Samsung Electronics Co Ltd v. Red Rock Analytics LLC

1. Case Identification

• Patent #: 7,346,313
• Filed: February 5, 2018
• Petitioner(s): Samsung Electronics Co., Ltd.
• Patent Owner(s): Red Rock Analytics, LLC
• Challenged Claims: 22, 26-37, 59, 63-74

2. Patent Overview

• Title: Transceiver with I/Q Gain Imbalance Calibration
• Brief Description: The ’313 patent relates to a transceiver system that calibrates gain imbalance between its in-phase (I) and quadrature (Q) channels. The system injects a calibration RF signal from the transmit chain's output back into the receive chain's input to measure and correct for the imbalance.

3. Grounds for Unpatentability

Ground 1: Claims 22, 30-32, 37, 59, 67-69, and 74 are obvious over Yellin, Su, and Admitted Prior Art (APA).

• Prior Art Relied Upon: Yellin (Patent 6,898,252), Su (Patent 6,272,322), and Admitted Prior Art (APA) from the ’313 patent specification.
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Yellin discloses a complete, albeit abstract, system for correcting I/Q mismatch in a device with transmit and receive paths. Yellin’s “mismatch trainer” performs the core functions of the claimed “calibration subsystem” by adjusting gain/phase parameters to minimize a cost function, thereby correcting for I/Q imbalance. Petitioner contended Su discloses a conventional transceiver architecture that provides a concrete implementation for Yellin's abstract system. A Person of Ordinary Skill in the Art (POSITA) would map Yellin’s functional blocks onto the conventional transceiver components of Su and the APA (e.g., heterodyne converters, amplifiers), which the ’313 patent itself acknowledges as known, to arrive at the claimed system. Specifically, Yellin’s mismatch trainer was asserted to be the claimed "processor" and "channel gain adjuster" that independently varies transmit and receive chain gains through an iterative calibration cycle, as claimed.
  • Motivation to Combine: A POSITA would combine Yellin's known I/Q mismatch correction technique with Su's conventional transceiver architecture to improve the performance of wireless devices. This addresses the well-known problem of I/Q imbalance with a predictable solution.
  • Expectation of Success: A POSITA would have a high expectation of success, as the combination involves applying a known correction method to a standard device architecture to solve a well-understood problem in RF communications.

Ground 2: Claims 26, 33, 63, and 70 are obvious over Yellin, Su, APA, and Faulkner.

• Prior Art Relied Upon: Yellin (Patent 6,898,252), Su (Patent 6,272,322), APA, and Faulkner ("Automatic Adjustment of Quadrature Modulators," Electronics Letters (1991)).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground builds on Ground 1 to address claims requiring the calibration signal to include a "sequence of pulses taking on purely real or imaginary values." Petitioner asserted that while Yellin discloses a "special transmission" for calibration, it does not specify the signal. Faulkner explicitly teaches correcting I/Q gain mismatch using test vectors that are purely real (A, 0) or purely imaginary (0, A). This sequence directly maps to the claim language.
  • Motivation to Combine: A POSITA, seeking to implement Yellin’s underspecified "special transmission," would have been motivated to use the well-known and computationally simple test sequence from Faulkner to achieve effective calibration.
  • Expectation of Success: The combination would predictably enhance the calibration process of the Yellin/Su system by implementing a standard, proven test vector sequence for I/Q mismatch correction.

Ground 3: Claims 27, 28, 34, 35, 64, 65, 71, and 72 are obvious over Yellin, Su, APA, and Sewerinson.

• Prior Art Relied Upon: Yellin (Patent 6,898,252), Su (Patent 6,272,322), APA, and Sewerinson (Patent 4,613,976).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground addresses claims requiring the calibration signal to include a "sampled phasor" or a "discrete phasor." Petitioner argued that Sewerinson teaches a Quadrature Phase Shift Keying (QPSK) modulation system where input data is represented by discrete I/Q vectors (phasors) from a signal constellation.
  • Motivation to Combine: Yellin suggests its system can use M-ary Phase Shift Keying (MPSK) modulation. A POSITA would find it obvious to use the specific, widely-practiced QPSK modulation taught by Sewerinson as a straightforward implementation of Yellin's more general MPSK disclosure. This would inherently result in a calibration signal composed of the claimed sampled or discrete phasors.
  • Expectation of Success: Using QPSK modulation is a standard engineering choice for implementing an MPSK system, and its application would predictably result in a phasor-based signal without altering Yellin's core calibration technique.

Ground 4: Claims 29, 36, 66, and 73 are obvious over Yellin, Su, APA, Sewerinson, and Haykin.

• Prior Art Relied Upon: Yellin (Patent 6,898,252), Su (Patent 6,272,322), APA, Sewerinson (Patent 4,613,976), and Haykin (Communication Systems, 4th ed. (2000)).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground targets claims that further limit the discrete phasor to "comprising j^n or -j^n." Petitioner asserted that the textbook Haykin describes two "commonly used" QPSK signal constellations. While one constellation matches Sewerinson's, the other uses phasors on the real and imaginary axes (0°, 90°, 180°, 270°). These on-axis phasors correspond mathematically to the values of j^n (for n=0, 1, 2, 3).
  • Motivation to Combine: A POSITA would recognize that the on-axis constellation from Haykin and the corner-based constellation from Sewerinson are well-known, interchangeable design choices for QPSK. They would be motivated to substitute Haykin's on-axis version for its simplicity and common usage.
  • Expectation of Success: This substitution is a simple design choice between two known, equivalent alternatives and would predictably result in a system using the claimed j^n phasors.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §325(d) would be inappropriate. It contended that the current petition does not present "the same or substantially the same prior art or arguments" as a previously denied IPR against the same patent (IPR2017-01490). The primary reference in this petition (Yellin) is different from the primary reference in the prior IPR (Warner). Petitioner also noted that it is a different entity than the petitioner in the earlier case, making certain factors for discretionary denial inapplicable.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 22, 26-37, 59, and 63-74 of the ’313 patent as unpatentable.