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

1. Case Identification

• Case #: IPR2025-00451
• Patent #: 9,954,631
• Filed: January 17, 2025
• Petitioner(s): AT&T Services, Inc., and Nokia of America Corp.
• Patent Owner(s): Adaptive Spectrum and Signal Alignment, Inc.
• Challenged Claims: 1, 3-6, 8-9, 11-16, 22-25, and 33-37

2. Patent Overview

• Title: Managing Crosstalk in Time Division Duplex Communication Systems
• Brief Description: The ’631 patent discloses methods for managing crosstalk interference in data communication systems, such as G.fast, that utilize multiple physical channels. The core technology involves scheduling upstream and downstream data transmissions into distinct, substantially non-simultaneous time slots across different physical channels to prevent interference.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over Bingham - Claims 1, 3-6, 34, and 37 are unpatentable under 35 U.S.C. §§102 and 103 over Bingham.

• Prior Art Relied Upon: Bingham (Patent 5,680,394).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Bingham discloses a time-division duplexed (TDD) data transmission method for coordinating communications over bundled subscriber lines, which are subject to crosstalk. Bingham explicitly teaches synchronizing upstream and downstream communication periods across multiple lines so that they are not transmitted at the same time, thereby avoiding near-end crosstalk. This arrangement, Petitioner asserted, directly teaches the limitations of claim 1, including scheduling upstream slots on a first channel and downstream slots on a second channel in a substantially non-simultaneous manner.
  • Motivation to Combine (for §103): Petitioner contended that if the claims are construed to require unidirectional channels (per their claim construction argument), Bingham still renders the claims obvious. Bingham’s system used bidirectional channels, which suffer from "turnaround time" when switching between transmitting and receiving. Petitioner argued a person of ordinary skill in the art (POSITA) would be motivated to modify Bingham's system to use separate, unidirectional channels—a known and simple solution to eliminate turnaround time and improve efficiency.
  • Expectation of Success: A POSITA would have had a high expectation of success in making this modification, as it represented a straightforward design choice to solve a well-understood problem in the art.

Ground 2: Obviousness over Strobel in view of Wei and/or Kuipers - Claims 1, 3-6, 8-9, 11-16, 22-25, and 33-37 are obvious over Strobel, alone or in view of Wei and/or Kuipers.

• Prior Art Relied Upon: Strobel (Patent 9,531,491), Wei (ITU Document 2012-06-4A-040), and Kuipers (ITU Document 2012-06-4A-061).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that Strobel, like the ’631 patent, is directed to managing crosstalk in emerging DSL systems like G.fast. Strobel disclosed a TDD system that uses time division duplexing between upstream and downstream transmissions across multiple physical channels in a cable binder. Strobel’s figures illustrated scheduling upstream data symbols on a first channel (US1) and downstream data symbols on a second channel (DS2) at different, non-overlapping times, thus teaching the core limitations of independent claim 1.
  • Motivation to Combine: Petitioner argued that a POSITA designing a G.fast system would naturally look to contemporaneous technical contributions to the G.fast standard, such as Wei and Kuipers, to implement or optimize the TDD system disclosed in Strobel.
    • To implement claim 3’s "off portion," a POSITA would combine Strobel with Wei. While Strobel taught guard times, Wei explicitly disclosed "quiet intervals" and a "discontinuous mode power save (DMPS) method" where transmission paths are turned off entirely, directly teaching an "off portion" to improve power efficiency, a known issue with TDD systems acknowledged by Strobel.
    • To implement claim 5’s "flexible" time slot boundaries, a POSITA would combine Strobel with Kuipers. While Strobel described time slots as "programmable," Kuipers provided explicit detail on a "flexible frame structure" that enables dynamic adaptation of time slots based on traffic load, directly addressing the system complexity that Strobel identified as a challenge.
  • Expectation of Success: A POSITA would have a reasonable expectation of success in combining these references because they all addressed the same technical field (G.fast standardization) and offered complementary solutions to known challenges like power consumption and system complexity.

• Additional Grounds: Petitioner asserted additional obviousness challenges based on specific combinations of Strobel, Wei, and Kuipers to address the limitations of various dependent claims, such as those related to power usage (claims 15, 16) and adapting scheduling to traffic requests (claims 9, 11).

4. Key Claim Construction Positions

• Petitioner argued that the term "physical channel" was subject to prosecution history disclaimer. To overcome prior art rejections (over Cioffi and Liu), the patentee allegedly disavowed systems with bidirectional channels, arguing that their invention used separate channels for upstream and downstream.
• Based on this disclaimer, Petitioner proposed the term should be construed to mean "a physical channel that transmits in only the upstream or the downstream, not both." This construction is central to Petitioner's argument that Bingham, which discloses bidirectional channels, would need to be modified to arrive at the claimed invention.

5. Arguments Regarding Discretionary Denial

• §325(d) - Same or Substantially the Same Art: Petitioner argued against discretionary denial under §325(d), contending that the asserted references (Bingham, Strobel, Wei, Kuipers) are materially different from the art considered by the Examiner during prosecution. The prior art of record focused on switch-based multiplexing, whereas the asserted references relate directly to time-division duplexing parameters in modern DSL systems.
• §314(a) - Fintiv Factors: Petitioner argued against discretionary denial under Fintiv, asserting that the parallel district court litigation is in its early stages, with claim construction and expert discovery not scheduled until well into 2025. Furthermore, Petitioner highlighted a pending motion to transfer venue, which creates significant uncertainty about the trial date and suggests it will occur long after the statutory deadline for a Final Written Decision in this inter partes review (IPR).

6. Relief Requested

• Petitioner requests the institution of an IPR and the cancellation of claims 1, 3-6, 8-9, 11-16, 22-25, and 33-37 of Patent 9,954,631 as unpatentable.