|reply to telcodad |
Re: Dream Modem - 24x8
This item »www.lightreading.com/blog.asp?bl···d=227176
on the Light Reading Cable site concisely lists the main areas in which DOCSIS 3.1 signaling will be significantly different from earlier versions:
Using a higher order of modulation, for greater spectral efficiency, could conceivably add at least 25 percent more capacity and up to 50 percent more over the same HFC network. Note that the proposed DVB-C2 specification in Europe has been tested to support 4096 QAM downstream within existing cable networks.
A new modulation format, Orthogonal Frequency-Division Multiplexing (OFDM), that takes efficiency and robustness to new levels. OFDM enables sub-carriers to be squeezed directly against one another, eliminating the need to use valuable RF spectrum as guard bands. At the same time, the longer symbol durations of the sub-carriers make OFDM more capable of dealing with impulse and burst noise than are SC-QAM guard bands.
The use of Low Density [Parity] Check (LDPC) coding to improve noise immunity by several dB over current Reed-Solomon encoding at similar channel efficiency, or to provide greater channel efficiency at the same MER (modulation error ratio).
An article about technology developed by Javelin (f/k/a Vyyo), that can help cable companies extend their operations above the current 1GHz limit, and enable new DOCSIS 3.1 features:Ex-Moto Execs Hope to Revive Javelin
By Jeff Baumgartner, Light Reading Cable - December 3, 2012