PTAB

IPR2016-00758

ZTE USA Inc v. Evolved Wireless LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method and Apparatus for Transmitting Preamble Sequence
  • Brief Description: The ’481 patent relates to methods and transmitters for generating and transmitting a preamble sequence on a random access channel (RACH) in a mobile communication system. The core disclosed technique involves repeating a specific base sequence N times to form a longer consecutive sequence and then concatenating a single cyclic prefix (CP) to its front end before transmission.

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, 8, and 9 are anticipated by or obvious over Panasonic 792

  • Prior Art Relied Upon: Panasonic 792 ("Random access burst evaluation in E-UTRA uplink," 3GPP Tdoc R1-060792, March 2006).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Panasonic 792, a technical contribution to the 3GPP standards body, discloses every element of independent claims 1 and 8. Specifically, Figure 1 of Panasonic 792 explicitly illustrates a RACH preamble structure consisting of a single cyclic prefix ("CP") followed by "M Repetition" of a "CAZAC sequence." This structure directly teaches generating a preamble by repeating a specific sequence to form a consecutive sequence and concatenating a single CP to its front end for transmission on a random access channel. For dependent claims 2 and 9, which require the specific sequence to be a Constant Amplitude Zero Auto Correlation (CAZAC) sequence, Panasonic 792 expressly discloses using a Zadoff-Chu sequence, a known type of CAZAC sequence.

Ground 2: Claims 3, 4, 10, and 11 are obvious over Panasonic 792 in view of Panasonic 114

  • Prior Art Relied Upon: Panasonic 792 and Panasonic 114 ("Random access design for E-UTRA uplink,” 3GPP Tdoc R1-061114, May 2006).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground asserted that the base preamble structure taught by Panasonic 792 would have been modified by a person of ordinary skill in the art (POSITA) based on the teachings of Panasonic 114. The challenged dependent claims add limitations related to applying a cyclic shift to the base CAZAC sequence. Panasonic 114 directly addresses this, comparing standard Zadoff-Chu sequences with cyclic-shifted versions and concluding that "cyclic-shifted CAZAC sequence has superior performance." It further proposes using these superior sequences for the RACH preamble. Claim 4 requires the cyclic shift value to be an integer multiple of a predetermined unit, which Petitioner argued is disclosed by Panasonic 114’s teaching of cyclic shift indices ranging from 1 to 8.
    • Motivation to Combine: A POSITA would combine these references because both were submitted by the same entity (Panasonic) to the same 3GPP working group (WG1) within two months of each other to solve the exact same problem: designing an optimal RACH preamble for the new LTE standard. Panasonic 114 expressly cites Panasonic 792, making the combination natural and predictable. The motivation was to improve the performance of the preamble structure in Panasonic 792 by incorporating the superior cyclic-shifted sequences disclosed in Panasonic 114.
    • Expectation of Success: The expectation of success would have been high, as applying cyclic shifts to CAZAC sequences was a well-understood technique for improving correlation properties and generating more usable preamble sequences.

Ground 3: Claims 6 and 13 are obvious over Panasonic 792, Panasonic 114, and Chu

  • Prior Art Relied Upon: Panasonic 792, Panasonic 114, and Chu ("Polyphase Codes with Good Periodic Correlation Properties," IEEE Transactions on Information Theory, July 1972).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on the combination of Panasonic 792 and Panasonic 114 to establish a preamble using cyclic-shifted CAZAC sequences. It adds the Chu reference to address claims 6 and 13, which further require that the cyclic shift is applied by multiplying the specific sequence by an exponential sequence. Petitioner contended that Chu, the seminal 1972 paper that first introduced the Zadoff-Chu sequence, explicitly teaches that cyclic shifts can be implemented by multiplying the base sequence by an exponential term.
    • Motivation to Combine: A POSITA, having decided to implement the cyclic-shifted sequences taught by the Panasonic references, would have been motivated to consult the foundational Chu paper to understand the underlying mathematics. Both Panasonic 792 and Panasonic 114 cite the Chu reference. Consulting Chu to determine the standard mathematical method for applying a cyclic shift would have been a logical and predictable step for anyone implementing the technology, not an inventive leap.
    • Expectation of Success: The expectation of success was certain, as Chu describes the definitive mathematical method for applying a linear phase shift to the sequence, which is functionally equivalent to a cyclic shift.

4. Key Claim Construction Positions

  • "consecutive sequence having a length (N*L)": Petitioner argued this term should be construed to mean a sequence that is contained entirely within a single transmission frame.
  • Basis for Construction: This proposed construction was based on prosecution history estoppel. During prosecution of the ’481 patent, the applicant overcame a rejection over a prior art reference (Jung) by arguing that Jung’s sequence was not "consecutive" because it was split across multiple frames. Petitioner asserted that this argument surrendered any claim scope covering sequences that span more than one frame.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 6, 8-11, and 13 of the ’481 patent as unpatentable.