Ericsson Inc v. Uniloc 2017 LLC

1. Case Identification

• Case #: IPR2020-00315
• Patent #: 7,075,917
• Filed: December 18, 2019
• Petitioner(s): Ericsson Inc.
• Patent Owner(s): Uniloc 2017 LLC
• Challenged Claims: 1-3, 9-10

2. Patent Overview

• Title: Wireless Network with a Data Exchange According to the ARQ Method
• Brief Description: The ’917 patent discloses a system and method for data exchange in a wireless network using a hybrid Automatic Repeat Request (ARQ) method. The purported improvements over the prior art involve detecting data transmission errors at the physical layer for faster retransmission requests and using abbreviated sequence numbers whose length varies to reduce communication overhead.

3. Grounds for Unpatentability

Ground 1: Obviousness over TR25.835 and Abrol - Claims 1-3 and 9-10 are obvious over TR25.835 in view of Abrol.

• Prior Art Relied Upon: TR25.835 (3G TR 25.835 V1.0.0, a 3rd Generation Partnership Project technical report) and Abrol (Patent 6,507,582).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that the combination of TR25.835 and Abrol taught every limitation of the challenged claims. TR25.835, a technical report on Hybrid ARQ, allegedly disclosed the foundational wireless network comprising terminals and a radio network controller. Specifically, Petitioner asserted that Chapter 7 of TR25.835 taught a "fast HARQ" implementation where the physical layer (Layer 1) performs error detection on received coded transport blocks, stores them in a buffer for potential retransmission, and sends acknowledgement (ACK) or negative acknowledgement (NAK) commands over a direct back channel to the transmitting physical layer. This was argued to satisfy most limitations of independent claim 1.
  • However, TR25.835 did not explicitly disclose using abbreviated sequence numbers. Petitioner contended that Abrol supplied this missing element. Abrol taught a method for generating shortened, unambiguous sequence numbers to reduce transmission overhead in wireless systems. Critically, Abrol allegedly taught that the length of these abbreviated numbers depends on the amount of data needing to be stored for potential retransmission (i.e., unacknowledged data), which Petitioner mapped to the claim limitation "whose length depends on the maximum number of coded transport blocks to be stored."
  • Dependent claim 2, which specified a hybrid ARQ method of type II or III, was argued to be explicitly taught by TR25.835. Petitioner asserted that independent claims 9 and 10, which are directed to a "radio network controller" and a "terminal" respectively, were obvious for the same reasons as claim 1. TR25.835 allegedly taught a symmetrical system where both the controller and terminals can function as the "transmitting side" or "receiving side," rendering the claims patentably indistinct from claim 1.
  • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would combine TR25.835 and Abrol to improve the efficiency of the fast HARQ system. Abrol's stated goal of "minimizing the overhead inherent" in error control protocols by shortening sequence numbers was said to directly align with TR25.835's objective of creating a faster, more efficient ARQ protocol. Petitioner asserted the references were highly compatible, as Abrol specifically mentioned its applicability to W-CDMA, a network protocol specified by 3GPP (the publisher of TR25.835). The combination was characterized as a simple and logical substitution of Abrol's abbreviated sequence numbers for the standard sequence numbers used in TR25.835's physical layer, leading to the predictable benefit of reduced overhead.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success in combining the references. The integration was argued to be a straightforward modification that would predictably yield a more efficient ARQ protocol without requiring any undue experimentation.

4. Key Claim Construction Positions

• Petitioner proposed that the claim term "back channel" should be construed to mean "a channel which is inserted directly between the receiving physical layer and the sending (or transmitting) physical layer (and not between the RLC layers)." This construction was central to its argument that TR25.835 taught the claimed physical-layer-to-physical-layer communication for sending ACK/NAK commands, distinguishing it from prior art systems where acknowledgements were handled at higher protocol layers.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §325(d) would be inappropriate because the core prior art and arguments were not previously presented to the USPTO. It contended that the Examiner did not consider Abrol at all during prosecution. Furthermore, the Examiner only had access to an earlier version of TR25.835 which lacked the critical "fast HARQ" teachings contained in Chapter 7 of the version relied upon in the petition. Petitioner also noted it was concurrently filing a motion for joinder with an already-instituted IPR (IPR2019-00973) that challenged the same claims on substantively identical grounds and evidence.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-3 and 9-10 of the ’917 patent as unpatentable under 35 U.S.C. §103.