PTAB

IPR2015-00240

2Wire Inc v. TQ Delta LLC

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1. Case Identification

2. Patent Overview

  • Title: System and Method for Scrambling the Phase of the Carriers in a Multicarrier Communications System
  • Brief Description: The ’008 patent describes a system for reducing the peak-to-average ratio (PAR) in multicarrier communication systems, such as Discrete Multitone (DMT) systems. The invention achieves this by scrambling the phase characteristics of carrier signals, computing a unique phase shift for each carrier based on a value determined independently of the data bits being transmitted (e.g., from a pseudo-random number generator), and combining this computed shift with the carrier's original phase.

3. Grounds for Unpatentability

Ground 1: Obviousness over Suzuki '614, Suzuki '415, and Admitted Prior Art

  • Claims Challenged: 1 and 14 are obvious over Suzuki ’614 in view of Suzuki ’415 and the Admitted Prior Art.
  • Prior Art Relied Upon: Suzuki ’614 (Patent 5,903,614), Suzuki ’415 (Patent 5,694,415), and Admitted Prior Art from the ’008 patent specification.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Suzuki ’614 discloses a multicarrier communication method (OFDM) that scrambles signal phases by multiplying each subcarrier by "different random phase shift data" to restore the original signal at the receiver. However, Suzuki ’614 does not detail how to generate this random data. Suzuki ’415 was argued to supply this missing element by teaching a system that uses an M-bit pseudo-random number generator (PRNG) to generate random numbers and a predetermined equation to convert these numbers into a phase shift, which is then combined with the original modulated signal.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would have been motivated to combine the teachings to implement the general random phase shifting of Suzuki ’614 with the specific, well-known PRNG and phase computation method from Suzuki ’415. Petitioner contended this was a simple substitution of one known element for another to obtain a predictable result, namely a functional system for random phase scrambling.
    • Expectation of Success: A POSITA would have had a high expectation of success because Suzuki ’415 provides a clear, detailed method for generating the exact type of random phase data that Suzuki ’614 required for its system to function.

Ground 2: Obviousness over Laroia, Suzuki '415, and T1.413

  • Claims Challenged: 1 and 14 are obvious over Laroia in view of Suzuki ’415 and T1.413.
  • Prior Art Relied Upon: Laroia (Patent 6,301,268), Suzuki ’415 (Patent 5,694,415), and T1.413 (an ANSI ADSL standard).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Laroia teaches a method to reduce PAR in multicarrier systems by partitioning subcarriers into disjoint sets and rotating their phases. Laroia suggests this partitioning can be done via "random assignment." Suzuki ’415 was again presented as disclosing a specific PRNG for generating random values suitable for this assignment. T1.413 was argued to provide the broader context, describing a standard Asymmetric Digital Subscriber Line (ADSL) multicarrier system and teaching the use of multiple carriers to modulate the same bits for frequency diversity.
    • Motivation to Combine: A POSITA would combine these references to implement Laroia's PAR-reduction technique in a standard ADSL system (T1.413) and use a known PRNG (Suzuki ’415) to perform the "random assignment" Laroia suggests. The combination represented applying a known technique to a known system to solve a known problem (high PAR).
    • Expectation of Success: Success was expected because the combination involved applying a specific implementation (Suzuki ’415) of a technique (phase scrambling from Laroia) within a standardized and well-understood communication framework (T1.413).

Ground 3: Obviousness over Fifield, Suzuki '415, and Admitted Prior Art

  • Claims Challenged: 1 and 14 are obvious over Fifield in view of Suzuki ’415 and the Admitted Prior Art.
  • Prior Art Relied Upon: Fifield (Patent 6,781,951), Suzuki ’415 (Patent 5,694,415), and Admitted Prior Art.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Fifield discloses improving the signal-to-noise ratio in an OFDM system by "randomising the initial phases" of the carriers, explicitly stating this randomization "could be done in a variety of ways known to the person skilled in the art." As in the other grounds, Petitioner asserted that Suzuki ’415 teaches one such well-known method: using a PRNG to generate random values and an equation to compute corresponding phase shifts. The Admitted Prior Art acknowledges that using the same data bits to modulate multiple carriers was a known method for frequency diversity.
    • Motivation to Combine: The motivation was said to be explicit in Fifield, which directly suggested using a known randomization method. A POSITA, when prompted by Fifield, would have naturally turned to a known, available technique like the one disclosed in Suzuki ’415 to implement the randomization.
    • Expectation of Success: A POSITA would have had a high expectation of success in combining these references, as Fifield expressly invited the use of a known technique for randomization, and Suzuki ’415 provided a detailed and functional example of such a technique.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1 and 14 of the ’008 patent as unpatentable.