PTAB

IPR2017-00209

RPX Corp v. Digital Audio Encoding Systems LLC

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1. Case Identification

2. Patent Overview

  • Title: Method and Apparatus for Encoding Signals
  • Brief Description: The ’037 patent describes methods and systems for encoding digitized audio signals. The core concept involves selecting an encoding format (e.g., bit rate) based on one or more detected properties of a processing device, where these properties are determined by transmitting a "test signal" to the processing device and detecting its response.

3. Grounds for Unpatentability

Ground 1: Anticipation over Ferriere - Claims 1-4, 9-11, 13, 17-21, 24-25, 29, 31-32 are anticipated by Ferriere under 35 U.S.C. §102.

  • Prior Art Relied Upon: Ferriere (Patent 5,835,495). Petitioner argued that Ferriere qualifies as prior art because the ’037 patent is not entitled to its claimed 1997 priority date due to a break in copendency, making its effective filing date June 2, 2005.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued Ferriere discloses every limitation of the challenged claims. Ferriere describes a teleconferencing system with an initiating communication unit (the control device) and a responding communication unit (the processing device). Each unit includes a codec (the encoding device) to encode and decode audio signals. To determine the optimal encoding format, the initiating unit sends its modem's effective bit rate to the responding unit; this transmission of information to determine a quality of the communication link is the claimed "test signal." The responding unit replies with the lower of the two units' modem bit rates, which the initiating unit then "detects" as a property of the processing device to select the highest supported encoding bit rate for the session. Ferriere also discloses dependent claim features, such as bit-rate reduction and real-time operation.
    • Key Aspects: This ground’s success relies on the argument that the ’037 patent’s priority claim is defective, which would make Ferriere, filed in 1995, valid §102 prior art.

Ground 2: Obviousness over Ferriere and Kudo - Claims 1-4, 7, 9-15, 17-21, 24-25, 29, and 31-32 are obvious over Ferriere in view of Kudo.

  • Prior Art Relied Upon: Ferriere (Patent 5,835,495) and Kudo (Patent 4,606,044).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Ferriere teaches the overall system architecture for bidirectional audio communication, including encoding, decoding, and selecting an encoding format based on device properties. Kudo teaches a method for automatically determining an optimal transmission rate by sending a known test signal pattern at various rates and receiving feedback on which rates were received correctly. This combination provides an alternative and more robust way to meet the "test signal" limitations of claims 1 and 17. The system would transmit Kudo's test signal to the processing device to determine the highest reliable bit rate, thereby detecting a property of the device.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Kudo's test signal procedure with Ferriere's teleconferencing system to improve performance. Ferriere's method only accounts for the maximum modem bit rate, whereas Kudo's method tests for real-world transmission path effects like phase delay and attenuation. A POSITA would be motivated to incorporate Kudo's technique to ensure a more reliable and optimized connection, selecting an encoding format based not just on theoretical maximums but on actual link quality.
    • Expectation of Success: The combination involved applying a known data rate testing technique (Kudo) to a standard communication system (Ferriere) to achieve the predictable result of improved connection reliability.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including combining Ferriere with Chen (a 1992 journal article) to render claim 11 (reciting psycho-acoustic source-encoding) obvious, and with Lin (Patent 5,189,543) to render claim 32 (reciting cable-less operation) obvious under an alternative claim interpretation. Further grounds combined Ferriere and Kudo with Chen or Lin.

4. Key Claim Construction Positions

  • "test signal": Petitioner proposed this term be construed according to its plain and ordinary meaning as "a transmission of information transmitted as part of determining the presence or quality of something." This broad construction was argued to encompass not only test patterns but also simple information exchanges, such as the modem bit-rate negotiation disclosed in Ferriere.
  • "storage means": For claim 7, Petitioner argued this term is a means-plus-function limitation under §112, ¶6, with the function being "storage." The corresponding structure would include the disclosed magnetic tapes, RAM, etc., and their equivalents. Petitioner argued that even under a broader interpretation not invoking §112, ¶6, the memory buffers implicit in Ferriere for its operation would meet the limitation.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 7, 9-15, 17-21, 24-25, 29, and 31-32 of the ’037 patent as unpatentable.