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Translation for Mr.Yao (from SARFT Broadcasting&TV association technical working committee): I think that Jorge is proposing one key question. When EPOC concept is proposed out, all of us love it very much: because it brings us one ideal system architecture:
end to end, and directly implement optical-electrical conversion on physical layer, without changing MPCP protocol. However, considering more carefully, it almost is impossible. We have the following doubts:
1)
CMC is the special ONU, which is not one terminal, and only forwards data, therefore, OLT management for it certainly is different, it is not defined
in EPON.
2)
CNU is different from ONU (though we hope both are completely the same), because all data is converted and forwarded via CMC, and every time when
CNC receives or sends data, it needs CMC cooperation. That is, CNU and CMC works at the same time, and OLT must have both cooperate well. This point also is not defined in EPON.
3)
Coax medium is far different from fiber, must consider anti-interference. It just makes its physical layer much more complicated than optical layer,
so the frame structure adapting optical layer cannot be the frame structure for coax medium layer.
4)
The ranging and power control for both fiber and coax is different from only fiber……
5)
Many problems are available when rates are different on 2 segments (fiber and coax)…..
Our proposal will propose the details about the above questions. Unfortunately, we cannot join the meeting, so we would have Chris Huang help addressing our proposal presentation
on behalf of us, and for questions, please the friends from Qualcom, Broadcom, Huawei, ZTE etc. together answer. We will hold one Seminar in Beijing on March 7, and communicate with them for details.
Thanks, Yanbin 'Chris' Huang Broadcom (博通公司) 18611179955 From:
姚永 [mailto:yy0412@xxxxxxxxx]
我认为Salinger, Jorge提出了一个关键问题，当提出EPoC这个概念的时候，我们大家都非常喜欢——因为它给了我们一个理想的系统架构：端到端，直接在物理层进行光、电转换，不改变MPCP协议。但仔细考虑一下，这几乎是不可能的。我们有以下几点疑问： 1、CMC是个特殊的ONU，它本身不是一个终端，只起数据转发作用，因此OLT对它的管理肯定不同，这在EPON里是没有定义的 2、CNU也不同于ONU（尽管我们希望完全相同），因为所有数据都要经过CMC转换、转发，每一次CNU接收或发送数据都要CMC协同。也就是说，CNU和CMC是同时工作的，OLT必须使二者协同工作。这更是EPON没有定义的。 3、同轴介质远不如光纤，必须考虑抗干扰，这就使得物理层比光要复杂得多，适配光的帧结构无法适配同轴需要的帧结构。 4、光纤和同轴两段测距和功率控制显然不同于单纯的光纤段。 5、如果两段速率等级不一致就会有更多问题。 我们的提案将会提出这些问题。十分遗憾，我们不能参加会议，我们的提案请Chris (Yanbin) Huang代为宣讲，提问请高通、博通、华为、中兴的朋友们共同解答，我们7号在北京有一次讨论，会跟他们充分沟通。谢谢！ 2012-03-02 姚永 发件人：Salinger, Jorge 发送时间：2012-03-02 13:15 主题：[802.3_EPOC] What is the problem with the
EPoC converter, and what is the CLT? 收件人：STDS-802-3-EPOC 抄送： Paul, David, Howard, and EPoC Study Group members, I'm expanding a discussion that I had with Marek, Ed, and Mark to the entire team. I know this will get unruly, but I see this as a
"white elephant in the room" for what seems like some sort of philosophical argument, so might as well get it out in the open. Also, I recognize that this was a subject of discussion during the meeting in Newport Beach, but I did not understand it then and
thought it might not be important. I see now that it is a key problem that if not resolved will haunt us forever. So, let's see if we can discuss it via Email and see if we can resolve it before the meeting in Hawaii. My initial statement of the problem to Ed, Mark and Marek, expanded for clarity, is: I struggle with what the CLT is, and what is the problem with the converter
that we need to define. I see the EPON and EPoC systems containing these components: EPON:
OLT <=== Fiber =====================================> ONUs EPoC:
OLT <=== Fiber ====> converter <=== HFC network ====> CNUs The bottom line is that I want to buy a standard OLT, and buy ONUs for customers I can connect via fiber. And, when I can't run fiber to customers, I want
to buy a converter between the fiber and the HFC network so I can use the same standard OLT, and use CNUs (an RF version of the ONU) for those customers attached to the HFC network. The FIRST KEY POINT here is that I want to use the same OLT. The SECOND KEY POINT is that I want to buy a passthrough device that will be invisible to the OLT, which will take the optical EPON
signals and convert them into RF signals. This passthrough device must be flexible in several ways, such as allowing me to use different portions of the RF spectrum, including more and less spectrum as available. The THIRD KEY POINT is that I want the CNU to be functionally equivalent to the ONU so that the OLT does not know the difference. I think that I want the RF PHY that the converter and the CNU will use to be defined at IEEE because that should make it easier for the vendors that will implement
the converter and the CNU to develop it. But people tell me that this will be a problem because, from what I understand, the IEEE does not specify converters or some such rationale. Because of that we
have to talk about a CLT instead of the OLT, to hide the converter inside the OLT (if I understood correctly). I hope I was able to keep the definition of the problem simple and clean enough to have a straightforward discussion of why we can't
do what I, and my esteemed MSO colleagues, need. So, what is the problem with the converter, and why is there a need to instead define a CLT which is something I don't want to have? Thanks! Jorge <="" p="">
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