PTAB

IPR2020-00038

Motorola Mobility LLC v. Uniloc 2017 LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Radio Communication System with Re-transmission and Threshold-Based Detection
  • Brief Description: The ’079 patent discloses a radio communication system where secondary stations use dedicated uplink time slots to request services from a primary station. The invention purports to improve performance by having a secondary station re-transmit its service request in consecutive time slots until an acknowledgement is received, and by having the primary station use a signal strength threshold to detect the request.

3. Grounds for Unpatentability

Ground 1: Claim 17 is obvious over Merakos (incorporating Kay) in view of Alamouti.

  • Prior Art Relied Upon: Merakos (Patent 5,521,925), Kay (Patent 5,299,198), and Alamouti (Patent 5,933,421).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Merakos discloses the foundational Time Division Multiple Access (TDMA) communication system where secondary stations (data stations) send service requests (Reverse Allocate Requests or RARs) to a primary station (base station) in allocated uplink time slots. Kay, which is incorporated by reference into Merakos, explicitly teaches the re-transmission feature of claim 17 by disclosing that these requests should be re-transmitted multiple times without waiting for an acknowledgement to achieve time diversity and combat signal fading. Petitioner asserted this combination teaches all limitations of claim 17 except for the threshold-based detection. Alamouti was argued to supply this missing element by teaching various diversity reception methods, including "scanning diversity," which explicitly detects signals by scanning them until one is found with a signal strength above a predetermined threshold.
    • Motivation to Combine (for §103 grounds): A Person of Ordinary Skill in the Art (POSITA) would combine Alamouti with the teachings of Merakos/Kay to solve the known problem of reliably detecting the re-transmitted signals. While Merakos/Kay taught re-transmission for diversity, they did not specify a detection method. A POSITA would look to a contemporaneous reference like Alamouti, which provides a known and effective solution (threshold-based scanning diversity), to complete the system and improve its overall performance and reliability.
    • Expectation of Success (for §103 grounds): A POSITA would have a reasonable expectation of success because combining a known transmission scheme (time diversity from Merakos/Kay) with a known detection method (thresholding from Alamouti) is a predictable application of established techniques to improve system performance.

Ground 2: Claim 17 is obvious over Merakos (incorporating Kay) in view of Borth.

  • Prior Art Relied Upon: Merakos (Patent 5,521,925), Kay (Patent 5,299,198), and Borth (Patent 4,829,543).
  • Core Argument for this Ground:
    • Prior Art Mapping: As in Ground 1, Petitioner contended that Merakos in view of the incorporated Kay reference discloses all elements of claim 17 except the specific threshold detection feature. Borth was argued to disclose a TDMA receiver for fading channels that explicitly detects the presence or absence of a signal in an assigned timeslot by comparing the signal's strength to a predetermined threshold value. This detector is precisely the feature missing from the Merakos/Kay combination.
    • Motivation to Combine (for §103 grounds): A POSITA seeking to improve the detection of the re-transmitted requests in the Merakos/Kay system would be motivated to incorporate the threshold detector from Borth. Borth is directed to the same field (TDMA receivers) and its title explicitly references solving issues in "Multipath Fading Channels," making it a natural source for a solution. Applying Borth's detector would improve the rate of correct signal detection and reduce false alarms for the RARs taught by Merakos/Kay.
    • Expectation of Success (for §103 grounds): Integrating Borth's well-known threshold detection feature into the base station of the Merakos/Kay system is a straightforward combination of prior art elements. The application would predictably yield a system with improved detection reliability, which is the exact problem a POSITA would be trying to solve.

4. Key Claim Construction Positions

  • Petitioner proposed that the term "acknowledgement" be construed as "a message sent from the primary station to the secondary station indicating the primary station's receipt of the secondary station's request."
  • This construction was argued to be critical to the obviousness argument, as it supports the position that the re-transmissions taught in the prior art occur "without waiting for an acknowledgement." The re-transmissions are performed for time diversity before any such acknowledgement message is sent by the primary station or received by the secondary station.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial of the inter partes review (IPR) would be inappropriate under both 35 U.S.C. §325(d) and §314(a). It was asserted that the prior art and arguments presented in the petition were entirely new and had not been considered during prosecution or in a prior IPR filed by other parties ("First Petitioners").
  • The petition contended that the General Plastic factors strongly favor institution. Key arguments included: Motorola was not "similarly situated" to the First Petitioners; Uniloc sued Motorola approximately nine months after the others, making Motorola's later filing reasonable; Motorola was not aware of the asserted prior art at the time of the first IPR filing; and instituting this IPR would be efficient as it only challenges one claim and the related district court case is stayed, making a Final Written Decision (FWD) likely before any trial.

6. Relief Requested

  • Petitioner requested that the Patent Trial and Appeal Board institute an inter partes review and cancel claim 17 of Patent 6,868,079 as unpatentable.