[opendtv] Re: Spectrum is too valuable

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Fri, 13 Nov 2015 02:46:28 +0000

Craig Birkmaier wrote:

http://www.lighterra.com/papers/videoencodingh264/

720p 1280x720 4.0 2.56 2496 64
720p HQ 1280x720 5.0 3.20 3072 128

As I pointed out, these numbers are on the low side,

No, Craig. You posted that link and those numbers to support your view, but
unfortunately you had not read the numbers you posted. That's why I said, focus
on the numbers that matter. In any of these lossy compression algorithms, you
can use more bit rate and get even better quality. But what I stated is what
your "proof" also states.

The infrastructure IS handling OTT TV delivery, even real HD, at the
level of demand needed today. You cannot have it both ways.

That's why you have to repurpose the cable broadcast spectrum. Then you can
have it both ways. That's what I've been trying to get across. Did you miss
that point all along? Look at the subject line: "Spectrum is too valuable."
That's the whole point.

And this is also important. If you read the DOCSIS 3.1 standard, you
will note that the **only** way DOCSIS 3.1 can manage ~10 Gb/s per PON
is by doing assuming these two points:

1. That there are no MPEG-2 TS broadcast streams on that PON. All
dedicated to broadband service, like I said.

That is clearly not true.

Did you read it, Craig? Ron posted some viewgraphs. Look toward the end. If you
do not repurpose the cable broadcast spectrum, then you will not achieve that
10 Gb/s capacity. You'll get something less.

Here is the quote from the standard, Section 5.1:

"DOCSIS 3.1 ultimate service goal of multi-gigabit per second in the downstream
direction and gigabit per second in the upstream direction resulted in
significant changes in the PHY layer approach compared to earlier DOCSIS
versions in addition to changes on the cable network assumptions. DOCSIS 3.1
focuses on the eventual use of the entire spectrum resources available in cable
environment by the CMTS and CM and on scalable cost effective techniques to
achieve full spectrum use."

2. That the usable spectrum is just about doubled, from ~900 MHz
to ~1800 MHz.

Can you point me to a 1.8 GHz HFC system Bert?

Read the standard. Why do you think you can wing it and get away with it,
Craig? You never have in the past.

So, Craig, how many households, at 5 Mb/s, could be fed from a single
PON? Or even at 15 Mb/s? How does that compare with your average of
500 households per PON today?

I already gave you the numbers at least twice.

But you didn't consider DOCSIS 3.1, which doubles the spectrum. In case you
didn't get this earlier, the spectral efficiency of DCOSIS 3.1 is NOT
significantly greater than that of DOCSIS 3.0. It is marginally greater, mostly
by saving on the 6 MHz channel guardbands. The real difference comes from the
fact that DOCSIS 3.1 can use a whole lot more spectrum.

So the answer is, with DOCSIS 3.1, if all the broadcast spectrum goes to
DOCSIS, a single PON can support 2000 homes with 5 Mb/s service, or 667 homes
with 15 Mb/s service (enough for three simultaneous HD streams).

How does that compare with your figures of between 25 and 2000 homes per PON
today, with an average of 500? Sounds to me like you can have it both ways. But
only if you repurpose that "too valuable" spectrum.

Bert



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