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A team of Columbia Engineering researchers has invented a technology—full-duplex radio integrated circuits (ICs)—that can be implemented in nanoscale CMOS to enable simultaneous transmission and reception at the same frequency in a wireless radio. Up to now, this has been thought to be impossible: transmitters and receivers either work at different times or at the same time but at different frequencies. The Columbia team, led by Electrical Engineering Associate Professor Harish Krishnaswamy, is the first to demonstrate an IC that can accomplish this. The researchers presented their work at the International Solid-State Circuits Conference (ISSCC) in San Francisco on February 25.
“This is a game-changer,” says Krishnaswamy, director of the Columbia high-Speed and Mm-wave IC (CoSMIC) Lab. “By leveraging our new technology, networks can effectively double the frequency spectrum resources available for devices like smartphones and tablets.”
http://engineering.columbia.edu/new-technology-may-double-radio-frequency-data-capacity-0
(Score: 3, Informative) by VLM on Thursday March 19 2015, @12:58PM
Basically, yeah. If you wanna see something with the same goals as the article look at a microwave gunplexor
Good luck googling because it uses a Gunn diode (named after the inventor Dr Gunn more than half a century ago) and the usual USA vs UK "we'll just randomly swap -or and -er word endings"
So a Gunn diode is simplistically a LED that emits microwaves instead of light. Or more accurately its like a N-type FET with onboard feedback that when placed in a waveguide and energized turns about 1% of input power into RF oscillation.
A gunnplexor is one of them diodes with a -10dB or so coupler into a detection diode and usually a varactor (electrically variable capacitor) to tune the thing.
The main problem they have is range. So every nanovolt of noise on the tuning diode magically becomes a white noise signal on the RX input eventually stronger than the incoming signal. Not to mention swamping the hell out of the RX if you manage to generate some power. If you had an infinitely noise free power and tune source, and an infinitely high IP3 and IMD rx it would work, but usually they pretty much suck.
In an actual system your multipath mitigation technique will get a real workout. If you have one. It can end up with better goodput / average bandwidth to do half duplex even if theoretically full duplex is possible. Or in summary, the idea pretty much sucks other than short range low efficiency stuff.
Aside from the theoretical limits, the sub 1% transmit efficiency and thermal drift and freq instability are gunplexor specific issues that probably don't apply to the article device.
You can make a doppler radar gun with little more than a Ku band gunplexor unit and some kind of audio-ish frequency display. Ham radio guys play with them. I have some Ku band ones in the basement. Good for little other than fooling around.
I guess you could stretch the definition and claim an ancient telegraph line or an obsolescent one-wire microcontroller interface also uses the same thing to TX or RX..
(Score: 2) by Geezer on Thursday March 19 2015, @01:55PM
Excellent reply. Thank you.
In trying to imagine practical applications given the limitations, maybe it might make a fancy replacement for internal bus cables, as long as the fan noise doesn't cancel everything.