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Posts Tagged ‘wireless’

Tesla’s experiment proved that the Earth itself could be used to conduct electricity, no wires necessary. He also experimented with electromagnetic induction, a phenomenon discovered 70 years before Tesla’s experiments by the English scientist Michael Faraday. In electromagnetic induction, an oscillating magnetic field around an electromagnet produces a current in a nearby conductor—in effect, the current jumps the gap. While it is airborne, electric energy exists as a magnetic field. Magnetic induction is used today in the contact plates on electric toothbrushes, transmitting a charge from the plastic-wrapped charging station to the battery inside the brush.

In 2006, Marin Soljacic, a physics professor at the Massachusetts Institute of Technology, sent wireless electricity across a room to light a 60-watt bulb. Soljacic used electromagnetic induction, but with a twist. By tuning the sending and receiving coils in his electromagnetic field to resonate at the same frequency and engage only at that frequency (the way glass will shatter when struck by sound waves of just the right pitch), the current is focused and bypasses everything else, humans included. Resonant coupling, as Soljacic’s process is known, is far more efficient than Tesla’s attempts, and safer too.

Soljacic has a company called WiTricity, and he can now send 3,000 watts across a room—or a garage, since 3,000 watts can charge an electric car.

Have a science question you've always wondered about? Send an email to fyi@popsci.com

Team leader Neal Patwari demonstrated the system by lying in a hospital bed surrounded by 20 wireless transceivers operating at a frequency of 2.4 gigahertz. He timed his breathing to be about 15 breaths per minute, confirming this measurement with a carbon dioxide detector. The algorithm accurately measures respiration within 0.4 to 0.2 breaths per minute based on only 30 seconds of data, much better than most monitors, which round off to the nearest full breath.

The system will also be cheaper than existing breath monitors, as it uses off-the-shelf wireless transceivers similar to the ones used for home computer networks. The next step for its development is for the team to determine if a different radio frequency could detect breathing better than 2.4 gigahertz and if the system could detect two people breathing at the same time, but not in unison. In addition to providing technology for use in hospitals, Patwari hopes to integrate the system into at-home baby monitors in five years or so.

[University of Utah via Engadget]

First things first: This theory popped up in a presentation Perlman gave at the NExTWORK conference, and only received a small mention. There was no demonstration, no real proof given, and since his proposal flies directly in the face of the Shannon-Hartley Theorem, a guideline for wireless technologies, we're not inclined to really believe his claims. But! Sometimes somebody says something so crazy with such confidence that you have to sit up and take notice, and this particular idea would have such massive effects on communications technology that we're bound to at least encourage discussion about it. That's not to be taken as an endorsement, though.

Now that the disclaimer is out of the way, here's what Perlman (all to briefly) proposed. DIDO is an entirely new radio system, with different towers and different chips that work in an (as yet undisclosed) entirely different way. He claims that DIDO would also be able to broadcast through solid objects that usually block cell signals, that it needs no bigger tower than a small base station "the size of a router," and that the base stations can broadcast a signal much farther than usual towers--up to 30 miles, at which point they'd be dealing with the curvature of the Earth, which Perlman says does not deter them.

Perlman said that his DIDO (distributed-input-distributed-output) system overcomes the traditional broadband system in which each user gets a small piece of the overall bandwidth of the tower to which they're connected. Instead, with DIDO, each user would be able to access the full speed of the tower.

Wired interviewed an electrical engineering professor who noted that elements of the Shannon-Hartley Theorem have in fact been disproved, or at least altered, with multiple-input-multiple-output systems, currently being used in the latest 4G tech. But nobody has yet seen Perlman's DIDO system in action, though he has patented it and insists he is "as confident" about DIDO as anything else he's ever designed. Us? We're skeptical--but that doesn't mean we wouldn't welcome a revolutionary wireless system.

[Wired

Zoosh me a $20?

You can read our full primer on NFC here, but as a basic summary, NFC is a short-range wireless tech similar to RFID, in which small chunks of information can be passed among devices like smartphones and all sorts of other appliances like point-of-sale units, subway entry points, and even less mechanical items like movie posters. There's only one major NFC-enabled smartphone--the Samsung Nexus S--in the U.S. at the moment, and the infrastructure is in its infancy, but other countries have robust NFC or NFC-type setups and all signs point to a North American embrace as well.

But NFC is a few years off, and Zoosh is here right now. Zoosh, coming from a small Silicon Valley startup, is a software solution that uses the audio hardware found in phones to communicate. As every phone is necessarily equipped with a speaker and microphone, Zoosh saw an opening to use that hardware, rather than create something new. To send data (whether it's a URL, a phone number, or payment information), Zoosh broadcasts ultrasonic audio in a frequency not audible to human ears, around 20,000Hz. A speaker in another phone (or, later, a point-of-sale unit, which the startup claims can be upgraded for only $30) picks up that audio and translates it back into the intended data. You can see it in action in this wholly Silicon Valley video.

What's most intriguing about Zoosh is its ease of adoption. All a smartphone needs is a simple app that unlocks its ability to communicate in this way, and there's no need to worry about compatibility, as all phones have the required hardware. We don't know many specifics at the moment--the speed of transfer and amount of data that can be transferred is still unknown--but it's a surprising and seemingly very practical solution. At least, it's a practical stopgap until NFC gets here.

[ComputerWorld]

One of the most enduring problems of maintaining a wireless connection, whether it's 3G, 4G, or Wi-Fi, is what's called the "handoff." Individual wireless access points like a cell tower or Wi-Fi router have a limited radius within which a device can connect to them. In the case of 3G or 4G towers, the idea is to have those radii overlap, so you're never without service, but that means at some point you'll have to "hand off" from one tower as you move more fully into the radius of another.

The way that's done now is very simple: Your phone connects to the tower or access point with the strongest signal. But that simplicity can lead to some very sloppy handoffs, during which you might lose your service and drop a call. This is particularly problematic when using Wi-Fi, which has a comparatively small radius of signal. If you turn on your phone while walking, you'll connect to the strongest signal. But what if you're actually walking into the radius of another access point? You'd be better off connecting to that one first, even though it might not be the stronger of the two signals, because then you'd avoid having to disconnect from the first signal and reconnect to the second.

A group of MIT researchers have created a way to use the GPS, accelerometer, and gyroscope found in many, if not most, smartphones to make smarter connections. By sensing your movement and predicting where you're heading, it can connect to the access point that makes the most sense. In tests, a cellphone using this system switched connections about 40% less frequently than it ordinarily would, which is better for both signal and battery life.

A caveat: These tests were carried out using Wi-Fi networks, which have a very small radius and have a much more pronounced handoff than, say, a 3G network. It seems likely that a 3G version of this system would have a much smaller effect: It's much harder to predict movement across the huge radius of a 3G tower, and handoffs tend to be much smoother, anyway. But that's not to say the system wouldn't help at least a little, and it's very cool that the project uses hardware that's already found in the phones, rather than requiring some sort of hardware upgrade.

[MIT]

Researchers took brain scans of 47 participants to directly measure how cell phones’ electromagnetic radiation affected their brain activity. That’s a departure from other studies in the cell phone radiation literature, which have largely consisted of observational studies, and which have been somewhat inconclusive due to biases and errors.

Each participant had a cell phone strapped to both ears and then underwent two 50-minute PET (positron emission tomography) scans, which measure brain activity by monitoring metabolism. In one scan, both cell phones were turned off; in the second, the right cell phone was turned on and played a recorded message, but with the sound muted so there would be no auditory interference.

The PET scans showed a 7 percent increase in activity in the part of the brain closest to the antenna, according to the study, published Wednesday in the Journal of the American Medical Association.

Importantly, the researchers said the increased activity was unlikely to be associated with heat from the phone, because it happened near the antenna instead of where the phone touched the head.

The new study is mum on the meaning of these findings, however — it could be good or bad, as lead author Nora D. Volkow, director of the National Institute on Drug Abuse, told the New York Times.

Previous studies have largely dismissed any ill effects from cell phone radiation, partly because the type of radiation emitted is pretty weak. Cell phones emit non-ionizing radiation, which is weaker than the type of radiation you’re exposed to while walking through an airport security scanner, for instance. Non-ionizing radiation does not break chemical bonds or interfere with DNA in the way that ionizing radiation does. As PopSci reported last year, the only universally recognized effect of non-ionizing radiation is minor heating of nearby tissue. The Federal Communications Commission sets limits for cell phone radiation below which that heating does not occur.

This study shows that there are other physiological effects beyond tissue warming, however. Researchers not involved in the work told the Times that the study even suggests different pathways for cancer and other health problems to develop, including the formation of free radicals and tissue swelling.

On the other hand, some studies suggest electromagnetic radiation could be good for you. In one study from 2010, University of South Florida researchers were surprised to find electromagnetic radiation from cell phones actually boosted the memories of young mice, and even reversed Alzheimer's symptoms in old mice. And Volkow said future research may show electromagnetic waves could be used for other therapeutic purposes.

The bottom line is that this study shows non-ionizing radiation from cell phones indeed has an effect on human brain function. Further studies will help explain just what effects mean for our health.

[via New York Times]

After shutting down its ailing FLO TV wireless video service in October, Qualcomm announced today that it will be selling the service’s precious 700 megahertz wireless spectrum to AT&T for around $1.9 billion to bolster its 4G network.

The deal, which is still pending regulatory approval, is perhaps the best possible outcome for Qualcomm, which never managed to find success with FLO TV. The company learned the hard way that consumers would rather watch video on their phones rather than buy a new device that requires a monthly fee. It’s also a coup for AT&T, which needs to scrape up as much wireless spectrum as possible to strengthen its upcoming LTE 4G network.

Qualcomm’s block of spectrum covers more than 300 million people across the country, including major cities like New York, Boston, Los Angeles and San Francisco. AT&T says that it intends to use the spectrum to increase the downstream speed and total capacity of its 4G network. The company will utilize carrier aggregation with the spectrum, a technology for LTE 4G networks that allows networks to use multiple frequencies to achieve high speeds, to combine its existing spectrum with Qualcomm’s.

Verizon recently launched its 4G LTE network, which serves around 110 million users. There aren’t any LTE phones available yet, but the company has a few 4G USB modems available. Verizon boasts that it has the largest contiguous swath of 700 MHz wireless spectrum in the continental US, meaning its network is already expansive without patching in multiple spectrum blocks. It’s not yet clear how AT&T’s LTE network will compete. AT&T is expected to launch its 4G LTE network some time in 2011.

AT&T says it will begin deploying the new spectrum once its handsets and networking equipment are ready. Both Qualcomm and AT&T expect the sale to close in the second half of 2011.

Tags: 4G, LTE, spectrum, wireless

Companies: AT&T, Qualcomm