Re: [8023-10GEPON] power budget ad hoc teleconference
Dear Dr.Frank Effenberger,
I am Hiroshi Hamano with Fujitsu Labs. and I would like to make some comments
in place of Takizawa with Fujitsu Access.
> 1. FEC Gain: I agree that RS(255,239) can only give you 3 dB with a PIN
> detector. But, why must we use RS(255,239)? That decision has not been
> made. I think that given all the challenges of 10G PON, each technical
> point needs to be pushed equally. So, I would like to ask for 4 dB from the
> FEC guru's out there. I think it can be done - the only issue is at what
> cost. But, if we don't set a target, we will never know.
>
> So, I think 4 dB is my 'planning number'. Let's see if we can make it.
I did not know that you are targeting Enhanced-FEC in your power budget,
instead of RS(255,239), and that is your proposal to FEC people.
Some Japanese venders also think about it to relax the tight power target
of the optical source.
My personal concern is that the burst-mode CDR would lock in properly
and smoothly in such a big noise environment of BER 10-2 using high-gain
FEC.
> 2. DFB source penalty: I think that the appropriate way to capture
> transmitter penalties of this type is to use the OMA definition of
> transmitter power. In this way, I would ask for the same OMA out of
> whatever transmitter. If a DFB needs to be operated at a really bad ER,
> then it will have to compensate for that with increased power to make the
> OMA number. So, I don't think this is a basic discrepancy.
I thought that your power budget uses ITU-T formalism.
This is, I think, important to understand easily what figure should be the
real target of each optical component. IEEE OMA description may clearly
separate ER, OMA, and Transmitter Penalty, especially in 803.2ah, and
it makes the standards consistency easier, but I am afraid most optics
engineers are used to ITU-T-like image in their design and testing.
The major difference between your budget and that of Japanese vendors is
2dB of ONU transmitter power (10G U/S B++), and that is just the degradation
of DFB with its low ER and waveform distortion. I think it should be
clearly pointed out to give component venders the comprehensive target.
> 3. APD overload - Yes, this is a big issue, definitely. I would just throw
> out one small hope, which is that the dynamic range of practical PONs tends
> not to be the 15 dB bogey. I think 10 dB is quite adequate. So, if we
> really get pushed, we might play that card.
If your proposal card wins the game, that will be a help for gasping venders
against tight power budgets. Personally I really want to support your idea,
but also worry that it is not easy to revise those figures in such a
co-existence case.
Best regards,
Hiroshi Hamano
Fujitsu Labs. Ltd.
%% Frank Effenberger <feffenberger@HUAWEI.COM>
%% Re: [8023-10GEPON] power budget ad hoc teleconference
%% Mon, 30 Apr 2007 21:07:28 -0400
> My comments in brief below:
> 1. FEC Gain: I agree that RS(255,239) can only give you 3 dB with a PIN
> detector. But, why must we use RS(255,239)? That decision has not been
> made. I think that given all the challenges of 10G PON, each technical
> point needs to be pushed equally. So, I would like to ask for 4 dB from the
> FEC guru's out there. I think it can be done - the only issue is at what
> cost. But, if we don't set a target, we will never know.
>
> So, I think 4 dB is my 'planning number'. Let's see if we can make it.
>
> 2. DFB source penalty: I think that the appropriate way to capture
> transmitter penalties of this type is to use the OMA definition of
> transmitter power. In this way, I would ask for the same OMA out of
> whatever transmitter. If a DFB needs to be operated at a really bad ER,
> then it will have to compensate for that with increased power to make the
> OMA number. So, I don't think this is a basic discrepancy.
>
> 3. APD overload - Yes, this is a big issue, definitely. I would just throw
> out one small hope, which is that the dynamic range of practical PONs tends
> not to be the 15 dB bogey. I think 10 dB is quite adequate. So, if we
> really get pushed, we might play that card.
>
> Thanks for your comments.
>
> Overall, I think the next useful step will be to develop OMA numbers
> suitable for spreadsheet analysis. That will take much of the trivial
> differences away, and leave us with the 'hard core differences'. I hope
> they are not too great!
>
> Sincerely,
> Frank E
>
>
> -----Original Message-----
> From: Motoyuki TAKIZAWA [mailto:mtaki@ACCESS.FUJITSU.COM]
> Sent: Monday, April 30, 2007 10:21 AM
> To: STDS-802-3-10GEPON@listserv.ieee.org
> Subject: Re: [8023-10GEPON] power budget ad hoc teleconference
>
> Dear Frank.E and Power Budget Ad hoc members,
>
> It seems Robert's e-mail and this mail have crossed in the post.
>
> Now we have two power budget proposals, one of which is estimated
> from 1G/10G differences and posted by you and the other one is
> estimated from the opinions of Japanese vendors experts and posted
> by me. I think it's time to discuss these two proposals and we might
> as well merge them into the draft proposals.
> Please feel free to ask about our proposals or make comments on it.
> If we can have a consensus of opinions, I would like you to put them
> into your table.
>
> Firstly, the followings are the comments on your proposals I discussed
> with some optics experts.
>
>
> 1. FEC gain
> In the last teleconference on April 10, it was already pointed out that
> 3-dB FEC gain is theoretically the maximum number for PIN receiver.
> RS(255,239) FEC coding gain is described as 5.9dB at BER of 10-12
> in terms of OSNR, optical-signal to optical-noise ratio, in several
> technical literatures(e.g. ITU-T G.series Supplement 39).
> As a PIN photodiode is an optical-power to electrical-current converter,
> electric signal power reflects the square of optical power, or twice in dB.
>
> PIN receiver sensitivity is determined by electric SNR,
> electric-signal-power
> to electric-circuit-noise ratio, and therefore the FEC coding gain in
> terms of optical input power will be halved to 3dB.
> ---10G D/S (p.8); PX20 and B++(1)
>
> 2. DFB DM optical source penalty
> It was also pointed out that 10G DFB DM optical source can be utilized
> at the extinction ratio ER up to 6 dB, instead of 9 dB, avoiding its deep
> ON/OFF switching to achieve 10G speed. Besides, it suffers serious
> waveform distortion from its own resonance frequency. As a result, the
> receiver sensitivity with the DFB transmitter is at least 2 dB worse
> than that with EML. (Regarding this 2 dB sensitivity difference, Hamano
> and Yokomoto suggested EML@ONU to relax the ONU optical source power
> requirement in the presentation I posted on 4/17.)
> FEC may somewhat relax the degradation not only by noise but by distortions
> and interference, but it is dangerous to count it now in the specs.
> ---10G U/S (p.7); PX10, PX20, B++(a), and B++(b)
>
> 3. APD receiver overload
> Around -5 dBm would be the maximum number for 10G APD receiver overload.
> Some vender here criticized that it may even lower.
> In APD receiver at its proper multiplication factor(M) setting,
> amplified signal current flows into TIA, and therefore better sensitivity
> can
> be achieved than that of PIN receiver.
> According to 10G transceiver experts, PIN receiver overload seems to
> be up to around 0dBm. But this APD-amplified signal current easily
> saturates the receiver circuit, and significantly decrease the overload.
> ---10G U/S (p.7); PX10, PX20, and B++(a)
> ---10G D/S (p.8); B++(2)
>
>
> Please find attached notes about the summary of Japanese discussions
> so far.
>
>
> Best regards,
> Motoyuki Takizawa
>
>
> On Wed, 18 Apr 2007 22:14:48 -0400
> Frank Effenberger <feffenberger@HUAWEI.COM> wrote:
>
> > Everybody,
> > Please find attached a new version of my power budgets, which is based on
> > the new ideas put forward in the call last week.
> >
> > I would like to point out that this work is based on certain system
> > engineering themes to develop the three power budget classes, all of which
> > have the goal of reducing the number of unique optics types to a minimum.
> >
> > The component engineers may gasp at some of the numbers that this approach
> > generates, but at least it sets some targets. We can then see how close
> we
> > can shoot.
> >
> > Next on my 'to-do' list is to transform these numbers into OMA formalism,
> > etc., for better plugging into the spreadsheet. I think that this will
> help
> > dispel some of the concern regarding optical path penalty.
> >
> > Regards,
> > Frank E.
> >
> >
> > -----Original Message-----
> > From: Lingle, Jr, Robert (Robert) [mailto:rlingle@OFSOPTICS.COM]
> > Sent: Wednesday, April 18, 2007 4:49 PM
> > To: STDS-802-3-10GEPON@listserv.ieee.org
> > Subject: Re: [8023-10GEPON] power budget ad hoc teleconference
> >
> > Please find attached notes from last week's call
> >
> > Robert
> >
> > -----Original Message-----
> > From: Lingle, Jr, Robert (Robert) [mailto:rlingle@OFSOPTICS.COM]
> > Sent: Tuesday, April 03, 2007 10:07 AM
> > To: STDS-802-3-10GEPON@listserv.ieee.org
> > Subject: [8023-10GEPON] power budget ad hoc teleconference
> >
> >
> > All,
> >
> > The next Power Budget Ad Hoc teleconference will occur on Tuesday April 10
> > at 7PM EST and Wednesday April 1 tentatively at 9AM EST. I may have to
> > travel Wednesday and ask your flexibility if I need to push this time to
> > 8:30AM or 9:30AM to accomodate.
> >
> > The topics will be a review of power budgets presented at the March
> Plenary
> > by Frank Effenberger and Wenbin Jiang, as well as implications of the
> > presentation by Stefanov on SOA output power issues.
> >
> > More details will follow.
> >
> > Robert
> >
> > Robert Lingle, Jr.
> > Fiber Design and Transmission Simulation
> > OFS Corporate R&D, Atlanta
> > 404-886-3581 (cell)
> > 770-798-5015 (office)
> >
>
> --
> Motoyuki Takizawa
> Fujitsu Access Ltd. R&D Center