PTAB

IPR2016-01349

ZTE USA Inc v. Evolved Wireless LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method and Transmitter for Transmitting Preamble Sequence
  • Brief Description: The ’481 patent relates to a data transmission method for generating and transmitting a preamble sequence in a mobile communication system’s random access channel (RACH). The invention involves creating a preamble by repeating a specific sequence of length L for N times to form a consecutive sequence, concatenating a single cyclic prefix (CP) to the front of this sequence, and then transmitting it.

3. Grounds for Unpatentability

Petitioner asserted two main sets of grounds contingent upon the construction of the claim preambles. The first set (Grounds 1A-1D) assumes the preambles are not limiting, while the second set (Grounds 2A-2D) addresses the claims if the preambles are deemed limiting.

Ground 1A: Anticipation of Claims 1 and 15 by IEEE802.16-2004

  • Prior Art Relied Upon: IEEE802.16-2004 (an IEEE Standard for Local and Metropolitan Area Networks).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that IEEE802.16-2004 fully anticipates the method of claim 1. Specifically, the standard’s description of the "long preamble" for initial ranging in a fixed broadband wireless access system discloses all claimed steps. It teaches generating a preamble from two consecutive Orthogonal Frequency Division Multiplexing (OFDM) symbols, where the first symbol consists of four repetitions (N=4) of a 64-sample fragment (L=64) preceded by a single cyclic prefix (CP). This structure is then transmitted by a subscriber station on a contention-based initial ranging channel, which functions as a random access channel. The dependent claim 15 limitations, which require the consecutive sequence to comprise N sequences and the CP to be identical to a rear part of the N-th sequence, were also argued to be explicitly taught by the standard.

Ground 1B: Obviousness of Claims 8 and 16 over IEEE802.16-2004 in view of Chou

  • Prior Art Relied Upon: IEEE802.16-2004 and Chou (Patent 8,977,258).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed apparatus claims 8 and 16. Petitioner asserted that while IEEE802.16-2004 teaches the preamble generation method and the requirement for a subscriber station to transmit it, Chou teaches the implementation of such a station. Chou discloses a stand-alone, fixed subscriber station designed to operate according to the IEEE 802.16-2004 standard, containing integrated Physical Layer (PHY) and Media Access Control (MAC) units necessary to perform the preamble generation and transmission functions.
    • Motivation to Combine: A POSITA would combine the method of IEEE802.16-2004 with the integrated hardware configuration of Chou because it was common practice to implement required functionalities within a single, compact device. This approach would reduce costs, latency, and potential interference associated with external preamble generation units.
    • Expectation of Success: A POSITA would have a high expectation of success in integrating a preamble generation unit into the subscriber station of IEEE802.16-2004, as Chou demonstrates the feasibility and utility of such integrated, standard-compliant devices.

Ground 1C: Obviousness of Claims 2-4 and 6 over IEEE802.16-2004 in view of Tan

  • Prior Art Relied Upon: IEEE802.16-2004 and Tan (Patent 8,000,305).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground addressed dependent claims related to the type of sequence used. While IEEE802.16-2004 discloses the preamble structure, Tan teaches specific enhancements applicable to 802.16 systems. Tan discloses using a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence for preambles to improve detection performance due to their low cross-correlation properties (claim 2). Tan further teaches applying a cyclic shift to the specific sequence to increase the total number of available RACH opportunities (claim 3), determining the shift value as an integer multiple of a predetermined unit (claim 4), and that applying the shift involves multiplying the sequence by an exponential sequence (claim 6).
    • Motivation to Combine: A POSITA would be motivated to use Tan’s CAZAC sequences in the IEEE802.16-2004 framework to achieve the known benefit of improved detection performance. Furthermore, a POSITA would be motivated to apply Tan's cyclic shifting technique to increase system capacity and reduce collision probability, which are well-understood goals in communication system design.
    • Expectation of Success: Success would be expected because Tan explicitly states its methods are applicable to 802.16 systems and solve known problems related to preamble performance and channel capacity.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including Ground 1D (combining IEEE802.16-2004, Chou, and Tan). It also presented a parallel set of grounds (2A, 2B, 2C, and 2D) that mirrored the combinations above but added the IEEE802.16e-2005 standard. These grounds were argued to render the claims obvious even if the preambles were construed as limiting to a "mobile communication system," as the IEEE802.16e-2005 standard explicitly extends the base 802.16-2004 framework to support mobile stations.

4. Key Claim Construction Positions

  • "in a mobile communication system" (preambles of claims 1 and 8): Petitioner’s primary position was that this preamble phrase is not limiting. It argued that the body of the claims recites a structurally complete invention and does not rely on the preamble for antecedent basis or definition.
  • Alternative Construction: Petitioner argued that if the Board were to find the preamble limiting, its broadest reasonable interpretation would encompass a communication system that includes both fixed and mobile devices. This construction is consistent with industry standards like IEEE802.16e-2005, which add mobile capabilities to an existing fixed wireless system. This alternative construction provides the basis for Grounds 2A-2D.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that its two sets of grounds (1A-D and 2A-D) are not redundant. They address distinct legal questions based on the two primary claim construction scenarios for the preamble (limiting vs. non-limiting), which would not be resolved until a final decision. Petitioner also contended that the grounds presented are not redundant with those in other IPR proceedings involving the same patent (IPR2016-00758, -00981, and -01342) because this petition relies on different prior art references, arguments, and evidence.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 6, 8-11, 13, 15, and 16 of the ’481 patent as unpatentable.