PTAB

IPR2021-00580

Cradlepoint Inc v. Sisvel Spa

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Data transmission method and data re-transmission method
  • Brief Description: The ’396 patent discloses a method and receiver for managing data retransmissions in wireless communication systems using an Automatic Repeat reQuest (ARQ) protocol. The invention uses a timer to differentiate between lost data blocks and those that are merely delayed, preventing unnecessary retransmission requests for out-of-sequence blocks.

3. Grounds for Unpatentability

Ground 1: Obviousness over Sachs - Claims 1-10 are obvious over Sachs.

  • Prior Art Relied Upon: Sachs (International Publication No. WO 02/091659).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sachs teaches every limitation of claims 1-10. Sachs addresses the same problem as the ’396 patent: preventing "spurious performed retransmissions" when data packets arrive correctly but out of sequence. Sachs discloses detecting a missed data block by identifying gaps in sequence numbers at a receiver's Radio Link Control (RLC) layer. Upon detection, Sachs teaches starting a timer (T_reorder) to delay triggering a retransmission request. If the missing packet is received before the timer expires, the timer is stopped, and no status report is sent. If the timer expires before the packet arrives, a status report—comprising both a positive acknowledgement (ACK) for received packets and a negative acknowledgement (NACK) for the missing packets—is transmitted to the sender to request retransmission. Petitioner contended this maps directly to the method steps of independent claim 1 and the receiver components of independent claim 8.
    • Key Aspects: Petitioner asserted that Sachs not only renders the claims obvious but anticipates them under 35 U.S.C. §102, as it discloses an identical solution to an identical problem.

Ground 2: Obviousness over Wei - Claims 1-5 and 7 are obvious over Wei.

  • Prior Art Relied Upon: Wei (Patent 6,987,780).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Wei independently teaches the core invention claimed in 1-5 and 7. Wei describes a system where, upon detecting a missing Radio Link Protocol (RLP) frame, a receiver RLP layer starts a "dynamic timer." If the missing frame is received while the timer is running, the receiver RLP sends a command to cancel the timer, thereby preventing an unnecessary NACK message from being sent. If the timer expires, an indication is sent that the frame is lost, and a NACK is transmitted to request retransmission. Wei also explicitly teaches transmitting status reports containing positive acknowledgements. Petitioner asserted this process discloses the claimed steps of detecting a missed block, starting a timer, stopping the timer upon receipt to prevent a status report, and transmitting a status report with an ACK after the timer expires.
    • Key Aspects: Similar to the Sachs argument, Petitioner contended that Wei also anticipates the claims under §102.

Ground 3: Obviousness over Wei in view of TS 25.322 - Claims 6 and 8-10 are obvious over Wei in view of TS 25.322.

  • Prior Art Relied Upon: Wei (Patent 6,987,780) and TS 25.322 (a 3GPP Technical Specification).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addresses claims that specify a Radio Link Control (RLC) entity and RLC Protocol Data Units (PDUs), which are specific to the 3GPP UMTS standard. Petitioner argued that while Wei teaches the core timer-based ARQ method in the context of a CDMA system's RLP layer, TS 25.322 explicitly defines the architecture and functions of the RLC layer for 3GPP UMTS systems. TS 25.322 describes an RLC entity that receives PDUs, detects missing PDUs via sequence numbers, and sends STATUS PDUs to acknowledge receipt or request retransmission. A person of ordinary skill in the art (POSITA) would apply Wei's method of using a dynamic timer to delay NACKs to the analogous RLC entity defined in TS 25.322. This combination supplies the express RLC and PDU limitations of claims 6 and 8-10.
    • Motivation to Combine: A POSITA would combine Wei and TS 25.322 because they address the same technical field of wireless data transmission and share analogous layered protocol architectures. Wei's teachings on improving retransmission efficiency in a CDMA system (cdma2000) would be seen as a straightforward and beneficial application to the similar WCDMA-based UMTS system specified by TS 25.322. The standards bodies for these systems (3GPP2 and 3GPP) were known to collaborate, making the cross-application of technical improvements a common practice.
    • Expectation of Success: A POSITA would have a high expectation of success because the underlying principles of ARQ, sequence numbers, and protocol layers (RLP vs. RLC) are analogous. Implementing Wei's timer logic within the well-defined RLC framework of TS 25.322 would be a predictable integration of known techniques.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial would be inappropriate.
  • Under 35 U.S.C. §325(d), denial was argued to be improper because none of the asserted prior art references (Sachs, Wei, or TS 25.322) were considered during the original prosecution of the ’396 patent.
  • Petitioner also argued against discretionary denial under Fintiv, asserting that the parallel district court proceedings were in their infancy, with trial dates far in the future and post-dating the expected Final Written Decision in the IPR. Furthermore, Petitioner stated its intent to seek a stay in the litigation, and argued the strong merits of the petition weighed heavily in favor of institution.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-10 of the ’396 patent as unpatentable.