# US 10,873,411 B1 · Optimizing spectral efficiency for a configuration of an optical network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,411 B1 - Document ID: US10873411B1 - Status: Granted - Kind: B1 - Application number: 16/661,381 - Filed: 2019-10-23 - Granted: 2020-12-22 - Earliest claimed: 2019-10-23 - Assignees: Cisco Technology, Inc. - Applicants: Cisco Technology, Inc. - Inventors: Giovanni Marenco; Claudio Crognale; Davide Sirtori - Web page: https://patentgrep.com/patent/US10873411B1 ## CPC - H04J 14/0227: {Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation} - H04B 10/07953: {Monitoring or measuring OSNR, BER or Q} - H04B 10/27: Arrangements for networking - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04B: TRANSMISSION ## Abstract A method of configuring an optical link with an optimized spectral efficiency and bit rate is provided. The method includes obtaining, by a controller of an optical network, a baseline configuration that includes a traffic mode that uses a predetermined channel spacing of a plurality of channels in a frequency spectrum. The plurality of channels are used for transmitting optical signals on an optical link in the optical network. The method further includes selecting three contiguous channels that include a center channel and two adjacent channels and while maintaining a performance parameter above or equal to a threshold value, moving the adjacent channels closer to the center channel and varying at least one transmission parameter, thereby reducing a spacing of the center channel. As such, a spectral frequency map is generated in which the channel spacing is reduced and an optical link is configured based on the spectral frequency map. ## Claims ### Claim 1 A method comprising: obtaining, by a controller of an optical network, a baseline configuration that includes a traffic mode that uses a predetermined channel spacing of a plurality of channels in a frequency spectrum, wherein the plurality of channels are used for transmitting optical signals on an optical link in the optical network; selecting, by the controller, three contiguous channels from among the plurality of channels of the frequency spectrum, wherein the three contiguous channels include a center channel and two adjacent channels; while maintaining a performance parameter above or equal to a threshold value, moving, by the controller, the two adjacent channels closer to the center channel, and varying, by the controller, at least one transmission parameter, thereby reducing a spacing of the center channel with respect to the two adjacent channels; generating, by the controller, a spectral frequency map in which the channel spacing is reduced with respect to the baseline configuration based on reducing the spacing of the center channel; and configuring, by the controller via an optical network element in the optical network, the optical link based on the spectral frequency map. ### Claim 2 (depends on 1) The method of claim 1, wherein selecting the three contiguous channels, moving the adjacent channels, and varying the at least one transmission parameter, are iteratively performed across a selected portion of the frequency spectrum based on a predetermined mapping granularity. ### Claim 3 (depends on 1) The method of claim 1, wherein the moving the adjacent channels and the varying of the at least one transmission parameter includes: increasing a value of the at least one transmission parameter on the center channel; shrinking the channel spacing of the two adjacent channels; measuring the performance parameter of the center channel; and determining whether the performance parameter of the center channel is above or equal to the threshold value. ### Claim 4 (depends on 3) The method of claim 3, wherein the moving the adjacent channels and the varying of the at least one transmission parameter further includes: based on determining that the performance parameter of the center channel is above or equal to the threshold value, increasing the value of the at least one transmission parameter, further shrinking the channel spacing of the two adjacent channels, and measuring the performance parameter of the center channel; and based on determining that the performance parameter of the center channel is less than the threshold value, decreasing the at least one transmission parameter to a previous value and returning the two adjacent channels to a previous channel spacing, thereby obtaining a tuned configuration of the center channel, and wherein generating the spectral frequency map includes applying the tuned configuration of the center channel to the spectral frequency map. ### Claim 5 (depends on 3) The method of claim 3, further comprising: selecting, by the controller, next three contiguous channels from among the plurality of channels of the frequency spectrum based on a predetermined mapping granularity; and moving the adjacent channels and varying the at least one transmission parameter for the next three contiguous channels to obtain a tuned configuration of the center channel of the next three contiguous channels, wherein the at least one transmission parameter includes a bit per symbol rate or a baud rate and the performance parameter includes a Q-factor, a bit error rate, or a forward error correction. ### Claim 6 (depends on 3) The method of claim 3, wherein measuring the performance parameter includes: measuring a bit error rate on the center channel; and deriving a Q-margin based on the bit error rate, wherein the transmission parameter includes a bits per symbol rate or a baud rate. ### Claim 7 (depends on 1) The method of claim 1, further comprising: interpolating the spectral frequency map to progressively shrink the plurality of channels of the frequency spectrum by minimizing bandwidth allocated to the plurality of channels and maximizing spectral efficiency at a predetermined line rate. ### Claim 8 (depends on 1) The method of claim 1, wherein obtaining the baseline configuration includes: determining whether the performance parameter of the optical link is available, the performance parameter including a signal-to-noise ratio; determining whether the performance parameter includes a plurality of performance related distribution values across the frequency spectrum; and setting the baseline configuration based on the performance parameter. ### Claim 9 (depends on 8) The method of claim 8, wherein setting the baseline configuration includes: setting the traffic mode to a default traffic mode based on the performance parameter not being available. ### Claim 10 (depends on 1) The method of claim 1, further comprising: determining an optimal traffic mode in which a line rate is optimized while keeping the performance parameter equal to or above the threshold value; and applying the optimal traffic mode to the baseline configuration. ### Claim 11 An apparatus comprising: a communication interface configured to enable network communications; a memory configured to store executable instructions; and a processor coupled to the communication interface and the memory and configured to perform operations including: obtaining a baseline configuration that includes a traffic mode that uses a predetermined channel spacing of a plurality of channels in a frequency spectrum, wherein the plurality of channels are used for transmitting optical signals on an optical link in an optical network; selecting three contiguous channels from among the plurality of channels of the frequency spectrum, wherein the three contiguous channels include a center channel and two adjacent channels; while maintaining a performance parameter above or equal to a threshold value, moving the adjacent channels closer to the center channel, and varying at least one transmission parameter, thereby reducing a spacing of the center channel with respect to the two adjacent channels; generating a spectral frequency map in which the channel spacing is reduced with respect to the baseline configuration based on reducing the spacing of the center channel; and configuring, via an optical network element in the optical network, the optical link based on the spectral frequency map. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein the processor is configured to iteratively perform selecting the three contiguous channels, moving the adjacent channels, and varying the at least one transmission parameter, across a selected portion of the frequency spectrum based on a predetermined mapping granularity. ### Claim 13 (depends on 11) The apparatus of claim 11, wherein the processor is configured to move the adjacent channels and to vary the at least one transmission parameter by: increasing a value of the at least one transmission parameter on the center channel; shrinking the channel spacing of the two adjacent channels; measuring the performance parameter of the center channel; and determining whether the performance parameter of the center channel is above or equal to the threshold value. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the processor is configured to move the two adjacent channels and to vary the at least one transmission parameter by: based on determining that the performance parameter of the center channel is above or equal to the threshold value, increasing the value of the at least one transmission parameter, further shrinking the channel spacing of the two adjacent channels, and measuring the performance parameter of the center channel; and based on determining that the performance parameter of the center channel is less than the threshold value, decreasing the at least one transmission parameter to a previous value and returning the two adjacent channels to a previous channel spacing, thereby obtaining a tuned configuration of the center channel, and wherein the processor is configured to generate the spectral frequency map by applying the tuned configuration of the center channel to the spectral frequency map. ### Claim 15 (depends on 13) The apparatus of claim 13, wherein the processor is further configured to: select next three contiguous channels from among the plurality of channels of the frequency spectrum based on a predetermined mapping granularity; and move the adjacent channels and vary the at least one transmission parameter for the next three contiguous channels to obtain a tuned configuration of the center channel of the next three contiguous channels, wherein the at least one transmission parameter includes a bit per symbol rate or a baud rate and the performance parameter includes a Q-factor, a bit error rate, or a forward error correction. ### Claim 16 One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor, cause the processor to perform operations including: obtaining a baseline configuration that includes a traffic mode that uses a predetermined channel spacing of a plurality of channels in a frequency spectrum, wherein the plurality of channels are used for transmitting optical signals on an optical link in an optical network; selecting three contiguous channels from among the plurality of channels of the frequency spectrum, wherein the three contiguous channels include a center channel and two adjacent channels; while maintaining a performance parameter above or equal to a threshold value, moving the adjacent channels closer to the center channel and varying at least one transmission parameter, thereby reducing a spacing of the center channel with respect to the two adjacent channels; generating a spectral frequency map in which the channel spacing is reduced with respect to the baseline configuration based on reducing the spacing of the center channel; and configuring, via an optical network element in the optical network, the optical link based on the spectral frequency map. ### Claim 17 (depends on 16) The one or more non-transitory computer readable storage media according to claim 16, wherein the instructions further cause the processor to iteratively perform selecting the three contiguous channels, moving the two adjacent channels, and varying the at least one transmission parameter, across a selected portion of the frequency spectrum based on a predetermined mapping granularity. ### Claim 18 (depends on 16) The one or more non-transitory computer readable storage media according to claim 16, wherein the instructions cause the processor to move the two adjacent channels and to vary the at least one transmission parameter by: increasing a value of the at least one transmission parameter on the center channel; shrinking the channel spacing of the two adjacent channels; measuring the performance parameter of the center channel; and determining whether the performance parameter of the center channel is above or equal to the threshold value. ### Claim 19 (depends on 18) The one or more non-transitory computer readable storage media according to claim 18, wherein the instructions cause the processor to move adjacent channels and to vary the at least one transmission parameter by: based on determining that the performance parameter of the center channel is above or equal to the threshold value, increasing the value of the at least one transmission parameter, further shrinking the channel spacing of the two adjacent channels, and measuring the performance parameter of the center channel; and based on determining that the performance parameter of the center channel is less than the threshold value, decreasing the at least one transmission parameter to a previous value and returning the two adjacent channels to a previous channel spacing, thereby obtaining a tuned configuration of the center channel, and wherein the instructions cause the processor to generate the spectral frequency map by applying the tuned configuration of the center channel to the spectral frequency map. ### Claim 20 (depends on 18) The one or more non-transitory computer readable storage media according to claim 18, wherein the instructions further cause the processor to perform additional operations of: selecting next three contiguous channels from among the plurality of channels of the frequency spectrum based on a predetermined mapping granularity; and moving the two adjacent channels and vary the at least one transmission parameter for the next three contiguous channels to obtain a tuned configuration of the center channel of the next three contiguous channels, wherein the at least one transmission parameter includes a bit per symbol rate or a baud rate and the performance parameter includes a Q-factor, a bit error rate, or a forward error correction.