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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