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All,
The EDC assumptions used for LRM (10G) development
was that the dispersion effect is linear. (ie every one or zero
is identical and the eye closure is created because the bit energy is not
confined within one bit period and smears out over multiple pulses such that
with superposition of the bits the eye closes. ie it's linear
ISI that is being compensated.). It also assumes that the ones and zeros
are inverts of each other. I think the problem for 1550nm DML is
likely to be chirp. Does anyone know if chirp has this deterministic
linear characterisitic and whether the ones and zeros are inverts of each
other. (I don't think they are).
I'm not suggesting that EDC can't help. I am
suggesting that a more complicated version of EDC might be needed than that
assumed for LRM, and the benefits achieved might not be as great as initially
expected.
Regards,
Mike Dudek From: Roger Merel [mailto:rmerel@GMAIL.COM] Sent: Friday, December 22, 2006 1:16 PM To: STDS-802-3-HSSG@listserv.ieee.org Subject: Re: [HSSG] <HSSG-FO> Fiber Optic Ad Hoc Teleconference 12/18/2006 All, To the extent that
dispersion penalties adversely affect the link budget (even if the link works)
for 1550nm 10G (or 20G/25G) using DMLs, one can consider using EDC to reclaim
some of those penalties. EDC at 10G is readily available, but yet not
presently available at 20/25G. -Roger From: Tsumura,
Eddie [mailto:etsumura@EXCELIGHT.COM] Hi
everyone, I would like to propose
the change of Reach (Technical) Feasibility Table what Chris
created. Please see attached
file. We confirmed that
1550nm DML is possible to support 10G-10km/40km. Also, it might be
possible to support 20G/25G-10km if only dispersion penalty is a
bottleneck. My proposed change is
as follows. 1) 10km,
1550nm, 10G DML: change to “yes” from “maybe” 2) 40km,
1550nm, 10G DML: change to “yes” or “maybe” from
“no” 3) 10km,
1550nm, 20G/25G DML: change to “maybe” from “no” Any comments are
welcomed for me. Have a happy
holiday! Eddie Eddie
Tsumura Vice president of
Engineering and Marketing Excelight
Communications
(A Sumitomo Electric
Company) Phone
919-361-1634 Fax
919-361-1619 From:
HSSG
Members, We held our
teleconference this morning but unfortunately, the bridge supplier I use had
changed their PIN system and I was forced to send out a new bridge number at the
last minute. I realize some people were unable to attend due to this occurrance,
and I give you my apologies. I am going to provide
the meeting notes below. If you see any need for correction to the notes, please
send an email to dan.dove@hp.com and I will
update the minutes before posting them on the HSSG-FOAH website. This will
prevent multiple messages with corrections being sent onto the reflector,
OK? Also, for all who are
interested, I am calling for presentations at the January Interim. Those
presentations should be specific to proving technical and economic feasibility
for a single-mode 10Km link, and for a 100m multi-mode link. It is important to
recognize that we are not trying to select a specific proposal at this time, but
to demonstrate to > 75% of the HSSG and IEEE 802.3 that we have proven these
things. Today's work was
focused on single-mode only, so we should be sure to get multi-mode
presentations on the table as well. Regards, Dan
Dove Chairman, HSSG FO
Adhoc ============================================== Meeting
Notes: Attendees:
Discussed the new table
additions and corrections made since last
teleconference; Discussed Chris Cole
Presentation; 10G
Rows: Matt: Discrete devices
available, extrapolation not necessarily valid For example, EMLs tend
to be larger, take up more wafer space Chris: Another thing
not captured, 10G DML @ 1550 not considered in green but maybe we should take it
off the study list because hard to build as monolithic
array Xaviar: Would like to
avoid taking things off at this point. Would like to present work showing it’s a
viable alternative. Chris: DML at 1550
gonna work at 40k?
Mike D: CWDM being
considered for all or just 1310? Chris: Does not address
this distinction. Slide 4 addresses some of this, but slide 3 is trying to
capture wavelength and transmitter type. This table does not capture "optimum"
or "implementation complexity". 20G
Rows: Chris discusses his
perspective. Nobody argued with his position that 20G 10K DML not
possible. 50G
Rows: General: Would be nice
to have 40K and 10K leverage common approach. Green applied where it appears to
be possible. Marc Lucent: Main
objective regarding DQPSK at 50 / 1310 is
dispersion? Chris: Yes, the
implementation for 50G 1550 looks large and therefore does not seem LAN
oriented. At 1310 makes better sense. Marc: For 40Km, 1550,
might make better sense for this longer reach. Chris: Yes, the
breakpoints for 10G are 1310 DML and 1550 EML, so this is consistent. For us,
its possible to set the breakpoint at 40-80Km. Question is, do we really want to
add the cost of this technology for 40Km. Marc: Chromatic
dispersion your primary concern? Chris: Looking forward
to presentations on this subject. Robert Lingle: Main
Point to have a pluggable in a small form factor and dispersion compensation may
prohibit this. Chris,
yes. Peter: Do you see an
activity to standardize a form factor for a module? Chris: yes. Likely done
outside IEEE. Peter: Would larger
group oppose having different form factors? Matt: With regard to
20/25G DML, been looking at 1310…wonder, at 10K, what were the dispersion
numbers that led you to your conclusion? Dan: My notes missed
some of the content on this part..it was pretty
dense..sorry; Chris: Is there a
breakpoint between 20G and 25G on DML? Chris: Could provide an
EML spec as long as it was possible to reduce cost in
future. Frank: We are dealing
with tech feasibility, we need to consider cost too. For example, with 25G, you
cannot do arrays, it creates a big cost issue. Chris: yes, this is
accurate. We need an economic feasibility table. Discussion of page 4:
Copying conclusions
from page 3 and modified format to make things more
visible; Why did 1550 get
eliminated? Concluded DMLs in the timeframe not feasible due to
dispersion. This conclusion has
been challenged and presentations may come in to address
that. For EML 20G 40Km is not
leveragable. Matt: Agrees with
earlier comment to allow for 1st gen to focus on EML with longterm DML targets…
maybe able to collapse rows 2,3 and 4,5 together. Chris: Would be good to
come up with an approach that allows this to
happen. Chris: We can add to
the format additional proposals per email and
discussion. Mike: Is the intent of
the cooling and grid columns to be 1 for 1 across? Chris: If no cooling,
drift will be larger and thus they should be cited
independently. Chris: Semi-cooling is
less precise than cooling, but offers a lower cost means..for example heating to
ensure minimum temps are eliminated. No more comments on
presentation. Some discussion on the upcoming meeting and it was stated by the
chair that we should build presentations for January's interim rather than
divide our attention on another phone conference. Teleconference
closed. |