Multiband Transmission refers to the simultaneous transmission of signals over multiple frequency bands, specifically the C-band and L-band in this case. This technique allows for increased data capacity and improved performance in optical communication systems. The GNPy quality-of-transmission estimator is optimized for such scenarios, enhancing the ability to predict signal quality and performance across these multiple bands while also improving computational efficiency and accuracy in predicting the generalized signal-to-noise ratio (GSNR).