Flexible placement of spectral inverters in optical networks

1. A method for placement of spectral inverters in an optical network, comprising:

identifying a first transmission path coupling a transmitter and a receiver, the first transmission path including a first node for assignment of a first spectral inverter;

estimating a first optical signal-to-noise ratio (OSNR) penalty of nonlinear phase noise (NLPN) on the first transmission path with the first spectral inverter assigned to the first node by

evaluating the OSNR penalty of NLPN from the transmitter to the receiver and from the receiver to the transmitter, and

selecting the higher OSNR penalty of NLPN as the first estimated OSNR penalty of NLPN; and

based on the first estimated OSNR penalty of NLPN being less than an NLPN penalty threshold, assigning the first spectral inverter to the first node.

2. The method of claim 1 , wherein the first node is located asymmetrically between the transmitter and the receiver.

3. The method of claim 1 , further comprising identifying a second node in the first transmission path for assignment of the first spectral inverter, wherein assigning the first spectral inverter to the second node is further based on:

estimating a second OSNR penalty of NLPN based on the first spectral inverter placed at the second node; and

determining the second estimated OSNR penalty of NLPN is equal to or greater than the first estimated OSNR penalty of NLPN.

4. The method of claim 1 , further comprising determining if an optical signal from the transmitter can be received by the receiver with the use of the spectral inverter.

5. The method of claim 1 , further comprising:

identifying a second transmission path between the transmitter and the receiver, the second transmission path including a second node for assignment of the first spectral inverter;

estimating a second OSNR penalty of NLPN on the second transmission path with the first spectral inverter assigned to the second node of the second transmission path; and

determining the second OSNR penalty of NLPN on the second transmission path is greater than the first NLPN on the first transmission path.

6. The method of claim 1 , further comprising:

based on the first OSNR penalty of NLPN being equal to or greater than an NLPN penalty threshold, determining if a second spectral inverter can be assigned to a second node on the first transmission path.

7. An optical network system for placement of spectral inverters, comprising:

a transmitter;

a receiver coupled to receive a signal transmitted by the transmitter;

a first transmission path coupling the transmitter and the receiver, the first transmission path including a first node;

a first spectral inverter assigned to the first node on the first transmission path, the first node selected for assignment based on:

estimating a first optical signal-to-noise ratio (OSNR) penalty of nonlinear phase noise (NLPN) on the first transmission path with the first spectral inverter assigned to the first node by

evaluating the OSNR penalty of NLPN from the transmitter to the receiver and from the receiver to the transmitter, and

selecting the higher OSNR penalty of NLPN as the first estimated OSNR penalty of NLPN; and

based on the first estimated OSNR penalty of NLPN being less than an NLPN penalty threshold, assigning the first spectral inverter to the first node.

8. The optical network system of claim 7 , wherein the first node is located asymmetrically between the transmitter and the receiver.

9. The optical network system of claim 7 , further comprising the first transmission path including a second node, and wherein assigning the first spectral inverter to the first node is further based on:

estimating a second OSNR penalty of NLPN based on the first spectral inverter placed at the second node; and

determining the second estimated OSNR penalty of NLPN is equal to or greater than the first estimated OSNR penalty of NLPN.

10. The optical network system of claim 7 , wherein the first node selected for assignment is further based on determining if an optical signal from the transmitter can be received by the receiver with the use of the spectral inverter.

11. The optical network system of claim 7 , further comprising:

a second transmission path between the transmitter and the receiver, the second transmission path including a second node for assignment of the first spectral inverter; and wherein the first node selected for assignment is further based on:

estimating a second OSNR penalty of NLPN on the second transmission path with the first spectral inverter assigned to the second node of the second transmission path; and

determining the second OSNR penalty of NLPN on the second transmission path is greater than the first OSNR penalty of NLPN on the first transmission path.

12. The optical network system of claim 7 , wherein the first node selected for assignment is further based on:

determining if the first OSNR penalty of NLPN is equal to or greater than an NLPN penalty threshold; and

determining if a second spectral inverter can be assigned to a second node on the first transmission path.

13. A system for placement of spectral inverters, comprising:

a processor configured to access non-transitory computer readable memory media, wherein the memory media store processor-executable instructions, the instructions, when executed by a processor, cause the processor to:

identify a first transmission path coupling a transmitter and a receiver, the first transmission path including a first node for assignment of a first spectral inverter;

estimate a first optical signal-to-noise ratio (OSNR) penalty of nonlinear phase noise (NLPN) on the first transmission path with the first spectral inverter assigned to the first node by

evaluating the OSNR penalty of NLPN from the transmitter to the receiver and from the receiver to the transmitter, and

selecting the higher OSNR penalty of NLPN as the first estimated OSNR penalty of NLPN; and

based on the first estimated OSNR penalty of NLPN being less than an NLPN penalty threshold, assign the first spectral inverter to the first node.

14. The system of claim 13 , wherein the first node is located asymmetrically between the transmitter and the receiver.

15. The system of claim 13 , further comprising instructions to identify a second node in the first transmission path for assignment of the first spectral inverter, wherein the instructions to assign the first spectral inverter to the first node include instructions to:

estimate a second OSNR penalty of NLPN based on the first spectral inverter placed at the second node; and

determine the second estimated OSNR penalty of NLPN is equal to or greater than the first estimated NLPN.

16. The system of claim 13 , further comprising instructions to determine if an optical signal from the transmitter can be received by the receiver with the use of the spectral inverter.

17. The system of claim 13 , further comprising instructions to:

identify a second transmission path between the transmitter and the receiver, the second transmission path including a second node for assignment of the first spectral inverter;

estimate a second OSNR penalty of NLPN on the second transmission path with the first spectral inverter assigned to the second node of the second transmission path; and

determine the second OSNR penalty of NLPN on the second transmission path is greater than the first OSNR penalty of NLPN on the first transmission path.