Systems and methods for channel additions over multiple cascaded optical nodes

• US 9,276,696 B2
• Filed: 10/19/2012
• Issued: 03/01/2016
• Est. Priority Date: 10/19/2012
• Status: Active Grant

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Al Sayeed, Choudhury A., Bownass, David C., Berg, Loren S., Boertjes, David W.
• Primary Examiner(s): Vanderpuye, Ken
• Assistant Examiner(s): LEE, JAI M
• Application Number:
  US13/655,567
• Publication Number:
  US 20140112660A1
• Time in Patent Office: 1,229 Days
• Field of Search: 398/94
• US Class Current: 1/1
• CPC Class Codes: H04B 10/0793 Network aspects, e.g. central monitoring of transmission parameters
• CPC Class Codes: H04B 10/07955 Monitoring or measuring power
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04J 14/02219 Distributed control

Abstract

A method, an optical node, and an optical network include a power controller configured to bring channels in-service in parallel over multiple cascaded optical nodes quickly, efficiently, and in a non-service affecting manner. The method, node, and network utilize multiple states of a control loop that maintains a stable response in downstream optical nodes as channels are added in parallel. Further, the power controller is configured to operate independently alleviating dependencies on other power controllers and removing the need for coordination between power controllers. The method, node, and network provide efficient turn up of dense wave division multiplexing (DWDM) services which is critical to optical layer functionality including optical layer restoration.

Claims

1. A method, comprising:

introducing a channel through a first node and a second node, wherein the channel is introduced simultaneously over the first node and the second node;

measuring power of the channel entering the first node and the channel entering the second node;

determining a first measured error of the channel based on a first target power and the measured power at the first node and a second measured error of the channel based on a second target power and the measured power at the second node;

performing a control loop using the first measured error at the first node and using the second measured error at the second node, wherein the first node and the second node perform the control loop simultaneously and independently of one another, and wherein each of the first node and the second node perform the control loop based only on their own measurements;

modifying parameters of the control loop at each of the first node and the second node with a plurality of states to maintain a stable response; and

adjusting power of the channel based on the modified control loop at each of the first node and the second node.

2. The method of claim 1, further comprising:

modifying the control loop at each of the first node and the second node to set a derivative coefficient to zero if an overshoot is detected in a previous iteration of the control loop.

3. The method of claim 1, further comprising:

modifying the control loop at each of the first node and the second node to select coefficients in such a way that a response remains always damped until complete convergence.

4. The method of claim 1, further comprising:

performing the control loop initially at each of the first node and the second node with coefficients selected for a damped unit step response;

modifying the control loop at the first node with a first damping factor once absolute magnitude of the first measured error is below a first threshold when the first node is not an ingress node for the channel;

modifying the control loop at the second node with the first damping factor once absolute magnitude of the second measured error is below the first threshold when the second node is not an ingress node for the channel;

modifying the control loop at the first node with a second damping factor once absolute magnitude of the first measured error is below a second threshold when the first node is not an ingress node for the channel; and

modifying the control loop at the second node with the second damping factor once absolute magnitude of the second measured error is below the second threshold when the second node is not an ingress node for the channel.

5. The method of claim 4, further comprising:

setting a proportional coefficient and an integral coefficient of the coefficients to zero at the first node when the first measured error is below the second threshold; and

setting the proportional coefficient and the integral coefficient of the coefficients to zero at the second node when the second measured error is below the second threshold.

6. The method of claim 1, further comprising:

modifying the control loop at the second node with an expected error change offset to dampen a response due to variable input power from the first node.

7. The method of claim 1, further comprising:

determining a first drive offset parameter for each iteration of the control loop to compensate for plant drift and aging effects at the first node; and

determining a second drive offset parameter for each iteration of the control loop to compensate for plant drift and aging effects at the second node.

8. The method of claim 1, wherein the first node and the second node utilize a same set of parameters and a same set of rules for adjusting the parameters, and wherein the first node and the second node do not communicate with one another with respect to the control loop.

9. The method of claim 8, wherein the second node is downstream from the first node, and wherein the second node utilizes the control loop and associated modifications to adjust the power of the channel while the first node is converging to its target power.

10. The method of claim 1, wherein the channel comprises a first channel, and further comprising:

introducing a second channel through the first node and the second node, wherein the second channel is introduced in parallel over the first node and the second node; and

performing the measuring, the determining, the performing, the modifying, and the adjusting steps with respect to the second channel independent of the first channel with independent parameters.

11. The method of claim 1, further comprising:

adjusting the power of the channel based on the modified control loop at each of the first node and the second node with any of a wavelength selective switch, a variable optical attenuator, an optical amplifier, and a dynamic gain equalizer.

12. The method of claim 1, wherein the channel comprises any of a wavelength, a group of wavelengths, a range of wavelengths, and a band of wavelengths.

13. An optical node, comprising:

at least one degree comprising components configured to selectively alter power of a channel being added to the at least one degree;

an optical power monitor measuring an output power of the channel out of the at least one degree; and

a power controller communicatively coupled to the at least one degree and the optical power monitor, wherein the power controller is configured to;

measure power of the channel being added to the at least one degree, wherein the channel is being added simultaneously over at least one additional node;

determine a measured error of the channel based on a target power and the measured power;

perform a control loop using the measured error, wherein the at least one additional node performs the control loop simultaneously and independently of the optical node, and wherein each of the optical node and the at least one additional node perform the control loop based only on their own measurements;

modify parameters of the control loop with a plurality of states to maintain a stable response; and

adjust power of the channel based on the modified control loop using the components to selectively alter the power.

14. The optical node of claim 13, wherein the power controller is further configured to:

modify the control loop to set a derivative coefficient to zero if an overshoot is detected in a previous iteration of the control loop.

15. The optical node of claim 13, wherein the power controller is further configured to:

modify the control loop to select coefficients in such a way that a response remains always damped until complete convergence.

16. The optical node of claim 13, wherein the power controller is further configured to:

perform the control loop initially with coefficients selected for a damped unit step response;

modify the control loop with a first damping factor once absolute magnitude of the measured error is below a first threshold when the optical node is not an ingress node for the channel; and

modify the control loop with a second damping factor once absolute magnitude of the measured error is below a second threshold when the optical node is not an ingress node for the channel.

17. The optical node of claim 13, wherein the at least one additional node performs the control loop in parallel with the optical node utilizing a same set of coefficients;

and wherein the power controller is further configured to;

modify the control loop at the optical node with an expected error change offset to dampen a response due to variable input power from the at least one additional node.

18. The optical node of claim 13, wherein the power controller is further configured to:

determine a drive offset parameter for each iteration of the control loop to compensate for plant drift and aging effects.

19. The optical node of claim 13, wherein the channel comprises a first channel, and wherein the power controller is further configured to:

detect a second channel being added to the at least one degree; and

perform the measure, the determine, the perform, the modify, and the adjust steps with respect to the second channel independent of the first channel with independent parameters.

20. An optical network, comprising:

N nodes interconnected therebetween, wherein each of the N nodes comprises;

at least one degree comprising components configured to selectively modify power of a channel being added thereto;

an optical power monitor measuring a power of the channel at least one degree; and

a power controller communicatively coupled to the at least one degree and the optical power monitor; and

a channel being added to M nodes of the N nodes simultaneously, M <

N;

wherein the power controller at each of the M nodes is configured to;

measure power of the channel through the at least one degree;

determine a measured error of the channel based on a target power and the measured power;

simultaneously and independently perform a control loop using the measured error, and wherein each of the M nodes perform the control loop based only on their own measurements;

modify parameters of the control loop with a plurality of states to maintain a stable response; and

adjust power of the channel based on the modified control loop using the components to selectively alter the power.