PTAB

IPR2024-00681

Dell Inc v. Ax Wireless LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Header Repetition in a Communications Environment
  • Brief Description: The ’262 patent discloses methods and systems for wireless communication using Orthogonal Frequency Division Multiplexing (OFDM) that accommodate different header repetition schemes. The technology allows devices operating in narrower frequency bands to use more repeated header symbols for increased reliability, while devices in wider bands use fewer repeated symbols to reduce overhead.

3. Grounds for Unpatentability

Ground 1: Claims 1-6, 8-14, 16-19, 21-30, and 32 are obvious over Hansen in view of WWiSE.

  • Prior Art Relied Upon: Hansen (Application # 2006/0182017) and WWiSE (IEEE 802.11-05/0149r5, a 2005 proposal).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Hansen disclosed a standard-compliant 802.11 wireless OFDM transceiver capable of operating in 20MHz and 40MHz bands. WWiSE, a proposal for the 802.11n standard, taught using different packet formats for Normal Range (NR) and Extended Range (ER) communications to improve performance. The challenged claims’ “first packet,” received in a “narrower frequency band” with more OFDM header symbols, was mapped to WWiSE’s ER packet, which used a duplicated header symbol (ER-SIG-N) for increased reliability in a 20MHz band. The claims’ “second packet,” with fewer header symbols received in a “wider frequency band,” was mapped to WWiSE’s NR packet, which lacked the duplicated header and could be used in a 40MHz band. Petitioner asserted that WWiSE’s disclosure of transmitting the duplicated ER-SIG-N header bits on different OFDM subcarriers than the original SIG-N bits met the limitation of repeating a header bit on a plurality of subcarriers.
    • Motivation to Combine: Petitioner contended a POSITA would combine these references for several reasons. First, Hansen expressly sought to create a compromise proposal based on aspects of the WWiSE industry group's proposals. Second, incorporating WWiSE’s ER capability was an application of a known technique—repeating header information for temporal diversity—to improve a known device (Hansen’s transceiver). This would predictably extend the communication range and improve reliability, particularly in noisy environments.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because both Hansen and WWiSE were based on the same evolving 802.11 standard. Modifying Hansen's transceiver to support WWiSE's packet formats, including adding fields for ER communication, was a commonplace modification for evolving communication technologies.

Ground 2: Claims 1-4, 8-12, 16-17, 21-28 and 32 are obvious over Zhang in view of Maltsev.

  • Prior Art Relied Upon: Zhang (Application # 2010/0260159) and Maltsev (Patent 7,349,436).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Zhang disclosed an OFDM system with distinct packet formats for legacy and newer devices operating in various bandwidths (20/40/80MHz). The “first packet” with more header symbols was mapped to Zhang’s “mixed-mode” packet (data unit 250), which included header fields (L-SIG, HT-SIG) for backward compatibility and was transmitted, for instance, in a 40MHz narrower band. The “second packet” with fewer symbols was mapped to Zhang’s “Greenfield” packet (data unit 200), which omitted the legacy fields and was transmitted in a wider 80MHz band. The header bits were different because the Greenfield packet lacked the legacy fields present in the mixed-mode packet. The limitation of repeating a header bit on multiple subcarriers was mapped to Zhang's disclosure of duplicating header fields (e.g., VHT-SIG1) across multiple 20MHz sub-bands within a wider channel.
    • Motivation to Combine: Petitioner asserted a POSITA would be motivated to combine Zhang’s packet formats with Maltsev’s teachings on flexible channel-width capability. Maltsev taught scanning a network to detect device capabilities and dynamically adapting the communication bandwidth, allowing simultaneous communication with narrowband and wideband devices. Applying Maltsev’s technique to Zhang’s system was presented as a simple substitution of one known element for another to obtain the predictable results of improved system efficiency, greater flexibility, and reduced inter-channel interference.
    • Expectation of Success: A POSITA would have expected success because both references operated in the same 802.11 environment. Maltsev’s method of providing flexible channel-width communications would be compatible with Zhang’s network packets, which already included header bits to indicate the transmission bandwidth, making the integration straightforward and predictable.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under Fintiv was inappropriate. It asserted that a filed Sotera stipulation removes any overlap with parallel district court litigation. Furthermore, Petitioner contended that the Fintiv factors weighed against denial, citing a motion to stay the litigation, a speculative trial date that is over thirty months away and conflicts with other scheduled trials, and the compelling and meritorious nature of the invalidity challenge presented in the petition.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-6, 8-14, 16-19, 21-30, and 32 of the ’262 patent as unpatentable.