PTAB

IPR2025-01069

Samsung Electronics Co Ltd v. Wilus Institute Of Standards Technology Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Wireless Communication Method and Wireless Communication Terminal for Coexistence with Legacy Wireless Communication Terminal
  • Brief Description: The ’077 patent discloses methods for wireless communication in an environment where non-legacy (e.g., IEEE 802.11ax) and legacy (e.g., 802.11ac) devices coexist. The technology uses a legacy signaling field (L-SIG) in a non-legacy frame to convey information, including frame duration, in a manner that allows non-legacy devices to extract additional information while maintaining backward compatibility.

3. Grounds for Unpatentability

Ground 1: Claims 1-5 and 8-12 are obvious over Bharadwaj in view of Yu

  • Prior Art Relied Upon: Bharadwaj (Application # 2016/0345202) and Yu (Application # 2016/0286012).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Bharadwaj taught a method for distinguishing between non-legacy (802.11ax) and legacy (802.11ac) transmissions by adding an integer m (1 or 2) to the L_LENGTH value in a legacy-compatible frame header. The remainder of L_LENGTH divided by 3 would signal the frame type. Bharadwaj also disclosed equations for a receiver to calculate the number of data symbols (Nsym). However, Petitioner contended that adding m would cause legacy devices, which are unaware of this modification, to miscalculate the frame duration and defer subsequent transmissions for longer than necessary. Yu addressed this exact problem of legacy compatibility by teaching the subtraction of a similar integer M from the L_LENGTH calculation, which allows non-legacy devices to receive extra information without altering how legacy devices calculate frame duration.
    • Motivation to Combine: A POSITA would combine Yu’s teaching of subtracting an integer with Bharadwaj’s signaling framework to solve the known problem of maintaining backward compatibility. This modification would allow legacy devices to correctly calculate frame duration and symbol count, preventing unnecessary deferrals, a well-understood goal in developing new wireless standards.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination involved substituting a simple mathematical operation (subtraction for addition) into established equations to achieve a predictable and highly desirable result (legacy compatibility).

Ground 2: Claims 4-5 and 11-12 are obvious over Bharadwaj in view of Yu and Azizi

  • Prior Art Relied Upon: Bharadwaj (Application # 2016/0345202), Yu (Application # 2016/0286012), and Azizi (Application # 2015/0139206).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on the Bharadwaj-Yu combination. Petitioner asserted that Azizi further taught using the L-SIG length field’s remainder (modulo 3) not only to distinguish legacy from non-legacy packets but also to determine a specific preamble format for the non-legacy packet (e.g., a short or long preamble). This directly addresses limitations in claims 4-5 and 11-12 concerning the processor determining the format of a non-legacy signaling field based on length information.
    • Motivation to Combine: A POSITA would be motivated to incorporate Azizi’s teachings into the Bharadwaj-Yu system to enhance its efficiency. By using the already-established signaling mechanism (the L-SIG length field remainder) to also select an appropriate preamble format based on channel conditions (e.g., short preamble for low-error indoor environments), the system could reduce overhead and improve performance.

Ground 3: Claims 6-7 and 13-14 are obvious over Bharadwaj in view of Yu and Kenney

  • Prior Art Relied Upon: Bharadwaj (Application # 2016/0345202), Yu (Application # 2016/0286012), and Kenney (Application # 2015/0139205).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground adds Kenney to the Bharadwaj-Yu combination. Petitioner argued that Kenney taught a more robust method for distinguishing between frame types by using two criteria in conjunction: (1) whether the length field is divisible by three, and (2) detecting phase rotation of the BPSK modulation on specific symbols following the L-SIG field. This maps to claim limitations requiring a determination based on a "modulation method of a third symbol after the legacy signaling field."
    • Motivation to Combine: A POSITA would combine Kenney’s dual-criteria approach with the Bharadwaj-Yu system to improve the reliability and robustness of frame type detection. Relying on both length value and modulation characteristics would reduce the chance of misidentification, a clear and desirable goal in wireless system design.
  • Additional Grounds: Petitioner asserted additional obviousness challenges (Grounds 2A-2C) based on Bharadwaj alone or in combination with Azizi or Kenney, arguing that Yu’s teachings represented a concept so well-known to a POSITA that the combinations would have been obvious even without an explicit reference to Yu.

4. Key Technical Contentions (Beyond Claim Construction)

  • Priority Date Challenge: Petitioner dedicated significant argument to contending that the ’077 patent is not entitled to its claimed June 29, 2015 priority date from Korean Application No. 10-2015-0092525. Petitioner argued the Korean application lacked written description support for the key claim elements, specifically the equations for obtaining information from a remaining value and determining the number of data symbols. If this argument prevails, the patent’s effective filing date would be no earlier than August 20, 2015, ensuring that all primary prior art references relied upon in the petition pre-date the invention.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial is unwarranted. It noted its intent to use the bifurcated briefing process proposed by the USPTO to rebut any such arguments raised by the Patent Owner.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-14 of the ’077 patent as unpatentable.