On 29/02/2016 11:13 PM, Bernard Robertson-Dunn wrote: > On 29/02/2016 5:55 PM, David Lochrin wrote: > >> Just for the record... Analogue or digital, 1980's synchronous modem or >> 2020 fibre, no matter what the technological cleverness any communication >> channel is subject to Shannon's Law. > True. >> This states that the maximum channel capacity is a function of transmitted >> power, bandwidth, and signal-to-noise ratio. > True, > > However, Shannon's law is silent on the number of channels that a medium > can carry. Fibre can carry many more channels than copper, coax or radio. > > Fibre modems, using Wavelength-division multiplexing can, currently, > handle up to 160 channels. This means that a basic 10 Gbit/s system over > a single fiber pair can be expanded to over 1.6 Tbit/s. [*] > > And just for the record, you don't have to change the fiber, just the > boxes at either end.
True. And just for the record, current WDM systems are 100Gbit/s and 200Gbit/s per channel, with 400Gbit/s and 1000Gbit/s coming from the labs. That means a single fibre pair can be expanded to over 10 - 20 Tbps total capacity, and growing. Just by changing the boxes on each end - and often not even having to change any amplifiers in the middle for long-haul runs. In the context of access networks to homes - WDM-PON, which provides for a dedicated optical wavelength channel per home, is commercially available already. Paul. _______________________________________________ Link mailing list [email protected] http://mailman.anu.edu.au/mailman/listinfo/link
