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Re: [8023-10GEPON] Downstream wavelength for 10G EPON



Dear Frank,

Thank you for providing your newly proposed wavelength plans.
I am Ken-Ichi Suzuki of NTT and I have comments as below.

In option C, in order to receive signals in both narrow (1574-1580 nm)
and wide (1580-1600 nm) band range, I think that the lower limits of an
optical filter pass-band must be 1574 nm.
If it is true, I think option C (called option D?) should be defined as
1574 ~ 1600 nm.

Considering the coexistence with RF video and the use of common optical
filter for each class, I think I can conclude option B and D are
acceptable for me.


These and the attached file are for my understanding.
Option A: 1560 ~ 1580 nm
Option A can receive signals in both narrow and wide wavelength ranges.
The central wavelength for PX10/20 is 1570 nm near one of CWDM grids.
Option A does not allow 10GEPON to coexist with RF video because of 0
guard band.

Option B: 1574 ~ 1594 nm
Option B can receive signals in both ranges.
The central wavelength is 1584 nm (near the anti-CWDM grid).
Option B allows 10GEPON to coexist with RF video with the guard band of
14 nm.

Option C: 1580 ~ 1600 nm
Option C can not receive signals in both ranges thus forcing us to
develop dedicated optical filters for each class.
The central wavelength is 1590 nm near one of CWDM grids.
Option C allows 10GEPON to coexist with RF video with the relatively
wider guard band of 20 nm.

Option D: 1574 ~ 1600 nm
Option D can receive signals in both ranges.
The central wavelength for PX10/20 can be selected at 1590 nm near one
of CWDM grids.
Option C allows 10GEPON to coexist with RF video with the guard band of
14 nm.

Best regards,
Ken-Ichi

At 2007/08/09 10:05 Frank Effenberger wrote:
> Dear All, 
> 
>  
> 
> I agreed at the last meeting to facilitate the development of a more
> inclusive wavelength plan for the downstream.  
> 
>  
> 
> The current situation is that the PX30 budget would seem to require cooled
> transmitters, and so the 6nm wide transmitter window centered at 1577nm is
> not an extra burden.  
> 
>  
> 
> However, for the PX10 and PX20 budgets, the OLT transmitter may be an
> uncooled type, both because the output power is low, and because in the case
> of PX10, the fiber distance is shorter and so dispersion control is less
> needed.  Therefore, there seems to be a justification for making the
> wavelength band for the PX10 and PX20 types wider.  
> 
>  
> 
> So, the question then becomes: how to make the window wider?  It was
> discussed at the meeting that the wider window should contain the narrow
> window inside of it.  This has the possibility of defining a universal ONT
> that can receive both the wide and narrow OLT signal.  How that actually
> works out in practice will have to be seen.  
> 
>  
> 
> One aspect to consider is the re-use of industry standard wavelength plans,
> since then components are already available.  From this perspective, the
> CWDM wavelength at 1571 leaps out as a potential band.  It is true that the
> CWDM band is actually from 1563 to 1577 nm, but that is meant for 0~70 C
> operation, and expansion to a 20nm width naturally occurs when the -40 to
> +85 C operation is considered.  So, proposal A would put the wider
> wavelength band at 1560nm to 1580nm.  
> 
>  
> 
> Of course, this choice would make co-existence with the video overlay
> impossible, with zero guard-band to the video band at 1550 to 1560nm.  This
> defeats the ¡®common ONT¡¯ idea, since it is impossible to make such an ONT.
> 
> 
>  
> 
> Supposing we want to consider the coexistence with video for these classes,
> then we must push the wavelength longer.  Starting at 1574, we could expand
> to a 1594nm.  This is rather strange, having a center wavelength at 1584,
> which is nearly the ¡®anti CWDM grid¡¯.  We could call this proposal B.  
> 
>  
> 
> On this alternative, we have sacrificed the compatibility with those OTDR
> filters we heard about.  This raises an inescapable conclusion: to broaden
> the band, we will sacrifice either the video overlay or the compatibility
> with certainly legacy OTDR filters.  It should be noted that there are even
> fewer system deployments with this particular OTDR constraint than the video
> overlay. 
> 
>  
> 
> Combining the two motivations above, we turn to the next longer CWDM
> wavelength: 1590nm.  This would define the band to be 1580 to 1600nm; called
> proposal C.  In most PONs, this wavelength has no difficulties of
> transmission.  It also provides a 20nm guard-band from the video, which is a
> little better than the 14 nm with the narrow plan.  It is disjoint with the
> narrow plan; however, it is in a part of the spectrum where the narrow plan
> seems not to care.  So, we could build an ONU that responds from 1576 to
> 1600, and that would receive both signals.  This is probably not the most
> practical solution, but at least it is possible.  
> 
>  
> 
> So, that¡¯s sort of what we have: 
> 
> Option A: 1560 ~ 1580nm
> 
> Option B: 1574 ~ 1594nm
> 
> Option C: 1580 ~ 1600nm  
> 
>  
> 
> I¡¯ll stop at this point, and leave the ¡®floor¡¯ open for comments.  
> 
>  
> 
> Sincerely,
> 
> Dr. Frank J. Effenberger      ¸¥À¼¿Ë °£·Ò²©¸ñ
> 
> Huawei Technologies USA
> 
> 1700 Alma Drive, Plano TX 75075
> 
> Office (732) 625 3002
> 
> Cell (908) 670 3889
> 
>  
> 
> 


-- 
Ken-Ichi Suzuki
NTT Access Network Service Systems Labs.
E-mail:kenyichi@ansl.ntt.co.jp
Tel:+81-43-211-3189/Fax:+81-43-211-8250

Comparison_of_wavelength_plans.ppt