| Thread Links | Date Links | ||||
|---|---|---|---|---|---|
| Thread Prev | Thread Next | Thread Index | Date Prev | Date Next | Date Index |
|
There is inherently no “framing block” if you are encoding the control symbols into the TCM constellation mapping directly. Hence you won’t find a “framing proposal” – it’s covered in the PAM-10 TCM mapping. This reduces the overhead and simplifies operation, and is similar to 1000BASE-T, where the control symbols are part of the constellation mapping itself. Optical systems, which tend to have bit-to-bit errors, often have such framing to help in protection against single-bit errors. Multi-level copper transmission systems, as you know, will generally have errors covering much more than 1 bit, and hence lend themselves to different approaches for encoding control bits.
I’m really not trying to be obtuse here, but can you point me to an example of the block diagram that you are looking for, when applied to a coded modulation system? (just reference a figure number in 802.3?) Perhaps then I can get you something more in line with what you’re looking for.
-george
-----Original Message-----
George,
Alternatively, if you and Sailesh can come up with a unified framing approach, that would make my job easier.
Regards,
Sanjay
cell (650) 704-7686 office (408) 653-2235
From:
stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On Behalf Of George Zimmerman No, our proposal does not call for additional framing at the bitstream level. They are instead, incorporated into the 10,000-8192 = 1808 4D PAM-10 constellation points beyond what is needed for shaping gain and carrying the information bits. By incorporating the control symbols directly into the PAM-10 codeword, and using receiver-based equalization, we require neither the feedback channel, nor additional baud rate overhead for control symbols.
In contrast, the TH precoded proposals may require an additional framing for updating the coefficients of the precoder, and this overhead was included in Sailesh’s original proposal, along with a much less efficient way to deal with the control symbols. The rate for such update would need some extensive study, as I haven’t seen ANY data on the variability of the LAN cabling characteristics over time, temperature, or equalizer variations with time-varying EMI.
On another note, thanks for the clarification on the process. We can discuss, making decisions easier and better informed, but try not to drive agreements on email, without a meeting of the group.
-george
-----Original Message-----
George,
Thanks. I did think the 64B/66B was at the bit-stream level and Sailesh (at the Albuquerque meeting) had also some framing at the symbol level over and beyond bit-level framing
Is there a need for framing at the bitstream level over and beyond what you do in the TCM mapping in your proposal?
You are correct in pointing out that group decisions must be formalized at a formal meeting through the voting process but I am not suggesting we bypass that process. Reaching agreement earlier (if it happens!) will will enable us to get the specific decision through the voting process quicker and possible let us address more issues within the time constraints of the next meeting.
Regards,
Sanjay
cell (650) 704-7686 office (408) 653-2235
From:
stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On Behalf Of George Zimmerman Sanjay – I have seen 2 other proposals, one by Sailesh, in his original procedure, and the other by myself (to incorporate the control symbols directly into the TCM mapping, and thus avoid the higher baud rates). There may be more brought to the group at the next meeting.
Discussion of these items might be useful on the reflector, however, we should refrain from trying to make group decisions without a formal meeting and voting process. -george -----Original Message-----
All,
I have seen a proposal from Sailesh Rao to use 10GBASE-R (Clause 49) 64B/66B framing for 10GBASE-T - see http://www.ieee802.org/3/an/public/mar04/rao_1_0304.pdf.
I don't recall seeing any other framing proposal. Is everyone in favor of using 64B/66B framing? If not, can you point me to alternative framing proposals?
If there aren't any alternative proposals, shall we, as a group, focus on developing this further?
Regards,
Sanjay Kasturia Editor-in-chief 802.3an
cell (650) 704-7686 office (408) 653-2235 fax (408) 844-8187
Teranetics Inc. 2953 Bunker Hill Lane, Suite 204 Santa Clara, CA 95054
|