PTAB

IPR2016-01021

Cisco Systems Inc v. TQ Delta LLC

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Petition
petition

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 ’158 patent describes a system and method for scrambling the phase characteristics of carrier signals in a multicarrier modulation system, such as a Digital Subscriber Line (DSL) system. The stated purpose of the phase scrambling is to reduce the peak-to-average power ratio (PAR) of the transmission signal.

3. Grounds for Unpatentability

Ground 1: Obviousness over Shively and Stopler - Claims 1, 2, 4, 15, 16, and 18 are obvious over Shively in view of Stopler.

  • Prior Art Relied Upon: Shively (Patent 6,144,696) and Stopler (Patent 6,625,219).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Shively disclosed a multicarrier DSL modem system that transmits the same bit of data over multiple, otherwise unusable subchannels to increase the overall data rate. This redundant transmission met the claim limitation of “modulating the at least one bit on a second carrier signal.” However, Petitioner asserted a person of ordinary skill in the art (POSITA) would recognize that transmitting the same bits on multiple carriers aligns their phases, creating a known high PAR problem. Stopler was presented as addressing this exact issue by teaching a multicarrier transmitter that employs a phase scrambler, using a pseudo-random number generator, to randomize the phase of carrier signals and thereby reduce the PAR.
    • Motivation to Combine: A POSITA would combine Shively and Stopler because it represented the application of a known technique (Stopler’s phase scrambling) to solve a known problem (high PAR) inherent in a similar system (Shively’s redundant bit transmission). The motivation was to improve Shively’s system by mitigating high PAR, allowing for the development of faster, less complex DSL modems.
    • Expectation of Success: A POSITA would have a high expectation of success because Stopler’s phase scrambling technique was designed specifically for multicarrier systems like the one described in Shively and directly addressed the PAR problem created by Shively’s method.

Ground 2: Obviousness over Shively, Stopler, and Gerszberg - Claims 3, 5, 14, 17, 19, and 28-30 are obvious over Shively in view of Stopler, and further in view of Gerszberg.

  • Prior Art Relied Upon: Shively (Patent 6,144,696), Stopler (Patent 6,625,219), and Gerszberg (Patent 6,424,646).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the base combination of Shively and Stopler. Petitioner argued that Gerszberg provided the teachings for specific dependent claims related to the application and implementation of the combined system. Gerszberg disclosed using various DSL technologies, including Very high data rate Digital Subscriber Line (VDSL), to provide services like high-speed internet access and video-on-demand. It also taught that DSL modems may be implemented using digital signal processors (DSPs). These disclosures mapped directly to dependent claims requiring “VDSL transceivers” (claims 3, 17), use for “high speed Internet access” (claims 5, 19), and inclusion of “digital signal processors” (claims 14, 28).
    • Motivation to Combine: A POSITA would combine Gerszberg with the Shively/Stopler system to implement it for its intended, commercially valuable purposes. Gerszberg described the specific applications and hardware (VDSL, internet services, DSPs) that were common in the field, making it a natural and obvious implementation choice for the base communication method. Further, Petitioner noted that Shively explicitly incorporated Gerszberg by reference.

Ground 3: Obviousness over Shively, Stopler, and Bremer - Claims 6, 9, 10, 12, 20, 23, 24, and 26 are obvious over Shively in view of Stopler, and further in view of Bremer.

  • Prior Art Relied Upon: Shively (Patent 6,144,696), Stopler (Patent 6,625,219), and Bremer (Patent 4,924,516).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground addressed claims requiring components in the second (receiving) transceiver to decode the scrambled signal sent by the first (transmitting) transceiver. Bremer taught the fundamental principle that a receiver must be equipped with components that are complementary to the transmitter to correctly decode a signal. Specifically, Bremer disclosed using a second, synchronized pseudo-random number generator in the receiver to reverse the encoding performed by a first pseudo-random number generator in the transmitter. This teaching mapped to claims requiring a “second pseudo-random number generator in the second transceiver” (claim 6).
    • Motivation to Combine: A POSITA implementing the Shively/Stopler transmitter with its pseudo-random phase scrambler would have necessarily considered the design of a compatible receiver. Bremer provided the explicit and well-understood solution: a matched-pair design where the receiver mirrors the transmitter's encoding functions. It would have been obvious to apply Bremer’s teaching to design a receiver for the Shively/Stopler system to enable end-to-end communication.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations including Gerszberg and Bremer together (Ground 4) and a further reference, Flammer (Patent 5,515,369), to teach synchronizing the pseudo-random number generators by transmitting a seed value (Ground 5).

4. Key Claim Construction Positions

  • “multicarrier”: Petitioner proposed that based on the specification, a POSITA would understand this term to mean or include “multiple carriers.”
  • “transceiver”: Petitioner proposed that consistent with the specification and dictionary definitions, this term should be construed as “a device, such as a modem, with a transmitter and a receiver.” This construction was important for establishing that the DSL modems in the prior art met the claim limitation.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and cancellation of claims 1-30 of the ’158 patent as unpatentable.