Re: [802.3_EPOC] Study Group Questions
Chris, thank you very much for translating Mr. Yao's comments, as they are
good discussion points.
The main thing that traditionally makes FDD more "rigid" or less flexible
than a TDD system is that when traversing amplifiers, you need to have a
clearly established split between the upstream and the downstream, which
cannot be changed without making changes to the amplifiers. In a passive
coax environment, this may not be the case, particularly with more modern
technologies, and is a point that we will likely want to investigate as we
go forward (or may be a factor in an eventual proposal).
Additionally, while it is correct that a single carrier approach also
would greatly limit flexibility, we do not necessarily need to consider
only single carrier approaches. In a multi-carrier approach, it may be
possible to work around any existing signals, thereby achieving a very
high degree of flexibility in terms of what spectrum is being used.
Depending on the degree of flexibility in the product, this could result
in a system that has the flexibility to work just about anywhere. Again,
it will depend on the technology contributions that are ultimately made,
but the potential is there.
Also, would you be willing to clarify your comment about taking a 10G EPOC
plan? I'm not sure I understand the intent or implication of that
statement. Given that it could be a requirement we could include coming
from the Study Group, it seems like there would be value in clarifying
that point.
Speaking of which, back to the original topic, I think a key activity for
the Study Group is going to be identifying the plant scenarios in which an
EPoC solution will need to exist and operate, so that we have those to
evaluate potential solutions against. That includes North American,
European, and Asian variants, since the ideal goal is to be able to
operate in all environments.
Thanks.
Matt
On 1/3/12 10:07 PM, "Chris (Yanbin) Huang" <chrish@xxxxxxxxxxxx> wrote:
>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 investment: 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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