"Twisted" OAM Beams Carry 2.5 Terabits Per Second 142
MrSeb writes "American and Israeli researchers have used twisted, vortex beams to transmit data at 2.5 terabits per second. As far as I can discern, this is the fastest wireless network ever created — by some margin. These twisted signals use orbital angular momentum (OAM) to cram much more data into a single stream, without using more spectrum. In current state-of-the-art transmission protocols (WiFi, LTE, COFDM), we only modulate the spin angular momentum (SAM) of radio waves, not the OAM. If you picture the Earth, SAM is our planet spinning on its axis, while OAM is our movement around the Sun. Basically, the breakthrough here is that researchers have created a wireless network protocol that uses both OAM and SAM. In this case, Alan Willner and fellow researchers from the University of Southern California, NASA's Jet Propulsion Laboratory, and Tel Aviv University, twisted together eight ~300Gbps visible light data streams using OAM. For the networking nerds, Willner's OAM link has a spectral efficiency of 95.7 bits per hertz; LTE maxes out at 16.32 bits/Hz; 802.11n is 2.4 bits/Hz. Digital TV (DVB-T) is just 0.55 bits/Hz. In short, this might just be exactly what our congested wireless spectrum needs."
Visible light is != wireless (Score:0, Informative)
Just what the subject says...
Here is a paper on this (Score:4, Informative)
http://iopscience.iop.org/1367-2630/14/3/033001/pdf/1367-2630_14_3_033001.pdf [iop.org]
I am still not sure exactly what the physics is here.
Re:Visible light is != wireless (Score:3, Informative)
Congratulations on your attempt at being pedantic, but the fact of the matter is that the common usage of the term "wireless network" in this article refers the transmission of radio waves. The submitter uses that term three times, and only sneaks in the term "light" once, obviously because visible light "wireless" transmissions are far less exciting than radio wave transmissions.
What is the use case of a visible light "wireless" network? Maybe point-to-point networks between buildings? I can't think of much else.
I suppose we could measure the transmission rate of future TV remotes in Libraries of Congress per second...
Re:Will it be practical? (Score:2, Informative)
Re:Holy Crap! (Score:5, Informative)
> crappy country
Someone woke up on the wrong side of bed this morning...
Finland is 338,424 km2. That makes it bigger than all but the four largest US states: Alaska, Texas, California and Montana. Providing great internet over an area that size is a decent accomplishment, one that the other 46 states apparently can't match despite being smaller than Finland.
Re:Lasers vs wireless (Score:2, Informative)
But laser (I'm assuming optical or IR) uses higher frequency carrier wave. That makes it easier to transmit more data per second. The real achievement here is not bits per second; it's bits per hertz. When OAM is applied to those frequencies, it'd be able even transmit even more.
Re:Will it be practical? (Score:3, Informative)
Re:Holy Crap! (Score:4, Informative)
I live 3 miles outside a city of 12,000, and 10 miles from Madison, WI. My choices are either, Satellite, local Wireless ISP (I currently pay $65/month for 1mb using 802.11b) or cellular (with 5GB data caps). There is no cable in my neighborhood of 100 homes (they say they will put it in if every single house signs a 2 year contract) and the phone company says we are somehow 40,000 feet from the central office, and won't even get us anyone to talk to about the fact that there are 8 fibers running a half mile down the road to connect areas..
Public service commission lists 20 communications providers for our zip code and says we are well covered. 17 of those are long distance phone/dialup providers. A regional telco (TDS) bought up all the rights to Wi-Max frequencies in the area, then decided after putting up 2 towers in the middle of madison, it was a pain, and seemingly abandoned all plans for it.. (and so far, still holds all the wi-max frequencies)