DirecTV LLC v. Entropic Communications LLC

1. Case Identification

• Case #: IPR2024-01062
• Patent #: 8,621,539
• Filed: July 1, 2024
• Petitioner(s): DirecTV, LLC
• Patent Owner(s): Entropic Communications, LLC
• Challenged Claims: 1-7

2. Patent Overview

• Title: Modem for Communication Across a Coaxial Network
• Brief Description: The ’539 patent discloses a modem for use in a multi-node coaxial cable network. The system uses an "Echo Profile Probe" packet transmitted between nodes to measure the node delay spread on the network, and then optimizes communication parameters, such as the preamble and cyclic prefix, in response to the measurement.

3. Grounds for Unpatentability

Ground 1: Obviousness over Hou and Konschak - Claim 1 is obvious over Hou in view of Konschak.

• Prior Art Relied Upon: Hou (Patent 6,898,755) and Konschak (European Patent Publication No. EP1065855).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Hou discloses a modem system for a coaxial network that measures channel characteristics, including "Echo Delay Spread," to adapt transmission parameters. Specifically, Hou teaches using these measurements to assign burst profiles with varying preamble lengths to improve bandwidth efficiency. Konschak teaches a method for adapting the length of cyclic extensions (prefixes) in an Orthogonal Frequency-Division Multiplexing (OFDM) system based on measured channel delay profiles to reduce transmission overhead. Petitioner asserted that the combination of Hou and Konschak teaches a MAC layer using a probe packet (argued to be the well-known RNG-REQ messages in Hou's DOCSIS-compliant system) to measure node delay spread. The MAC layer then optimizes the preamble (taught by Hou) and the cyclic prefix (taught by Konschak) in response to that measurement.
  • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Hou and Konschak to improve the performance of Hou’s cable modem system. A POSITA would incorporate OFDM techniques, as taught by Konschak, into Hou's system to combat known multipath effects. Both references address the common goal of optimizing communication parameters to improve bandwidth efficiency. Given that Hou already measures delay spread, and the relationship between delay spread and cyclic prefix was well-known, applying Konschak’s cyclic prefix adaptation was presented as a predictable solution to further reduce overhead.
  • Expectation of Success: Petitioner contended that a POSITA would have a reasonable expectation of success. The combination joins known elements (Hou's parameter adjustment based on measurement, Konschak's cyclic prefix adaptation) that perform their known functions to achieve the predictable result of improved bandwidth efficiency in a cable network.

Ground 2: Obviousness over Hou, Konschak, and Dapper - Claims 2-7 are obvious over Hou, Konschak, and Dapper.

• Prior Art Relied Upon: Hou (Patent 6,898,755), Konschak (EP1065855), and Dapper (Patent 6,366,585).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground builds on the Hou-Konschak combination by adding Dapper to teach the limitations of the dependent claims. Petitioner argued Dapper teaches improving OFDM communications with techniques that map directly to the challenged claims. For claims 2 and 5, Dapper discloses scrambling payload data with pseudorandom sequences to generate pseudo random time domain samples, which increases robustness. For claims 3 and 6, Dapper teaches that using Binary Phase-Shift Keying (BPSK) modulation on a single carrier at the center frequency is preferred for control channels to provide robustness and avoid interference. For claims 4 and 7, Petitioner argued that the DOCSIS standard, which Hou’s system uses, dictates that the MAC layer provides the packet length via a standard header field, a step that would be necessary when adding a variable-length payload (like Konschak’s reference symbol) to a fixed-length ranging message.
  • Motivation to Combine: A POSITA, having created the Hou-Konschak system, would be motivated to incorporate Dapper’s teachings to further enhance the system's performance and robustness. Dapper provides known solutions for known problems in point-to-multipoint OFDM networks, such as preventing unwanted spectral effects and ensuring robust control signaling. The similar technical goals and system architectures of the references would have prompted a POSITA to integrate Dapper’s improvements.
  • Expectation of Success: The addition of Dapper's teachings to the Hou-Konschak combination represents a predictable application of known techniques to solve known problems. A POSITA would have reasonably expected that implementing Dapper’s methods for scrambling data and using robust modulation would successfully improve the reliability of the combined system.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial of institution is not warranted.
• Fintiv Factors: Petitioner asserted that denial under Fintiv is inappropriate because no trial date has been set in the parallel district court litigation, the parties have not substantially invested in that litigation, and a Final Written Decision (FWD) in the inter partes review (IPR) would issue months before any estimated trial date.
• §325(d) Factors: Petitioner argued that denial under 35 U.S.C. §325(d) is unwarranted because the grounds presented in the petition rely on combinations of prior art that were not previously presented to or evaluated by the patent examiner during prosecution.

5. Relief Requested

• Petitioner requests institution of an IPR for claims 1-7 of the ’539 patent and cancellation of those claims as unpatentable.