In-line Estimation of Optical BER SNR

摘要

DWDM optical communication systems that transport bandwidth exceeding Tbps per fiber require fast and cost-effective methods to measure the transmission performance parameters of the optical link and the receiver at each system port. The reason is that fiber non-linearity and component degradation affect the quality of signal and the overall channel performance. However, in many applications, it suffices to verify whether the receiving channel meets the minimum performance criteria. In such case, simple and conclusive methods should be used to measure quickly and in-situ the channel performance parameters. Such parameters in optical communication are the bit error rate (BER), signal to noise ration (SNR), Q-factor, noise factor (NF), received optical power level, and more. In this paper, we describe a statistical sampling methodology that estimates these channel performance parameters in a very short interval and for all-practical purposes in real-time, which also is protocol independent; that is, performance is not estimated according to error detecting codes embedded on the signal of asynchronous data payloads such as in GbE, synchronous such as SDH/SONET.