Guaranteeing the BER in transparent optical networks using OOKsignaling

摘要

A network consisting of transparent optical nodes (TONs) cannprovide high speed end-to-end communication paths with very lownbit-error rates (BERs). However, owing to component crosstalk and otherndegradations at TONs, the BER of a particular communication pathntraversing several TONs can be degraded by a few orders of magnitudeneven in the absence of component failure. Monitoring thenquality-of-service (QoS) of a communication path has typically relied onnsporadic BER testing and operation monitoring by the nodes using probensignals. Intermittent BER testing cannot provide continuous monitoringnof the network QoS. On the other hand, the use of probe signals is notnsensitive enough to detect the BER degradation. This work investigates annovel approach of monitoring service degradation at individual nodesnusing a wrap-around device which taps and compares signals from theninput and the output at each TON along the lightpath. We propose anmodification using hard limiters at TON inputs and derive the BER valuenthat this modified method can guarantee in the presence of signalndegradation due to coherent crosstalk at TONs