PTAB

IPR2018-00740

Sonitor Technologies Inc v. Centrak LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Synchronization of Real-Time Location Systems
  • Brief Description: The ’030 patent discloses a real-time location system (RTLS) that uses radio frequency (RF) signals to provide timing synchronization to other system components. The purported novelty is using a dedicated RF base station to transmit timing information to infrared (IR) or ultrasonic base stations, which allows portable tags to conserve battery power by activating their receivers only when a transmission is expected.

3. Grounds for Unpatentability

Ground 1: Obviousness over Corrado and Welles - Claims 1, 2, 4, 6, 9, 12, 14, 24, 28, and 29 are obvious over Corrado in view of Welles.

  • Prior Art Relied Upon: Corrado (Application # 2008/0061967) and Welles (Patent 6,970,097).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Corrado disclosed an RTLS where portable tags are triggered by IR or ultrasonic signals from non-synchronized "illuminators" (base stations) to transmit their ID via RF to a reader. This system suffered from potential interference if multiple illuminators were used in the same area. Welles disclosed a similar ultrasonic RTLS that solved this interference problem by using a central RF "locating receiver" to transmit synchronization codes to its ultrasonic "room transmitters," ensuring they transmit at different times.
    • Motivation to Combine: A POSITA would combine Welles's RF synchronization method with Corrado's RTLS to overcome the known problem of interference in systems with multiple ultrasonic or IR transmitters. This combination would allow for more accurate and reliable location tracking within a single room or complex area, a recognized goal in the art.
    • Expectation of Success: Petitioner asserted success would be predictable because the systems were very similar. Corrado’s components, including its RF readers and illuminators, were already described as being capable of the bi-directional RF communication necessary to implement Welles's synchronization scheme.

Ground 2: Obviousness over Corrado, Welles, and O'Hara - Claims 3, 5, 10, 11, 13, 21, 22, 25-27, and 30 are obvious over the combination of Corrado, Welles, and O'Hara.

  • Prior Art Relied Upon: Corrado (Application # 2008/0061967), Welles (Patent 6,970,097), and O'Hara (IEEE 802.11 Handbook: A Designer's Companion, 1999).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on the Corrado and Welles combination by adding the teachings of O'Hara. O'Hara described the well-known IEEE 802.11 (Wi-Fi) standard, including its timing synchronization function (TSF). This function uses periodic "Beacon" frames containing timestamps, as well as a "Probe Request/Response" mechanism, for devices to synchronize with a network access point.
    • Motivation to Combine: A POSITA would have been motivated to incorporate O'Hara's standard Wi-Fi synchronization methods into the Corrado/Welles system to further improve performance, particularly the battery life of the portable tags. Corrado's tags wasted power by waking periodically to listen for signals that might not be present. O'Hara's TSF would allow the tags to synchronize precisely with base station transmissions, enabling them to remain in a low-power sleep mode until the exact moment a signal was expected.
    • Expectation of Success: The combination was asserted to be predictable, as Corrado itself disclosed that its RF readers could be equipped with a wireless 802.11 system, expressly suggesting the compatibility of the technologies.

Ground 3: Obviousness over Su and Schrum - Claims 15-20 and 34 are obvious over Su in view of Schrum.

  • Prior Art Relied Upon: Su ("Time-Diffusion Synchronization Protocol for Wireless Sensor Networks," an April 2005 journal article) and Schrum (Application # 2005/0265306).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground challenges claims related to synchronizing RF base stations, independent of the RTLS context. Petitioner argued Su disclosed a "Time-Diffusion" protocol where a master node receives timing information from a time server and "diffuses" it through a network of sensor nodes. Schrum disclosed a method for synchronizing wireless devices using a "superframe" timing structure, where devices transmit beacons at a specific offset relative to a superframe boundary to avoid collisions.
    • Motivation to Combine: A POSITA would have been motivated to apply Schrum’s teaching of transmitting an explicit offset value as a distinct data field to Su’s time-diffusion protocol. In Su, nodes calculate an offset based on estimated delay. Explicitly transmitting the offset, as taught by Schrum, would provide receiving nodes with more precise data for synchronization, allowing them to better account for how "stale" the timing information is relative to the original broadcast from the master node.
    • Expectation of Success: Combining these known synchronization techniques from the same field of wireless networking would predictably result in a more robust and accurate synchronized network.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations incorporating Cheng (Application # 2005/0124306) for its teaching of using a time server for accurate time, and Crimmins (Patent 5,917,425) for disclosing a separate decoder for processing received signals.

4. Key Claim Construction Positions

  • "base station": Petitioner argued this term should be construed as "a non-portable wireless communication device." This construction was based on the specification consistently distinguishing between portable devices (tags) and base stations, which are described as stationary infrastructure mounted on walls or ceilings. This distinction is critical to understanding the claimed system architecture.

5. Key Technical Contentions (Beyond Claim Construction)

  • Priority Date Challenge: Petitioner argued that claims reciting "ultrasonic base stations" (e.g., independent claims 1 and 7) are not entitled to the 2007 priority date of the '269 Provisional application. The '269 Provisional was alleged to only disclose infrared (IR) and RF base stations, with no mention or support for ultrasonic technology. Because ultrasound and IR/RF are fundamentally different physical phenomena, Petitioner contended the effective filing date for these claims is the 2008 filing date of a later application, making Corrado (filed in 2007) available as prior art.

6. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under §325(d), asserting that the primary prior art references relied upon in the petition (Corrado, O'Hara, Cheng, Su, and Schrum) were never presented to or considered by the USPTO examiner during prosecution. While the examiner considered Welles and Crimmins, Petitioner contended the new references and the arguments based upon them are not cumulative and raise substantial new questions of patentability that warrant review.

7. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-35 of the '030 patent as unpatentable.