Optical supervisory channel

Patent metadata

Field	Value
Publication number	US-9544050-B2
Application number	US-201114356929-A
Country	US
Kind code	B2
Filing date	Nov 9, 2011
Priority date	Nov 9, 2011
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A supervisory channel is provided on an optical path ( 31 ) between nodes of an optical communication network. The nodes are arranged to use a set of wavelengths allocated for carrying traffic channels. An optical signal ( 16 ) which carries a supervisory channel is generated at a supervisory channel transmitter ( 15 ) and added ( 12 ) to the optical path ( 31 ) downstream of an optical amplifier ( 11 ). The optical signal ( 16 ) has a wavelength which is one of the set of wavelengths allocated for carrying traffic. The method is performed at a time when the wavelength is not being used to carry traffic. An impairment parameter of the received optical signal is measured at a supervisory channel receiver ( 15 ). The receiver is a coherent receiver and the impairment parameter is chromatic dispersion or polarization mode dispersion.

First claim

The invention claimed is:

1. A method of providing a supervisory channel on an optical path between a first node and a second node of an optical communication network, the first node comprising an optical amplifier, the first node being arranged to use a set of wavelengths normally used for carrying traffic channels, the method comprising:
the first node generating an optical signal which carries a supervisory channel at a supervisory channel transmitter; and
the first node adding the optical signal to the optical path downstream of the optical amplifier, wherein
the optical signal has a wavelength which is one of the wavelengths normally used for carrying traffic,
the first node performs the method at a time when the wavelength is not being used to carry traffic, and
the step of adding the optical signal to the optical path downstream of the optical amplifier consists of adding the optical signal to the optical path at a point of the optical path that is located between an output of the optical amplifier and an input of the second node, wherein
the supervisory channel transmitter comprises an optical source which is capable of operating at any of the set of wavelengths normally used for carrying traffic channels, and the step of generating an optical signal comprises tuning the optical source to a selected wavelength within the set of wavelengths normally used to carry traffic.

2. The method according to claim 1 , further comprising blocking passage of the optical signal during periods when the optical source of the supervisory channel transmitter is tuned to a different wavelength.

3. The method according to claim 1 , further comprising sequentially generating a plurality of optical signals, wherein
each one of the sequentially generated optical signals carries a supervisory channel,
each one of the sequentially generated optical signals is sequentially added to the optical path downstream of the optical amplifier,
each one of the sequentially generated optical signals has a different wavelength than each one of the other sequentially generated optical signals, and
each one of the sequentially generated optical signals has a wavelength that is normally used for carrying traffic.

4. The method of claim 1 , wherein the step of generating an optical signal by a supervisory channel transmitter comprises generating an optical signal having a bit rate which is less than a bit rate of a signal which will be used to carry traffic on the same wavelength.

5. The method of claim 1 , further comprising receiving supervisory data from another node of the optical communications network at the first node and wherein the supervisory channel transmitted by the first node carries at least some of the received supervisory data.

6. A computer program product comprising a non-transitory computer readable medium storing instructions which, when executed by a processor, cause the processor to perform the method of claim 1 .

7. A method of providing a supervisory channel on an optical path between an output of an optical amplifier of a first node of an optical communication network and an input of an optical amplifier of a second node of the optical communication network, the first and second nodes being arranged to use a set of wavelengths allocated for carrying traffic channels, the method comprising:
removing from the optical path at a point located upstream of the optical amplifier of the second node an optical signal that carries a supervisory channel, wherein the optical signal was added to the optical path a point located between the output of the optical amplifier of the first node and the input of the optical amplifier of the second node;
receiving the optical signal at a supervisory channel receiver; and
measuring at least one impairment parameter of the received optical signal, wherein
the optical signal has a wavelength which is one of the set of wavelengths allocated for carrying traffic,
the method is performed at a time when the wavelength is not being used to carry traffic, and
the step of removing the optical signal from the optical path at a point located upstream of the optical amplifier consists of removing the optical signal from the optical path at a point that is located between the input of the optical amplifier and the output of the first node, wherein
the supervisory channel receiver is a coherent receiver and the at least one impairment parameter is one of: chromatic dispersion (CD) and polarization mode dispersion (PMD).

8. The method according to claim 7 , wherein the supervisory channel receiver is a coherent receiver and the at least one impairment parameter is polarization mode dispersion (PMD).

9. The method according to claim 7 , further comprising sending the measurement of the at least one impairment parameter to another network node.

10. The method of claim 7 , further comprising causing the supervisory channel receiver to sequentially operate at each of a plurality of the set of wavelengths which are normally used to carry traffic channels.

11. A method of acquiring impairment parameter values for an optical path between a first node and a second node of an optical communication network comprising:
controlling the first node of the network to perform the method according to claim 1 at a first wavelength; and
controlling the second node of the network to perform a method comprising:
removing from the optical path at a point located upstream of the optical amplifier of the second node an optical signal that carries a supervisory channel;
receiving the optical signal at a supervisory channel receiver; and
measuring at least one impairment parameter of the received optical signal.

12. The method according to claim 11 , further comprising at least one of:
using the impairment value in a routing and/or wavelength assignment process;
using the impairment value to validate a previously calculated route; and
using the impairment value to monitor transmission quality of the span.

13. An apparatus for use at a first node of an optical communication network for providing a supervisory channel on an optical path between an output of an optical amplifier of the first node and an input of a second node of the optical communication network, the first node being arranged to use a set of wavelengths allocated for carrying traffic channels, the apparatus comprising:
a supervisory channel transmitter for generating an optical signal carrying the supervisory channel;
an optical coupler for adding the optical signal to the optical path at a point of the optical path located between the output of the optical amplifier and the input of the second node, wherein
the optical signal has a wavelength which is one of the set of wavelengths normally used for carrying traffic, and
the supervisory channel transmitter is arranged to generate the optical signal when the wavelength is not being used to carry traffic.

14. An apparatus, the apparatus comprising:
an optical filter for removing an optical signal from an optical path optically connecting an output of an optical amplifier of a first node and an input of an optical amplifier of a second node, wherein the optical signal carries a supervisory channel, and wherein the optical filter is configured to remove the optical signal from the optical path at a position of the optical path that is located between the output of the first node and the input of the optical amplifier; and
a supervisory channel receiver arranged to receive the optical signal and to measure at least one impairment parameter of the received optical signal, wherein
the optical signal has a waveleng

Assignees

• Cavaliere Fabio
• Bottari Giulio
• ERICSSON TELEFON AB L M (publ)

Inventors

• Cavaliere Fabio
• Bottari Giulio

Classifications

• H04B10/0775 Primary

  Performance monitoring and measurement of transmission parameters · CPC title

• H04J14/025

  using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU · CPC title

• H04J14/0282 Primary

  WDM tree architectures · CPC title

• H04J14/0247

  Sharing one wavelength for at least a group of ONUs · CPC title

• H04J14/0234

  using multiple wavelengths · CPC title