PTAB

IPR2017-01889

Sprint Spectrum LP v. General Access Solutions Ltd

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1. Case Identification

2. Patent Overview

  • Title: Wireless Access System Using Selectively Adaptable Beam Forming in TDD Frames and Method of Operation
  • Brief Description: The ’931 patent discloses a wireless access system using time division duplex (TDD) communication between base stations and wireless access devices. The system employs selectively adaptable beam forming, where a base station transmits a broad, multi-sector broadcast signal at the start of a frame, followed by narrow, directed scanning beam signals containing data traffic to devices within specific sectors of a cell site.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1-3, 6-7, 10-12, 15-16, 19-21, 24-25, and 28-29 under 35 U.S.C. §102 by Vornefeld

  • Prior Art Relied Upon: Vornefeld ("SDMA Techniques for Wireless ATM," IEEE Communications Magazine (November 1999)).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Vornefeld, which describes space-division multiple access (SDMA) techniques for a HIPERLAN/2 system, discloses every element of the challenged claims. Vornefeld teaches a TDD system where base stations use smart array antennas for beamforming. Petitioner asserted that Vornefeld's MAC frame structure "starts with two broadcast channels, the broadcast channel (BCH) and the frame channel (FCH)," which convey signaling information concerning the "whole radio cell" (i.e., multiple sectors). This is followed by a downlink phase where directive beams transmit data to specific mobile terminals (MTs) within a sector, anticipating the ’931 patent's core concept of a broad broadcast followed by directed data transmission.
    • Key Aspects: Petitioner contended the frame channel (FCH) in Vornefeld, which contains "announcements and reservations" for individual MTs, is equivalent to the "first beam map" recited in the dependent claims.

Ground 2: Obviousness of Claims 4-5, 8-9, 13-14, 17-18, 22-23, and 26-27 over Vornefeld in view of Ahy

  • Prior Art Relied Upon: Vornefeld (IEEE Communications Magazine (November 1999)) and Ahy (Patent 7,366,133).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claims requiring the beam map to identify modulation formats or forward error correction (FEC) code levels. Petitioner argued that while Vornefeld provides the foundational TDD beamforming system, it does not explicitly disclose communicating these specific parameters. Ahy, however, teaches an adaptive multipoint system where a base station controller communicates parameters, including "modulation type" (e.g., QPSK, 16QAM) and FEC levels, to customer premises equipment (CPE) at the beginning of a TDD frame to optimize the link.
    • Motivation to Combine: A POSITA would combine Ahy's teaching of adaptive parameter optimization with Vornefeld's spatially extended MAC protocol. Both references describe TDD-based systems with centralized base station control. Combining them would be a predictable way to improve the performance and robustness of Vornefeld's system by allowing it to adapt to changing channel conditions, a well-known technique.
    • Expectation of Success: The combination would involve using known techniques to improve similar methods, yielding predictable results. A POSITA would have recognized that the parameter-setting fields in Ahy's TDD frame could be incorporated into the broadcast/frame channels of Vornefeld's MAC protocol with a high expectation of success.

Ground 3: Obviousness of Claims 1-3, 6-7, 10-12, 15-16, 19-21, 24-25, and 28-29 over Vornefeld in view of Andersson

  • Prior Art Relied Upon: Vornefeld (IEEE Communications Magazine (November 1999)) and Andersson (Patent 6,470,177).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground was presented as an alternative to Ground 1, in case Vornefeld was found not to teach transmitting a broadcast signal across multiple sectors. Petitioner argued Andersson explicitly discloses this missing element. Andersson describes cellular systems with sectored cells and teaches transmitting a broadcast control channel (or beacon) across all sectors by using an omnidirectional antenna or by combining the broadcast signal for transmission via each individual sector antenna.
    • Motivation to Combine: Vornefeld focuses on the MAC protocol for beamforming but is "largely silent on the design of a physical layer and hardware implementation." A POSITA designing a system based on Vornefeld's protocol would have looked to references like Andersson for hardware architecture. Andersson's method of ensuring cell-wide broadcast coverage was a known solution to a common problem.
    • Expectation of Success: A POSITA would have been motivated to apply Andersson's efficient broadcast hardware architecture to Vornefeld's TDD MAC protocol to improve spectral efficiency and solve trunking inefficiency, achieving the stated advantages of Andersson. The combination was an obvious application of known techniques to yield predictable improvements.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including Ground 4 (claims 4-5, 8-9, etc. over Vornefeld, Andersson, and Ahy) and Ground 5 (all claims 1-29 over Newman (Patent 5,684,491) in view of Ahy and Andersson), which relied on similar motivations to combine to supply features related to adaptive parameters and multi-sector broadcast capabilities.

4. Key Claim Construction Positions

  • "sector": Petitioner proposed this term be construed as an "arc of a cell site served by an individual antenna or antenna array." This construction was argued to be supported by the specification, which describes a cell consisting of multiple sectors, each covering a specific degree arc and being served by its own antenna. This definition is critical to establishing the distinction between a multi-sector broadcast signal and a single-sector directed data signal.
  • "directed scanning beam signal[s]": Petitioner proposed this term be construed as "signals transmitted using a beam pattern directed within a sector." The petition argued that while the exact term is not in the specification, the concept is described as using "pre-programmed sets of directed beam patterns to cover a cell in an angular fashion," with each beam directed to subscribers within a sector. This construction is central to mapping the prior art's focused transmissions to the claims.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-29 of the ’931 patent as unpatentable.