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IPR2021-01394

Solid Inc v. CommScope Technologies LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Point-To-Multipoint Digital Radio Frequency Transport
  • Brief Description: The ’402 patent describes a digital distributed antenna system for extending radio frequency (RF) signals into areas with poor coverage. The system includes a digital host unit that communicates with a base station and multiple remote units, with a key feature being the host unit’s ability to digitally sum uplink signals received from the various remote units before forwarding them to the base station.

3. Grounds for Unpatentability

Ground 1: Obviousness over Oh - Claims 1-2, 5-7, 10-21, 24, 25, 27-32, 35-44, 47, 48, 51, 52, 55, and 56 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, a Korean patent application, discloses all elements of the challenged claims. Oh teaches a "Digital Optic Repeater" system with a "master unit" (analogous to the ’402 patent's host unit) and multiple "slave units" (analogous to the remote units) connected by optical lines to extend RF signals into "radio wave shadow areas." Crucially, Petitioner asserted that Oh's master unit performs the central inventive concept of the ’402 patent: a host-based digital summing operation. In Oh's reverse path, digital sample data from multiple slave units is sent to "digital combiners" in the master unit, which aggregate the digital signals from each remote unit to create a combined signal for transmission to the base station. This digital summing of signals from multiple remotes at the host unit allegedly maps directly to the limitations of independent claim 1. Petitioner further contended that Oh teaches the processing of these summed digital samples (e.g., D/A conversion, upconversion) to create a final analog RF signal for the base station, satisfying the "base station processing" limitation.

Ground 2: Obviousness over Oh in view of Schwartz - Claims 3, 4, 22, 23, 33, 34, 45, 46, 53, and 54 are obvious over Oh in view of Schwartz.

  • Prior Art Relied Upon: Oh (Korean Laid-Open Disclosure No. KR1999-0064537) and Schwartz (Patent 5,883,882).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon Oh by adding Schwartz to teach network expansion capabilities. Claims 3 and 4 require coupling remote units to the host unit via a "shared wired communication link" and an "intermediary digital expansion unit." Petitioner argued that while Oh's system architecture shows each remote unit having a dedicated optical port on the host, Schwartz discloses a network topology with "intermediate stations" that act as repeaters or branching points. These intermediate stations can be daisy-chained, allowing the network to expand to "any number of" remote stations beyond the physical port limitations of the host. The combination of Oh’s digital system with Schwartz’s expandable topology allegedly renders claims requiring shared links and intermediary expansion units obvious.
    • Motivation to Combine: A POSITA would recognize that Oh's exemplary system is limited in scale by the number of optical ports on its master unit. To create a larger, more scalable RF distribution network (e.g., for a large building or arena), a POSITA would combine Oh’s advanced digital transport method with the well-known network expansion topologies taught by Schwartz, which discloses using intermediate stations to overcome host port limitations.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination involved applying a known network expansion technique (Schwartz) to an improved signal transport system (Oh) to achieve the predictable result of increased scalability.

Ground 3: Obviousness over Oh in view of Allpress - Claims 8, 9, 26, 49, 50, and 57 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 that the "base station processing" functionality be performed by software. Petitioner contended that while Oh discloses a hardware-based implementation for its reverse master unit's processing functions (D/A converters, mixers, etc.), Allpress teaches a "Software-Defined Transceiver." Allpress explicitly describes the advantages of software-based systems, including reduced cost, increased portability, and flexibility over "duplicative hardware" implementations. Petitioner argued that the software-based transmitter in Allpress performs functions (e.g., up-conversion) analogous to the hardware-based "base station processing" functions in Oh's master unit.
    • Motivation to Combine: A POSITA would be motivated to implement Oh's hardware-based processing functions in software, as taught by Allpress, to gain the well-understood benefits of cost reduction, improved flexibility, and easier modifications. Replacing known hardware components with their software equivalents was a common and logical design choice for a POSITA seeking to improve system efficiency and reduce complexity.
    • Expectation of Success: The expectation of success would be high, as it involved implementing known signal processing functions in software rather than hardware, a predictable modification that leverages the known advantages of software-defined radio technology.

4. Relief Requested

  • Petitioner requested the institution of an inter partes review and cancellation of claims 1-57 of the ’402 patent as unpatentable.