PTAB

IPR2024-00431

Comcast Corp v. Entropic Communications LLC

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Petition
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1. Case Identification

2. Patent Overview

  • Title: Broadband Network for Coaxial Cable Using Multi-Carrier Modulation
  • Brief Description: The ’518 patent discloses a local area network (LAN) that operates over coaxial building wiring. The system uses multi-carrier modulation techniques, such as Orthogonal Frequency Division Multiplexing (OFDM), and a bit-loading protocol to overcome channel impairments by adjusting data transmission rates on sub-carriers based on their estimated signal-to-noise ratios (SNRs).

3. Grounds for Unpatentability

Ground 1: Claims 1-4 are obvious over Afshary in view of Mirfakhraei.

  • Prior Art Relied Upon: Afshary (Application # 2006/0218593) and Mirfakhraei (European Patent Publication No. 1087586A2).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued Afshary taught the foundational coaxial cable LAN, including at least two network devices, splitters, and coaxial wiring for communication. However, Afshary used a single-carrier modulation scheme. Mirfakhraei taught the missing elements: a multi-carrier communication protocol (Discrete Multi-Tone or DMT) that uses bit-loading to improve data throughput and robustness. Mirfakhraei explicitly disclosed a multi-carrier modulator and demodulator. Critically, Mirfakhraei also taught the use of "handshake signals" (equivalent to the claimed "probe messages") comprising a predetermined, known signal transmitted between transceivers to estimate the SNR for each sub-channel, which is then used to determine the bit-loading profile (i.e., selecting modulation order).
    • Motivation to Combine: Petitioner contended a person of ordinary skill in the art (POSITA) would combine Mirfakhraei's advanced multi-carrier modulation and bit-loading techniques into Afshary’s basic coaxial cable LAN. The motivation was to improve the data transmission rate and reliability of Afshary's network. Coaxial cable is a known harsh communication medium with variable frequency response, and Mirfakhraei's DMT bit-loading protocol was well-suited to mitigate such impairments, representing a known solution to a known problem.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because the combination involved applying a known technique (Mirfakhraei's DMT/bit-loading) to a known device (Afshary's coax LAN) to achieve the predictable result of improved network performance and robustness.

Ground 2: Claim 2 is obvious over Afshary and Mirfakhraei in further view of Welles.

  • Prior Art Relied Upon: Afshary (Application # 2006/0218593), Mirfakhraei (European Patent Publication No. 1087586A2), and Welles (Patent 6,737,984).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground was asserted to address the "means for determining signal activity" limitation in claim 2. While Petitioner argued the Afshary-Mirfakhraei combination taught this, Welles was introduced as an alternative teaching. Welles disclosed a LAN over power lines where transceivers used an envelope detector to scan a frequency range to determine if it was already in use by another device or affected by noise. This function of measuring received signal power to find a clear channel for communication directly maps to the claimed "means for determining signal activity" and "selects a frequency band for operation that is not used by other services."
    • Motivation to Combine: A POSITA would be motivated to incorporate Welles’s simple and effective envelope detector into the Afshary-Mirfakhraei system. Afshary explicitly described a goal of operating its LAN on a frequency range not used by other services (like cable TV) on the same coaxial cable. Welles provided a straightforward and known method for detecting signal activity to ensure that communications would not disturb, or be disturbed by, existing services, thus furthering Afshary's stated goal.
    • Expectation of Success: The proposed implementation would be well within the skill of a POSITA. Combining a known channel-sensing technique (Welles's envelope detector) with a communication system (Afshary-Mirfakhraei) to avoid interference is a common design choice that yields the predictable result of finding a clear communication channel.

4. Key Claim Construction Positions

  • Petitioner argued that three terms in the challenged claims invoked pre-AIA §112 ¶ 6 as means-plus-function limitations and proposed constructions based on structures and algorithms disclosed in the ’518 patent’s specification.
  • "means for determining signal activity" (claim 2): The function is "determining signal activity." Petitioner identified corresponding structures as either a receiver performing a Fast Fourier Transform (FFT) on data samples from an A/D converter or an envelope detector.
  • "means for producing and transmitting a probe message" (claim 4): The function is "producing and transmitting a probe message." Petitioner identified the corresponding structure as a processor executing an algorithm for generating and transmitting a signal known to a receiving device.
  • "means for receiving and analyzing a probe message to determine a bit loading profile..." (claim 4): The function is "receiving and analyzing a probe message to determine a bit loading profile." Petitioner identified the corresponding structure as a processor executing an algorithm for receiving a known signal, determining an SNR for each subchannel based on it, and determining bit-loading based on the SNR.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under both Fintiv and General Plastic.
  • Fintiv Factors: Petitioner asserted that Fintiv denial was unwarranted because no trial date had been set in the parallel district court litigation, the court's investment had been minimal, and the IPR challenged all four claims of the ’518 patent while only claims 1 and 3 were asserted in court, reducing issue overlap.
  • General Plastic Factors: An unrelated party (Dish Network) had previously filed an IPR (IPR2024-00393) against claims 1 and 3 of the same patent. Petitioner argued this should not trigger denial because Comcast and Dish are unrelated competitors with no cooperation in preparing their petitions. Further, the current petition was filed less than a month after the first, challenges a different scope of claims (1-4 vs. 1 and 3), and relies on different prior art references, meriting a separate review.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4 of the ’518 patent as unpatentable under 35 U.S.C. §103.