TurboCode LLC v. Biotronik Se & Co KG

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: TurboCode LLC (Texas)
  • Defendant: Biotronik SE & Co. KG (Germany)
  • Plaintiff’s Counsel: Direction IP Law
• Case Identification: 2:25-cv-00320, E.D. Tex., 03/31/2025
• Venue Allegations: Plaintiff alleges venue is proper because Defendant has committed acts of infringement within the Eastern District of Texas.
• Core Dispute: Plaintiff alleges that Defendant’s medical devices equipped with 4G/LTE cellular communication capabilities infringe a patent related to efficient turbo code decoder architectures for wireless systems.
• Technical Context: The technology concerns forward error correction, specifically turbo codes, which are essential for ensuring reliable data transmission in modern wireless communication standards like 4G/LTE.
• Key Procedural History: The patent-in-suit, U.S. Patent No. 6,813,742, survived an Ex Parte Reexamination, with a Reexamination Certificate issued on February 10, 2009. The asserted claim, claim 6, was amended during this proceeding, which may suggest a strengthened presumption of validity against prior art considered by the U.S. Patent and Trademark Office.

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," issued November 2, 2004

The Invention Explained

• Problem Addressed: The patent's background section notes that prior art turbo code decoders, while effective, were computationally complex, power-intensive, and costly. These drawbacks made them impractical for consumer-grade, power-limited portable wireless devices, such as 3G mobile phones, which require high data throughput and energy efficiency (’742 Patent, col. 2:15-28).
• The Patented Solution: The invention discloses a decoder architecture using two serially connected, pipelined "Soft-In/Soft-Out" (SISO) Log-MAP decoders. This design uses an iterative process where decoded information from one decoder is passed to the other through memory modules (an interleaver and de-interleaver) to progressively refine the accuracy of the decoded data (’742 Patent, Fig. 4). By performing calculations in the logarithmic domain, the architecture avoids complex multiplier circuits in favor of simpler, faster adder circuits, thereby increasing speed and reducing power consumption (’742 Patent, col. 2:53-58, col. 3:1-4).
• Technical Importance: The described architecture aimed to make the superior error-correction performance of turbo codes practical for mass-market, high-speed wireless communication devices by creating a simpler, lower-cost, and more power-efficient implementation (’742 Patent, col. 2:32-40).

Key Claims at a Glance

• The complaint asserts independent method claim 6, as amended by the Ex Parte Reexamination Certificate (Compl. ¶12).
• The essential elements of asserted claim 6 include:
  • A method for iteratively decoding received baseband signals.
  • Providing an input buffer with at least three shift registers to generate first, second, and third shifted input signals.
  • Providing first and second soft decision decoders serially coupled in a circular circuit, with specific signal routing from the input buffer to each decoder.
  • Providing at least one memory module coupled to the output of each decoder, where the output of the second decoder's memory is fed back as an input to the first decoder.
  • Processing systematic and extrinsic information using a maximum a posteriori (MAP) or equivalent logarithm approximation algorithm.
  • Generating a soft decision based on that algorithm.
  • Weighing and storing the soft decision information into the memory module.
  • Performing iterative decoding for a predetermined number of times, where an output from the last decoder is fed back to the first, and then propagates through the decoders in a circular circuit.
• The complaint’s prayer for relief requests judgment on "one or more claims" of the ’742 Patent (Compl. p. 20, ¶a).

III. The Accused Instrumentality

Product Identification

• The complaint identifies the Accused Instrumentalities as the CardioMessenger Smart Transmitter, Renamic Neo, and Prospera Spinal Cord Stimulation System with Embrace One (Compl. ¶12).

Functionality and Market Context

• These are medical monitoring and therapy devices that incorporate cellular communication modules for transmitting data wirelessly to a central service center (Compl. ¶16). The complaint alleges these products operate on 4G/LTE networks and, in doing so, comply with the 3rd Generation Partnership Project (3GPP) technical standards that govern such communications (Compl. ¶12, 14, 19). An image in the complaint for the Renamic Neo product explicitly advertises an "Integrated 4G/3G internet stick" (Compl. p. 6). Another visual, a technical manual for the CardioMessenger Smart, lists its supported LTE frequencies (Compl. p. 5). The core of the infringement allegation is that compliance with these 3GPP standards, which mandate the use of turbo codes for error correction, necessarily means the devices practice the patented method (Compl. ¶19).

IV. Analysis of Infringement Allegations

’742 Patent Infringement Allegations

Identified Points of Contention

• Scope Questions: A central question is whether compliance with the 3GPP standards for LTE requires the specific decoder architecture recited in claim 6. The complaint largely infers the structure and function of the decoder from specifications that primarily detail the encoder (Compl. ¶18, ¶24). The case may turn on whether the standard permits alternative, non-infringing decoder implementations.
• Technical Questions: The complaint maps the claim’s specific "circular circuit" with two decoders to the general concept of iterative decoding and feedback loops in the LTE standard (Compl. ¶24). A key technical question will be what evidence demonstrates that the accused devices' actual chip-level implementation contains the specific two-decoder feedback structure, as opposed to a different form of iterative processing (like HARQ combining) that may not map to the claim limitations.

V. Key Claim Terms for Construction

The Term: "serially coupled in a circular circuit"

• Context and Importance: This term is central to the patent's claimed architecture. The infringement case depends on whether the iterative processes in the accused LTE-compliant devices can be characterized as having this specific structure. Practitioners may focus on this term because the complaint maps it to the general iterative nature of turbo coding, while the patent depicts a more specific feedback loop between two distinct decoder blocks (’742 Patent, Fig. 4).
• Intrinsic Evidence for a Broader Interpretation: The patent describes the overall system as operating in a "feedback loop" and performing "re-iterative decoding of data back-and-forth between the two Log-MAP decoders" (’742 Patent, col. 4:10-11, col. 2:58-60). This language could support an interpretation covering any system where decoding stages iteratively exchange and refine data.
• Intrinsic Evidence for a Narrower Interpretation: The patent’s Figure 4 shows a distinct structural arrangement where the output of "Decoder B" is routed through "De-Interleaver Memory 45" to become an input for "Decoder A." This could support a narrower construction requiring a specific two-component loop, not just a general iterative process.

The Term: "weighing and storing soft decision information"

• Context and Importance: This term describes a key step in the iterative process. A dispute could arise over whether the accused devices perform both "weighing" (e.g., generating a Log-Likelihood Ratio) and "storing" in the manner claimed. The complaint argues this is an inherent part of standard Turbo decoding (Compl. ¶22).
• Intrinsic Evidence for a Broader Interpretation: The patent does not define "weighing" in great detail, which could allow the term to cover any calculation of probabilistic values (soft decisions) that are subsequently stored for the next iteration.
• Intrinsic Evidence for a Narrower Interpretation: The term appears in the re-examined claim, and its addition may have been intended to capture a specific step. A defendant could argue it requires more than just storing a calculated soft value, perhaps implying a distinct scaling or modification step that is not present in their implementation.

VI. Other Allegations

• Indirect Infringement: The complaint does not plead a separate count for indirect infringement.
• Willful Infringement: The complaint does not plead willful infringement. It alleges only "constructive notice" of the patent, which is generally insufficient to support a claim for enhanced damages (Compl. ¶26).

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

• A core issue will be one of standards-based inference: Does compliance with the 3GPP LTE standard, which primarily defines the encoder, necessarily compel the use of a decoder that practices every specific structural and functional step of the asserted method claim? The court will need to determine if the standard allows for alternative, non-infringing decoder designs.
• A key evidentiary question will be one of architectural mapping: What is the actual hardware and/or software architecture of the decoders in the accused medical devices? The case will likely depend on whether Plaintiff can show that this real-world implementation mirrors the specific "circular circuit" with two decoders as claimed, or if there is a fundamental mismatch between the patent’s specific architecture and the more general iterative processes (e.g., HARQ) used in the accused products.