Posted on 02/14/2011 1:00:58 PM PST by decimon
A new technology that allows wireless signals to be sent and received simultaneously on a single channel has been developed by Stanford researchers. Their research could help build faster, more efficient communication networks, at least doubling the speed of existing networks.
"Wireless communication is a one-way street. Over."
Radio traffic can flow in only one direction at a time on a specific frequency, hence the frequent use of "over" by pilots and air traffic controllers, walkie-talkie users and emergency personnel as they take turns speaking.
But now, Stanford researchers have developed the first wireless radios that can send and receive signals at the same time.
This immediately makes them twice as fast as existing technology, and with further tweaking will likely lead to even faster and more efficient networks in the future.
"Textbooks say you can't do it," said Philip Levis, assistant professor of computer science and of electrical engineering. "The new system completely reworks our assumptions about how wireless networks can be designed," he said.
Cell phone networks allow users to talk and listen simultaneously, but they use a work-around that is expensive and requires careful planning, making the technique less feasible for other wireless networks, including Wi-Fi.
(Excerpt) Read more at news.stanford.edu ...
cool
but, what happens when something is broadcast continuously?
I don't know how this works. But if it does work then it looks like a real good thing.
Oh great, twice as much information flow! I can’t keep up with it now. ;>) Read their paper here:
http://sing.stanford.edu/pubs/sing-10-00.pdf
Not true, it's merely a matter of separating signal and noise. It should be possible for a sender/receiver to use "noise cancelling" logic to cancel what it is sending from what it is receiving at the same time. I didn't read the rest of the article. Is this what they did?
Absolute and utter bullcrap.
As an RF engineer and amateur radio operator, I can tell you that this has been done for DECADES. Just one example: the 10 GHz repeater built by the San Bernadino Microwave Society. They used spatial diversity to transmit and receive on the same frequency at the same time.
Dang, I hate how journalists (and idiot professors) explain things like this.
I recall reading claims like this back in the 1970s from a British firm doing defense work. I think it was Plessy.
The problem is, of course, to try to null out the transmitted signal to get at the received signal coming back to you on the same transmission line. This would mean a null of at least 130 decibels on the transmitted signal.
You'd have to start with the mother-of-all directional couplers and then back that up with some black magic DSP on the front end of the receiver.
Even changing reflections of the transmitted signal off nearby objects would bollix the null, requiring some extraordinary technology to maintain it.
But therein may lie an interesting application for 'continuous-wave' radar.
I'm still using two tin cans and a piece of waxed string to communicate!
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