DCT

1:22-cv-01160

TurboCode LLC v. D Link Corp

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:22-cv-01160, W.D. Tex., 11/09/2022
  • Venue Allegations: Venue is asserted on the basis that Defendant is a foreign corporation, and under 28 U.S.C. § 1391(c), venue is proper in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendant’s 3G and 4G/LTE-capable routers infringe a patent related to high-speed, efficient architectures for turbo code decoders.
  • Technical Context: The technology concerns error correction codes (specifically, "turbo codes") used to ensure data integrity in high-speed wireless communication standards like 3G and 4G/LTE.
  • Key Procedural History: Plaintiff states it has successfully enforced its intellectual property rights against other parties and that its enforcement is ongoing. The complaint also alleges that Plaintiff provided Defendant with formal notice of infringement on October 18, 2021, more than a year prior to filing the suit. A reexamination certificate for the patent-in-suit was issued on February 10, 2009, which cancelled claims 5 and 8 and amended claims 1-4, 6, and 7.

Case Timeline

Date Event
2001-01-02 ’742 Patent Priority Date
2004-11-02 ’742 Patent Issue Date
2009-02-10 ’742 Patent Reexamination Certificate Issued
2016-01-01 Start of Alleged Infringement Period for Accused Products
2021-10-18 Plaintiff Provides Formal Notice of Infringement to Defendant
2021-12-31 End of Alleged Infringement Period for Accused Products
2022-11-09 Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,813,742 - "High speed turbo codes decoder for 3G using pipelined SISO log-map decoders architecture"

  • Patent Identification: U.S. Patent No. 6,813,742, "High speed turbo codes decoder for 3G using pipelined SISO log-map decoders architecture", issued November 2, 2004.

The Invention Explained

  • Problem Addressed: The patent describes that while turbo codes offer significant improvements in error correction for wireless communications, their decoding process was traditionally computationally complex, requiring many multiplications and additions. This complexity made them costly and slow to implement in semiconductor (ASIC) devices, posing a barrier to their use in power-limited, high-throughput consumer products like 3G mobile devices (’742 Patent, col. 1:45-60).
  • The Patented Solution: The invention proposes a decoder architecture that uses two "pipelined" Soft-In/Soft-Out (SISO) Log-MAP decoders operating iteratively. This pipelined structure, illustrated in the system block diagram of Figure 4, allows one decoder to process data while another receives data, increasing throughput (’742 Patent, col. 2:42-49). The use of a "Log-MAP" algorithm, which operates in the logarithmic domain, replaces complex multiplications with simpler binary adder circuits, making the decoder faster, more power-efficient, and easier to implement in an ASIC (’742 Patent, col. 2:56-60; Abstract).
  • Technical Importance: This architecture aimed to make the powerful error-correction capabilities of turbo codes practical for the high-speed, low-power demands of emerging 3G cellular and personal communication devices (’742 Patent, col. 2:32-40).

Key Claims at a Glance

  • The complaint asserts independent claim 6 and its dependent claims (Compl. ¶24). As amended by the Reexamination Certificate, independent claim 6 recites:
    • A method for iteratively decoding sequences of received baseband signals.
    • Providing an input buffer with at least three shift registers to receive an input signal and generate first, second, and third shifted input signals.
    • Providing first and second "soft decision decoders" that are "serially coupled in a circular circuit," with the first decoder receiving the first and second shifted signals and the second decoder receiving the third shifted signal.
    • Processing "systematic information data and extrinsic information data" using a maximum a posteriori (MAP) probability algorithm or a logarithm approximation.
    • Generating a "soft decision" based on the MAP algorithm.
    • Storing the soft decision information in a memory module.
    • Performing iterative decoding for a predetermined number of times, where an output from the last decoder is fed back as an input to the first decoder.

III. The Accused Instrumentality

Product Identification

  • The "Exemplary Accused Products" are the D-Link models DWR-222 (4G LTE USB Adapter), DWR-910 (4G LTE USB Router), DWR-932C (4G LTE Mobile Router), and DWR-921 (4 Port 4G LTE Router) (Compl. ¶16).

Functionality and Market Context

  • The accused products are mobile networking devices that provide internet connectivity over 3G and 4G/LTE cellular networks (Compl. ¶¶16-17). The complaint alleges these products are designed to comply with the 3rd Generation Partnership Project (3GPP) standards governing such communications (Compl. ¶16). A technical specifications table for the DWR-932C is included in the complaint, which lists support for UMTS/HSDPA/HSUPA (3G) and FDD-LTE (4G) frequency bands. (Compl. ¶18). A user manual excerpt for the DWR-222 is also provided, showing icons for 2G, 3G, and 4G network types (Compl. ¶20-21). The complaint alleges these products "process data utilizing a sliding window having a predetermined block size" for memory and energy efficiency (Compl. ¶21).

IV. Analysis of Infringement Allegations

The complaint references a claim chart in Exhibit 3 detailing the infringement of claim 6, but this exhibit was not filed with the complaint (Compl. ¶29). The narrative infringement theory is summarized below.

The complaint’s infringement theory appears to be grounded in the allegation that the accused products are standard-compliant. It alleges that because the products have 3G and/or 4G/LTE capabilities and comply with the relevant 3GPP standards, they necessarily practice the methods claimed in the ’742 Patent (Compl. ¶¶24, 29). Turbo coding is a required component of these standards for error correction. The complaint asserts that the elements of claim 6 are practiced by these products, which were made, used, or sold by D-Link (Compl. ¶29). The allegation that the products "process data utilizing a sliding window having a predetermined block size" (Compl. ¶21) appears intended to map onto the patent's claimed method of processing blocks of data iteratively. The technical specifications for the DWR-932 LTE Router, showing UMTS and FDD-LTE support, are presented as evidence of the product's infringing capabilities (Compl. ¶18).

Identified Points of Contention

  • Architectural Questions: The central question will be whether compliance with the 3G/4G standards necessarily requires implementation of the specific architecture of claim 6, including "first and second soft decision decoders serially coupled in a circular circuit." A defendant may argue that the standards permit multiple, non-infringing decoder designs. The complaint does not provide evidence of the accused products' specific internal hardware or software architecture.
  • Evidentiary Questions: What evidence does the complaint provide that the accused products perform each step of the claimed method? The allegation regarding a "sliding window" (Compl. ¶21) is presented without technical support linking it to the claimed "iterative decoding" process or the functions of the "soft decision decoders." The case may depend on whether infringement can be inferred from standards-compliance and high-level product descriptions, or if it will require detailed reverse engineering or technical discovery of the accused devices.

V. Key Claim Terms for Construction

  • The Term: "serially coupled in a circular circuit" (from amended Claim 6)
  • Context and Importance: This term is central as it defines the unique feedback architecture of the claimed dual-decoder system. The infringement analysis will depend heavily on whether the accused products' decoders are arranged in a manner that falls within the scope of this term. Practitioners may focus on this term because it appears to be the core structural limitation distinguishing the invention from a generic turbo decoder.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: A party might argue the term should be construed broadly to cover any iterative decoding system where the "extrinsic information" output from one decoding stage is passed to the next, as is fundamental to turbo decoding. The specification describes this functional relationship: "in an iterative pipelined decoding, the decoder A 42 reads data from De-interleaver memory 45 and writes results data into Interleaver memory 43, the decoder B 44 reads data from Interleaver memory 43 and write results into De-interleaver" (’742 Patent, col. 8:60-66).
    • Evidence for a Narrower Interpretation: A party could argue the term requires the specific two-decoder pipelined structure depicted in Figure 4, where two distinct decoders (42, 44) are connected via interleaver and de-interleaver memories (43, 45) and operate in a sequence controlled by a specific state machine (TDCLSM 47, detailed in FIG. 22). This interpretation would be narrower, requiring a specific structural and operational arrangement beyond a mere functional data feedback loop (’742 Patent, col. 9:26-40).

VI. Other Allegations

  • Indirect Infringement: The complaint alleges inducement, stating that D-Link instructed and encouraged customers to infringe by providing product instructions and specifications (Compl. ¶25). It also alleges contributory infringement, asserting that D-Link offers to sell components that are material to practicing the invention, are not staple articles of commerce, and that D-Link knew were especially adapted for infringement (Compl. ¶26).
  • Willful Infringement: Willfulness is alleged based on Defendant’s continued infringement after receiving "notice of infringement" on October 18, 2021 (Compl. ¶¶22, 25). The prayer for relief explicitly requests enhanced damages for willful infringement (Compl. p. 9).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A core issue will be one of architectural proof: Can Plaintiff produce evidence that the accused D-Link routers, beyond merely complying with 3G/4G standards, implement the specific "serially coupled in a circular circuit" architecture recited in claim 6, or will discovery reveal a different, non-infringing turbo decoder implementation?
  • A key legal question will be one of standards-essentiality: Does the language of the asserted claim read so directly onto the mandatory portions of the 3GPP standards that compliance with the standard is sufficient to establish infringement of every claim element, or are there limitations in the claim (such as the specific circular coupling) that describe an optional implementation?
  • A central evidentiary question will be one of technical mapping: How does the complaint's high-level allegation of processing data in a "sliding window" (Compl. ¶21) correspond to the specific method steps of the asserted claim, such as processing "systematic information data and extrinsic information data" and "performing... iterative decoding"? The connection between the public-facing evidence and the claimed technical process remains to be established.