PTAB

IPR2015-01185

ZTE USA Inc v. Adaptix Inc

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1. Case Identification

2. Patent Overview

  • Title: OFDMA With Adaptive Subcarrier-Cluster Configuration and Selective Loading
  • Brief Description: The ’748 patent discloses methods and systems for wireless communication using Orthogonal Frequency Division Multiple Access (OFDMA). The technology centers on a subscriber device measuring channel quality for various subcarriers, selecting a set of candidate subcarriers based on this measurement, 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 (DE 19800953 C1), Hashem (6,721,569), and Hashem II (6,701,129), which is incorporated by reference into Hashem.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of Ritter and Hashem disclosed all limitations of the challenged claims. Ritter, an OFDMA system, taught a mobile station measuring the quality of frequency "segments" (clusters of subcarriers), determining preferred segments, and transmitting information about these preferred segments to a base station in a "sequence of suitability" determined by the mobile station itself. Petitioner contended this disclosed the key limitations of a subscriber selecting candidate subcarriers and providing feedback with an "arbitrarily ordering," as the order of preferred segments was determined by and known only to the mobile station, not the base station. Hashem, an OFDM system, taught a remote unit measuring channel quality (e.g., signal-to-interference ratio) for subcarriers based on pilot symbols received from a base station. Hashem also disclosed providing feedback that identifies acceptable groups of subcarriers along with a quality metric for those groups. This was mapped to the claim limitations requiring measurement of channel and interference information based on pilot symbols and providing feedback with an SINR value.
    • Motivation to Combine: Petitioner asserted that a person of ordinary skill in the art (POSITA) would have been motivated to combine the teachings of these references. Both Ritter and Hashem addressed the same problem of dynamic subcarrier allocation in multi-carrier systems. A POSITA would combine Hashem’s well-known use of pilot symbols for channel measurement with Ritter’s system to achieve more predictable and reliable results than Ritter’s method of measuring data symbols. Furthermore, a POSITA would have been motivated to include a quality metric like SINR (from Hashem) along with the identification of candidate clusters in the feedback sent to Ritter’s base station. This would provide the base station with more detailed information, thereby improving its ability to perform efficient and accurate subcarrier allocation among multiple users.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in making this combination. Applying Hashem's established technique of using pilot symbols for channel estimation to Ritter's OFDMA framework was a straightforward substitution of one known technique for another to improve a known system. The result—more accurate channel information leading to better resource allocation—was predictable.

4. Key Claim Construction Positions

  • "arbitrarily ordering" / "arbitrarily ordered" (claims 6, 19): Petitioner argued for a construction of "ordering in a list of which the entries and/or their order is unknown to the base station." This construction was central to its argument that Ritter met the limitation, as Ritter's mobile station independently determines both the preferred segments (the entries) and their "sequence of suitability" (the order) before sending the feedback list to the base station.
  • "channel and interference information" (claims 6, 8, 19, 21): Petitioner proposed this term be construed to at least include "signal-to-interference plus noise ratio (SINR) information." This interpretation was based on the patent's specification and was crucial for mapping the teachings of Hashem, which explicitly discloses measuring signal-to-interference ratio, onto the claims.
  • "pilot symbols" (claims 6, 8, 19, 21): The proposed construction was "symbols, sequences, or signals known to both base station and subscriber." This broad construction allowed Petitioner to argue that the pilot signals taught in Hashem II (incorporated into Hashem) for determining signal-to-interference ratio satisfied this claim element.

5. Relief Requested

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