Abstract: A method (100) for facilitating Optical Supervisory Channel (OSC) communications between a main site and a plurality of remote sites in an optical network is disclosed. The main and remote sites are comprised within a Radio Access Network and the main and remote sites are connected via a point to multipoint optical infrastructure. The method comprises receiving an OSC signal on an OSC from the main site (120), sequentially routing OSC signals on the OSC to each of the remote sites in a daisy chain configuration (140) and returning an OSC signal received on the OSC from a last of the remote sites in the daisy chain configuration to the main site (160), the OSC being transported over the point to multipoint optical infrastructure (170). Also disclosed are a method (500) for performing OSC communications in an optical network, a hub node (300, 400), a remote site node (600, 800) and a system (900) for communications in an optical network.

Abstract: According to embodiments of the present disclosure, apparatus is provided for protecting an optical link arranged to carry upstream optical signals and downstream optical signals. The apparatus comprises a first detector arranged to selectively detect a downstream optical signal received at a second port having a first wavelength and a second detector arranged to selectively detect a downstream optical signal received at the second port having a second wavelength different from the first wavelength. The apparatus further comprises control circuitry arranged to cause a protection switch to selectively couple a third port to the second port instead of to the first port based on the detecting by the first detector and the second detector. Also provided is a second apparatus for protecting the optical link.

Abstract: A method (100) for facilitating Optical Supervisory Channel (OSC) communications between a main site and a plurality of remote sites in an optical network is disclosed. The main and remote sites are comprised within a Radio Access Network and the main and remote sites are connected via a point to multipoint optical infrastructure. The method comprises receiving an OSC signal on an OSC from the main site (120), sequentially routing OSC signals on the OSC to each of the remote sites in a daisy chain configuration (140) and returning an OSC signal received on the OSC from a last of the remote sites in the daisy chain configuration to the main site (160), the OSC being transported over the point to multipoint optical infrastructure (170). Also disclosed are a method (500) for performing OSC communications in an optical network, a hub node (300, 400), a remote site node (600, 800) and a system (900) for communications in an optical network.

Abstract: According to embodiments of the present disclosure, apparatus is provided for protecting an optical link arranged to carry upstream optical signals and downstream optical signals. The apparatus comprises a first detector arranged to selectively detect a downstream optical signal received at a second port having a first wavelength and a second detector arranged to selectively detect a downstream optical signal received at the second port having a second wavelength different from the first wavelength. The apparatus further comprises control circuitry arranged to cause a protection switch to selectively couple a third port to the second port instead of to the first port based on the detecting by the first detector and the second detector. Also provided is a second apparatus for protecting the optical link.

Abstract: A bidirectional WDM optical communications link has WDM signals sent in opposite directions along a shared optical path and using at least one common wavelength. An optical amplifier (20, 21, 22, 70, A1D, A2U, A2D) optically amplifies (144) a first WDM signal separately from a second WDM signal in the other direction. This separated optical amplification is controlled (134) according to indications of transmission quality at the common wavelength, to alter the relative optical powers of the first and second WDM signals to enable crosstalk at the common wavelength to be limited. Cross talk at the common wavelength can be improved by rebalancing relative amounts of cross talk in the different directions, to enable the capacity benefits of using a common wavelength for both directions to be obtained while using greater optical signal power. This is particularly useful where the optical power is asymmetric, such as in WDM PON systems.

Abstract: A bidirectional WDM optical communications link has WDM signals sent in opposite directions along a shared optical path and using at least one common wavelength. An optical amplifier (20, 21, 22, 70, A1D, A2U, A2D) optically amplifies (144) a first WDM signal separately from a second WDM signal in the other direction. This separated optical amplification is controlled (134) according to indications of transmission quality at the common wavelength, to alter the relative optical powers of the first and second WDM signals to enable crosstalk at the common wavelength to be limited. Cross talk at the common wavelength can be improved by rebalancing relative amounts of cross talk in the different directions, to enable the capacity benefits of using a common wavelength for both directions to be obtained while using greater optical signal power. This is particularly useful where the optical power is asymmetric, such as in WDM PON systems.