Re: [802.3_EPOC] Study Group Questions
From the HFC evolution point of view, moving from N+m to N+n, where n<m, will be a progressive process with extended time lines; at the end of this process whether it will be N+0 is still a question as far as economy is concerned. The strength of Ethernet/EPON over Cable is the potential to provide more scalable upstream and downstream data services over HFC plants without the expensive N+0 upgrade. Therefore, passive cable plant should NOT be an assumption for EPOC project.
TDD – Time Division Duplex was introduces during the early evolution process of HFC under constrains of limited RF spectra availability in the analog/QAM video dominated cable plants. It is a temporally solution to certain degree. Some of the TDD based EOC solutions were adopted from home networking standards such as Homeplug and MoCA that are not scale well in access network.
From the technology point of view, TDD is half duplex; Ethernet has moved away from it long time ago. As has been pointed out, EPON does not support half duplex mode. In order to make TDD work in the application we targeted for, either EPON MAC need to be changed substantially or a cable MAC need to be introduced; either way backward compatibility with EPON will be a problem.
Regards,
Eugene
-----Original Message-----
From: Chris (Yanbin) Huang [mailto:chrish@xxxxxxxxxxxx]
Sent: Wednesday, January 04, 2012 12:08 AM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Study Group Questions
I would like to translate Mr.Yao following email for your reference.
"Is it good for EPOC to fit for some portion of Markets, or all Markets? FDD technology implementation is simplier, but its spectrum allocation plan is very difficult, especially for the whole global, is very difficult to be unified. It is different from DOCSIS: one Downstream channel of DOCSIS only needs 8MHz and narrower spectrum. If FDD mode is used, EPOC should take 10G EPOC plan, otherwise, the following upgrade cannot be backforward-compatible, but 10G system spectrum allocation is very difficult to plan. For neighboring channel interference, EPOC system also is completely different from DOCSIS: DOCSIS is based on multi-channels, so FDD has big advantage, but EPOC is based on single channel (it is very difficult to find the spectrum meeting multi-channels). "4G" tech just is to support both TDD and FDD. FDD is relatively eaiser to support 'active relay', but I doubt whether it is worthy, considering spectrum allocation plan difficulty and coax network reconstruction in!
vestment: It is better to extend fiber reach and remove amplifiers, than to reconstruct/upgrade coax network.
Chris (Yanbin) Huang
________________________________________
From: 姚永Gmail [yy0412@xxxxxxxxx]
Sent: Tuesday, January 03, 2012 3:21 PM
To: STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_EPOC] Study Group Questions
是只适应一部分市场好还是适应所有市场好？
FDD技术实现比较简单，但频谱规划很困难，特别是针对全球，很难统一。这和DOCSIS不同——一个下行信道只需要8MHz及以下频谱，如果采用FDD方式，应该按照10GEPOC规划，否则后续升级无法后向兼容，而10G系统频谱很难规划；对于邻信道干扰，在EPOC系统也和DOCSIS完全不同——DOCSIS是多信道应用，FDD有很大好处，但EPOC是单信道应用（很难找到满足多信道的频谱）。4G就是同时支持TDD和FDD的。FDD比较容易支持有源中继，但考虑到频谱规划的难度和改造的投资，我很怀疑是否值得——与其改造同轴网，还不如光纤延伸，取消放大器。
姚永
----- Original Message -----
From: "Matthew Schmitt" <m.schmitt@xxxxxxxxxxxxx>
To: <STDS-802-3-EPOC@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, January 04, 2012 6:46 AM
Subject: Re: [802.3_EPOC] Study Group Questions
> Alex,
>
> In response to your comment below to me...
>
> I'm not sure I agree that a TDD system inherently provides more spectral
> flexibility than an FDD system in a passive coax environment. Depending
> on the PHY layer, you can do quite a bit of steering regardless of FDD vs.
> TDD. I will agree that a TDD solution can provide advantages in terms of
> the relative allocation of bandwidth to upstream vs. downstream operation,
> although only with a MAC designed to support such features.
>
> That said, I'm more than open to being proven wrong, and so I will
> definitely look forward to your presentation to highlight why you believe
> TDD had advantages over FDD.
>
> BTW, I also tend to agree with others on this thread that it's MUCH
> preferred if we can develop a single solution. Without that, you end up
> with a fragmented market, and it's much harder to achieve the same
> economies of scale that you could have with a single, unified solution.
> If it's simply not possible to come up with a single unified solution, so
> be it; but I think that should be our goal if at all possible.
>
> Thanks.
>
> Matt
>
>
>
> On 12/15/11 7:48 PM, "Liu, Alex" <alexliu@xxxxxxxxxxxxxxxx> wrote:
>
>>Ed,
>>
>>Let me reiterate some of the finer points of my previous missive: (1) TDD
>>systems have a wide footprint in China in part due to their spectral
>>convenience, (2) TDD should be an optional profile in addition to and not
>>in place of FDD. I do believe that market enthusiasm for, and acceptance
>>of, this standard and its ensuing products should be our guiding
>>principle, and not doctrinal orthodoxy within a standards framework. If
>>things weren't so, Ethernet would have never abandoned CSMA/CD for
>>first-mile applications.
>>
>>More specifically, it is clear that an FDD RF system that directly maps
>>to the dedicated wavelengths in fiber and thus the EPON protocol is most
>>appropriate for the N. American MSO environment. I would like to raise
>>the possibility that this is not necessarily true for China. Passive
>>cable plant coupled with haphazard spectrum planning makes for an
>>inviting TDD target. There are then the orthodoxies emanating from the
>>Chinese side. If we are serious about targeting the China market, I
>>suggest we consider SARFT's input.
>>
>>@Matt: TDD's ability to operate in unpaired spectrum makes "lively"
>>spectrum plans possible in China. Perhaps this is improperly termed
>>"coexistence with" and is better called "steering around" existing TV and
>>data systems. This additional degree of freedom may perhaps be attractive
>>to N. American operators as well.
>>
>>@Mark: we *are* working toward a single standard. Transparent EPON
>>protocol operation over coax is the goal and FDD RF operation should be
>>the mandatory supported mode. Employing the modern PHY proposals being
>>developed in an optional TDD mode should not detract from this stated
>>goal. LTE offers an instructive precedent.
>>
>>Alex
>>
>
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