Drop-link monitoring in Passive Optical Networks

Capabilities to monitor drop-links in Passive Optical Networks are discussed in this paper. Main techniques are evaluated in terms of accuracy and sensitivity of detecting a fault beyond the optical remote node followed by energy-efficiency considerations of those. Some estimates of signal-to-crosstalk ratio are recalled justifying the possibility of partial by-pass of loss incurred by the Optical Time Domain Reflectometer signal in the remote node.