Stormborn Tech LLC v. Digi Intl Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Stormborn Technologies LLC (Texas)
  • Defendant: Digi International, Inc. (Delaware)
  • Plaintiff’s Counsel: SAND, SEBOLT & WERNOW CO., LPA
• Case Identification: 8:22-cv-02213, M.D. Fla., 09/26/2022
• Venue Allegations: Venue is alleged to be proper in the Middle District of Florida because Defendant maintains a "regular and established place of business" within the district.
• Core Dispute: Plaintiff alleges that Defendant’s "Digi Connect Cellular Router" infringes a patent related to a wireless communication system that dynamically adjusts its data transmission rate based on error rates measured at the receiver.
• Technical Context: The technology addresses a fundamental challenge in spread-spectrum wireless communications: maintaining reliable, high-speed data transfer in the presence of signal interference, particularly at the edges of cellular coverage areas.
• Key Procedural History: The complaint notes that in prior litigation involving the same patent (Stormborn Technologies, LLC v. TopCon Positioning Systems, Inc.), a court held that a representative claim was not impermissibly abstract because it was tied to the concrete structure of a "command processor." The patent-in-suit is a reissue patent with a prosecution history dating back to an application filed in 2000.

Case Timeline

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

U.S. Reissue Patent No. RE44,199 - "Variable throughput reduction communications system and method"

The Invention Explained

• Problem Addressed: The patent’s background section describes a problem in multi-cell wireless systems where a remote device near a cell boundary experiences significant interference from adjacent cells, which can degrade a signal below a usable level (’199 Patent, col. 1:50-57). Conventional methods to overcome this interference, such as increasing the system's processing gain, were inefficient because they required reducing the data rate and making physical changes to the receiver's architecture (’199 Patent, col. 1:58-66).
• The Patented Solution: The invention is a closed-loop feedback system for dynamically controlling data throughput. A receiver monitors the "error rate" of incoming data by analyzing the decoded signals (’199 Patent, col. 2:58-62). Based on this measured error rate, a "command processor" at the receiver generates a "data-rate control signal" and transmits it back to the original transmitter. This signal instructs the transmitter to adjust its data rate—for instance, by sending redundant data over parallel channels to improve robustness—thereby adapting to changing signal conditions without altering the receiver's hardware (’199 Patent, Abstract; col. 8:5-15).
• Technical Importance: This adaptive rate-control mechanism allows a wireless system to intelligently manage the trade-off between transmission speed and reliability in response to real-time channel conditions, a core principle in modern wireless communication standards (’199 Patent, col. 2:10-16).

Key Claims at a Glance

• The complaint asserts independent claims 11 (a receiver system) and 13 (a corresponding method) (Compl. ¶¶ 18, 20, 55).
• The essential elements of independent claim 11 include:
  • demodulator circuitry for detecting transmitted signals;
  • decoder circuitry for Forward Error Correction (FEC) decoding, providing multiple decoded channels, each having an "error rate";
  • command processor circuitry that is "responsive to the error rate" and generates a "data-rate control signal" to control the transmitter's data rate;
  • transmitting circuitry to send this control signal back to the transmitter; and
  • multiplexer circuitry to combine the decoded channels into a single data stream.
• Independent claim 13 recites a method with steps that mirror the functions of the circuitry in claim 11.
• The complaint also asserts dependent claim 14 and reserves the right to assert additional dependent claims (Compl. ¶¶ 55, 72).

III. The Accused Instrumentality

Product Identification

The complaint identifies the "Digi Connect Cellular Router" as the Accused Product, while noting that its investigation into other potentially infringing products is ongoing (Compl. ¶56 & n.1).

Functionality and Market Context

The complaint alleges that the Accused Product practices the patented method for recovering wireless data but does not provide specific details on how the product operates (Compl. ¶56). The infringement allegations are primarily based on references to an external claim chart exhibit, which was not filed with the complaint, leaving the precise technical basis for the infringement claim unspecified in the pleading itself (Compl. ¶¶ 57-63). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint alleges infringement of at least claims 13 and 14 but refers to an external exhibit (Exhibit C) for its claim chart, which is not available for analysis. The narrative allegations in the complaint have been used to construct the summary below.

RE44,199 Infringement Allegations

Identified Points of Contention

• Technical Questions: The complaint’s allegations are conclusory and lack specific factual support showing how the Accused Product operates. A central question will be what evidence Plaintiff can produce to show that the "Digi Connect Cellular Router" actually performs the specific feedback loop required by the claims. Specifically, does it generate a control signal based on the "error rate of the decoded channels," as opposed to other signal quality metrics (e.g., Signal-to-Noise Ratio), and transmit that specific signal back to the data transmitter to control its operation?
• Scope Questions: The case may turn on whether standardized link adaptation protocols used in modern cellular technologies (e.g., Hybrid ARQ in LTE/5G) fall within the scope of the claims. This raises the question of whether such protocols meet the claim limitation of a "command processor circuitry responsive to the error rate" that generates a "data-rate control signal" as described in the ’199 Patent.

V. Key Claim Terms for Construction

The Term

"command processor circuitry responsive to the error rate of the decoded channels for generating a data-rate control signal"

Context and Importance

This term recites the core functional element of the invention. Its construction will be critical, as it will determine whether the claim covers only the specific feedback mechanism detailed in the patent or extends to other, more common forms of link adaptation in modern wireless systems.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: The claims use broad, functional language. The specification describes the processor's function as to "determine[] a desired-data rate, and generate[] a data-rate command signal," which a plaintiff may argue supports a construction not limited to a specific algorithm (’199 Patent, col. 4:62-65).
• Evidence for a Narrower Interpretation: The specification repeatedly links the processor's operation to a "syndrome signal" generated by the FEC decoder (’199 Patent, Abstract; col. 2:58-62; col. 8:8-11). A defendant may argue this context limits the claim to systems where the control signal is generated directly from the FEC decoder's output, as opposed to systems using other general signal quality metrics.

VI. Other Allegations

Indirect Infringement

The complaint includes a count for induced infringement, alleging that Defendant encourages its customers to infringe by selling the Accused Product for a use that infringes claim 13 (Compl. ¶74). It further alleges the product is not a staple article of commerce suitable for substantial non-infringing use (Compl. ¶75).

Willful Infringement

The complaint alleges that Defendant has had knowledge of its infringement "at least as of the service of the present Complaint" (Compl. ¶67). This allegation may support a claim for post-suit willful infringement. The prayer for relief seeks enhanced damages (Compl., p. 20, ¶f).

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

1. A key evidentiary question will be one of technical operation: Can Plaintiff produce evidence to demonstrate that the accused router’s internal functions map onto the specific feedback architecture of the asserted claims, particularly the generation of a control signal derived from the "error rate of the decoded channels"?
2. A central legal issue will be one of claim scope: How will the court construe the term "command processor circuitry responsive to the error rate"? A narrow construction tied to the FEC "syndrome signal" described in the specification could distinguish the invention from link adaptation methods used in modern cellular standards, while a broader construction may raise questions of validity over prior art.
3. A likely threshold dispute will concern patent eligibility: Despite a favorable mention of a prior ruling (Compl. ¶54), Defendant may challenge the claims under 35 U.S.C. § 101, raising the question of whether claims directed to generating a control signal based on a calculated error rate constitute an abstract idea without a sufficient inventive concept embodied in a concrete technical application.