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IPR2021-01392

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 ’218 patent describes a digital distributed antenna system for extending radio frequency (RF) coverage into areas with poor signal reception. The system includes a host unit that communicates with a base station and multiple remote units, which digitize RF signals for transport and perform digital summing of upstream signals from multiple remote units at the host unit.

3. Grounds for Unpatentability

Ground 1: Claims 1-10, 12-14, 16-20, 23-25, and 27-28 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 discloses a digital optical repeater system, teaches every element of the challenged claims. Oh’s system includes a "master unit" (analogous to the claimed "host unit") and multiple "slave units" (analogous to "remote units") to extend RF signals into "radio wave shadow areas." In the upstream path, Oh's slave units digitize received analog RF signals and transmit the resulting digital samples to the master unit. Critically, Petitioner asserted that Oh’s master unit performs the claimed digital summing. Oh’s "digital combiners" receive four 12-bit digital samples (one from each of four slave units for a given frequency band) and combine them to create a 14-bit signal. Petitioner contended this "combining" is the same as the claimed "digital summing," as it aggregates digital values and results in a signal with a higher resolution, thus rendering the core inventive concept obvious.
    • Key Aspects: The central argument was that Oh, a reference not considered during prosecution, directly discloses the key claimed feature of upstream digital summing at a host unit, which was a basis for the patent's allowance.

Ground 2: Claims 11, 15, 21-22, and 26 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 addressed claims reciting a "digital expansion unit." Petitioner argued that Oh provides the fundamental digital RF transport system with upstream summing, as established in Ground 1. Schwartz, which describes an analog RF distribution system, was cited for its teaching of using "intermediate stations" to expand network coverage. These intermediate stations function as repeaters or branching points, allowing a central station to connect to more remote units than its physical ports would otherwise permit, including through daisy-chaining. Petitioner asserted that applying Schwartz’s scalable network topology to Oh’s digital system would result in a "digital expansion unit" that performs the functions recited in the claims, such as summing signals from a second plurality of remote units and communicating them to the host unit.
    • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would be motivated to combine Oh and Schwartz for clear, predictable reasons. Oh itself describes analog systems like Schwartz as "Conventional Technology," creating a direct incentive to apply Oh’s digital improvements to such known topologies. A POSITA would recognize that Oh’s system is limited by the number of optical ports on its master unit (four in the example). To create a larger, more scalable network (e.g., for a large building or arena), a POSITA would look to known expansion techniques, such as the intermediate stations taught by Schwartz, to overcome this limitation.
    • Expectation of Success: A POSITA would have a reasonable expectation of success in combining the references. The combination involved applying a known network expansion topology (Schwartz) to a digital transport system (Oh) to achieve the predictable benefit of increased scalability. The digital implementation of Schwartz's analog combining function—digital summing—was already taught by Oh's base system, making the integration straightforward.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-28 of Patent 8,326,218 as unpatentable.