Optical network unit, central office node and methods of configuring an optical network unit

A central office (CO) node for a passive optical network (PON), the CO node comprising:

• a plurality of optical line terminations (OLTs) operable at respective channel wavelengths of the PON, one of the OLTs being allocated to a control channel;
• and
• a controller comprising at least one processor and memory containing instructions executable by the at least one processor whereby the CO node is operative to:
• transmit a downstream control channel signal from the allocated OLT at a downstream control channel wavelength;
• determine allocated operating wavelengths for an Optical Network Unit (ONU) of the PON;
• and
• transmit a further downstream control channel signal from the allocated OLT at the downstream control channel wavelength, the further downstream control channel signal carrying an indication of the allocated operating wavelengths for the ONU;
• wherein to determine allocated operating wavelengths the CO node is operative to either:
• (a) receive at the allocated OLT an upstream control channel signal from the ONU at an upstream control channel wavelength, the upstream control channel signal carrying an indication of an identification (ID) of the ONU and determine the allocated operating wavelengths for the ONU depending on the ID;
• or
• (b) obtain operating wavelengths from a wavelengths allocation table contained in the memory until all wavelengths within the wavelengths allocation table have been allocated and then use the control channel wavelengths as operating wavelengths for a final ONU.

A method of configuring an optical network unit (ONU) of a passive optical network (PON), the ONU comprising a tunable transmitter and a tunable receiver, the method comprising steps of:

• if the tunable transmitter is on, switching the tunable transmitter off and if the tunable receiver is off, switching the tunable receiver on;
• determining an availability of a control channel;
• receiving a downstream control channel signal at a downstream control channel wavelength from a central office (CO) node of the PON, the downstream control channel signal carrying an indication of allocated operating wavelengths for the ONU;
• setting an operating wavelength of the tunable receiver to an allocated operating wavelength and setting the operating wavelength of the tunable transmitter to an allocated operating wavelength;
• and
• switching the tunable transmitter on.

A method of controlling an operating wavelength of an optical network unit (ONU) of a passive optical network (PON), the ONU comprising a tunable transmitter and a tunable receiver, the method comprising steps at a central office (CO) node of the PON of:

• transmitting a downstream control channel signal from an Optical Line Terminal (OLT), allocated for a control channel from a plurality of optical line terminations (OLTs) operable at respective channel wavelengths of the PON, at a downstream control channel wavelength;
• determining allocated operating wavelengths for an ONU of the PON;
• and
• transmitting a further downstream control channel signal from the allocated OLT at the downstream control channel wavelength, the further downstream control channel signal carrying an indication of the allocated operating wavelengths for the ONU;
• and
• wherein said determining allocated operating wavelengths comprises either:
• (a) receiving, at the OLT allocated for the control channel, an upstream control channel signal from the ONU at an upstream control channel wavelength, the upstream control channel signal carrying an indication of an identification (ID) of the ONU and determining the allocated operating wavelengths for the ONU depending on the ID;
• or
• (b) obtaining operating wavelengths from a wavelengths allocation table until all wavelengths within the wavelengths allocation table have been allocated and then use the control channel wavelengths as operating wavelengths for a final ONU.