Crosstalk Performance Analysis: ENRZ, NRZ, PAM3, and PAM4

The performances of Ensemble non return-to-zero (ENRZ) under the interferences of crosstalk, along with non-return-to-zero (NRZ), pulse amplitude modulation of three-level (PAM3), and pulse amplitude modulation of four-level (PAM4) are investigated. Two scenarios, 0 dB and high loss, with varying levels of dual-side far-end crosstalk (FEXT) and near-end crosstalk applied, are studied. A detailed description of the ENRZ algorithm is provided. The reasons that lead to the performance edge of ENRZ in contrast to the rest three modulations are analyzed. The methodologies of injecting the crosstalk interferences into the differential/multiwire channels are discussed. A widely existing issue in computing FEXT is pointed out, with the recommended technique presented. A holistic channel simulation method called frequency domain matrix multiplication is employed in this study for its better handling of multiwire-based channels. The simulated eye diagrams obtained with the four modulation techniques are compared and analyzed. The study shows that ENRZ's inherence of insensitivity to channel loss makes it remain robust under the interferences of crosstalk in comparison with the other three types of modulations. Meanwhile, overall ENRZ and NRZ are more robust than PAM3 and PAM4 when the crosstalk level increases.