PTAB

IPR2025-00447

Samsung Electronics Co Ltd v. Vasu Holdings LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method for Roaming Between Wireless Networks
  • Brief Description: The ’154 patent discloses a method for a mobile communication device to roam between different wireless networks, such as from a WiFi network to a cellular network, without disrupting an in-progress phone call. The method uses an "interface server" to facilitate the network switch, which is triggered when the signal strength of the initial connection drops below a predetermined threshold.

3. Grounds for Unpatentability

Ground 1: Obviousness over Iizuka and Enzmann - Claims 1, 2, 4, 43, and 45-47 are obvious over Iizuka in view of Enzmann.

  • Prior Art Relied Upon: Iizuka (Application # US2005/0282541) and Enzmann (Application # US2005/0136927).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Iizuka disclosed a method for a mobile terminal to seamlessly roam between a wireless LAN (WLAN) and a wireless telephone network. Iizuka’s system used a "call-management server" that functioned as the claimed "interface server" by connecting to both network types to manage call handovers. In Iizuka, a mobile device on a VoIP call over the WLAN monitors the connection quality. When the signal deteriorates, the terminal notifies the call-management server, which then establishes a second voice call link through the cellular network to the same end destination. Critically, Petitioner asserted that Iizuka taught this second link is established while the initial VoIP call "still continues," thus meeting the "without disrupting" limitation that was key to the patent's allowance.
    • Motivation to Combine: Petitioner contended that while Iizuka taught switching when the WLAN signal "deviates from a predetermined criterion," Enzmann provided a more sophisticated and practical condition for this switch. Enzmann taught monitoring signal strengths of both the current 802.1x network and the target cellular network. A handover would only occur if the 802.1x signal dropped below a first threshold and the cellular signal was above a second threshold. A POSITA would combine Enzmann’s dual-condition logic with Iizuka’s roaming framework to create a more robust system. This would prevent inefficient "ping-ponging" between networks and avoid switching to a cellular network that could not adequately support the call, thereby improving overall call quality and system efficiency.
    • Expectation of Success: The combination would have been a predictable implementation, as Iizuka already disclosed the concept of monitoring signal intensity as a trigger. Modifying this trigger to incorporate Enzmann's more specific, dual-threshold criteria was presented as a straightforward design choice with a high expectation of success.

Ground 2: Obviousness over Iizuka, Enzmann, and Inoue - Claims 1, 2, 4, 43, and 45-47 are obvious over Iizuka in view of Enzmann and Inoue.

  • Prior Art Relied Upon: Iizuka (’541 application), Enzmann (’927 application), and Inoue (Application # US2007/0146475).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground leveraged the Iizuka/Enzmann combination and added Inoue's teachings to address specific limitations regarding client interaction and terminating the first link. Petitioner argued that Inoue disclosed the standard Session Initiation Protocol (SIP) procedure for ending a call by transmitting a "BYE request signal" to a wireless terminal. This directly taught the claim limitation of "notifying the mobile communication device to terminate transmission." Further, Inoue explicitly taught that a wireless terminal includes a "SIP client" used to manage communication links, including sending instructions to switch networks based on signal strength measurements, which satisfied the "with a client" limitations.
    • Motivation to Combine: Petitioner asserted that while Iizuka’s system used SIP and described disconnecting the initial session, it lacked specific details on the termination mechanism. A POSITA implementing Iizuka’s system would have been motivated to look to a reference like Inoue to supply the standard, well-known SIP termination protocol. Using a SIP BYE message, as taught by Inoue, would ensure an orderly session termination, preventing data loss and potential call disruption. Integrating a SIP client from Inoue into Iizuka's mobile terminal was argued as a natural and necessary step to facilitate the SIP communications already disclosed by Iizuka.
    • Expectation of Success: Because Iizuka's system was already based on SIP, incorporating standard SIP features like a BYE message and a SIP client from Inoue was a predictable design choice that would ensure proper protocol adherence and functionality.
  • Additional Grounds: Petitioner asserted further obviousness challenges for claims 45-47 based on combinations including Sundar (Application # US2003/0134638). Sundar was cited for its teachings of an interface server (a control switch) coupled to a separate, standalone gateway device (a Media Gateway) that is bidirectionally coupled to a packet-switched telephone network, allegedly rendering the dependent claims concerning the gateway device obvious.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under both 35 U.S.C. §325(d) and §314(a). For §325(d), Petitioner contended that the primary references (Iizuka, Enzmann, Inoue) were never cited or considered by the Examiner during prosecution. For §314(a) under the Fintiv factors, Petitioner asserted that the co-pending district court case is in its early stages, with a trial date set for November 2025, well after the statutory deadline for a Final Written Decision in the IPR. Petitioner also stated its intent to seek a stay of the litigation pending the IPR outcome.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1, 2, 4, 43, and 45-47 of the ’154 patent as unpatentable under 35 U.S.C. §103.