Tag Archives: Comunication

New method piggybacks data on radio waves to make singing posters and smart cities

A new technique developed by University of Washington engineers will allow “smart” objects to communicate directly with your car or smartphone.

Image credits JudaM / Pixabay.

A bus stop billboard could do much more than just advertise local attractions — why not enable it to send your smartphone a link with directions to the venue, maybe even a discount for your ticket? A t-shirt could do more than just clothe you while you run — why not have it monitor your vital signs, keeping an eye out for any emergency? Well, that’s exactly what one team from the University of Washington wants to do.

The problem is that up until now we didn’t have any viable way to power these devices for any meaningful period of time. So the team decided to swap out internal power sources for a ubiquitous form of energy in modern cities — ambient radio signals.

“The challenge is that radio technologies like WiFi, Bluetooth and conventional FM radios would last less than half a day with a coin cell battery when transmitting,” explains co-author and UW electrical engineering doctoral student Vikram Iyer. “So we developed a new way of communication where we send information by reflecting ambient FM radio signals that are already in the air, which consumes close to zero power.”

“FM radio signals are everywhere. You can listen to music or news in your car and it’s a common way for us to get our information,” adds co-author and UW computer science and engineering doctoral student Anran Wang. “So what we do is basically make each of these everyday objects into a mini FM radio station at almost zero power.”

They’re the first research team to ever prove this method of harnessing existing radio signals — called “backscattering” — actually works. Their system transmits messages by encoding data into these waves and then reflecting them without affecting the original transmissions.

Singing posters

To prove that their technology works, they created a “singing poster” for band Simply Three and placed it at a bus stop. The poster could transmit an ad and sample of the band’s music to a smartphone up to 12 feet away (3.6 meters) or to a car up to 60 feet (9 meters) away. The audio and image data were transmitted an ambient signal — a news broadcast from a local NPR radio station.

The poster uses a low-power reflector that can tap into the radio broadcast and manipulate the signal in such a way as to piggy-back the desired data on top of the signal. This data is distinct enough from the original wave to be picked up by a smartphone receiver on an unoccupied frequency in the FM radio band, not interfering with any other technology.

“Our system doesn’t disturb existing FM radio frequencies,” said co-author Joshua Smith, UW associate professor of computer science and engineering and of electrical engineering. “We send our messages on an adjacent band that no one is using — so we can piggyback on your favorite news or music channel without disturbing the original transmission.”

“Because of the unique structure of FM radio signals, multiplying the original signal with the backscattered signal actually produces an additive frequency change,” adds co-author Vamsi Talla, a UW postdoctoral researcher in computer science and engineering. “These frequency changes can be decoded as audio on the normal FM receivers built into cars and smartphones.”

Beyond this method of adding data to an unused frequency, the team demonstrated two more methods for transferring data using FM backscatter: one which simply overlays the new information on top of the existing signals, and one that relies on cooperation between two smartphones to decode the message.

In the team’s demonstrations, the total power consumption of the backscatter system was 11 microwatts, which could be easily supplied by a tiny coin-cell battery for a couple of years or powered using tiny solar cells. Connectivity requiring such a low level of power can also be used to create smart fabrics and clothes. The researchers from the UW Networks & Mobile Systems Lab used a conductive thread to sew an antenna into a T-shirt which was able to similarly backscatter data at rates of up to 3.2 kilobits per second.

The end game isn’t to make smart posters of clothes alone — but entire smart cities which can talk to you for almost no power requirement.

“What we want to do is enable smart cities and fabrics where everyday objects in outdoor environments — whether it’s posters or street signs or even the shirt you’re wearing — can ‘talk’ to you by sending information to your phone or car,” concludes lead faculty and UW assistant professor of computer science and engineering Shyam Gollakota.

The full paper “FM Backscatter: Enabling Connected Cities and Smart Fabrics” will be presented in Boston at the 14th USENIX Symposium on Networked Systems Design and Implementation this month.

Using your body as your personal LAN, or what I dub the Bluebody technology.

Everyone knows that the body is used to communicate way more information than we do by speech, almost unconsciously, but researchers at the University of California, San Diego, are aiming to take that to a whole new level.

They are in the early stages of developing technology that will use your body as the communication medium, which they say will, with some refinement, work as a lower-power and much more secure alternative to Bluetooth for wearable gadgets, such as smart watches or health trackers.

And it uses magnets. Sort-of.
Image via slashgear

Patrick Mercier, assistant professor at UCSD and co-director of the Center for Wearable Sensors belonging to the University, says that while the Bluetooth radios embedded in many gadgets are useful for transmitting data over short distances, they’re not that great at it when there’s a body in the way. Our flesh and blood tends to absorb the radio signals Bluetooth technology relies on to move data from one device to another—which means more power has to be expended to communicate via Bluetooth to make up for it.

What are bodies aren’t as good at absorbing though, are magnetic fields. Mercier and graduate student Jiwoong Park have thus set their eyes on them to help them create new technology that would make communication more efficient by sending such signals through, well…us.

Mercier and Park experimented by wrapping insulated coils of copper wire around a person’s head, legs, and arms. An electrical current was used to generate magnetic fields with the coils, and they measured how the magnetic waves were picked up by the other coils via the body.

The coils are “trying to use the arm as a guide, of sorts, to guide the magnetic wave across to the other side of the body,” Mercier says.

They then measured how much of the signal was lost from one body part to the next (arm to head or arm to arm, for example) – it was a staggering 10 million times less that what they’d measure for Bluetooth. This leads them to think it could be used to make wearable gadgets that use way less power for communication.

Mercier also believes the technology will be more secure than Bluetooth, since tapping into a wireless network is much more inconspicuous than tapping into a person’s buttocks. To those worried about any adverse health effects the signal might have, Mercier says that the field being generated is harmless. “orders of magnitude” lower than an MRI.

The technology is still just in the early prototype phase; Mercier says that while they have some “preliminary” prototypes that they’ve used to transfer brain activity data from a coil around the head to a coil around the wrist, and from there to a connected computer, it isn’t integrated into a wearable gadget yet. He adds that they’re also planning to do some experiments through which they’ll transfer something like the data from a heart-rate monitor across this sort of link to a smartwatch.

However, Mercier suspects the technology won’t be as useful for gadgets that don’t wrap around the body—like smartphones or a sensor-containing patch you might stick on your body—because they won’t propagate the magnetic waves through the body in the same way.