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AnonTechie writes:
According to an article from The Register, a team from Stanford University has patented technology that could halve the bandwidth that a mobile provider needs.
Operating under the name Kumu Networks, they are showcasing tech which they claim would exactly double throughput. Radio equipment (such as mobile phones) would be able to send and receive on the same frequency through a process similar to noise-cancelling headphones; by knowing what a base station is transmitting it can cancel out the information from the very faint signal it receives.
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Radio Tech Could Halve Bandwidth Needs
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(Score: 1) by EvilJim on Thursday February 27 2014, @06:07PM
What ever happened to single sideband? didn't that allow two transmissions on the same frequency simulataneously? with only an annoying amount of bleed over if I remember correctly.
(Score: 2, Informative) by sfm on Thursday February 27 2014, @06:21PM
Single Side Band (SSB) was intended to reduce bandwidth (or more importantly, increase power) of the desired signal by removing redundant and unneeded information. For AM transmission, the carrier and both sidebands are typically sent. The lower sideband is a mirror of the upper sideband and the carrier is is simply a placeholder. By removing one sideband and suppressing the carrier, more power could be applied to the remaining sideband. The system was perfected in the 40's and 50's and works well.
Cellphone communication is significantly different from this and cannot benefit from using it. (Unfortunately)
(Score: 1) by EvilJim on Thursday February 27 2014, @06:31PM
Thanks, if I had mod points this hour you'd get one. I've still got an Aussie 27mhz SSB cb sitting in a box at home, never did get around to converting it to NZ 26mhz
(Score: 1) by Snotnose on Thursday February 27 2014, @06:32PM
Cuz we all wanna sound like Donald Duck when talking to mom :)
(Score: 1) by goody on Thursday February 27 2014, @11:29PM
It may have given that impression on CB, but no, SSB does not allow two transmissions on the same frequency. With SSB the signal took half the bandwidth of the original CB AM signals. One sideband (lower) could occupy the lower half of the channel, and the other sideband (upper) could occupy the upper half of the channel. Neither sideband ever occupied the same frequency space simultaneously.
(Score: 1) by EvilJim on Friday February 28 2014, @12:26AM
really? I thought upper sideband was the upper half of the modulated carrier waveform and lower the lower half, the BFO control would provide the missing half of the carrier waveform, technically giving you two channels on the one carrier frequency? - too lazy to google.
(Score: 1) by EvilJim on Friday February 28 2014, @12:42AM
righto, had a wiki-peek and saw my understanding was slightly off, mind you I was about 11-12 years old when it was explained to me. http://en.wikipedia.org/wiki/Single-sideband_modul ation [wikipedia.org]
(Score: 1) by sfm on Friday February 28 2014, @01:53AM
Agreed, with SSB there cannot be 2 continuous signals sharing the same bandwidth. That stated, since a typical SSB signal takes ~half the bandwidth of an equivalent AM signal, it does allow for 2 different SSB channels in the space of one AM channel.
While the isolation is not always great, with SSB it is certainly possible to have two simultaneous conversations, one on the upper sideband and one on the lower.