PTAB

IPR2025-00174

Ericsson Inc v. Motorola Mobility LLC

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1. Case Identification

2. Patent Overview

  • Title: DEMODULATION REFERENCE SIGNAL CONFIGURATION
  • Brief Description: The ’130 patent is directed to apparatuses and methods for configuring Demodulation Reference Signals (DMRS) in a wireless communication system. The technology involves a processor determining a DMRS configuration for a physical downlink shared channel (PDSCH) that carries remaining minimum system information (RMSI).

3. Grounds for Unpatentability

Ground 1: Claims 11-20 Anticipated by or Obvious over TR 38.912

  • Prior Art Relied Upon: 3GPP TR 38.912 v14.0.0 (“TR 38.912”), a 3rd Generation Partnership Project technical report on New Radio (NR) access technology.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that TR 38.912, a foundational document for the 5G standard, discloses all elements of the challenged claims. It describes a base station (gNB) with a processor that determines DMRS configurations for the NR-PDSCH. The document explicitly states that "remaining minimum system information is transmitted in shared downlink channel via NR-PDSCH," directly meeting a key limitation of independent claims 11 and 18. Petitioner asserted that TR 38.912 discloses numerous configurable DMRS aspects, such as "variable/configurable DM-RS patterns," "front-loaded DM-RS," and "additional DM-RS," which satisfy the claim requirement for a configuration comprising at least two of the listed attributes (per the adopted claim construction).
    • Key Aspects: For dependent claims, Petitioner contended that TR 38.912 discloses predefined configurations (e.g., a fixed timing for DMRS location, claim 15) and that using a control resource set (CORESET) or downlink control information (DCI) to indicate the DMRS configuration (claims 16, 17, 20) would have been obvious implementations to a person of ordinary skill in the art (POSITA) based on the disclosures.

Ground 2: Claims 15-16 are Obvious over TR 38.912 in view of R1-1710789

  • Prior Art Relied Upon: TR 38.912 and R1-1710789 ("MediaTek"), a technical contribution to a 3GPP working group.
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground provides an alternative basis for finding claims 15 and 16 obvious. Petitioner asserted that TR 38.912 provides the foundational 5G NR system as described in Ground 1. MediaTek, which addresses DMRS structures, explicitly proposes a default configuration and a mechanism for indicating additional DMRS. Specifically, MediaTek teaches that a "front-loaded DMRS structure is supported in default," directly mapping to the "predefined" configuration required by claim 15. Furthermore, MediaTek proposes that "the network can indicate additional DMRS on the last symbol of the CORESET via the CORESET configuration if needed," directly teaching the limitation of claim 16.
    • Motivation to Combine: A POSITA developing the 5G NR system described in TR 38.912 would have looked to contemporaneous 3GPP technical contributions like MediaTek for specific implementation details and solutions to open issues, such as DMRS configuration. Both documents are part of the same standards development process, address the same technical challenges, and were intended to work together within the same system.
    • Expectation of Success: A POSITA would have had a high expectation of success in combining the teachings, as MediaTek's proposals were designed to be compatible with and build upon the framework established in TR 38.912.

Ground 3: Claims 11-20 Anticipated by or Obvious over R1-1710294

  • Prior Art Relied Upon: R1-1710294 ("LG"), a technical contribution by LG Electronics to a 3GPP working group.

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that LG, on its own, anticipates or renders obvious all challenged claims. LG discloses a gNB that determines DMRS configurations for a broadcast PDSCH used to transmit System Information Blocks (SIBs), which constitutes "remaining minimum system information." LG describes multiple predefined DMRS configurations (e.g., "Front-load DMRS Configuration 1" and "Configuration 2") and options for configuring the "presence of and the number of additional DMRS," thereby disclosing at least a first and second configuration as required by claims 11 and 18. For dependent claims, LG discloses an array of predefined DMRS configurations (claim 15) and explicitly teaches that DMRS configuration can be indicated via MIB in PBCH or through DCI (claims 16, 17, 20).
    • Key Aspects: This ground asserts that a single, targeted 3GPP contribution from June 2017 contains all the necessary elements of the invention claimed in the ’130 patent, whose priority date is also in June 2017.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on the combination of TR 38.912 and LG (Ground 3) and the combination of LG and MediaTek (Ground 5), which relied on similar motivations to combine and mapped the references in a complementary manner.

4. Key Claim Construction Positions

  • For the purposes of this IPR, Petitioner adopted the claim constructions advocated by Patent Owner Motorola in a parallel ITC proceeding to demonstrate invalidity even under Patent Owner's own interpretations.
  • "the demodulation reference signal configuration comprises a first configuration... or some combination thereof" (claims 11, 18): Petitioner adopted Motorola's construction that this phrase requires the configuration to comprise "at least two of" the six listed attributes (e.g., a first configuration, a second configuration, a mapping order, etc.).
  • "the remaining minimum system information channel" (claims 12, 13): To resolve an antecedent basis issue with the independent claims, Petitioner adopted Motorola’s proposal to construe this term as "the physical downlink shared channel carrying remaining minimum system information."

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 11-20 of Patent 11,184,130 as unpatentable.