Re:'Li-fi 100 times faster than wi-fi'
by hamiltonkibbe on Saturday November 28, 2015 @02:59AM
(#10640422)
IR comma doesn't the frequwncy of the light as a carrier, it uses pulsed IR (on=1 off=0 usually in the KHz range) the limitation is usually the rise time of the LEDs
Re:'Li-fi 100 times faster than wi-fi'
by analognoise on Saturday November 28, 2015 @10:22AM
(#10641262)
Yeah, but I wondered what the absolute upper limit would be. Good point about the rise time of the LEDs though.
Re:'Li-fi 100 times faster than wi-fi'
by Someone on Saturday November 28, 2015 @03:56AM
(#10640537)
Symbols/second = baud (https://en.m.wikipedia.org/wiki/Baud)
And, ignoring other physical or 'current technology' limits, you can put as many bits in each symbol as you like.
Re:'Li-fi 100 times faster than wi-fi'
by analognoise on Saturday November 28, 2015 @10:26AM
(#10641271)
Thank you! Can't believe I couldn't remember that word, although I never really understood why you can put as many bits in each symbol as you like - it seems like that would just mean stuff an infinite number of bits into each one? (Obviously silly, but then why is it defined that way?) - Great, now I have to read about that this morning. :)
Re:'Li-fi 100 times faster than wi-fi'
by Sanddancer on Saturday November 28, 2015 @02:02AM
(#10640311)
Yeah, there is the Shannon Limit which gives the theoretical max, I was more trying to get at there not being a reason why we'd be stuck at remote control/irda speeds.
https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampli...
IR has a frequency of between 430THz and 300GHz, so Max bandwidth would be between 215Tsymbols and 150Gsymbols (I used symbols instead of bits because I forgot the right term...)
So there is an information-theory limit, as I understand it. If I was ever wrong, this is the right crowd to find the person who will correct me!