# US 2008/0187313 A1 · Countermeasures for idle pattern SRS interference in ethernet optical network systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0187313 A1 - Document ID: US20080187313A1 - Status: Published application - Kind: A1 - Application number: 12/002,321 - Filed: 2007-12-14 - Published: 2008-08-07 - Earliest claimed: 2005-08-10 - Assignees: Enablence USA FTTX Networks Inc. - Inventors: James O. Farmer; Alan M. Brown; John J. Kenny; Stephen Thomas - Web page: https://patentgrep.com/patent/US20080187313A1 ## CPC - H04J 14/0226: {Fixed carrier allocation, e.g. according to service} - H04B 10/2537: due to scattering processes, e.g. Raman or Brillouin scattering - H04J 14/0227: {Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation} - H04J 14/0232: {for downstream transmission} - H04J 14/0247: {Sharing one wavelength for at least a group of ONUs} - H04J 14/0252: {Sharing one wavelength for at least a group of ONUs, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU} - H04J 14/0282: {WDM tree architectures} - 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 Optical networks as defined by the IEEE 802.3ah standard suffer from Stimulated Raman Scattering (SRS) that causes data transmission at a first optical wavelength to interfere with broadcast video transmission at a second optical wavelength in single mode optical fibers. The problem is exacerbated when data is not being transmitted across the network; and instead, an idle pattern transmission is being transmitted in order to keep the network synchronized. The repetitive nature of the idle pattern transmission leads to the SRS optical interference effect. This optical interference effect is mitigated when countermeasures are implemented to modify the idle pattern transmissions or to transmit random data in place of the idle pattern transmissions. ## Claims ### Claim at position 1 1-20. (canceled) ### Claim 21 A method for mitigating the effects of optical interference from optical data signals comprising the steps of: receiving input; determining whether the input comprises data and if the input comprises data, then converting the data from an electrical domain to a digital optical domain; determining whether the input comprises one of an absence of data and an idle pattern; if the input comprised one of an absence of data and an idle pattern, generating substitute data in an electrical domain that reduces power at one or more harmonics in the electrical domain such that a concentration of power in the digital optical domain is minimized when the substitute data is converted into the digital optical domain; in response to detecting one of an absence of data and an idle pattern, converting the substitute data from the electrical domain to the digital optical domain so that data transmission in the digital optical domain is substantially continuous when the input comprises one of an absence of data and an idle pattern; and propagating the substitute data in the digital optical domain. ### Claim 22 (depends on 21) The method of claim 21, wherein propagating the substitute data in the digital optical domain further comprises propagating the substitute data in the digital optical domain along with other optical signals in an analog optical domain through a single optical waveguide, the substitute data in the digital optical domain comprising minimal concentration of optical power for reducing any optical interference between the substitute data and the other optical signals caused by physical properties of the single optical waveguide combined with selected optical wavelengths and optical power of the substitute data and the other optical signals ### Claim 23 (depends on 21) The method of claim 21, wherein receiving input comprises receiving input from a routing device. ### Claim 24 (depends on 22) The method of claim 22, wherein propagating the substitute data in the digital optical domain along with other optical signals in an analog optical domain through a single optical waveguide comprises propagating the substitute data in the digital optical domain along with video information in an analog optical domain. ### Claim 25 (depends on 21) The method of claim 21, wherein the step of generating substitute data further comprises generating non-repetitive random data and assigning the random data to a non-existent MAC address. ### Claim 26 (depends on 21) The method of claim 21, wherein the step of generating substitute data further comprises alternating between different idle code pairs based upon a random variable function. ### Claim 27 (depends on 21) The method of claim 21, wherein determining whether the input comprises one of an absence of data and an idle pattern comprises determining whether the input comprises one of an absence of data and an idle pattern with a pattern recognition circuit. ### Claim 28 (depends on 21) The method of claim 21, wherein generating substitute data in an electrical domain that reduces power at one or more harmonics in the electrical domain comprises generating the substitute data with a shift register. ### Claim 29 A method for reducing optical interference between data and other information propagated over a single optical waveguide comprising: monitoring input in an electrical domain; determining whether the input comprises data and if the input comprises data, then converting the data from an electrical domain to a digital optical domain; determining if the input comprises one of an absence of data and an idle pattern; generating substitute data in the electrical domain that reduces power at one or more harmonics in the electrical domain such that a concentration of energy in the digital optical domain is minimized when the substitute data is converted into the digital optical domain; if the data comprises one of an absence of data and an idle pattern code, then converting the substitute data into the digital optical domain by modulating the substitute data on a digital optical carrier with a first optical wavelength so that data transmission in the digital optical domain is substantially continuous when the input comprises one of an absence of data and an idle pattern; and propagating the digital optical carrier along an optical waveguide, wherein the substitute data in the digital optical domain comprises minimal concentration of optical power for substantially reducing optical interference. ### Claim 30 (depends on 29) The method of claim 29, further comprising: receiving information in an electrical domain; and converting the information into an analog optical domain by modulating the information on an analog optical carrier having a second optical wavelength. ### Claim 31 (depends on 30) The method of claim 30, further comprising: combining the analog and digital optical carriers; and propagating the analog and digital optical carriers along the optical waveguide. ### Claim 32 (depends on 30) The method of claim 30, wherein the information comprises video information. ### Claim 33 (depends on 29) The method of claim 29, wherein the step of generating substitute data further comprises generating non-repetitive random data and assigning the random data to a non-existent MAC address. ### Claim 34 A method for reducing optical interference in a single optical waveguide comprising: generating random data assigned with a low priority that reduces power at one or more harmonics in the electrical domain such that a concentration of power in a digital optical domain is minimized when the random data is converted into the digital optical domain; determining if any higher priority data is present for digital optical transmission; if higher priority data is not present, then inserting the random data with the low priority for digital optical transmission so that data transmission in the digital optical domain is substantially continuous when higher priority data is not present; and converting the random data into the digital optical domain by modulating the random data on a digital optical carrier with a second optical wavelength ### Claim 35 (depends on 34) The method of claim 34, further comprising converting information other than data into an analog optical domain by modulating the other information on an analog optical carrier with a first optical wavelength; ### Claim 36 (depends on 35) The method of claim 35, further comprising combining the analog and digital optical carriers. ### Claim 37 (depends on 35) The method of claim 35, further comprising propagating the analog and digital optical carriers along the single optical waveguide wherein the random data comprising minimal concentration of optical power substantially reduces any optical interference between the analog and digital optical carriers caused by physical properties of the single optical waveguide combined with selected optical wavelengths and optical power of the random data and other information. ### Claim 38 (depends on 35) The method of claim 35, wherein the information other than data comprises video information. ### Claim 39 An optical network comprising: a routing device for assigning data to optical taps that are coupled to one or more subscribers; an idle pattern replacement device coupled to the routing device for determining whether data received from the routing device comprises one of an idle pattern and an absence of data, for generating substitute data in an electrical domain when one of an idle pattern and absence of data is detected so that data transmission in a digital optical domain is substantially continuous, the substitute data reducing power at one or more harmonics in the electrical domain such that a concentration of energy in the digital optical domain is minimized when the substitute idle pattern is converted into the optical domain; and an optical transmitter for converting the substitute data from the electrical domain to the digital optical domain and for propagating the substitute data in the digital optical domain, the substitute data comprising minimal concentration of optical power for reducing optical interference. ### Claim 40 (depends on 37) The optical network of claim 37, wherein the idle pattern replacement device comprises a downstream data shift register, a replacement data shift register, and a data initializer.