SPEC: statistical performance estimation circuit for multiple channel equalization in DWDM

The power level of communications channels needs to be maintained above specified threshold levels in order to meet the acceptable channel performance at the receiver. The performance of a channel depends on the collective interaction of many factors such as transmission medium, attenuation, bit rate, modulation method, noise, jitter, and more. The channel performance is typically measured in terms of bit error rate, signal to noise ratio, Q-factor, signal power, and others. In optical communications, there are hundreds of channels in a single fiber, in which each channel suffers performance degradations differently because optical amplifiers do not have a flat gain over all channels and/or because photon-matter non-linear interactions are channel selective. In communication, this is addressed with channel performance monitoring and channel equalization; current practices perform equalization on a per channel basis and not in real-time. In this paper, we review optical channel performance and a statistical performance estimation method. Based on this method, we describe the functional blocks of a statistical performance estimation circuit (SPEC). Using the SPEC, we describe a method and a protocol for multiple channel equalization in-service and in real-time.