[opendtv] Re: Spectrum is too valuable

  • From: Craig Birkmaier <brewmastercraig@xxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Thu, 05 Nov 2015 10:42:01 -0500

On Nov 5, 2015, at 7:35 AM, Ron Economos <w6rz@xxxxxxxxxxx> wrote:


It's the other way around. All DOCSIS 2.0 and 3.0 downstream data is
encapsulated in 188-byte MPEG-2 TS packets. It has to be, because the ITU-T
J.83B 256QAM format requires 188-byte TS packets.

Fair enough. This makes sense given the fact that through DOCSIS 3.0 all
traffic was using the standard channel bandwidths in each region (e.g. U.S. = 6
MHz, Europe = 8 MHz).

What is going to happen with DOCSIS 3.1, which uses 4096 QAM and eliminates the
6 and 8 MHz channels? This seems a bit confusing, as what I see in the
description on Wiki is that much smaller channels using OFDM subcarriers will
be combined into channels as large as 200 MHz:

DOCSIS 3.1
First released October 2013, and updated several times since. The DOCSIS 3.1
suite of specifications supports capacities of at least 10 Gbit/s downstream
and 1 Gbit/s upstream using 4096 QAM. The new specs do away with 6 MHz and 8
MHz wide channel spacing and instead use smaller (20 kHz to 50 kHz wide)
orthogonal frequency-division multiplexing (OFDM) subcarriers; these can be
bonded inside a block spectrum that could end up being about 200 MHz wide.

So will MPEG-2 TS still be used to encapsulate IP packets, or will another
transport protocol be used?

Regards
Craig

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