PTAB

IPR2023-00818

AT&T Corp AT&T Communications LLC AT&T Services Inc v. Dali Wireless Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Distributed Antenna System
  • Brief Description: The ’499 patent describes a "field reconfigurable" distributed antenna system (DAS) for wireless communications. The system employs digital access units (DAUs), also referred to as baseband units, to flexibly manage, control, and route radio resources from signal sources to a plurality of remote units based on network needs.

3. Grounds for Unpatentability

Ground 1: Obviousness over Wu - Claims 1-5, 8-11, 13-16, and 18-19 are obvious over Wu.

  • Prior Art Relied Upon: Wu (Application # 2010/0128676).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Wu discloses all elements of the challenged independent claims. Wu describes a "Carrier Channel Distribution System" where a base transceiver station (BTS), comprising a transceiver (signal source) and host units (baseband unit), routes carrier channels (radio resources) to remote transceiver units (RTUs). Petitioner asserted that Wu’s host units digitize and send representations of these radio resources to the RTUs. Critically, Wu teaches a configurable routing policy that can dynamically allocate "more channels" to a region to increase bandwidth based on conditions like traffic load. Petitioner contended this directly teaches sending a first set of radio resources at a first time and a different, second set of radio resources at a second time, as required by the independent claims.
    • Key Aspects: Petitioner emphasized that the Board had previously instituted an inter partes review (IPR) and canceled claims of the parent ’178 patent based on nearly identical arguments that Wu anticipated or rendered obvious substantially similar claims.

Ground 2: Obviousness over Wu and Sabat-552 - Claims 6, 7, 12, and 17 are obvious over Wu in view of Sabat-552.

  • Prior Art Relied Upon: Wu (Application # 2010/0128676) and Sabat-552 (Patent 6,963,552).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addresses dependent claims that add limitations requiring the baseband unit to have an interface to communicatively couple with one or more additional baseband units. Petitioner argued that while Wu teaches the core reconfigurable DAS, Sabat-552 explicitly teaches an open-access RF distribution system with multiple "hub sites" (baseband units) connected by "digital cross-connects." Sabat-552 discloses that signals received at one hub can be transmitted to remote units connected to other hubs, both directly and indirectly (passing through an intervening hub). This combination, Petitioner asserted, teaches the claimed system of interconnected baseband units.
    • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would combine the teachings of Wu and Sabat-552 to create a more scalable and efficient DAS. A POSITA would incorporate Sabat-552's interconnected hub architecture into Wu’s system to expand coverage area without the high cost of building new base stations. Sabat-552 explicitly teaches that this architecture facilitates infrastructure sharing among different service providers, a known and desirable goal in the industry.
    • Expectation of Success: A POSITA would have a reasonable expectation of success in combining the systems, as both relate to digital signal distribution in wireless networks, and the interconnection of network hubs was a known technique for network expansion.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that the Board should not exercise its discretion to deny institution under 35 U.S.C. §325(d) because, although Wu was before the examiner, it was part of a large Information Disclosure Statement and the examiner’s failure to appreciate its teachings constituted a material error.
  • Petitioner also argued against discretionary denial under §314(a) based on the Fintiv factors. Petitioner contended that the merits of the petition are exceptionally strong, as evidenced by the Board's institution of a parallel IPR (IPR2022-01419) on identical grounds, which this petition seeks to join. Furthermore, Petitioner asserted that there is minimal overlap with the related district court litigation, and that the efficiency and integrity of the IPR process would be best served by institution.

5. Relief Requested

  • Petitioner requested institution of an IPR and cancellation of claims 1-19 of the ’499 patent as unpatentable under 35 U.S.C. §103.