PTAB

IPR2018-00091

Unified Patents Inc v. Cellular Communications Equipment LLC

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1. Case Identification

2. Patent Overview

  • Title: Changing Downlink Control Channel Format Based on Cross-Carrier Scheduling
  • Brief Description: The ’770 patent relates to a method for changing the format of a downlink control channel in a wireless communication system. The format is changed to include a carrier indication field (CIF) when cross-carrier scheduling is enabled and to exclude the CIF when it is disabled, with the change being triggered by explicit signaling between a network and user equipment.

3. Grounds for Unpatentability

Ground 1: Obviousness over Earnshaw - Claims 1-4, 6, 8-13, 15, and 17-24 are obvious over Earnshaw.

  • Prior Art Relied Upon: Earnshaw (WO 2011/053857 A1).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Earnshaw taught all limitations of the independent claims. Earnshaw described "DCI set switching" procedures, which included switching a downlink control channel format from a non-CIF format (like LTE Release 8) to a CIF format, and vice-versa. This format change was taught to occur in conjunction with "multi-carrier activation" (enabling cross-carrier scheduling) or "multi-carrier deactivation" (disabling cross-carrier scheduling). Crucially, Earnshaw disclosed that this switching was initiated by an explicit Radio Resource Control (RRC) command sent from the network access node (eNB) to the user equipment (UE).
    • Key Aspects: This ground asserted that the core inventive concept—tying a DCI format change to the enabling/disabling of cross-carrier scheduling via explicit signaling—was entirely disclosed by a single reference not considered during prosecution.

Ground 2: Obviousness over Earnshaw and Nory - Claims 5 and 14 are obvious over Earnshaw in view of Nory.

  • Prior Art Relied Upon: Earnshaw (WO 2011/053857 A1) and Nory (Application # 2011/0205978).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed dependent claims 5 and 14, which required the changed format (with a CIF) to be indicated on each cell of the user equipment's configured set of component carriers. While Earnshaw taught using a CIF on at least one carrier to enable cross-carrier scheduling, Nory was argued to supply the missing "each cell" limitation. Nory taught that an eNodeB can configure a UE to include a CIF on a "subset of CCs," which a person of ordinary skill in the art (POSITA) would understand includes the entire set as one possible subset.
    • Motivation to Combine: A POSITA would combine Nory's teaching with Earnshaw's system as an obvious design choice to optimize functionality. Implementing CIF DCIs on all component carriers, rather than just some, was one of a few predictable solutions that would reduce the network signaling required to reconfigure the carrier set later, thus improving system efficiency.
    • Expectation of Success: The combination was presented as a simple application of a known option (using CIFs on all carriers) to an existing system (Earnshaw's), with a high expectation of success.

Ground 3: Obviousness over Earnshaw and Iwamura - Claims 7 and 16 are obvious over Earnshaw in view of Iwamura.

  • Prior Art Relied Upon: Earnshaw (WO 2011/053857 A1) and Iwamura ("Carrier Aggregation Framework in 3GPP LTE-Advanced," a 2010 article).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground targeted dependent claims 7 and 16, which specified that the switching between enabled and disabled cross-carrier scheduling was achieved by adding or removing a component carrier from the configured set. Earnshaw taught switching between single-carrier and multi-carrier modes but did not specify the exact mechanism. Petitioner asserted Iwamura explicitly taught this mechanism, disclosing that RRC signaling is used to "add, remove, or reconfigure additional serving cells to the UE."
    • Motivation to Combine: A POSITA, seeking to implement Earnshaw’s general teaching of switching between single and multi-carrier modes, would have been motivated to look for a specific, known method for doing so. Iwamura provided this well-known technique. The combination involved applying a known technique from Iwamura to a known method from Earnshaw to achieve the predictable result of a specific carrier mode change.
    • Expectation of Success: Petitioner argued a POSITA would have a high expectation of success in implementing this combination, as it amounted to filling in a specific, known implementation detail in Earnshaw's broader framework.

Ground 4: Obviousness over Nory, Pan, and the LG April Meeting Note - Claims 1, 10, and 19 are obvious over Nory in view of Pan and the LG April Meeting Note.

  • Prior Art Relied Upon: Nory (Application # 2011/0205978), Pan (Application # 2010/0215011), and the LG April Meeting Note ("Uncertain Period Handling for CIF Initialization and Release," a 2010 technical document).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground presented an alternative basis for invalidating the independent claims. Nory was argued to teach switching from a non-CIF format to a CIF format upon enabling cross-carrier scheduling via explicit RRC signaling. However, Nory was less clear about the reverse process. The LG April Meeting Note was introduced to explicitly teach using a CIF-less format for non-cross-carrier scheduling. Pan was cited primarily to provide express support for the preamble language requiring a "processor" and "computer-readable medium," which Nory may not have explicitly detailed.
    • Motivation to Combine: A POSITA would combine Nory and the LG April Meeting Note as they both address the same technical problem of CIF presence/absence in carrier aggregation. The LG April Meeting Note provided a clear, beneficial solution (using a non-CIF format to reduce signaling overhead) for an ambiguity in Nory. Pan would be combined to provide the conventional hardware basis for implementing the methods of Nory and the LG April Meeting Note.
    • Expectation of Success: The combination was argued to be a predictable assembly of prior art elements from the same technical field to create a more complete and efficient system.

4. Key Claim Construction Positions

  • "serving cell" / "cell[s]": Petitioner proposed this term be construed as "serving cell, cell, or component carrier." This construction was argued to be supported by the patent's own specification and was critical for mapping prior art that used the term "component carrier" to the claims.
  • "being enabled for cross carrier scheduling" / "being disabled for cross carrier scheduling": Petitioner proposed constructions defining these terms by their technical function: "enabled" means using a control channel on one carrier to schedule resources on other carriers, while "disabled" means a control channel on a carrier only schedules resources on that same carrier. This linked the claim language to the specific technical operations described in the prior art.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and cancellation of claims 1-24 of Patent 8,902,770 as unpatentable under 35 U.S.C. §103.