Alan PT LAU  (The Hong Kong Polytechnic University)

Multi-symbol DSP techniques for discrete eigenvalue transmissions based

Abstract
For discrete eigenvalue transmissions (or soliton transmissions), one seeks to encode as much information as possible in each degree of freedom and shorten the distance between neighboring pulses to increase the overall bit rate. However, such attempts would result in nonlinear inter-symbol interference (ISI) across multiple symbols and significantly degrade transmission performance. We hereby demonstrate analytically and experimentally that one can considerably improve soliton transmission performance by intentionally allowing neighboring solitons to interact and collide during propagation and exchange positions at the receiver followed by standard NFT processing. This can be achieved by designing neighboring solitons’ eigenvalues 𝝀 to have opposite signs in the real part while the magnitude |𝕽(𝝀)| is optimized for a given transmission distance so that neighboring transmitted pulses would have swapped their timing positions at the receiver. We further investigated joint modulation of discrete eigenvalue 𝝀 and 𝒃 -coefficents 𝒃(𝝀) and developed a suite of multi-symbol digital signal processing (DSP) techniques to exploit the statistical correlations between the continuous and discrete eigenvalues and 𝒃 -coefficents to mitigate nonlinear distortions and improve detection performance. We jointly modulate 𝝀 with 16-QAM and 𝒃(𝝀) with 16-APSK and experimentally demonstrate 64 Gb/s (net 54 Gb/s) over 1200 km with the proposed multi-symbol DSP algorithms.