Re: [STDS-802-3-EPOC] Evaluation Criteria and Requirements Ad Hoc Minutes

[Geoff Thompson <thompson@xxxxxxxx>]

Marek-
Just a historical note...
Such timing specifications were common for PHYs when 802.3 was 
specifying PHYs for CSMA/CD systems.
Round trip delay was a crucial parameter in determining the diameter of 
a CSMA/CD network.
The numbers used for the initial work in that area can be found in Annex 
B of 802.3.

It was only when we went to full duplex systems that this type of 
material fell into disuse.
(CSMA/CD is, of course, just an access arbitration method for TDD)

Best regards,
    Geoff

On 161//13 12:14 PM, Marek Hajduczenia wrote:
> Duane,
>
> First it would need to demonstrated that such a symmetry can be 
> achieved with such a tight tolerance (I cannot even think or where to 
> start to guarantee something like that), and only then draw 
> conclusions on what the synchronization / frequency tolerance should 
> be. Putting requirements into our project which are either system 
> level requirements or have no evaluation as to their impact on the 
> complexity / cost / performance of what we are trying to do, is just 
> asking for trouble.
>
> Let's not put the cart before the horse.
>
> Marek
>
> *From:* Duane Remein [mailto:Duane.Remein@xxxxxxxxxx]
> *Sent:* Wednesday, 16 January, 2013 08:03 PM
> *To:* Marek Hajduczenia; STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
> *Cc:* Duane Remein
> *Subject:* RE: [STDS-802-3-EPOC] Evaluation Criteria and Requirements 
> Ad Hoc Minutes
>
> Marek,
>
> I agree with you that this is a system level specification. But I 
> think we need to develop PHY level specifications that ensure a system 
> can meet this level of synchronization. I don't think this will be 
> much beyond adding a requirement that EPoC US path and DS path within 
> a PHY have a symmetrical delay within some bounds (such as ± 1 or 2 TQ 
> ). While it is true that we didn't do this for EPON we may have gotten 
> lucky. If it is relatively easy to accomplish I think such a 
> requirement is in order.
>
> Best Regards,
>
> Duane
>
> FutureWei Technologies Inc.
>
> duane.remein@xxxxxxxxxx <mailto:duane.remein@xxxxxxxxxx>
>
> Director, Access R&D
>
> 919 418 4741
>
> Raleigh, NC
>
> *From:* Marek Hajduczenia [mailto:marek.hajduczenia@xxxxxx]
> *Sent:* Wednesday, January 16, 2013 12:15 PM
> *To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx 
> <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
> *Subject:* Re: [STDS-802-3-EPOC] Evaluation Criteria and Requirements 
> Ad Hoc Minutes
>
> Steve,
>
> I'd like to request that the minutes reflect concerns Leo and I 
> brought forward in relation to the frequency and synchronization 
> precision requirements. We believe these are not PHY specific 
> requirements, but system level requirements. If such a requirement 
> does find its way into PHY spec, there is no way to verify it 
> separately, i.e., nobody measures what part of the system level 
> precision budget is consumed in PHY alone.
>
> I'd also like to have it recorded in the minutes (as mentioned on the 
> call) that EPON does support mobile backhaul services with **no** 
> requirements of this type thrown into the PHY specs.
>
> Furthermore, I believe it was also mentioned that such a requirement 
> would overly burden devices that are not expected to carry mobile 
> backhaul services. However, in the PHY spec it is not possible to 
> distinguish one from another (there is just a PHY), given that 802.3 
> does not provide product specs. Such system level requirements should 
> be brought forward to the group that deals with a system level design.
>
> Regards
>
> Marek
>
> *From:* Shellhammer, Steve [mailto:sshellha@xxxxxxxxxxxxxxxx]
> *Sent:* Wednesday, 16 January, 2013 05:04 PM
> *To:* STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx 
> <mailto:STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
> *Subject:* [STDS-802-3-EPOC] Evaluation Criteria and Requirements Ad 
> Hoc Minutes
>
> All,
>
>                Attached are the minutes for the Evaluation Criteria 
> and Requirements Ad Hoc meeting this morning, and also the latest open 
> issues list.
>
> Steve
>
> ------------------------------------------------------------------------
>
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>
> <="" p="">
>
>
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