PTAB

IPR2025-00492

Nokia Of America Corp v. Adaptive Spectrum Signal Alignment Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method for Evaluating Operational Characteristics of a Multi-Line DSL System
  • Brief Description: The ’458 patent discloses methods for evaluating operational characteristics of multi-line, vectored Digital Subscriber Line (DSL) systems to mitigate crosstalk interference. The technology involves collecting operational data from DSL modems, generating Dynamic Spectrum Management (DSM) data quantities such as Xlog(u,n) and Xlin(u,n) to represent crosstalk coupling, and using this data to improve system performance.

3. Grounds for Unpatentability

Ground 1: Obviousness over Rezvani and Cendrillon I - Claims 1-2, 4-5, 7, 9-10, 12, 14-15 are obvious over Rezvani in view of Cendrillon I.

  • Prior Art Relied Upon: Rezvani (Patent 7,356,049) and Cendrillon I (a 2003 conference paper titled "Partial Crosstalk Cancellation Exploiting Line and Tone Selection in VDSL").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Rezvani taught a method for optimizing channel capacity in multi-line DSL systems by generating an interference matrix to characterize crosstalk. Rezvani’s method involved injecting known training sequences into subscriber lines (meeting the "exciting" limitation of claim 1), monitoring interference on other lines to acquire output data (meeting the "acquiring" limitation), and ranking the interferer channels "in order of importance." Petitioner asserted that Cendrillon I taught a more efficient "partial crosstalk cancellation" scheme that explicitly focused on cancelling only the "largest crosstalkers" on each tone, which are "sorted in order of crosstalk strength" (completing the "ordering" limitation). The resulting ordered data would then be used to generate a data quantity and send instructions to modems to mitigate the identified crosstalk, as taught by Rezvani.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Cendrillon I's partial cancellation method with Rezvani's system to improve signaling efficiency. Both references address mitigating crosstalk in bundled DSL lines. A POSITA would be motivated to apply Cendrillon I’s targeted, less computationally complex cancellation technique to the interference matrix generated by Rezvani's method, thereby improving performance without the overhead of full cancellation.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because both references characterize crosstalk contributions in a similar and compatible manner. Rezvani’s training phase for generating an interference matrix would provide the precise data needed to identify the largest crosstalkers, enabling the straightforward application of Cendrillon I’s partial cancellation algorithm.

Ground 2: Obviousness over Rezvani, Cendrillon I, and G.992.3 - Claim 11 is obvious over Rezvani in view of Cendrillon I and G.992.3.

  • Prior Art Relied Upon: Rezvani (Patent 7,356,049), Cendrillon I (a 2003 conference paper), and G.992.3 (an ITU-T Recommendation for the ADSL2 standard).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on Ground 1 and specifically targets the data format of the Xlin(u,n) quantity required by claim 11. Claim 11 recites representing Xlin(u,n) in a linear format using a scale(u) factor and a normalized complex number a(u,n)+j*b(u,n) coded as 16-bit integers. Petitioner argued that G.992.3, a well-known ADSL2 standard, disclosed this exact data format (Hlin(f)) for representing single-line channel characteristics. A POSITA would have found it obvious to apply this standard format to the multi-line crosstalk transfer function derived from the Rezvani and Cendrillon I combination.
    • Motivation to Combine: After combining Rezvani and Cendrillon I, a POSITA would be motivated to use the standardized data format from G.992.3 to represent the resulting crosstalk data. Rezvani itself guided a POSITA to consider relevant xDSL standards. Using a known, standardized format would ensure compatibility with existing DSL equipment, reduce data storage requirements, and provide an effective, established method for conveying line characteristic data without requiring significant modification to the underlying mitigation techniques.
    • Expectation of Success: Success would be expected because the channel characteristics in Rezvani and Cendrillon I were represented in a manner analogous to the formats in G.992.3. Applying the standard Hlin(f) format to characterize the multi-line crosstalk interference matrix is a predictable and straightforward implementation of a known standard for its intended purpose of characterizing channel effects.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial would be inappropriate. Under 35 U.S.C. §325(d), Petitioner contended that the specific prior art combinations and arguments were not before the examiner during prosecution, making them not cumulative. Under 35 U.S.C. §314(a) and the Fintiv factors, Petitioner asserted that denial is unwarranted because:
    • Petitioner (Nokia) is not a party to the co-pending district court litigation against its customer, AT&T.
    • The district court trial date is highly uncertain and likely to be delayed past the IPR statutory deadline due to a pending motion to transfer venue or stay for arbitration.
    • The co-pending litigation is in its early stages, with minimal investment of judicial resources.
    • There is incomplete overlap between the proceedings, as the district court ordered the Patent Owner to reduce the number of asserted claims to six, meaning not all eleven claims challenged in the IPR will be adjudicated at trial.
  • Petitioner also argued that General Plastic factors do not apply, as this is the first and only IPR filed against the ’458 patent, raising no concerns of serial petitions.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-2, 4-5, 7, 9-12, and 14-15 of Patent 7,593,458 as unpatentable.