Tag Archives: wifi

New approach creates power out of thin WiFi

Researchers at the National University of Singapore (NUS) and the Tohoku University (TU), Japan, are working to make a device near you powered by the WiFi signals that are commonplace in the modern world.

Image via Pixabay.

Wireless networks are everywhere in towns and cities today. They connect a million devices to the Internet, day in, day out. Needless to say, that’s a lot of energy — over the 2.4GHz radio frequency that such networks use — being beamed all around us all the time. New research is working to harness this energy for a useful purpose, such as charging (for now, tiny) devices.

Airdropping charge

“We are surrounded by WiFi signals, but when we are not using them to access the Internet, they are inactive, and this is a huge waste. Our latest result is a step towards turning readily-available 2.4GHz radio waves into a green source of energy, hence reducing the need for batteries to power electronics that we use regularly.”

“In this way, small electric gadgets and sensors can be powered wirelessly by using radio frequency waves as part of the Internet of Things. With the advent of smart homes and cities, our work could give rise to energy-efficient applications in communication, computing, and neuromorphic systems,” said Professor Yang Hyunsoo from the NUS Department of Electrical and Computer Engineering, who led the research.

The team developed a new technology that uses tiny smart devices known as spin-torque oscillators (STOs), which can harvest and convert wireless radio waves into power for devices. They showed that these devices can successfully harvest energy from WiFi signals and that they could generate enough energy to power a light-emitting diode (LED) wirelessly, without using a battery.

STOs are devices that can receive radio signals and transform them into microwaves. Although that sounds amazing, they’re still an emerging technology, and are still quite inefficient at their job. Currently, STOs are only able to output low levels of power.

One workaround we’re using right now is to stack several STOs together, but this isn’t always viable: many devices have spatial constraints because nobody likes chunky items. Individual STOs are also limited in the range of frequencies they can react to, generally limited to only a few hundred MHz, which further complicates their use.

The team’s solution was to use an array of eight STOs connected in a series. This was then used to convert the 2.4 GHz electromagnetic radio waves used by WiFi into a direct voltage signal (electrical current), fed to a capacitor, and used to light a 1.6-volt LED. Five seconds of charging time on the capacitor was enough to keep the LED lit for one minute with the wireless power switched off.

As part of the research, they also performed a comparison between the STOs series design they used and a parallel design. The latter, they explain, has better time-domain stability, spectral noise behavior, and control over impedance mismatch — or, more to the point for us laymen, it’s better for wireless transmission. The series layout is more efficient at harvesting energy.

“Aside from coming up with an STO array for wireless transmission and energy harvesting, our work also demonstrated control over the synchronising state of coupled STOs using injection locking from an external radio-frequency source,” explains Dr Raghav Sharma, the first author of the paper.

“These results are important for prospective applications of synchronised STOs, such as fast-speed neuromorphic computing.”

In the future, the team plans to increase the number of STOs in their array, and test it for wirelessly charging other devices and sensors. They also hope to get interest from industry in developing on-chip STOs for self-sustained smart systems.

The paper “Electrically connected spin-torque oscillators array for 2.4 GHz WiFi band transmission and energy harvesting” has been published in the journal Nature Communications.

Typical Li-Fi setup. Credit: Bloomberg.

Dutch researchers demonstrate 42.8 gbps connection using Li-Fi. It’s 100 times faster than the best Wi-Fi

Schematic of LiFi operating principle. Credit: Flickr.

Schematic of LiFi operating principle. Credit: Flickr.

WiFi can become extremely irritating especially when too many connections get logged on to the same hotspot. That’s just an inherent fault of WiFi whose protocols share the bandwidth even if that ultimately means no user gets satisfied. Try splitting an apple into 20 pieces — everyone will still stay hungry. One solution would be to grow more apples but in the case of WiFi that’s getting increasingly challenging because the technology is nearing its limits. That’s why some researchers are exploring new technologies, among them a form of wireless local area networking based on light waves aptly called Li-Fi.

To get an idea of Li-Fi’s potential, it’s enough to learn about the performance recently demonstrated by researchers at the Eindhoven University of Technology. Their device has an incredible capacity of 40Gbit/s per ray over a distance of 2.5 meters. That’s roughly 100 times faster than the best WiFi routers which can clock in 300 Mbps.  

The operating principle is rather simple which is good news because it means it can be easily and cheaply scaled by the industry. The wireless data itself is beamed from a few central antennas that very precisely direct rays of light supplied by an optical fiber. Typically, these antennas, which have no moving parts, and require no maintenance or power, can be fitted on the ceiling. Inside each antenna is a pair of gratings that radiate light at different wavelengths and at different angles, a technique called ‘passive diffraction gratings.’

Typical Li-Fi setup. Credit: Bloomberg.

Typical Li-Fi setup. Credit: Bloomberg.

The first Li-Fis designed at the beginning of this decade beamed light waves from LED lamps and overheads at breakneck speed. Immediately, these devices blew everyone away with their high data transfer rate, up to 10 times faster than the WiFi state of the art but the limitations made these early Li-Fis rather impractical. For one, just like WiFi, these systems used the same single ‘light bulb’ to connect to multiple devices which means that the same connection sharing problems arise. Secondly, optical light waves can’t penetrate walls, unlike WiFi’s radio waves. This is a good thing if you want an extremely secure network but for the average consumer, it’s a drag.

Wi-Fi signal can pass through walls but Li-Fi just bounces off. This is Li-Fi's main limitation unless you care a lot about privacy. Credit: Bloomberg

Wi-Fi signal can pass through walls but Li-Fi just bounces off. This is Li-Fi’s main limitation unless you care a lot about privacy. Credit: Bloomberg

The Dutch researchers’ Li-Fi does away with the first limitation. Data is transferred using infrared light with wavelengths of 1500 nanometers and higher which is invisible and harmless, though infrared still can’t penetrate walls because the energy is too low and gets absorbed by the concrete. This doesn’t necessarily have to be an issue because as a user leaves a room and out of the range of a light antenna, then another antenna strapped on the ceiling of the next room can take over.

The main innovation lies in the fact that every connected device gets its own ray of light which solves all those congestion issues with Wi-Fi.

By now you must be excited. Unfortunately, professor of broadband communication technology Ton Koonen says the technology is still five years away until it can reach homes so don’t throw away that annoying WiFi router just yet.

'Shush, honey! The router is watching.' Credit: psfk.com

WiFi can be used to distinguish between household members with up to 95% accuracy

'Shush, honey! The router is watching.' Credit: psfk.com

‘Shush, honey! The router is watching.’ Credit: psfk.com

WiFi routers have become as ubiquitous today as toasters, but the former can be far more versatile. Besides feeding your computers and handheld devices with the elixir called internet, WiFi radiowave interferences can be used to discern between family members, as Chinese researchers recently demonstrated. By exploiting this phenomenon, the researchers say the smart homes of the future could create custom environments which are to the liking of each family member. For instance, when mom’s in the living room the lighting can be automatically tuned to a lower contrast and the display mounted on the wall can be turned on to her favorite program. When dad’s in the same room, it will look and feel different, per his specifications.

“It is based on the observation that each person has specific influence patterns to the surrounding WIFI signal while moving indoors, regarding their body shape characteristics and motion patterns. The influence can be captured by the Channel State Information (CSI) time series of WIFI. Specifically, a combination of Principal Component Analysis (PCA), Discrete Wavelet Transform (DWT) and Dynamic Time Warping (DTW) techniques is used for CSI waveform-based human identification. We implemented the system in a 6m*5m smart home environment and recruited 9 users for data collection and evaluation,” the researchers from the  Northwestern Polytechnical University in Xi’an, China, wrote in their study. 

Because human bodies block radio waves, and because each person’s shape, size, and even gait leaves a characteristic mark on the wave that’s picked up by the WiFi receiver, it’s possible to distinguish mom from dad. When the researchers tested their algorithm on two people walking in a room between a router and a computer, they could discern between the two persons with a 95 percent accuracy. For six people, that accuracy dropped to 89 percent. Though the experiments were made with adult men and women, the Chinese researchers say their algorithm should pick up children as well.

If you found this creepy, though, wait until learn about all the other crazy things you can do with with a router. Things like read lips, see through walls, identify people from a group or sniff keys. 

 

This is the first CMOS full duplex receiver IC with integrated magnetic-free circulator. Credit: Negar Reiskarimian, Columbia Engineering

Researchers double WiFi broadband while halving chip size

A new circuit was demonstrated at the 2016 IEEE International Solid- State Circuits Conference this past February that can, among other things, double Wi-Fi speed, while halving the size of the chip. The researchers at Columbia Engineering invented a new technology they call “full-duplex radio integrated circuits” which uses only one antenna to simultaneously transmit and receive at the same wireless radio frequency.

This is the first CMOS full duplex receiver IC with integrated magnetic-free circulator. Credit: Negar Reiskarimian, Columbia Engineering

This is the first CMOS full duplex receiver IC with integrated magnetic-free circulator. Credit: Negar Reiskarimian, Columbia Engineering

“This technology could revolutionize the field of telecommunications,” says Krishnaswamy, director of the Columbia High-Speed and Mm-wave IC (CoSMIC) Lab. “Our circulator is the first to be put on a silicon chip, and we get literally orders of magnitude better performance than prior work. Full-duplex communications, where the transmitter and the receiver operate at the same time and at the same frequency, has become a critical research area and now we’ve shown that WiFi capacity can be doubled on a nanoscale silicon chip with a single antenna. This has enormous implications for devices like smartphones and tablets.”

Key to full-duplex communications which virtually double the useful bandwidth in wireless communications is the circulator. This device transmits the signal entering a port to the next port in rotation. For instance, a three-port circulator where the three ports are “transmit” (1), “receive” (2) and “antenna” (3) works by routing (1) to (3), and (3) to (2). This way, you don’t get (1) to (2) which would’ve meant hearing yourself in a closed loop.

For more than 60 years, these sort of circulators have been used by the industry to provide two-way communications on the same frequency channel, but they are not widely adopted because of the large size, weight and cost associated with using magnets and magnetic materials. These magnets are essential to a working circulator because they “break” Lorentz Reciprocity — a physical constraint of most electronic structures that forces electromagnetic waves to travel in the same manner in forward and reverse directions.

(a) A simplified circuit diagram of the circulator is shown. Electronic commutation across a bank of N=8 capacitors is performed using reciprocal, passive transistor-based switches without direct-current bias. The staggered commutated network enables miniaturization of the unmodulated 3λ/4 ring using three C-L-C sections. (b) The microphotograph of the fabricated IC is shown along with a close-up photograph of the fabricated printed circuit board with the IC housed in a quad-flat no-leads (QFN) package and interfaced with the off-chip inductors. The largest dimension of the prototype is 5 mm or λ/80 at the operating frequency of 750 MHz. Credit: Nature Communications

(a) A simplified circuit diagram of the circulator is shown. Electronic commutation across a bank of N=8 capacitors is performed using reciprocal, passive transistor-based switches without direct-current bias. The staggered commutated network enables miniaturization of the unmodulated 3λ/4 ring using three C-L-C sections. (b) The microphotograph of the fabricated IC is shown along with a close-up photograph of the fabricated printed circuit board with the IC housed in a quad-flat no-leads (QFN) package and interfaced with the off-chip inductors. The largest dimension of the prototype is 5 mm or λ/80 at the operating frequency of 750 MHz. Credit: Nature Communications

Electrical Engineering Associate Professor Harish Krishnaswam and colleagues made a breakthrough by scrapping the magnets and using a mini-circulator that rotates the signal across a set of capacitors. They then devised a working prototype of a full-duplex system on a nanoscale silicon chip.

“Being able to put the circulator on the same chip as the rest of the radio has the potential to significantly reduce the size of the system, enhance its performance, and introduce new functionalities critical to full duplex,” says PhD student Jin Zhou, who integrated the circulator with the full-duplex receiver that featured additional echo cancellation.

There’s a myriad of potential applications, from better radar, to faster WiFi, to isolator that prevent high-power transmitters from being damaged by back-reflections from the antenna. Anything that uses half-duplex functions, or virtually all cell phones and WiFi routers, could double performance.

“What really excites me about this research is that we were able to make a contribution at a theoretically fundamental level, which led to the publication in Nature Communications, and also able to demonstrate a practical RF circulator integrated with a full-duplex receiver that exhibited a factor of nearly a billion in echo cancellation, making it the first practical full-duplex receiver chip and which led to the publication in the 2016 IEEE ISSCC,” Krishnaswamy adds. “It is rare for a single piece of research, or even a research group, to bridge fundamental theoretical contributions with implementations of practical relevance. It is extremely rewarding to supervise graduate students who were able to do that!”

Findings appeared in Nature Communications.

The microchip for wearable devices developed by researchers at JPL and UCLA reflects wireless signals instead of using regular transmitters and receivers. Credit: JPL-Caltech/UCLA

New WiFi chip uses 100 times less power with minimal loss of quality

Nearly all communication devices today, whether we’re speaking of smartphones, tablets or notebooks, rely on WiFi signal to connect to the internet and transmit data. With the rise of the Internet of Things, WiFi will become even more ubiquitous. However, enabling an active WiFi connection also eats up a lot of power. When I have WiFi on, my smartphone goes dead in under 24 hours, compared to 48 or more otherwise. In fact, according to a report, the routers that keep us constantly connected to the Internet – now in nearly 90 million American homes – uses about $1 billion worth of electricity annually. But in a bid to cut WiFi power waste in space, NASA might inadvertently change this situation forever.

The microchip for wearable devices developed by researchers at JPL and UCLA reflects wireless signals instead of using regular transmitters and receivers. Credit: JPL-Caltech/UCLA

The microchip for wearable devices developed by researchers at JPL and UCLA reflects wireless signals instead of using regular transmitters and receivers. Credit: JPL-Caltech/UCLA

A NASA engineer,  Adrian Tang, closely working with UCLA professor M.C. Frank Chang, developed a new WiFi chip that allegedly uses 100 times less energy. The point was to develop a new technology that might save energy on the International Space Station, but in doing so the chip could also save power in mobile devices across the world.

To communicate over WiFi, your mobile device sends a signal to the router, which the router decodes and sends a new signal back to be read by the smartphone. This back and forth dance costs a lot of power. The chip developed by Tang reflects a constant signal sent by a specialized router, instead of generating a new signal. All the data is embedded in the reflected signal, so essentially all the heavy lifting is done by the router – not the receiving device.

Despite saving a lot of power, the data transmission isn’t that much affected. In test runs, the researchers managed to transfer data at speeds of 330 megabits per second which is actually a lot more than most consumer routers. My own home router only works at 100 Mbs/second, for instance.

“You can send a video in a couple of seconds, but you don’t consume the energy of the wearable device. The transmitter externally is expending energy – not the watch or other wearable,” Chang said.

The biggest challenge was to isolate the reflected signal, given WiFi bounces off all the surfaces in a room.

“When you send a signal to the room, the whole room reflects back to you,” Tang said. “So you need to figure out what’s coming from the wearable and what’s coming from the background and get rid of the background.”

The challenge was handled by the specialized router that is able to discern what new data is being sent via the reflected signals. Both NASA and UCLA are now closely working together to find a partner that could turn the new technology into a commercial system.

story via JPL

Man sues neighbor for irritating his ‘electromagnetic allergies’

There are weird lawsuits you can understand, and then there are just weird lawsuits. If you find this sort of things interesting, you gotta listen to this: a man from Santa Fe filed a half a million dollars trial against his neighbor for using and iPhone and other wireless devices that trigger his ‘electrocmegnetic allergies’.

Wi Fi - the new yin and yang

Wi Fi - the new yin and yang

Yahoo News reports that Arthur F., the plaintiff has been sleeping at his friends or in his car in order to avoid the electromagnetic waves created by the Wi-Fi devices from the nearby house. He allegedly suffers Electromagnetic Sensitivity, with symptoms that include “nausea, vertigo, diarrhea, ringing in the ears, severe headaches and body aches, crippling joint pains, insomnia, impaired vision, impaired muscular control”, as well as others, even worse.

Even more, he’s not alone in his battle. Apparently there’s a whole group in Santa Fe that intends to remove all Wi-Fi hot spots because people are suffering from this sort of allergy. But wait, it’s not even an allergy; they want to classify it as a disability and are claiming Americans with Disabilities Act. What’s your take on this? If you ask me, it’s just a bunch of people trying to make some fuss and money where they shouldn’t but… I may be wrong.