TurboCode LLC v. Thales DIS USA Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: TurboCode LLC (Texas)
  • Defendant: Thales DIS USA, Inc. (Delaware)
  • Plaintiff’s Counsel: Direction IP Law
• Case Identification: 6:24-cv-00311, W.D. Tex., 06/07/2024
• Venue Allegations: Venue is alleged based on Defendant maintaining a regular and established place of business in the Western District of Texas.
• Core Dispute: Plaintiff alleges that Defendant’s SIM and eSIM products, by virtue of complying with 3G and 4G/LTE cellular standards, infringe a patent related to high-speed turbo code decoder architectures.
• Technical Context: Turbo codes are a class of high-performance forward error correction codes used to achieve reliable data transfer in noisy communication channels, and were fundamental to the performance of 3G and 4G cellular systems.
• Key Procedural History: The patent-in-suit, originally issued in 2004, was the subject of an ex parte reexamination request filed in 2006. A Reexamination Certificate was issued in 2009, amending the asserted claim. This post-grant review by the USPTO, which confirmed the patentability of the amended claims over prior art, may be presented by the Plaintiff as evidence of the patent's validity.

Case Timeline

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"

The Invention Explained

• Problem Addressed: The patent addresses the challenge that prior art turbo code decoders, while effective, were computationally complex, requiring many multiplications and additions. This made them costly, power-hungry, and slow to implement in the ASIC (Application-Specific Integrated Circuit) chips needed for mass-market consumer devices like 3G mobile phones. (’742 Patent, col. 1:46–61).
• The Patented Solution: The invention proposes a decoder architecture using two serially connected "SISO Log-MAP" decoders that operate in a pipelined, iterative feedback loop. This design simplifies the required circuitry by performing calculations in the logarithmic domain, which primarily requires simpler adder circuits instead of complex multipliers. The architecture is described as enabling higher data throughput, with a decoded output produced each clock cycle, making it more practical for high-speed wireless applications. (’742 Patent, Abstract; col. 2:31–51).
• Technical Importance: This architectural approach sought to make powerful error correction feasible within the size, cost, and power constraints of portable 3G communication devices, a critical step for enabling high-data-rate mobile services. (’742 Patent, col. 2:23–29).

Key Claims at a Glance

• The complaint asserts independent claim 6, as amended by the Ex Parte Reexamination Certificate. (Compl. ¶12-13).
• Essential elements of reexamined Claim 6 include:
  • Providing an input buffer with at least three shift registers for generating first, second, and third shifted input signals.
  • Providing first and second soft decision decoders serially coupled in a circular circuit, processing soft decision data from the preceding decoder.
  • Providing at least one memory module coupled to the decoders' outputs, where the output from the second decoder's memory module is fed back to the first decoder's input.
  • Processing systematic and extrinsic information data using a maximum a posteriori (MAP) probability algorithm or a logarithm approximation thereof.
  • Generating a soft decision based on this algorithm.
  • Weighing and storing the soft decision information into the memory module.
  • Performing iterative decoding for a predetermined number of times in a circular circuit.
• The complaint does not explicitly reserve the right to assert dependent claims.

III. The Accused Instrumentality

Product Identification

The complaint identifies "Plug 85, Plug 105, and Quad SIM and eSIM" products as the "Accused Instrumentalities." (Compl. ¶12). A table from Defendant's marketing materials shows these products are intended for Domestic, Industrial, and Automotive IoT applications. This marketing table describes the "Network Techno" for these products as supporting "2G, 3G, LTE, 5G." (Compl. ¶14, p. 5).

Functionality and Market Context

• The complaint alleges that these products infringe by complying with 3G and 4G/LTE standards as specified by the 3rd Generation Partnership Project (3GPP), specifically releases 8-11. (Compl. ¶12).
• The core of the infringement allegation is that any device compliant with these standards must necessarily implement an iterative turbo decoder that practices the patented method. The complaint argues that it was not commercially feasible to implement such decoders in a non-iterative manner. (Compl. ¶17).

IV. Analysis of Infringement Allegations

'742 Patent Infringement Allegations

Identified Points of Contention

• Standards Compliance vs. Infringement: A central issue will be whether Plaintiff's reliance on 3G/4G standards documents is sufficient to demonstrate infringement. Defendant may argue that while its products are standards-compliant, their specific, proprietary implementation of the turbo decoder differs from the general descriptions in the standards and does not meet all claim limitations.
• Scope Questions: The patent is titled and described as a "pipelined" architecture, which it claims produces a "decoded output data... each clock cycle" (’742 Patent, col. 2:58-60). The complaint describes the accused process as "iterative" (Compl. ¶17). While amended Claim 6 uses the term "iteratively decoding," the relationship between the patent's specific "pipelined" embodiment and the allegedly infringing "iterative" process will likely be a point of dispute.
• Technical Questions: What evidence demonstrates that the accused Thales products, which include modern eSIMs, actually implement the specific algorithms and data flows (e.g., the BCJR algorithm, the ecall_fec.c source code logic) cited from public standards and academic papers? The complaint's infringement theory rests on the assertion that all commercial decoders are "functionally equivalent" to the diagrams presented (Compl. ¶19, ¶25).

V. Key Claim Terms for Construction

Claim Term: "weighing... soft decision information"

• Context and Importance: This term, added during reexamination, is critical because it describes a specific action performed on the soft decision data before storage. The complaint alleges this is met by "normalization" steps in the standard's reference code (Compl. ¶37, ¶39). The definition will determine if a simple storage of a calculated value meets the limitation, or if a separate, distinct "weighing" or "normalization" step is required.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent does not define "weighing," and the term itself is broad. A party could argue it encompasses any mathematical modification of the soft decision value before it is stored or used in the next iteration.
  • Evidence for a Narrower Interpretation: The term was added to Claim 6 during reexamination, suggesting it was necessary to distinguish the invention from prior art. The prosecution history of that reexamination (not included in the complaint) would be highly relevant. Lacking that, a party could argue from the patent's overall focus on specific Log-MAP algorithms that "weighing" must refer to a specific, known step within those algorithms, rather than any general modification.

Claim Term: "soft decision decoders"

• Context and Importance: The patent specification repeatedly refers to the inventive decoders as "SISO Log-MAP Decoders" (’742 Patent, col. 4:9-11). The complaint maps this term to the "constituent decoders" of the 3GPP standard architecture (Compl. ¶23). Whether this term is limited to the specific "Log-MAP" type described in the specification, or covers any decoder that outputs a "soft decision" (a probability or likelihood), will be key to the scope of infringement.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: Claim 6 uses the general term "soft decision decoders," not the more specific "Log-MAP" term. A party could argue that if the patentee intended to limit the claim to Log-MAP decoders, they would have done so explicitly.
  • Evidence for a Narrower Interpretation: A party could argue that the specification consistently and exclusively describes the invention in the context of Log-MAP decoders, implicitly defining the claimed "soft decision decoders" as such. The patent states an object is "To utilize SISO Log-MAP decoder for faster decoding" (’742 Patent, col. 2:53-54), potentially limiting the invention to that embodiment.

VI. Other Allegations

• Indirect Infringement: The complaint does not contain a count for indirect infringement.
• Willful Infringement: The complaint does not contain a count for willful infringement or a request for enhanced damages in its prayer for relief.

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

• A core issue will be one of evidentiary sufficiency: Can Plaintiff prove infringement by demonstrating the accused products' compliance with 3G/4G standards, or will it be required to produce evidence, such as from reverse engineering, showing that Defendant's specific, proprietary silicon architecture practices every element of the asserted claim?
• A key question of claim construction will be whether the terms in reexamined Claim 6, such as "weighing", can be interpreted broadly enough to read on the generalized functions described in public standards documents, or if they are implicitly limited to the specific "pipelined Log-MAP" architecture detailed in the patent's specification.
• A central technical dispute will likely focus on the operational details of the accused decoders. Does the accused system's iterative feedback loop function as the "circular circuit" claimed, and does its processing of probability data constitute the claimed "processing", "generating", and "weighing" steps?