PTAB

IPR2025-01509

Southwest Airlines Co v. Intellectual Ventures II LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Communications in a Wireless Network
  • Brief Description: The ’000 patent describes a closed-loop feedback control method between a base station and user equipment (UE). The technology aims to adapt systems designed for Time Division Duplex (TDD) operation to function in Frequency Division Duplex (FDD) mode, where channel reciprocity is unavailable, by defining an uplink physical control channel for channel estimation and a downlink channel for feeding back control information.

3. Grounds for Unpatentability

Ground 1: Claims 1-24 are obvious over Papasakellariou, Classon, and Liu.

  • Prior Art Relied Upon: Papasakellariou (Patent 8,417,248), Classon (Application # 2007/0058595), and Liu (Patent 7,817,605).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination teaches all limitations of the independent claims (1, 7, 13, 19). Papasakellariou disclosed a base station instructing a UE to transmit a Sounding Reference Signal (SRS) on specific resources for channel condition estimation, establishing the core uplink physical signal and resource allocation concepts. Classon provided a compatible frame structure for an FDD system, teaching the use of predetermined time slots for control channels and other time slots for data channels, with control and data channels being time-multiplexed. Liu supplemented this by disclosing a shared physical downlink control channel that transmits control information (like power control commands) to a plurality of UEs, where the number of bits sent is based on the number of user-specific fields of control information.
    • Motivation to Combine: A POSITA would combine these references because they all address complementary aspects of 3GPP LTE system development. Papasakellariou and Classon both focused on OFDM-based systems within the 3GPP framework. A POSITA would have looked to a known method like Liu’s for implementing a multi-user shared control channel to complete the system defined by Papasakellariou and Classon. The 3GPP standardization process itself encouraged combining insights from different contributions to create optimized solutions.
    • Expectation of Success: The combination was presented as a predictable step in developing an uplink power control methodology for the evolving 3GPP LTE standard, reflecting the normal course of collaborative development with a reasonable expectation of success.

Ground 2: Claims 1-24 are obvious over Muharemovic, Onggosanusi, and Classon.

  • Prior Art Relied Upon: Muharemovic (Application # 2008/0045260), Onggosanusi (Patent 7,668,564), and Classon (Application # 2007/0058595).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted this combination also renders the claims obvious. Muharemovic and Onggosanusi together taught a closed-loop power control system where a UE transmits an uplink sounding signal, the base station measures channel conditions based on the signal, and then transmits power control commands back to the UE over a downlink control channel. Muharemovic specifically disclosed that the sounding signal (uplink physical signal) and data transmissions (physical uplink shared channel) occur in different resources within a sub-frame. Onggosanusi further taught that the downlink control channel can be shared among multiple UEs, with the number of bits in a power control command being variable. Classon, as in Ground 1, provided the necessary physical uplink and downlink frame structure to implement the power control methods of Muharemovic and Onggosanusi.
    • Motivation to Combine: A POSITA would combine Muharemovic and Onggosanusi as both directly addressed the problem of uplink power control in OFDM-based systems within the 3GPP standardization effort. Their teachings were seen as complementary contributions within the same technology space. Classon was also oriented to 3GPP LTE development and disclosed a physical channel structure compatible with the closed-loop power control methods of the primary references, making its inclusion a logical step for implementation.
    • Expectation of Success: Petitioner argued that combining these references would have been a predictable, routine step to develop a robust uplink power control methodology for the 3GPP LTE cellular system, requiring no undue experimentation.

4. Key Claim Construction Positions

  • Petitioner addressed the construction of "time interval" by adopting the Board's interpretation from a related IPR (IPR2022-01130). The Board previously construed "time interval" to mean a "timeslot" and interpreted the claim language to require a dedicated timeslot for the uplink physical signal (UL_Beacon) that is separate from timeslots used for data transmission over the physical uplink shared channel. Petitioner adopted this construction for the purposes of the petition.

5. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 1-24 of Patent 11,032,000 as unpatentable.