PTAB

IPR2016-01009

Cisco Systems Inc v. TQ Delta LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Multicarrier Modulation Messaging for Power Level Per Subchannel Information
  • Brief Description: The ’412 patent describes a system for exchanging diagnostic and test information between transceivers over a digital subscriber line (DSL). The system uses discrete multi-tone (DMT) modulation with multiple carriers to transmit data variables, such as power levels and noise information, for each subchannel.

3. Grounds for Unpatentability

Ground 1: Obviousness over Milbrandt, Chang, Hwang, and ANSI T1.413 - Claims 9-12, 15-18, and 21 are obvious over the combination of four prior art references.

  • Prior Art Relied Upon: Milbrandt (Patent 6,636,603), Chang (Patent 6,891,803), Hwang (Patent 6,590,893), and ANSI T1.413 (a 1995 ADSL standard).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of references taught every element of the challenged claims. Milbrandt disclosed the foundational system of using a DSL modem to collect and transmit test information, including line noise and power spectrum density per sub-frequency, using DMT modulation. Chang supplemented Milbrandt by teaching the specific measurement of "background noise" on an idle channel and the use of non-transitory memory (ROM, FLASH) to store executable instructions for a modem. Hwang further detailed the ADSL technology used by Milbrandt by explicitly teaching the use of Quadrature Amplitude Modulation (QAM) with more than one bit per subchannel (up to 15 bits) to increase data throughput. Finally, ANSI T1.413, an industry standard explicitly referenced by Milbrandt, disclosed the standard practice of transmitting per-subchannel data, such as bits and gains information, in an ordered "array" format for efficiency and interoperability. The combination, therefore, rendered obvious the claimed method of transmitting test information (like power levels or noise) as an array using QAM with more than one bit per subchannel.
    • Motivation to Combine: A POSITA would combine these references for predictable improvements.
      • A POSITA would modify Milbrandt’s system with Chang’s technique for measuring background noise to gain a more complete understanding of line characteristics, thereby improving service quality and reliability. Incorporating Chang's disclosure of non-transitory memory was a well-known method for retaining instructions on power-down.
      • A POSITA would incorporate Hwang’s teaching of using higher-bit-rate QAM (up to 15 bits/subchannel) into the Milbrandt/Chang system to achieve the known benefit of increased data throughput and more efficient communication.
      • Because Milbrandt and Hwang both expressly stated compliance with the ANSI T1.413 standard, a POSITA would have been directly motivated to consult the standard. This would lead to implementing its teachings, such as transmitting per-subchannel data in an efficient array format to ensure interoperability and simplify processing.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in combining these references because it involved applying known data modulation techniques (Hwang), standard data formatting (ANSI), and established measurement methods (Chang) to a conventional DSL testing system (Milbrandt) to achieve the predictable results of improved performance, higher throughput, and standards compliance.

4. Key Claim Construction Positions

  • "frequency domain received idle channel noise information" (claims 16-18): Petitioner argued this term, not explicitly defined in the patent, should be construed as "information about the background noise present in each of a plurality of frequency subchannels when the subchannels are not in use." This construction was critical to mapping Chang's disclosure of measuring "background noise" when no signals are being transmitted.
  • "during Showtime" (claim 15): Petitioner contended this term, a known term of art in ADSL standards, should be interpreted as "during normal communications of an ANSI T1.413-compliant device." This allowed Petitioner to map Milbrandt’s measurements taken "during operation" to the claim limitation, as Milbrandt’s system was disclosed to be ANSI T1.413 compliant.
  • "array" (claims 9-12, 15-18, 21): Petitioner proposed that "array" be given its ordinary meaning of "an ordered collection of multiple data items of the same type." This construction was essential for applying the teachings of the ANSI T1.413 standard, which describes transmitting bits and gains information for numerous sub-carriers as an ordered sequence.

5. Relief Requested

  • Petitioner requested the Board institute an inter partes review of claims 9-12, 15-18, and 21 of the ’412 patent and cancel those claims as unpatentable.