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IPR2025-01166

AT&T Services Inc v. USTA Technology LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Interference Management in Wireless Communication Networks
  • Brief Description: The ’720 patent relates to methods for managing interference in a radio communications network. The technology involves a first node that receives instructions to avoid using certain frequencies, filters its transmission signals to remove power from those frequencies, and then simultaneously transmits to multiple other nodes using an 802.11-based Orthogonal Frequency-Division Multiplexing (OFDM) protocol, with transmit power adjusted based on received feedback.

3. Grounds for Unpatentability

Ground 1: Obviousness over Walton, 802.11a, and Hamabe - Claims 19, 22-33, 36-43, 45-46, 49-58, 60-75, 77-93, 95, and 96 are obvious over Walton in view of 802.11a and Hamabe.

  • Prior Art Relied Upon: Walton (Application # 2003/0125040), 802.11a (an IEEE Standard), and Hamabe (Application # 2001/0016499).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the primary combination discloses the core limitations of the challenged claims. Walton taught a multi-user, multiple-input multiple-output (MIMO) system using OFDM that could simultaneously transmit independent data streams to multiple receiver units based on compressed channel state information (CSI) feedback. The IEEE 802.11a standard provided the well-known framework for wireless LANs operating in the 5 GHz band using an OFDM physical (PHY) layer. Hamabe taught a method for avoiding interference where a mobile station determines a carrier frequency must be changed and transmits "control information"—an instruction—to a base station to avoid using a plurality of frequencies. Petitioner asserted that implementing Walton’s advanced MIMO techniques on the standard 802.11a platform and incorporating Hamabe’s interference-avoidance signaling renders the claimed invention obvious. Specifically, Hamabe’s "control information" met the "instruction" limitation, while compliance with 802.11a's standard channelization and spectral mask requirements met the "filtering" limitation. Walton's use of CSI feedback for multi-user transmissions met the feedback-based power control limitations.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references for several reasons. First, Walton explicitly proposed its MIMO techniques for use in wireless OFDM LAN systems, making the widely adopted 802.11a standard a natural and obvious choice for implementation. Second, regulatory bodies required systems operating in the 5 GHz band, such as 802.11a, to include mechanisms for Dynamic Frequency Selection (DFS) to detect and avoid interference with incumbent systems like radar. This regulatory pressure would motivate a POSITA to seek known interference avoidance solutions like that taught by Hamabe.
    • Expectation of Success: A POSITA would have a high expectation of success. Walton and 802.11a shared the same fundamental OFDM architecture, and Walton’s inventors themselves later proposed their techniques for inclusion in subsequent 802.11 standards. Integrating Hamabe’s method was a predictable solution to a known regulatory problem.

Ground 2: Obviousness over Walton, 802.11a, Hamabe, and Gubbi - Claims 47 and 48 are obvious over the combination in Ground 1 further in view of Gubbi.

  • Prior Art Relied Upon: Walton (Application # 2003/0125040), 802.11a (an IEEE Standard), Hamabe (Application # 2001/0016499), and Gubbi (Patent 6,934,752).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination of Walton, 802.11a, and Hamabe by adding the teachings of Gubbi to address the specific limitations of claims 47 and 48. These claims required that network forwarding decisions be guided by instantaneous information from a media access control (MAC) layer (claim 47) to eliminate latency effects (claim 48). Petitioner argued that Gubbi addressed unacceptable latencies in 802.11 networks by introducing MAC layer extensions, including a "Proxy Point Coordinator" (PPC). A PPC could act as a repeater or intermediary, forwarding frames between two devices when their direct link was poor. Gubbi taught that this forwarding decision was guided by MAC layer commands and information, thus meeting the limitation of claim 47. By stepping in to forward messages and overcome poor links, the PPC directly addressed and eliminated the dominant end-to-end latency effect caused by channel access delay, as recited in claim 48.
    • Motivation to Combine: A POSITA would combine Gubbi with the primary combination because Gubbi explicitly taught its MAC enhancements as a compatible "supplement" to the 802.11 standard to solve known problems with latency, particularly for streaming media. Since the primary combination was based on the 802.11 standard, a POSITA would find it obvious to incorporate Gubbi's compatible, performance-enhancing solutions to improve Quality of Service (QoS).
    • Expectation of Success: Success would be expected because Gubbi was expressly designed to be fully compatible with the existing 802.11 MAC definition, ensuring it could be integrated into the Walton/802.11a/Hamabe system without requiring substantial modification.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 19, 22-33, 36-43, 45-58, 60-75, 77-93, 95, and 96 of Patent RE47,720 as unpatentable.