PTAB

IPR2014-01524

Sony Mobile Communications USA Inc v. Adaptix Inc

Log In

1. Case Identification

2. Patent Overview

  • Title: Method and Apparatus for Subcarrier Selection in a Multi-Access Communication System
  • Brief Description: The ’748 patent discloses techniques for selecting and allocating resources in a wireless Orthogonal Frequency-Division Multiple-Access (OFDMA) communication system. The technology involves a subscriber device measuring channel quality for various subcarriers, selecting a preferred set of "candidate subcarriers," and sending feedback to a base station, which then allocates resources based on this feedback.

3. Grounds for Unpatentability

Ground 1: Obviousness over Ritter and Hashem - Claims 6, 8-9, and 19-22 are obvious over Ritter in view of Hashem.

  • Prior Art Relied Upon: Ritter (German Patent DE19800953) and Hashem (Patent 6,721,569).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Ritter, which describes an OFDMA system, taught most elements of the challenged claims, including a mobile station measuring the quality of frequency "segments" (clusters of subcarriers), determining suitable segments, and sending a priority list to the base station for allocation. Ritter disclosed that the mobile station determines both the preferred segments and their order in a "sequence of suitability," which Petitioner asserted meets the "arbitrarily ordering" limitation because the list's entries and order are unknown to the base station. Hashem was introduced to teach the use of pilot symbols for measuring channel quality (specifically, Signal-to-Interference Ratio, or SIR) and including an index and quality value (e.g., SINR) with the feedback, which Ritter did not explicitly disclose.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Ritter and Hashem to improve subcarrier selection in Ritter’s OFDMA system. Petitioner contended that using pilot tones, as taught by Hashem, was a known and obvious alternative for measuring subcarrier signal and interference information. Furthermore, because Ritter taught that the base station selects subcarriers based on "quality characteristics," a POSITA would have been motivated to include specific quality metrics like SINR in the feedback, as Hashem taught, to provide the base station with better data for its allocation decisions.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in incorporating Hashem’s pilot-based measurement and feedback techniques into Ritter’s system, as these were well-known methods for improving the efficiency of resource allocation in OFDMA systems.

Ground 2: Obviousness over IEEE and Chuang - Claims 6, 8-9, 11, and 19-22 are obvious over IEEE in view of Chuang.

  • Prior Art Relied Upon: IEEE (IEEE Communications Magazine, Jul. 2000) and Chuang (an Aug. 1998 journal article titled "Spectrum Resource Allocation for Wireless Packet Access...").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that the IEEE article described an OFDMA system where mobile devices report "transmission quality" for each "resource," which could be a subcarrier cluster. This combination was argued to teach all challenged limitations. Chuang, which is explicitly cited by IEEE as the source of its resource assignment algorithm, provided the specific details. Chuang taught a Dynamic Packet Assignment (DPA) technique where a mobile station measures channels in a "channel priority order," determines an "acceptable channel list," and sends this list to the base station. Petitioner argued this constituted "arbitrarily ordering" because the mobile station determines the actual entries on the list, making them unknown to the base station in advance. The combination further taught providing feedback with SINR values and the base station selecting from the candidate list to resolve conflicts.
    • Motivation to Combine: The motivation to combine was exceptionally strong because the IEEE article and Chuang are interrelated teachings describing the same Advanced Cellular Internet Service (ACIS). IEEE expressly cited Chuang for its DPA algorithm. The authors of the relevant IEEE article were also co-authors of Chuang, making the combination a natural and foreseeable step for a POSITA seeking to implement the system described.
    • Expectation of Success: Success was expected because the combination merely involved applying the specific, detailed algorithm from Chuang to the broader OFDMA system framework described in IEEE, which itself directed the reader to Chuang for those details.

Ground 3: Obviousness over IEEE and Cimini - Claims 6, 8-9, 11, and 19-22 are obvious over IEEE in view of Cimini.

  • Prior Art Relied Upon: IEEE (IEEE Communications Magazine, Jul. 2000) and Cimini (an Oct. 1998 journal article titled "Advanced Cellular Internet Service (ACIS)").

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground was substantively similar to the ground based on IEEE and Chuang. The IEEE article provided the OFDMA system context. Cimini, which describes the same ACIS system as Chuang and shares common authors, also disclosed a DPA technique where mobile stations perform interference measurements based on a "channel priority order" and feed back a "list of acceptable channels." Cimini also disclosed dividing the channel into clusters of tones. Petitioner argued this combination taught all limitations, including a mobile station generating an "arbitrarily ordered" list of candidate subcarrier clusters with associated quality metrics and a base station selecting from that list.
    • Motivation to Combine: As with Chuang, the motivation was strong because IEEE and Cimini are interrelated teachings on the same ACIS system. IEEE cited Cimini as a source for the control channel functions of its DPA technique. The authors of the IEEE article and Cimini were also related. A POSITA would have naturally consulted Cimini to understand and implement the system described in IEEE.
    • Expectation of Success: The expectation of success was high for the same reasons as the IEEE/Chuang combination: it involved combining two directly related, co-authored publications describing different aspects of the same underlying communication system.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge against claim 11 based on the combination of Ritter and Frodigh (Patent 5,726,978).

4. Key Claim Construction Positions

Petitioner argued for the following Broadest Reasonable Interpretations (BRI) for key terms:

  • "arbitrarily order[ed][ing]": Proposed construction was "ordering in a list of which the entries and/or their order is unknown to the base station." Petitioner argued this was critical because the specification distinguished arbitrary ordering, which requires indices in the feedback, from ordering known to the base station, which does not.
  • "SINR": Proposed construction was "signal-to-interference-plus-noise ratio and related measures such as signal-to-interference ratio (SIR), carrier-to-interference-plus-noise ratio (C/(I+N)), and carrier-to-interference ratio (C/I)." Petitioner argued these terms were often used interchangeably in the art.
  • "subcarriers [of][from] the set of subcarriers selected by the [first] base station": Proposed construction was "subcarriers that the base station has chosen from the set of candidate subcarriers selected by the subscriber." This construction implies a two-step selection process, first by the subscriber and then by the base station from the subscriber's proposed list.

5. Arguments Regarding Discretionary Denial

  • Petitioner noted that while a separate IPR was pending for the ’748 patent (IPR2014-01406), this petition presented "substantially different prior art and arguments." It also argued that its grounds encompassed not only the district court's claim constructions but also alternative constructions proposed by the Patent Owner, justifying a separate review under 35 U.S.C. §325(d).

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and cancellation of claims 6, 8-9, 11, and 19-22 of Patent 6,947,748 as unpatentable under 35 U.S.C. §103.