RPX Corp v. Digital Audio Encoding Systems LLC

1. Case Identification

• Case #: IPR2017-00212
• Patent #: 7,490,037
• Filed: November 7, 2016
• Petitioner(s): RPX Corporation
• Patent Owner(s): Digital Audio Encoding Systems, LLC
• Challenged Claims: 5-6, 8, 22-23, 26-28, and 30

2. Patent Overview

• Title: Method and Apparatus for Encoding Signals
• Brief Description: The ’037 patent describes a method for encoding signals, particularly digitized audio, where the encoding format (e.g., bit rate) is selected to correspond to properties of a receiving/processing device. The system determines these properties by transmitting a test signal to the processing device and detecting a response.

3. Grounds for Unpatentability

Ground 1: Obviousness over Ferriere and Kalra - Claims 5 and 6 are obvious over Ferriere in view of Kalra.

• Prior Art Relied Upon: Ferriere (Patent 5,835,495) and Kalra (Patent 5,953,506).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Ferriere, a teleconferencing system, discloses the independent claims' limitations of an encoding device, a processing device, and a control device that determines an encoding format based on a property of the processing device. Ferriere’s system determines the encoding bit rate based on the effective bit rate of the receiving modem, which is determined via a test signal exchange. Kalra, which teaches a real-time streaming system, adds the specific limitation of claim 5 by disclosing that the encoding format should correspond to the processor power (CPU constraint) of the client computer to ensure real-time processing.
  • Motivation to Combine: A POSITA would combine Kalra’s teachings with Ferriere’s system to optimize the quality of transmitted audio based on the receiving device's processing capabilities, not just its network connection speed. This would ensure the device could decode and play the audio in real time without interruption, a stated goal of both references.
  • Expectation of Success: The combination involved applying known techniques for assessing client-side processing power (from Kalra) to an existing framework for adaptive bitrate selection (in Ferriere), which would have been a straightforward implementation for a POSITA.

Ground 2: Obviousness over Ferriere and Schulzrinne - Claims 8, 23, 26, and 30 are obvious over Ferriere in view of Schulzrinne.

• Prior Art Relied Upon: Ferriere (Patent 5,835,495) and Schulzrinne (a 1992 technical report titled "Voice Communication Across the Internet: A Network Voice Terminal").
• Core Argument for this Ground:
  • Prior Art Mapping: Ferriere provides the base system for adaptive audio encoding. Schulzrinne discloses a network voice conferencing tool (NEVOT) with an extensive graphical user interface that allows a user to manually configure and monitor numerous parameters, including encoding algorithms and sampling rates. This addresses the limitations in claims 8 and 23 requiring a user to "preset the desired encoding format" via a "display/input device." Claim 26's requirement that "all settings can be implemented manually" is met by Schulzrinne's "heavily parameterized" interface. Claim 30's "level display" is taught by Schulzrinne's VU meter for displaying audio loudness.
  • Motivation to Combine: A POSITA would combine Schulzrinne’s user interface with Ferriere’s system to provide users with an override option for troubleshooting and performance analysis. Ferriere's automated determination of the optimal encoding format might not be ideal in all network conditions, and providing manual controls as taught by Schulzrinne would offer a beneficial tool for advanced users to fine-tune performance.
  • Expectation of Success: Incorporating a graphical user interface for parameter configuration into a teleconferencing system was a well-known design choice, and a POSITA would have reasonably expected success in adding such functionality to Ferriere's system.

Ground 3: Obviousness over Ferriere and Hluchyj - Claim 22 is obvious over Ferriere in view of Hluchyj.

• Prior Art Relied Upon: Ferriere (Patent 5,835,495) and Hluchyj (Patent 5,115,429).

• Core Argument for this Ground:

  • Prior Art Mapping: Ferriere teaches a system that uses a test signal (modem bitrate information) to determine an encoding rate. Claim 22 requires that the "test signal is an encoded audio signal." Hluchyj discloses a system for managing bidirectional voice communication that specifically uses a packet of encoded audio as a test signal to detect network congestion. Upon detecting congestion from a response to this test signal, the system lowers its coding rate.
  • Motivation to Combine: A POSITA would modify Ferriere’s system to use Hluchyj's technique for detecting network congestion. This would enhance Ferriere’s ability to provide "optimal quality" by making the system responsive not just to modem speed but also to real-time network path congestion, a common and known problem. Using an encoded audio packet as the test signal is a more direct way of testing the actual transmission path for the media being sent.
  • Expectation of Success: Implementing Hluchyj's congestion detection mechanism, which uses audio packets analogous to Ferriere's audio data blocks, would have been a predictable modification for a POSITA seeking to improve the robustness of Ferriere's real-time communication system.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combining Ferriere with Riddle (Patent 5,857,189) for displaying transmission time, and with Barraclough (Patent 5,539,741) for mixing audio signals. Petitioner also asserted grounds combining Ferriere and Kudo (Patent 4,606,044) with each of the other secondary references, arguing Kudo provided an alternative, well-known test signal procedure.

4. Key Claim Construction Positions

• "signal": Petitioner proposed that the plain and ordinary meaning is a "transmission of information," encompassing waveforms, encoded bit streams, data packets, and other information transmissions.
• "test signal": Petitioner proposed this term means a "transmission of information transmitted as part of determining the presence or quality of something." This broad construction allows various network handshaking signals or data packets in the prior art to meet the limitation.
• "test signal generator": Following from the above, Petitioner argued this is simply something that generates a "test signal," which could be a component of a larger communication unit.

5. Key Technical Contentions (Beyond Claim Construction)

• Loss of Priority Date: A central contention was that the ’037 patent was not entitled to its claimed 1997 priority date. Petitioner argued that the patent's parent application was abandoned on March 2, 2005, and the application for the ’037 patent was not filed until June 2, 2005, breaking the chain of co-pendency required under 35 U.S.C. §120. This would make the patent's effective filing date June 2, 2005, rendering numerous references, including Ferriere, prior art under §102(b).

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 5-6, 8, 22-23, 26-28, and 30 of the ’037 patent as unpatentable.