slot — and we're talking milliseconds — during which to send data.

The researchers dub this technique Wi-FM, describing it in a new paper presented Tuesday at the IEEE International Conference on Network Protocols in San Francisco.

The paper outlines one possible scheduling algorithm that would help Wi-Fi devices coordinate by using an FM signal. But as with many things in the industry, Kuzmanovic says others could come up with alternative approaches to reach the same goals with some universal parameters.

And while individually people could start adapting software on their Wi-Fi devices to adopt the Wi-FM technique, Kuzmanovic says the system would work best industrywide. His hope is for Google or Apple to spread the idea through its operating system, though he hasn't heard from the industry yet.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Alina Selyukh is a business correspondent at NPR, where she follows the path of the retail and tech industries, tracking how America's biggest companies are influencing the way we spend our time, money, and energy.
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