PTAB

IPR2021-01393

Solid Inc v. CommScope Technologies LLC

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Point-to-Multipoint Digital Radio Frequency Transport
  • Brief Description: The ’286 patent discloses a digital distributed antenna system designed to extend radio frequency (RF) coverage into areas with poor signal reception. The system comprises a digital host unit that communicates with a base station and multiple remote units, which digitize uplink RF signals, transmit them to the host unit where they are digitally summed, and then forward a composite analog signal to the base station.

3. Grounds for Unpatentability

Ground 1: Obviousness over Oh - Claims 1-4, 7-17, 19-34, and 37-39 are obvious over Oh.

  • Prior Art Relied Upon: Oh (Korean Laid-Open Disclosure No. KR1999-0064537).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Oh, which was not considered during prosecution, discloses a "Digital Optic Repeater" system that renders the challenged claims obvious. Oh’s system includes a "master unit" (analogous to the patent’s "first unit") and multiple "slave units" (analogous to the "plurality of second units") that extend RF signals into "radio wave shadow areas." Petitioner contended that the key limitation of independent claim 1—a first unit that "digitally sums corresponding digital RF samples"—is explicitly taught by Oh. Oh’s master unit receives digital samples from multiple slave units and uses "digital combiners" to aggregate the signals from each slave unit for each frequency band, which Petitioner asserted is the claimed digital summing. The summed digital signals are then converted to analog and transmitted to the base station, meeting further limitations of the claims.
    • Key Aspects: The central argument was that the Examiner's allowance was based on the digital summing feature, a feature Petitioner alleged is clearly present in Oh’s digital combiners but was not before the original Examiner.

Ground 2: Obviousness over Oh in view of Allpress - Claims 5-6, 18, 35-36, and 40 are obvious over Oh in view of Allpress.

  • Prior Art Relied Upon: Oh (Korean Laid-Open Disclosure No. KR1999-0064537) and Allpress (Patent 6,496,546).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claims requiring software-based processing (e.g., claim 5: "software configured to perform the base station processing"). Petitioner argued that while Oh discloses a hardware-based implementation for its post-summing processing, Allpress teaches a "Software-Defined Transceiver" for wireless systems. Allpress discloses that functions like up-conversion and filtering, analogous to the post-summing processing in Oh’s master unit, can be performed by software-defined devices. The combination of Oh's architecture with Allpress's software implementation renders the software-specific claims obvious.
    • Motivation to Combine: A POSITA would combine Oh with Allpress to gain the well-known benefits of software-defined systems. Allpress explicitly teaches that software implementation offers cost and complexity advantages over "duplicative hardware," is not "standards specific," and allows for greater portability and easier modification. A POSITA would have been motivated to replace Oh’s hardware-based processing components with the more flexible and cost-effective software solutions taught by Allpress.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in implementing Oh’s signal processing functions in software. Allpress provides a clear disclosure of software-defined transmitters and receivers performing analogous functions, demonstrating the technical feasibility of such an implementation.

4. Key Technical Contentions (Beyond Claim Construction)

  • "Base Station Processing": Petitioner argued that the term "base station processing," which is not defined in the ’286 patent, should be interpreted broadly based on the patent owner’s litigation positions in a related case. Petitioner contended this term encompasses processing that occurs within the host unit itself in preparation for transmission to a base station, not just processing at the base station. This interpretation was crucial for mapping Oh’s master unit, which performs digital-to-analog conversion and up-conversion after summing, to the claims reciting this limitation.
  • "Digital Radio Frequency (RF) Samples": Citing a prior litigation report from the patent owner's expert, Petitioner argued that "digital RF" as used in the patent is a broad term. It can refer to samples of baseband signals, intermediate frequency signals, or direct RF signals. This contention supported the argument that Oh’s digitization of intermediate frequency signals met the claim limitation of generating "digital RF samples."

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-40 of Patent 8,577,286 as unpatentable.