PTAB

IPR2025-00789

Samsung Electronics Co Ltd v. GenghisComm Holdings LLC

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Multicarrier sub-layer for direct sequence channel and multiple-access coding
  • Brief Description: The ’786 patent describes methods and systems for wireless communications that implement complex-valued spreading, such as Discrete Fourier Transform (DFT) spreading, and Orthogonal Frequency Division Multiplexing (OFDM) modulation.

3. Grounds for Unpatentability

Ground 1: Obviousness over Galda and Brüninghaus - Claims 1-2 and 6-9 are obvious over Galda in view of Brüninghaus.

  • Prior Art Relied Upon: Galda (a 2002 IEEE conference paper) and Brüninghaus (a 1998 IEEE conference paper).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Galda taught a method of communication in an OFDM system that meets most limitations of independent claim 1. Galda disclosed using a first set of complex-valued codes (from a DFT spreading matrix) to encode data symbols, selecting and applying these symbols to a plurality of subcarriers, producing a spread-OFDM signal, and transmitting it. However, Galda did not explicitly teach using a second set of codes that are the complex conjugates of the first set to recover the data at the receiver.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Galda with Brüninghaus to supply the missing element. Brüninghaus, which shared an author with Galda, described an equivalent OFDM-CDM system where despreading at the receiver was achieved using an "inverse Fast-Fourier matrix," explicitly identified as the Hermitian transpose ([H]H) of the spreading matrix. A POSITA would have understood the Hermitian transpose to be the complex conjugate transpose. The motivation was to implement a known and predictable method for reversing the spreading operation to recover the transmitted data, as taught by Brüninghaus, within the system described by Galda.
    • Expectation of Success: A POSITA would have a high expectation of success, as applying the complex conjugate of spreading codes to perform despreading was a well-understood mathematical technique for inverting the transmitter's operation.

Ground 2: Obviousness over Kaiser and Bury - Claims 1-2 and 6-9 are obvious over Kaiser in view of Bury.

  • Prior Art Relied Upon: Kaiser (a 1998 Ph.D. thesis) and Bury (a 2000 IEEE conference paper).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner contended that Kaiser disclosed an SS-MC-MA (Spread Spectrum Multi-Carrier Multiple Access) transmitter that taught most elements of the challenged claims, including selecting subcarriers, encoding data, applying symbols to subcarriers, and transmitting a spread-OFDM signal. Critically, Kaiser explicitly taught using the "conjugate complex user specific spreading code" at the receiver to despread the signal. However, Kaiser used Walsh-Hadamard codes for spreading, which are not complex-valued.
    • Motivation to Combine: A POSITA would have been motivated to replace Kaiser’s Walsh-Hadamard spreading codes with the complex-valued DFT spreading codes taught by Bury. Bury directly compared Walsh-Hadamard spreading to "Fourier spreading" (DFT spreading) in similar multi-carrier systems and concluded that Fourier spreading was the "best choice" for improving performance by reducing the peak-to-average power ratio (PAPR). This provided an explicit reason to modify Kaiser's system with Bury's superior and complex-valued spreading technique to achieve the predictable benefit of improved PAPR.
    • Expectation of Success: A POSITA would have reasonably expected success in substituting one known spreading technique (DFT) for another (Walsh-Hadamard) in Kaiser's existing system architecture to gain the known advantages described by Bury.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on the same core combinations but with the addition of Dowling (Patent 6,597,745). These grounds argued that Dowling, which taught implementing transmitter functions as software modules on programmable processors, rendered obvious the apparatus and computer program product claims (10-11, 15-18, 19-20, 24-27). The motivation was to apply the known technique of software implementation to the systems of Galda/Brüninghaus or Kaiser/Bury to gain the predictable benefits of flexibility and updatability over fixed hardware.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under 35 U.S.C. §314(a) based on Fintiv factors would be inappropriate. The petition asserted that the parallel district court case was in its early stages with minimal investment, a Markman hearing was not yet scheduled, and a trial was not expected until April 2026, making a Final Written Decision (FWD) likely only a few months after trial. Petitioner further committed to seeking a stay and provided a Sotera stipulation, agreeing not to pursue the same invalidity grounds in district court if the inter partes review (IPR) is instituted. Finally, Petitioner argued the compelling merits and the fact that the primary prior art was never considered during prosecution weigh heavily in favor of institution.

5. Relief Requested

  • Petitioner requests institution of an IPR and cancellation of claims 1-2, 6-11, 15-18, 19-20, and 24-27 of the ’786 patent as unpatentable.