Accurate statistical analysis of high-speed links with PAM-4 modulation

Do statistical methods developed for NRZ signals work for PAM-4 modulation? Not entirely. We show that some basic principles (e.g., edge-based analysis, conversion of jitter PDF into vertical noise) remain valid, but the solution flow should be modified. Modifications include: the number of PMF accumulators, their initialization and input-output connections, weight factors, transition probabilities, and their relationships to the high-order correlation coefficients.