PTAB

IPR2025-00395

AT&T Services Inc v. Adaptive Spectrum Signal Alignment Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Dynamically Adjusting Forward Error Correction in DSL Systems
  • Brief Description: The ’669 patent discloses a method for dynamically adjusting Reed-Solomon codeword parameters for Forward Error Correction (FEC) in Digital Subscriber Line (DSL) transmissions. The system repeatedly acquires Measured Error Values (MEVs) representing impulse noise, compares them against a Target Error Value (TEV), and adjusts a Codeword Composition Ratio (CCR) to optimize performance based on changing channel conditions.

3. Grounds for Unpatentability

Ground 1: Obviousness over Cooper and Li - Claims 1-4, 11, 14-17, 19-20, 23, and 26-29 are obvious over Cooper in view of Li.

  • Prior Art Relied Upon: Cooper (Patent 6,772,388) and Li (Application # 2002/0140991).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Cooper taught all limitations of the challenged claims. Cooper described an "adaptive and dynamic forward error correction scheme" that changes the ratio between payload and error-correcting bytes in a Reed-Solomon codeword. This adjustment was based on comparing a calculated bit error rate (CBER) to a target bit error rate (TBER), a process Petitioner asserted is directly analogous to the ’669 patent’s method of acquiring MEVs, comparing them to a TEV, and adjusting the CCR. Petitioner mapped Cooper’s process of repeatedly calculating the CBER after initialization to the claimed limitation of acquiring MEVs after modem training.
    • Motivation to Combine: Petitioner contended that while Cooper taught the claimed method for use on "twisted pair copper wires," it did not explicitly name a "DSL modem." Li remedied this by disclosing an ADSL modem that uses a similar FEC scheme and complies with known DSL standards. A person of ordinary skill in the art (POSITA) would combine Cooper’s established dynamic FEC method with Li's standard-compliant DSL modem to gain the predictable benefits of applying a known optimization technique to a standard communications platform, thereby ensuring interoperability.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because Cooper’s adaptive FEC scheme was designed for the exact communication medium—twisted pair wires—used by the DSL modems disclosed in Li.

Ground 2: Obviousness over Klayman and Li - Claims 1-4, 11, 14-17, 19-20, 23, and 26-29 are obvious over Klayman in view of Li.

  • Prior Art Relied Upon: Klayman (Patent 5,699,365) and Li (Application # 2002/0140991).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Klayman disclosed a dynamic error correction method that provides for "dynamically changing forward error correction parameters based upon communication channel conditions, such as noise levels or error rates." Klayman’s method involved monitoring a channel parameter (e.g., bit error rate), comparing it to a threshold level, and revising the degree of FEC if the parameter fell outside a predetermined variance. Petitioner asserted this process directly mapped to the claimed method of acquiring, analyzing, and adjusting based on error values. Klayman's disclosure of monitoring for "burst errors" was equated to the claimed "impulse noise events."
    • Motivation to Combine: The motivation was presented as analogous to Ground 1. Klayman taught its adaptive FEC scheme for use over "twisted pair wires," which a POSITA would recognize as a DSL communication medium. A POSITA would have been motivated to implement Klayman's dynamic FEC scheme in a standard-compliant DSL modem, as taught by Li, to improve the performance of a known, widely used system with a known technique.
    • Expectation of Success: Success was expected because Klayman’s method was suitable for the communication medium, and Li provided a standard component (an ADSL modem) for implementing such a method on that medium.

4. Key Claim Construction Positions

  • "Means for" Limitations: Petitioner argued that independent claim 1 recited several "means for" limitations governed by 35 U.S.C. §112, para. 6. Petitioner identified corresponding structures in the ’669 patent's specification for each claimed function. For example, the "means for repeatedly acquiring Measured transmission Error Values (MEVs)" was mapped to the structure of a "transmission error value monitor." These constructions were central to Petitioner’s argument that the prior art, which disclosed analogous structures like microcontrollers and processors performing the same functions, rendered the claims obvious.

5. Arguments Regarding Discretionary Denial

  • Arguments Against §325(d) Denial: Petitioner argued that institution should not be denied under §325(d) because the prior art references and combinations asserted in the petition (Cooper, Klayman, and Li) are new. These references and the specific invalidity arguments based on them were not before the Examiner during the original prosecution.
  • Arguments Against Discretionary Denial under Fintiv: Petitioner argued that the Fintiv factors weighed against discretionary denial under §314(a). Key reasons included: the co-pending district court trial date is not scheduled until at least September 2025 and is likely to be delayed further by pending motions; the litigation is in its early stages with no significant investment of court resources; the petition presents strong merits; and there is an incomplete overlap of parties, as Petitioner Nokia is not a party to the underlying litigation.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 11, 14-17, 19-20, 23, and 26-29 of the ’669 patent as unpatentable.