[opendtv] Re: Spectrum is too valuable

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Thu, 19 Nov 2015 01:00:42 +0000

Craig Birkmaier wrote:

Read this, from your own source:

------------------------
http://www.fiercetelecom.com/story/cox-accelerate-gigabit-broadband-plans-docsis-31-2017/2015-09-23

Ultimately, the DOCSIS 3.1 standard-based CPE will be able to deliver up to
10/1 Gbps. Early versions will be capable of supporting nearly 5/1 Gbps.

The move to leverage DOCSIS 3.1-based gear will enable Cox to achieve its
goal of delivering 1 Gbps services throughout its serving area. Ahead of
DOCSIS 3.1, the service provider has been rolling out 1 Gbps service in
select markets using FTTH technology, including Baton Rouge, Las Vegas, New
Orleans, Phoenix, San Diego, and across Virginia.

When it initially debuted its 1 Gbps service last year, the cable MSO said it
would leverage a mix of GPON-based FTTP technology and extend into the
remaining area of the market using DOCSIS 3.1-enabled equipment when it
becomes available.
------------------------

All they are deploying is **1 Gb/s broadband**, using DOCSIS 3.0 or
whatever GPON scheme they have now. Read the first sentence in that
quote again, to grasp the unspoken words. If you want to deploy 5 Mb/s
in 900 MHz ("early versions"), or 10 Mb/s in 1800 MHz (DOCSIS 3.1),
you have to eliminate the wasteful broadcast spectrum.

That is 1 Gbps to ONE home, not one PON divided by the number of
homes served by that PON.

Whoa, Craig, you're *so seriously* uninformed. You're talking nonsense. Why do
you think they are called passive optical networks, Craig? Answer: they are
passively split, shared among multiple households. Read up what a PON is:

------------------------------
http://electronicdesign.com/what-s-difference-between/what-s-difference-between-epon-and-gpon-optical-fiber-networks

A PON is a fiber network that only uses fiber and passive components like
splitters and combiners rather than active components like amplifiers,
repeaters, or shaping circuits. Such networks cost significantly less than
those using active components. ...

The typical PON arrangement is a point to multi-point (P2MP) network where a
central optical line terminal (OLT) at the service provider's facility
distributes TV or Internet service to as many as 16 to 128 customers per fiber
line (see the figure). Optical splitters, passive optical devices that divide a
single optical signal into multiple equal but lower-power signals, distribute
the signals to users. ...

GPON uses optical wavelength division multiplexing (WDM) so a single fiber can
be used for both downstream and upstream data. A laser on a wavelength (λ) of
1490 nm transmits downstream data. Upstream data transmits on a wavelength of
1310 nm. If TV is being distributed, a wavelength of 1550 nm is used.

While each ONU gets the full downstream rate of 2.488 Gbits/s, GPON uses a time
division multiple access (TDMA) format to allocate a specific timeslot to each
user. This divides the bandwidth so each user gets a fraction such as 100
Mbits/s depending upon how the service provider allocates it.
------------------------------

A GPON, Craig, has an aggregate capacity of roughly 1-2 Gb/s downstream,
depending on which type. That's what they are referring to. Not to reach home.

They plan to offer 1 Gbps TO EACH HOME over HFC systems by 2017. To do this
it will likely require far fewer that 500 customers per PON.

Far fewer? Do the math, Craig. We already determined that with DOCSIS 3.1, in
the old 900 MHz plant, you can offer about 5 Mb/s aggregate downstream capacity
in the neighborhood (don't forget that some MHz is taken up by upstream
traffic), but ONLY if you eliminate all broadcast traffic. So tell us, Craig.
**If you repurpose all of the broadcast spectrum**, how many homes can be
passed with a single DOCSIS 3.1 PON, in a 900 MHz cable plant, if each home
wants 1 Gb/s? It's a really simple calculation.

Talk about a disconnect!

Indeed. No wonder you aren't getting any of this.

First, almost anyone who wants "Internet-delivered TV" can get it today
from the cable/FIOS systems. 80% of U.S. homes have access to 25/3
broadband service today.

A refreshing change of tune, from someone who was claiming we are decades away
from being able to do this. So tell us, Craig, if you have a 2.4 Gb/s GPON
feeding the neighborhood, how many homes can be served, if each one wants 25
Mb/s downstream>

Amazing.

Bert



----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.

Other related posts:

  1. Home
  2. opendtv
  3. Archive
  4. 11-2015