PTAB

IPR2016-01020

Cisco Systems Inc v. TQ Delta LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: System and Method for Scrambling Using a Bit Scrambler and a Phase Scrambler
  • Brief Description: The ’243 patent discloses a communications system using multicarrier modulation, such as Digital Subscriber Line (DSL). The system employs a bit scrambler followed by a phase scrambler to randomize the phase characteristics of carrier signals, with the stated purpose of reducing the peak-to-average power ratio (PAR) of the final transmission signal.

3. Grounds for Unpatentability

Ground 1: Obviousness over Shively and Stopler - Claims 1-3, 7-9, 13-16, and 20-22 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 taught a method for increasing data rates in a multicarrier DSL system by transmitting the same data bit redundantly over multiple subchannels, particularly those otherwise unusable due to noise. Petitioner contended that a person of ordinary skill in the art (POSITA) would have immediately recognized that this redundant transmission of phase-aligned signals would create a high PAR, a well-known problem. Stopler was presented as teaching a solution to this exact problem by disclosing a multicarrier transmitter that uses a bit scrambler followed by a phase scrambler to randomize the phases of carrier signals, thereby reducing PAR. The combination of Shively’s redundant transmission method with Stopler’s PAR-reduction technique was argued to render the core limitations of independent claims 1, 13, and 20 obvious.
    • Motivation to Combine: A POSITA would combine Shively and Stopler because it represents the simple application of a known technique (Stopler's phase scrambling) to solve a known and predictable problem (high PAR) inherent in a similar system (Shively's redundant transmission). The motivation was to improve the performance of Shively's system by mitigating the high PAR, allowing for the development of faster DSL modems without requiring more complex and expensive circuitry.
    • Expectation of Success: Petitioner asserted that a POSITA would have had a high expectation of success. Applying a known PAR-reduction technique to a system exhibiting a high PAR was a well-understood engineering choice with predictable results.

Ground 2: Obviousness over Shively, Stopler, and Gerszberg - Claims 4-6, 10-12, 17-19, and 23-25 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 combination of Shively and Stopler for the core scrambling and transmission method. Petitioner introduced Gerszberg to teach the specific applications recited in the remaining dependent claims. Gerszberg disclosed using DSL and discrete multi-tone (DMT) modulation—the same technologies found in Shively and Stopler—to provide a variety of data services. These services explicitly included high-speed internet access, video transport, and communication over wireless connections. Petitioner argued that these disclosures directly map onto the limitations of claims requiring a "wireless transceiver," a "cable transceiver," a "DSL transceiver," or a transceiver "operable for high speed internet access" or "to transport video."
    • Motivation to Combine: Petitioner provided two primary motivations. First, Shively expressly incorporated Gerszberg by reference, making the combination explicit. Second, a POSITA would have been motivated by clear market demand to apply the improved transmission system of Shively and Stopler to provide the popular data services described by Gerszberg. Combining the references was merely using the underlying DSL technology for its intended and well-known purposes, such as providing internet and video services.
    • Expectation of Success: A POSITA would have reasonably expected success in implementing the combined Shively/Stopler transmission method in systems configured for the applications taught by Gerszberg. This constituted a predictable combination of known elements for their established functions.

4. Key Claim Construction Positions

  • "multicarrier" (claims 1-25): Petitioner proposed this term be construed to mean "multiple carriers," consistent with the specification’s description of a "conventional multicarrier communications system" using a "combination of multiple carriers."
  • "transceiver" (claims 1-12, 15-17, 20, 22, and 23): Petitioner proposed this term be construed as "a device, such as a modem, with a transmitter and a receiver." This construction was based on the specification’s examples and supported by a technical dictionary definition.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-25 of the ’243 patent as unpatentable.