PTAB

IPR2016-01008

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 exchanging diagnostic and test information between transceivers over a digital subscriber line (DSL). This information, which includes power level, idle channel noise, and signal-to-noise ratio (SNR) data, is exchanged using multicarrier modulation with a quadrature amplitude modulation (QAM) scheme encoding more than one bit per carrier.

3. Grounds for Unpatentability

Ground 1: Obviousness over Milbrandt, Hwang, and ANSI T1.413 - Claims 1-8, 13, 14, 19, and 20 are obvious over Milbrandt in view of Hwang and ANSI T1.413.

  • Prior Art Relied Upon: Milbrandt (Patent 6,636,603), Hwang (Patent 6,590,893), and ANSI T1.413 (a 1995 industry standard).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of these references taught every element of the challenged claims. Milbrandt disclosed the foundational DSL system for testing telephone lines, measuring characteristics like line noise and power spectrum density per sub-frequency, and transmitting this test data from a subscriber modem to a central office modem. Milbrandt also taught organizing this data in a grid (array) and noted its system complied with ADSL standards like ANSI T1.413. However, Milbrandt did not explicitly detail the modulation scheme. Hwang filled this gap by describing the use of discrete multi-tone (DMT) modulation with QAM to transmit up to 15 bits of data per subchannel, thus teaching the claimed limitation of using QAM with "more than 1 bit per subchannel." Finally, the ANSI T1.413 standard, which Milbrandt explicitly referenced, taught the transmission of test data—specifically including SNR and power levels—as an ordered array indexed by sub-carrier number. It also taught measuring power levels based on a "REVERB" signal, which maps to dependent claims.
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would combine Milbrandt and Hwang because they describe different aspects of the same ADSL technology. A POSITA would look to Hwang to supply the specific high-bit-rate modulation details for implementing Milbrandt’s system to achieve the predictable result of higher data throughput. A POSITA would be further motivated to incorporate the teachings of ANSI T1.413 because Milbrandt expressly stated its system was designed to be compliant with that standard. This provides a direct and explicit reason to consult the standard for implementation details, such as how to format and transmit per-subchannel test data (as an array) and how to perform standardized measurements (like SNR) to ensure interoperability and robust performance.
    • Expectation of Success: Petitioner asserted that a POSITA would have a high expectation of success. The combination involved applying a known modulation technique (QAM from Hwang) and a standard data transmission format (arrays from ANSI T1.413) to a known type of system (Milbrandt's DSL testing system). These were all well-understood technologies in the field, and their combination would have yielded only predictable improvements in efficiency and standards compliance.

4. Key Claim Construction Positions

  • "during Showtime": Petitioner argued this term, critical to claims requiring measurements during operation (e.g., claim 13), should be construed as "during normal communications of an ANSI T1.413-compliant device." This construction was based on its established meaning as a term of art within the ADSL industry and the ANSI T1.413 standard itself, which describes "showtime" as the normal steady-state transmission mode.
  • "array": Petitioner proposed construing this term according to its ordinary meaning as "an ordered collection of multiple data items of the same type." This construction was central to mapping prior art that organized per-subchannel data in grids or ordered sequences (as in Milbrandt and ANSI T1.413) to the claims requiring an array format for power level or SNR information.
  • "transceiver": Petitioner adopted the standard definition of a "transceiver" as "a device, such as a modem, with a transmitter and receiver," a combination of the words transmitter and receiver.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-8, 13, 14, 19, and 20 of the ’412 patent as unpatentable under 35 U.S.C. §103.