Estimating Network Components PDL Using Performance Statistical Measurements

In this paper, we propose a novel technique to estimate the polarization-dependent loss (PDL) of a reconfigurable optical add-drop multiplexer (ROADMs) in a terrestrial optical network. The idea is to monitor the signal-to-noise ratio (SNR) distribution induced by PDL of signals transmitted over short links at different network nodes and infer the PDL elements through linear regression. 

The distribution statistical information, such as means and variances, can be collected by transceivers and sent to a central controller. The PDL regression algorithm and the methodology to acquire the statistical information are presented. We check the method accuracy for different link configurations. 

We show that our technique well predicts the ROADMs PDL obtaining an 80% uncertainty cut compared to the datasheet for a ROADM at emission and 40% for a ROADM in transit in the worst-case scenario. We also test the method over simulations of typical terrestrial network links. We consider two light paths (LPs) as an example of a realistic network and show that PDL estimation allows reducing network SNR margins by more than 0.2 dB on these links.