Marek, Hal,
I have the same impression with the wording “at least’
that it is ‘encouraging’ or ‘incline’ for more than one PHY as the most likely scenario.
Replacing with “at most two PHYs” would offer an upper bound on the number of possible
PHYs to be defined while implying a desire or effort of this group to define toward
a single PHY.
Best,
Rick
From: Hal Roberts
[mailto:Hal.Roberts@xxxxxxxxx]
Sent: Tuesday, May 08, 2012 2:29 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Latest objectives proposal
Marek,
I agree there is no worry about more than two PHYs. So here is a
modified proposal.
Specify at least one PHY and two PHYs if necessary to support subscriber access networks using the EPON protocol and
operating on point--‐to--‐multipoint RF distribution plants comprised of
all--‐coaxial cable or hybrid fiber/coaxial media.
If others think the current wording will not be confusing when
going to IEEE for SG approval then I am not adamant about it. I know the
EPoC group has this understanding, it is outside readers who may find the
current text indicating a preference for more than one PHY.
Hal
From: Marek Hajduczenia
[mailto:marek.hajduczenia@xxxxxxxxx]
Sent: Tuesday, May 08, 2012 4:20 PM
To: Hal Roberts; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_EPOC] Latest objectives proposal
Never before was there a problem with such an “understanding”. I
would not be averse to the change you propose, but see it as unnecessary
nonetheless. We have spoken until now about two cable plant types (at most) so
it would be a clear indication for two PHYs (at most)
From: Hal Roberts [mailto:Hal.Roberts@xxxxxxxxx]
Sent: 08 May 2012 22:10
To: Marek Hajduczenia; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_EPOC] Latest objectives proposal
If you think “at least one PHY” must remain, then we should have
more than an ‘understanding’ that the industry is driving towards a single PHY
solution. The way it reads now, one might think that if we define one PHY we
meet our objectives and if we define multiple PHYs we exceed our
objectives.
The following wording does not preclude two PHYs but doesn’t
require the reader to have ‘an understanding’ that the industry is driving to a
single PHY solution.
Specify at least one PHY and at most two PHYs if necessary to support subscriber access networks
using the EPON protocol and operating on point--‐to--‐multipoint RF
distribution plants comprised of all--‐coaxial cable or hybrid fiber/coaxial
media, with a goal to limit
From: Marek Hajduczenia [mailto:marek.hajduczenia@xxxxxxxxx]
Sent: Tuesday, May 08, 2012 3:50 PM
To: Hal Roberts; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_EPOC] Latest objectives proposal
Neither are my preferred choices of words – I would certainly
like to have them nailed down further.
However, given the discussion we had at the last meeting, I
think leaving the option of doing two PHYs is OK as long as we understand that
the industry is driving towards a single PHY solution. Put it in other words.
If we write down “one PHY” and a year from now we figure out we need two, we
need at least to modify objectives, which is not as easy as it seems. If we
write down “at least one PHY” right now and one year from now we figure out we
can do everything with a single PHY, we are good to go.
From the safety perspective, I think it is prudent to leave it
as it is and work diligently to make sure no more than one PHY is needed.
Marek
From: Hal Roberts [mailto:Hal.Roberts@xxxxxxxxx]
Sent: 08 May 2012 21:36
To: Marek Hajduczenia; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_EPOC] Latest objectives proposal
Marek,
Define “minimal augmentation to MPCP” for me please.
There are plenty of undefined terms in the document, I don’t see
why the term “flexibility” has a higher burden than other terms.
We will define flexibility more precisely when we know what the
channel models are. If you are still confused what flexibility means it means
variable “QAM constellation density, FEC, guard interval and frame structure”.
We should eliminate the opening for multiple PHYs until someone
can show that we can’t do what other standards 802.16e, LTE have done with more
difficult channel model variations.
Hal
From: Marek Hajduczenia [mailto:marek.hajduczenia@xxxxxxxxx]
Sent: Tuesday, May 08, 2012 3:25 PM
To: Hal Roberts; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_EPOC] Latest objectives proposal
Hal,
Define “enough flexibility” for me, please.
Marek
From: Hal Roberts [mailto:Hal.Roberts@xxxxxxxxx]
Sent: 08 May 2012 21:21
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Latest objectives proposal
Charaf,
Yes, I have heard the same and would submit the same reasoning I
sent out before, “If a single PHY can operate over the wildly varying
conditions found in wireless transmission (i.e. LTE or Wi-Fi with huge swings
in signal strength, interference, multipath etc) surely a single PHY should
suffice within the more controlled cable environment”.
Obviously the PHY parameters would have to be adjustable, i.e.
QAM constellation density, FEC, guard interval and others. This is what is done
in LTE and Wi-Fi.
What shouldn’t need to change is subcarrier spacing, symbol
duration and other more difficult to change parameters.
As I sent out before, “The burden of proof should be on
demonstrating the need for two PHYs.”
Having said all of that, it is much more likely that two PHYs
might be considered to work well with TDD vs FDD.
With FDD the downstream would be a continuous signal (with idle
patterns when no data is sent) just like DOCSIS which allows easy
synchronization to the downlink and eliminates the need for preambles at the
beginning of a burst (i.e. there are no bursts in the downstream).
Whereas with TDD we have to define downstream frames and upstream frames along
with guard times.
LTE solves this with two types of frame structures, Type 1 for
FDD and Type 2 for TDD (see below).
As long as we consider two frame structures as defined under one
single PHY then we still need only one PHY.
“The burden of proof should be on demonstrating the need for two
PHYs.”
Therefore I would suggest a variation on Gomez’ suggestion:
"Specify one PHY to support
subscriber access networks using the EPON protocol and operating on
point-‐to-‐multipoint
RF distribution plants comprised of all-‐coaxial cable or hybrid fiber/coaxial
media, with enough flexibility to operate both below and above 1GHz and in
TDD or FDD duplexing modes."
Thanks,
Hal
From: Charaf HANNA [mailto:charaf.hanna@xxxxxx]
Sent: Tuesday, May 08, 2012 2:37 PM
To: Hal Roberts; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: RE: [802.3_EPOC] Latest objectives proposal
Gentlemen,
From the 5 Criteria discussion, it seems to me the reference to
more than 1 PHY has to do with passive versus active coax plants rather than
below versus above 1 GHz.
Charaf
From: Hal Roberts [mailto:Hal.Roberts@xxxxxxxxx]
Sent: Tuesday, May 08, 2012 2:03 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Latest objectives proposal
Kevin,
If a single PHY can operate over the wildly varying conditions
found in wireless transmission (i.e. LTE or Wi-Fi with huge swings in signal
strength, interference, multipath etc) surely a single PHY should suffice
within the more controlled cable environment.
Hal
From: Noll, Kevin [mailto:kevin.noll@xxxxxxxxxxx]
Sent: Tuesday, May 08, 2012 1:53 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Latest objectives proposal
There
is some concern that operating in the lower bands is significantly different
than operating above 1GHz, thus the PHY might need to be
different. The reason for "at least one" is not to have equal
and competing specifications, but to allow for two implementations that address
multiple sets of coaxial conditions.
If
the same goal can be attained by a single configurable PHY, then we would
probably be okay with that.
--kan--
From: "Gomez Chano (LQNA MED)" <Chano.Gomez@xxxxxxxxxx>
To: Kevin Noll <kevin.noll@xxxxxxxxxxx>
Cc: "<STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>"
<STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Subject: Re: [802.3_EPOC] Latest objectives proposal
Hi,
I
did not attend the last conference calls, but I have been following progress
through the reflector. I have a question about the wording in Objective 1,
which is now
"Specify
at least one PHY to support subscriber access […]"
while
previous proposal was:
"Specify
a PHY to support subscriber access networks […] "
Can
somebody clarify the rationale for the new wording, which seems to
"almost" encourage the group to develop more than one PHY? We have
all seen other IEEE groups that quickly yielded to the temptation of adopting
multiple PHYs as soon as they realized that having the group agree on a single
PHY was hard work. I would hate to see the same thing happening in EPoC, as
this would cause market fragmentation and slow down adoption.
The
objective should be "one PHY". Only if the group finds at a later
stage a very good reason to develop more than one PHY then that option should
be considered.
Just
to be clear, for me it would be OK if the PHY for downstream and upstream
channels have different parameters. As long as vendors do not have to face the
decision of choosing between multiple and equally valid PHY options when
implementing their products, that would still qualify as "one PHY"
for me.
Best
Regards
Chano
Gómez
Lantiq
North America
On
May 8, 2012, at 9:38 AM, Noll, Kevin wrote:
<epoc_objectives_for_may_2012.pdf>
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