PTAB

IPR2025-00241

Cisco Systems Inc v. WSOU Investments LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Control of Raman Amplification
  • Brief Description: The ’721 patent discloses a method and apparatus for controlling and optimizing Raman amplification in optical transmission systems. The purported novelty is a matrix multiplication technique where a vector of deviations, representing the difference between measured and target channel powers, is projected into a space defined by a Raman gain matrix to determine optimal power settings for the pump lasers.

3. Grounds for Unpatentability

Ground 1: Obviousness over Sugaya - Claims 1, 2, 4, 6, 19, and 21 are obvious over Sugaya.

  • Prior Art Relied Upon: Sugaya (Application # 2004/019615).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sugaya taught the same matrix multiplication technique claimed in the ’721 patent for the same purpose of optimizing Raman pump power. Sugaya was shown to disclose a method that involves measuring signal power deviations across wavelength blocks, representing these deviations as a vector, and multiplying this vector by an inverse gain matrix. Petitioner asserted this directly maps to the ’721 patent’s central limitation of “projecting the deviations into a space that defines Raman gain profiles.” Sugaya’s Equation 2.12, which calculates pump power changes (ΔPₚ) from measured power deviations (ΔPₛ) using a gain matrix (Bᵢⱼ⁻¹), was presented as teaching the claimed invention. The resulting calculated values in Sugaya were argued to be the claimed "projected deviations," which are then used to determine the final "power setting values" for the pump lasers.
    • Key Aspects: The core of this ground is the direct structural and functional equivalence alleged between Sugaya's mathematical process for pump control and the method recited in the challenged claims of the ’721 patent.

Ground 2: Obviousness over Sugaya in view of Farmer - Claims 1, 2, 4, 6, 19, and 21 are obvious over Sugaya in view of Farmer.

  • Prior Art Relied Upon: Sugaya (Application # 2004/019615) and Farmer (Patent 6,907,051).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground reinforces the arguments from Ground 1 and addresses any potential distinction drawn between Sugaya’s use of "wavelength blocks" and the claims' reference to individual channels or wavelengths. Petitioner contended that Farmer explicitly taught measuring and optimizing power levels for individual signal wavelengths to maintain Raman gain flatness. Farmer was also shown to disclose a nearly identical matrix multiplication technique, where a vector of desired power changes is multiplied by an inverse differential gain matrix to determine the required change in pump emitter currents. The combination of Sugaya's overall method with Farmer's specific teaching of individual wavelength measurement was argued to render the claimed invention obvious.
    • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would combine Sugaya and Farmer to improve the performance of Sugaya’s system. A POSITA would have recognized the benefit of applying Sugaya’s optimization algorithm to the more granular, individual wavelength measurements taught by Farmer to achieve a flatter, more precisely controlled Raman gain across the entire signal spectrum, a well-known goal in the field.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because both Sugaya and Farmer used the same fundamental matrix multiplication approach to solve the same technical problem. Applying Sugaya’s known algorithm to the individual wavelength data from Farmer’s technique was presented as a predictable application of known principles to achieve an expected improvement in gain flatness.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial would be inappropriate under both §314(a) and §325(d).
  • Fintiv Factors (§314(a)): Petitioner asserted that the parallel district court litigation was in its very early stages, with key events like the Markman hearing scheduled well after the Board’s institution decision deadline. Petitioner also filed the IPR petition promptly after being served with the complaint and stipulated that, if trial is instituted, it will not pursue the same invalidity grounds in the district court litigation.
  • §325(d): Petitioner argued that denial is not warranted because the primary prior art references, Sugaya and Farmer, were never presented to or considered by the Examiner during the original prosecution of the ’721 patent. Therefore, the petition raised new arguments and art not previously evaluated by the USPTO.

5. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 1, 2, 4, 6, 19, and 21 of the ’721 patent as unpatentable under 35 U.S.C. §103.