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Hi Chris, Thanks for the contributions. You may have addressed some of these questions at the microphone (on
cole_3bs_01a_0714) or verbally, yet as someone who has been unable to attend the calls/meetings, I’d appreciate your patience in addressing the questions. 1) Quantization (*) noise: I count three penalties in your draft budget containing quantization noise. I am concerned that you are overestimating by putting it into three line items. (a) modulation penalty <adding 0.2dB for “exact levels”>;
(b) TDP- on slide 4 of cole_02_0814_smf, you indicate that TDP includes quantization <unclear constituent pieces of TDP>; (c) TIA & Quantization penalties on the RX. These are all reasonable sources of penalty to further investigate, yet I’m concerned that
your comparison table probably mixes some cells which are well known with others that have more rigorous experimental basis such that the reader may inadvertently draw conclusions which are not beneficial for the industry. In particular, what is the basis
of the RX Quantization penalty? Do you have a reference? 2) FEC Coding Gain on KP4 vs. KR4: (this refers to
cole_3bs_01a_0714): I believe you used the 1e-15 input BER for the KP4 and the 1e-12 input BER for KR4 (leveraging
zhai_400_01_0713). Also, I noted on on slide 8, you took a 0.5dB OMA relaxation to accommodate a ~3% rate increase in KP4 vs. KR4 – this seems excessive. I didn’t notice KR4 mentioned in
cole_02_0814_smf, is there a reason that you are selecting KP vs. KR? 3) TDP: On slide 8 of
cole_3bs_01a_0714, you have a 2.0 dB penalty for PAM4 2x λs DML KP4 FEC, yet on slide 5 of
cole_02_0814_smf, this has shifted to a 1.5dB penalty. Why did the TDP change? Conversely, the “4x100G KP4 FEC PAM4 MOD” column in your ad hoc preso has 2.5dB versus a 2dB penalty in the July presentation – why the change? Any references you can point
to? (seems strange that the 8x got easier yet the 4x got harder?) As you can tell from
mazzini_01a_0814_smf, we are trying to understand the behavior & best characterize penalties. 4) FEC Optical Gain: Based on verbal conversations with IC folks, I do not believe the halving of NCG (page 6, row “FEC Optical Gain v. 1e-12 BER”
cole_02_0814_smf) is appropriate. I am trying to find a better approximation. If you have a good reference (beyond the generic intensity vs. E-field) I’d appreciate seeing it. 5) OMA Eye v. EyeSNR: Suggestion that you move to using Eye SNR (see slide 7 of
mazzini_01a_0814_smf). As we are moving into links that leverage FEC/DSP, I think it is appropriate that we adopt SNR terminology rather than eye openings. thanks --matt traverso |