PTAB

IPR2015-00239

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 ’721 patent discloses a method intended to reduce the peak-to-average ratio (PAR) in multicarrier communication systems, such as those using discrete multitone (DMT) modulation. The invention involves scrambling the phase of carrier signals by generating a value independent of the data bits, computing a phase shift from that value, and combining the computed shift with the carrier's original phase characteristic.

3. Grounds for Unpatentability

Ground 1: Claim 1 is obvious over Suzuki ’614, 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.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Suzuki ’614 discloses a multicarrier communication system (OFDM) that modulates an input bit stream and scrambles carrier phases using random phase shifts. However, Suzuki ’614 allegedly does not describe in detail how to generate these random phase shifts. Petitioner contended that Suzuki ’415 remedies this by teaching a specific method for this purpose: generating a value (an M-bit random number) independent of the input data bits, using a predetermined equation to convert that number into a phase shift, and combining the resulting phase shift with the original signal's phase. The Admitted Prior Art was cited to establish the general background of multicarrier transceivers and DMT modulation.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references to provide the system in Suzuki ’614 with a specific, known method for generating the random phase shifts it generally requires. Suzuki '415 provides a clear, functional implementation for the randomization concept described in Suzuki '614, making the combination a logical step to create a complete system.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination merely involves implementing a known randomization technique (from Suzuki ’415) into a system from the same technical field that was designed to utilize such a technique.

Ground 2: Claim 1 is obvious over Laroia in view of T1.413 and the Admitted Prior Art.

  • Prior Art Relied Upon: Laroia (Patent 6,301,268) and T1.413 (ANSI T1.413-1998).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Laroia teaches a method to reduce PAR in a multicarrier DSL system by scrambling signal phases. Laroia allegedly discloses all key steps of claim 1: associating an independent value with each carrier (e.g., using a Golay sequence or random assignment), computing a phase shift based on that value (using the equation e^(imπ/2)), and combining the shift with the original phase characteristic by rotating the signal elements.
    • Motivation to Combine: A POSITA would combine Laroia with the T1.413 standard because Laroia teaches a PAR-reduction technique for ADSL systems and T1.413 is the well-established industry standard for implementing such systems. Laroia itself references the T1.413 standard, providing a direct link. Therefore, a POSITA would naturally look to the T1.413 standard to supply the conventional network structures needed to implement Laroia's method.
    • Expectation of Success: Success would be highly expected, as Laroia’s method is directly applicable to the standardized DSL systems described in T1.413, and both references operate in the same, well-defined technical space.

Ground 3: Claim 1 is obvious over Fifield in view of Suzuki ’415.

  • Prior Art Relied Upon: Fifield (Patent 6,781,951) and Suzuki '415 (Patent 5,694,415).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Fifield discloses a multicarrier OFDM communication system with two transceivers and explicitly teaches "randomising the initial phase shifts of its carriers" to improve the signal-to-noise ratio. Crucially, Fifield states this randomization "could be done in a variety of ways known to the person skilled in the art," but does not specify a particular method.
    • Motivation to Combine: The motivation stems directly from Fifield's disclosure, which provides an express invitation to incorporate a known randomization method. A POSITA reading Fifield would be directly motivated to search for and implement a known technique to fulfill this general teaching. Suzuki '415 provides exactly such a well-known method: generating random numbers independent of the data and using a predetermined equation to create phase shifts.
    • Expectation of Success: A POSITA would reasonably expect success because the combination involves applying a specific, known, and readily available technique (from Suzuki '415) to solve a problem explicitly identified in a system from the same technical field (Fifield).

4. Relief Requested

  • Petitioner requests institution of IPR and cancellation of claim 1 of Patent 7,471,721 as unpatentable.