研究目的

To investigate the impact of the assumed channel distribution on the achievable rate for coherent optical transmission systems, focusing on distributions in up to four dimensions and comparing single channel and wavelength-division multiplexing (WDM) transmission over links with and without inline dispersion compensation.

研究成果

The study concludes that for most practical scenarios, assuming that the transmission channel has independent and identically distributed Gaussian (iidG) distribution of the noise in each dimension is a good approximation. However, for systems with inline dispersion compensation, gains can be achieved by using four-dimensional distributions, especially with adaptive mean values. The difference between generalized mutual information (GMI) and mutual information (MI) estimates using 2D-iidG or 1D-iidG distributions is negligible for all cases.

研究不足

The study is limited to specific transmission scenarios (single channel and WDM transmission with and without inline dispersion compensation) and does not incorporate digital back propagation (DBP) in the DSP used in this study. The analysis applies to a discrete-time channel starting with the digital-to-analog converters (DACs), and choices made in the transmitter on pulse-shaping or dispersion pre-compensation influence the achievable rate.