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Yan For the simulations I arranged the codebook with sets of code groups with running disparity in the range -3 to +3, the same as 4B3T. And implemented the running disparity with a simple choice of the positive or negative code group based
on the current running disparity being positive or negative. It is possible to implement the running disparity using the same scheme as 802.3cg and bound the running disparity to +/-1.5. I have not simulated this arrangement yet, but I don’t expect any difference. An 8B6T set of code groups can be chosen that have a running disparity in the range -1 to +1. However, increasing the distance between the 6T code groups means choosing 6T code groups with a greater range of disparity. Yes, there is a concern that impulse noise (at 1 kV or 2 kV) may cause symbols errors. As there is with PAM-4 modulation. However, the wider spacing of 6T code groups gives greater immunity to AWGN and PAM-3 gives greater immunity to impulse
noise. Resulting is fewer bits errors for a FEC to deal with compared to using PAM-4.
Brian From: Zhuangyan (Yan) <zhuangyan.zhuang@xxxxxxxxxx>
Hi Brian, Thank you for the response and bring to the list… Noticed that the disparity of 8B6T code pair in 100BASE-T4 is
±1 and your proposal is
±3, any reason for that? And also, with code group, it may provide SNR margin against AWGN, but there still have concern on the EFT (even under 1kv, the signal is still
impact, not even for the 2kv worst case in 61000-4-4). Thank you very much~ Best Regards, Yan From: Murray, Brian <Brian.Murray@xxxxxxxxxx>
Yan 8B6T line coding was used in 100BASE-T4, 802.3u-1995. 23. Physical Coding Sublayer (PCS), Physical Medium Attachment (PMA) sublayer and baseband medium, type 100BASE-T4 So this coding scheme has been around for a long time. I don’t know what RS coding scheme might be used or if we need to use RS coding. That requires some more study. Brian From: Zhuangyan (Yan) <zhuangyan.zhuang@xxxxxxxxxx>
Hi Brian, Thanks for your presentation today. But still confused with how 8B6T LC works... May I ask any reference in IEEE 802.3 that previously introduce this code groups? Can you elaborate a
bit on this? Also, with this coding scheme, which RS FEC do you think we can choose for the 500m reach? Thank you very much~ Best Regards, Yan Brian To unsubscribe from the STDS-802-3-SPEP2P list, click the following link:
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