PTAB

IPR2025-00927

Lenovo United States Inc v. Collision Communications Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Combinational Hybrid Turbo-MUD
  • Brief Description: The ’492 discloses a hybrid Multi-User Detector (MUD) system for processing signals in a wireless communication system, such as a cellular base station. The system's purported novelty is a "MUD decision unit" that uses decision criteria to select an appropriate detector from at least two available MUDs to remove interference and isolate signals for each user.

3. Grounds for Unpatentability

Ground 1A: Obviousness over McElwain and Wang - Claims 1-3, 5-13, and 15-17 are obvious over McElwain in view of Wang.

  • Prior Art Relied Upon: McElwain (Application # 2004/0213360) and Wang (International Publication No. WO2006/092090).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that McElwain taught a cellular base station with a MUD system nearly identical to the prior art system acknowledged in the ’492 patent, including a parameter estimator, a MUD, a bank of decoders, and iterative feedback loops. McElwain acknowledged the tradeoff between complex, accurate MUDs and simpler, less accurate ones. Petitioner asserted that Wang addressed this exact tradeoff by teaching a system that selects an appropriate MUD algorithm from several available options based on determined channel interference characteristics. Wang’s channel environment detection and classification module, which selects a MUD, was argued to be the claimed "multi-user detector decision unit."
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine McElwain’s MUD system with Wang’s MUD selection technique to efficiently manage the tradeoff between computational resource consumption and accuracy, a problem acknowledged by both references. Wang’s method of selecting a MUD based on real-time interference characteristics (e.g., via eigendecomposition of a correlation matrix, as recited in claim 3) provided a clear solution to improve the performance of McElwain’s system, especially under changing signal conditions.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because both references described base station receivers using predictable electrical components and software to remove signal interference, making the integration of Wang’s selection logic into McElwain’s architecture straightforward.

Ground 2A: Obviousness over Mills and Liu - Claims 1-3, 5-13, and 15-17 are obvious over Mills in view of Liu.

  • Prior Art Relied Upon: Mills (Application # 2003/0193966) and Liu (Application # 2006/0188031).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Mills disclosed a receiver with an iterative MUD system, including a parameter estimator, a multi-user decoder, and a bank of single-user decoders, similar to McElwain. Like McElwain, Mills also acknowledged the tradeoff between low and high complexity MUDs. Petitioner contended that Liu provided the missing element of a MUD decision unit, disclosing a "demodulation scheme selection logic" that selects one of three available decoders (a single-user decoder, a linear multi-user decoder, and a nonlinear multi-user decoder) to process received signals. Liu’s selection was based on criteria such as signal strength, signal-to-noise ratio, or expected bit error rate, which Petitioner mapped to the "decision criteria" of the challenged claims.
    • Motivation to Combine: A POSITA would combine Mills’s iterative MUD system with Liu’s selection logic to conserve system resources and improve performance. By selecting a MUD with appropriate complexity for the current signal conditions, as taught by Liu, the combined system would yield high accuracy while conserving power and processing resources, directly addressing the tradeoff acknowledged in Mills. Selecting a MUD based on predicted performance (e.g., expected bit error rate) was argued to be an advantageous and well-known engineering choice.
    • Expectation of Success: A POSITA would expect success in combining these references, as both related to well-understood receiver architectures. Implementing Liu's selection logic to choose between different decoders within the framework of Mills's system involved predictable design modifications.

  • Additional Grounds: Petitioner asserted Ground 1B, arguing claims 1-3, 5-13, and 15-17 are obvious over McElwain and Sampath (Application # 2007/0060061), where Sampath provided a demodulator selector that uses expected Signal-to-Interference-Plus-Noise Ratio (SINR) as a metric to choose between MUDs of varying complexity. Petitioner also asserted Ground 2B, arguing claims 10-13 and 15-16 are obvious over the Mills-Liu combination further in view of Sampath, to explicitly teach low, medium, and high complexity MUDs.

4. Key Claim Construction Positions

  • "multi-user detector decision unit" (claims 1 and 10): Petitioner noted that a District Court previously construed this term as a means-plus-function term under 35 U.S.C. §112, sixth paragraph. The function is using "decision criteria" to "determine a selected multi-user detector." The corresponding structure was identified in the specification as "MUD decision unit 220" and "decision logic unit 520," which must be able to perform one or more of the patent's disclosed algorithms (e.g., using thresholds for number of symbols, correlation matrix, expected bit error rate, SINR, etc.). Petitioner argued their obviousness analysis applied regardless of whether this construction was adopted.

5. Arguments Regarding Discretionary Denial

  • Petitioner stated that discretionary denial is unwarranted. They noted their intent to use the bifurcated briefing process proposed in a March 26, 2025, USPTO memorandum to rebut any discretionary denial arguments raised by the Patent Owner.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-3, 5-13, and 15-17 of the ’492 patent as unpatentable.