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New WiFi Standards, Double the Data?
morkeleb writes "According to the New York Times (free reg. req.), just when you thought it was safe to stock your home or office the 802.11x way, another possibility springs up. From Stanford and Bell Labs comes an approach using MIMO, which 'relies on taking advantage of huge amounts of computing power to send numbers of signals from closely spaced antennas', thereby enhancing range and throughput. Looks like Intel and Nokia are interested in the technology, as well as a number of highroller venture capitalist groups."
Google has this article, too. No reg required.
PALO ALTO, Calif., Aug. 17 -- Airgo Networks, a heavily financed Silicon Valley start-up, plans on Monday to introduce an alternative to the popular Wi-Fi wireless data standard for connecting to the Internet, capable of doubling Wi-Fi's already high speed and extending its range. Airgo's technology is just one example, industry executives said, of the continued emergence of new companies, undercutting recent fears that wireless technology innovation is slowing and is in danger of being dominated by a few large established concerns. "Just as the revolution starts to happen, some people are saying that it's over," said Craig Mathias, president of the Farpoint Group, a industry consulting firm in Ashland, Mass. "Clearly, we are in the early days of wireless data." Airgo's technology, known as multiple-in, multiple-out, or MIMO, relies on taking advantage of huge amounts of computing power to send numbers of signals from closely spaced antennas. By doing so, Airgo is able to squeeze in and out more data than conventional wireless data arrangements. But Airgo faces a big challenge in winning broad support for an approach that is not compatible with the existing Wi-Fi standards. The company said it hopes to create markets by seeking out consumer wireless equipment companies serving local area networks, hoping that in a hotly contested marketplace, a higher-speed, greater-range option will soon prove advantageous, even if it is not compatible with existing software. On Monday, Airgo will announce a chip set that extends the speed at which data can be delivered to a computer by wireless radio signal, to as much as 108 megabits a second. Current Wi-Fi standards are capable of data speeds ranging from 11 to 54 megabits a second. The company says the signal can be sent farther as well -- from two to six times as far as current Wi-Fi technology, which typically reaches only about 100 to 150 feet from a transmitter connected to the Internet. "We've created a new currency that is better range and better performance," Airgo's chief executive, Greg Raleigh, said. The industry is working to define a new generation of Wi-Fi that could take data rates to 200 megabits or even higher, and Mr. Raleigh said Airgo would propose its technology for the standard. In addition to computer communications applications, Mr. Raleigh said he expects new consumer uses for very high speed wireless, like data connections for HDTV television sets and other home appliances. Michael Kleeman, chief technology officer of Cometa Networks of San Francisco, which is installing Wi-Fi access points nationally, said: "People are beginning to realize that it is important to focus on the radio frequency side of the equation. Now, people are paying attention to antennas." Airgo's MIMO technology was pioneered at Stanford University, Bell Laboratories and other research centers. It is an example of the shift to what are known as smart antennas, an approach that is being widely adopted in the wireless networking world. Other companies are also striving to develop antenna technologies to improve wireless data service. These include Vivato, a wireless technology company that is using antennas to direct beams, and the leading chip maker Intel, which has acquired the intellectual property of another Silicon Valley MIMO company, IoSpan Wireless. Airgo, whose founders started and then sold Clarity Wireless to Cisco Systems in 1998, has so far raised a total of $52 million in venture capital from OVP Venture Partners, Sevin Rosen Funds, Nokia Venture Partners and Accel Partners.
This comment was randomly generated by a school of piranhas chewing on the PCB of a Microsoft Natural Keyboard.
And your point is ... ?
What you just said is "I live in SF where people don't encrypt their AP links and I have too much time on my hands". What's that got anything to do with the article?
-1: Offtopic
From the website... Full support for 802.11b/a/g standards and additional standards allows for an unprecedented level of backwards compatibility and performance at all data rates. Seems to me it is. Anyone know for sure?
The sending of this message pretty much inconveniences everyone involved.
According to this Infoworld article, Airgo Networks is working on enhancing 802.11a. This is not a new version of 802.11.
--- I'm Green Hornet's sidekick not Inspector Clouseau's!
It seems that the NYT article is in error. The press release from Airgo says that their solution is based on the 802.11 standard, and "supports all 802.11 a, b, and g modes and also extends rates to 108 Mbps" . The qoute is from their press release which is here.
http://www.airgonetworks.com/news.html
Enjoy.
Don't say 802.11x when you mean 802.11*. 802.11x is a wireless security standard. As far as I can tell, this article has nothing to do with 802.11x. I see this error a lot.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
MIMO uses multiple antennas spaced more than half a wavelength apart on both transmitter and receiver. By doing so the signal recevied at each antenna experiences independent multipath fading. By using this information it is possible to send an independent data stream to each antenna on the same channel, i.e N antennas = N-times the datarate.
This is all done by linear algebra and matrix inversions which is probably the origin of the "taking advantage of huge amounts of computing power" claims in the articel. For more info check out this paper
they're triangulating their target then sync'ing the antenna's to that. it's a dynamically retargetable directional. i'm sure they'll find a way to get it classified as directional, because, well, it is.
The idea behind MIMO is that wireless signal are orthgonal in space. Think about it this way:
Lets say I have three transmit antennas, sending three signals (x,y, and z). I also have three (or more) receive antennas (1, 2, and 3).
The first thing I do is train my receivers by having the transmitters transmit a known signal one at a time, such that when transmitter x is transmitting, at receiver 1 I receive a signal (a1*x), at receiver 2 I get (a2*x), and at receiver 3 I get (a3*x). When y transmits, I get (b[1,2,3]*y) and similarly for z (c[1,2,3]*z) at my receivers. Since I know what x,y, and z are supposed to be at this point, I can calculate values for a[1,2,3], b[1,2,3], and c[1,2,3].
After the training sequence is complete, I begin transmitting on all three at once and assume a,b, and c haven't changed that much (a reasonable assumption as long you're not moving much) leaving me with:
Rx1 = a1*x + b1*y + c1*z
Rx2 = a2*x + b2*y + c2*z
Rx3 = a3*x + b3*y + c3*z
Given that the only unknowns in this equation are x,y and z, its perfectly solvable.
Unfortunately, its not quite that simple. The signals will mutually interfere, so a long process begins where you estimate one signal and start subtracting it and then estimate and subtract the other signals based on your result and then keep repeating process until your estimation is satisfactory.
On the bright side, though, the rayleigh-fading nature of the channel (in a nutshell, the dynamics of reflected signals cause signal strength to vary wildy at the receiver depending on location) means that antennas one-half wavelength apart will maxmize the relative energy difference of the different signals at different antennas. Thus, you're hoping (usually correctly, unless the receiver is on a satellite or a large open area) that each signal will be most powerful at a different antenna making the signal-estimation phase much quicker (ie, if the received signal x is way more powerful than y or z on antenna 1, x is easy to estimate which in turn makes y and z easier to estimate).
Tim