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."
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