Ericsson Inc v. Intellectual Ventures II LLC

1. Case Identification

• Case #: IPR2015-01664
• Patent #: 7,787,431
• Filed: August 3, 2015
• Petitioner(s): Ericsson Inc. and Telefonaktiebolaget LM Ericsson
• Patent Owner(s): Intellectual Ventures II LLC
• Challenged Claims: 8-12 and 18-22

2. Patent Overview

• Title: Methods and Apparatus for Multi-Carrier Communications with Variable Channel Bandwidth
• Brief Description: The ’431 patent describes multi-carrier communication systems, such as those using Orthogonal Frequency Division Multiplexing (OFDM). The technology centers on using a defined "core-band" within a larger variable bandwidth to transmit a "primary preamble" with specific signal properties to enable radio operations.

3. Grounds for Unpatentability

Ground 1: Obviousness over Dulin, Yamaura, Hwang, and Zhuang - Claims 8-12 and 18-22 are obvious over Dulin, Yamaura, Hwang, and Zhuang.

• Prior Art Relied Upon: Dulin (Application # 2002/0055356), Yamaura (Patent 7,782,750), Hwang (an IEEE technical submission from March 2004), and Zhuang (Patent 7,426,175).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that the prior art references, when combined, teach every limitation of the challenged claims. Independent claims 8 (apparatus) and 18 (method) require three core aspects: (1) a variable bandwidth OFDMA system with a defined "core-band," (2) a primary preamble transmitted within that core-band, and (3) specific preamble properties (e.g., good autocorrelation, low cross-correlation, and low peak-to-average ratio).
    • Dulin was asserted to teach a foundational OFDMA cellular base station that supports variable bandwidth by assigning different frequency blocks to users. It provides the basic system architecture.
    • Yamaura was asserted to teach transmitting control signals and a preamble within a narrow frequency band, centered at an operating frequency, to reduce receiver complexity and power consumption. This narrow band serves as the claimed "core-band."
    • Hwang was asserted to teach a scalable OFDMA system with a plurality of possible operating channel bandwidths (e.g., 2.5, 5, 10, 20 MHz), achieved by varying the number of subcarriers. This disclosure was crucial to meet the ’431 patent's specific definition of "core-band" as being no larger than the smallest possible operating bandwidth. Hwang also taught grouping subcarriers into "bins," satisfying the "plurality of subcarrier groups" limitation.
    • Zhuang was asserted to teach the specific preamble properties that were added during prosecution to secure allowance of the claims. Zhuang discloses Generalized Chirp-Like (GCL) sequences expressly designed for use as preambles in OFDM systems to have ideal autocorrelation, optimal cross-correlation, and a low peak-to-average power ratio (PAPR).
  • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would have been motivated to combine the references to achieve predictable benefits.
    • A POSITA would combine Yamaura's efficient narrow-band control channel with Dulin's OFDMA framework to provide necessary control signaling (e.g., Dulin's frame map) in a power-efficient manner.
    • A POSITA would incorporate Hwang's scalable bandwidth teachings into the Dulin/Yamaura system to add operational flexibility, a well-known objective in wireless system design. This combination would result in a system with multiple operating bandwidths and a narrow control channel that meets the patent’s "core-band" definition.
    • A POSITA implementing the preamble taught by Yamaura would naturally seek sequences with good performance characteristics. Zhuang provided an off-the-shelf solution with its GCL sequences, which were known to be optimized for the exact properties (autocorrelation, cross-correlation, PAPR) recited in the claims.
  • Expectation of Success: Petitioner argued that a POSITA would have had a reasonable expectation of success because the combination involved applying known techniques (scalable bandwidth, optimized preamble sequences) to a standard OFDMA system to achieve predictable improvements in flexibility and performance.

4. Key Claim Construction Positions

• "core-band": Petitioner argued this term should be construed according to its explicit definition in the specification: "a frequency segment that is not greater than the smallest operating channel bandwidth among all the possible spectral bands that the receiver is designed to operate with." This construction was central to Petitioner's argument for including Hwang, as it requires a system capable of operating at multiple distinct bandwidths.
• "primary preamble": Petitioner proposed this term means "a signal transmitted near the beginning of a frame, and occupying only the core band," based on its usage in the specification.
• "peak-to-average ratio": Petitioner argued that in the context of OFDM systems, a POSITA would understand this term to mean "peak-to-average power ratio" (PAPR), a standard metric of concern.

5. Arguments Regarding Discretionary Denial

• This petition was filed after the Board declined to institute review on the same claims in a prior IPR (IPR2014-01195). Petitioner presented extensive arguments that discretionary denial under 35 U.S.C. §325(d) would be inappropriate.
• The core argument was that the present petition relied on new prior art (Dulin, Hwang, and Kerr) that was not, and could not have been, reasonably discovered by Petitioner before filing the initial petition.
• Petitioner further alleged that an investigation revealed the named inventors of the ’431 patent had attended an IEEE standards meeting where the new prior art was presented, yet this art was never disclosed to the PTO during prosecution. Petitioner argued that Patent Owner should not benefit from the inventors' failure to disclose material prior art.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 8-12 and 18-22 of the ’431 patent as unpatentable.