DCT

2:25-cv-01164

CommPlex Systems LLC v. DZS Inc

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:25-cv-01164, E.D. Tex., 11/26/2025
  • Venue Allegations: Plaintiff alleges venue is proper because Defendant maintains an established place of business in the Eastern District of Texas and has committed acts of patent infringement in the district.
  • Core Dispute: Plaintiff alleges that Defendant’s unspecified products infringe a patent related to communication systems that use multiple orthogonal frequencies for sending and receiving digital data.
  • Technical Context: The technology at issue concerns methods for increasing the rate and efficiency of digital data transmission over limited bandwidth by using frequency shift keying with multiple, coordinated carrier frequencies.
  • Key Procedural History: The complaint does not mention any prior litigation, licensing history, or administrative proceedings related to the patent-in-suit.

Case Timeline

Date Event
2006-10-30 U.S. Patent No. 7,864,900 Priority Date
2011-01-04 U.S. Patent No. 7,864,900 Issues
2025-11-26 Complaint Filed

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

U.S. Patent No. 7,864,900 - "Communication system for sending and receiving digital data," issued January 4, 2011

The Invention Explained

  • Problem Addressed: The patent's background describes limitations in conventional Frequency Shift Keying (FSK) communication systems, such as inaccurate frequency determination, distortion of the mark/space ratio in demodulated data, and the need for improved data capacity over narrow bandwidths (’900 Patent, col. 1:15-2:65).
  • The Patented Solution: The invention proposes a communication system using multiple orthogonal, locked frequencies to represent data, referred to as a "Multiple Orthogonal locked frequencies Narrow Band Frequency Shift Keying (Mary-NBFSK) system" (’900 Patent, col. 3:9-12). Instead of a single carrier frequency shifting between two states (binary FSK), the system transmits one or more frequencies simultaneously from a larger set of available orthogonal frequencies to encode more data per symbol, thereby increasing the data rate and code density per hertz of bandwidth (’900 Patent, Abstract; col. 4:23-31). This is facilitated by encoders and decoders that use look-up tables to convert binary data into specific frequency combinations and vice versa (’900 Patent, col. 6:52-61).
  • Technical Importance: The described approach aims to achieve higher data transmission rates within a given bandwidth compared to traditional FSK methods, which is a persistent goal in digital communications technology (’900 Patent, col. 3:11-15).

Key Claims at a Glance

  • The complaint asserts infringement of "one or more claims" of the ’900 Patent but focuses on "exemplary claims" identified in an external exhibit (Compl. ¶11). Claim 1 is the first independent claim of the patent.
  • Independent Claim 1:
    • A communication system for sending and receiving data, comprising: a transmitter and a receiver wherein a general binary coded Orthogonal Frequency-Division Multiplexing carrier scheme is provided between said transmitter and said receiver to thereby increase code density and data rate per Hz of bandwidth;
    • a plurality of narrow band carrier frequencies, wherein, said narrow band frequencies are orthogonal and are transmitted in a binary code to represent data; and
    • wherein, said narrow band carrier frequencies includes narrow band separation between orthogonal carriers of the order of 0.1 MHz and providing a bandwidth of the order of 3.2 MHz for 32 carriers thereby allowing said bandwidth to transmit at least 6 Mbps in a 2 of 32 Orthogonal Frequency-Division Multiplexing.
  • The complaint does not explicitly reserve the right to assert dependent claims but refers generally to "one or more claims" (Compl. ¶11).

III. The Accused Instrumentality

Product Identification

The complaint does not name any specific accused products in its main body. It refers to "Exemplary Defendant Products" that are purportedly identified in charts attached as Exhibit 2 (Compl. ¶11, ¶16). This exhibit was not provided.

Functionality and Market Context

The complaint does not describe the specific functionality or market context of the accused products. It alleges in a conclusory manner that the "Exemplary Defendant Products practice the technology claimed by the '900 Patent" (Compl. ¶16).

IV. Analysis of Infringement Allegations

The complaint incorporates its infringement allegations by reference to claim charts in an external "Exhibit 2," which is not included in the provided filings (Compl. ¶17). The narrative alleges that Defendant’s products "satisfy all elements of the Exemplary '900 Patent Claims" either literally or under the doctrine of equivalents (Compl. ¶16). Without access to the claim charts or a description of the accused products, a detailed analysis of the infringement theory is not possible.

No probative visual evidence provided in complaint.

  • Identified Points of Contention: Based on the patent claims and the general nature of the allegations, several points of contention may arise once the accused technology is identified.
    • Scope Questions: A central question will likely be whether the accused products implement a "general binary coded Orthogonal Frequency-Division Multiplexing carrier scheme" as required by Claim 1. The definition and scope of this term, particularly its relation to the patent’s "Mary-NBFSK" embodiment, will be critical.
    • Technical Questions: A factual dispute may center on whether the accused products utilize "narrow band carrier frequencies" with the specific "narrow band separation" of "the order of 0.1 MHz" and a total bandwidth of "the order of 3.2 MHz for 32 carriers" as recited in Claim 1. The complaint provides no evidence on this point.

V. Key Claim Terms for Construction

  • The Term: "Orthogonal Frequency-Division Multiplexing carrier scheme"

    • Context and Importance: This term appears in the preamble of Claim 1 and sets the technological framework for the entire claim. The defendant may argue this term confines the claim to conventional OFDM systems, while the plaintiff may argue it should be read more broadly in light of the patent’s disclosure of a "Mary-NBFSK" system. The interpretation will determine whether the claim reads on a wider or narrower range of multi-carrier communication technologies.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The claim uses the qualifier "general binary coded," which may suggest the term is not limited to a specific implementation but encompasses a class of systems that use orthogonal carriers to encode binary data (’900 Patent, col. 9:18-24). The specification also refers to the invention more broadly as a "Multiple (m) carrier Narrow Band Frequency Modulation (NBFM) system using orthogonal frequencies" (’900 Patent, col. 2:65-67).
      • Evidence for a Narrower Interpretation: The specification heavily details a "Multiple Orthogonal locked frequencies Narrow Band Frequency Shift Keying (Mary-NBFSK) system" (’900 Patent, col. 3:9-12; col. 4:10-12). A defendant may argue that the claim term should be construed as being limited to this specific FSK-based embodiment, rather than the broader field of OFDM.

  • The Term: "narrow band carrier frequencies"

    • Context and Importance: This term in Claim 1 is further defined by specific numerical parameters ("separation... of the order of 0.1 MHz," "bandwidth of the order of 3.2 MHz for 32 carriers"). The dispute will likely focus on the meaning of "of the order of," which introduces ambiguity. The resolution will determine how closely an accused system's frequency plan must match the patent's example to infringe.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The phrase "of the order of" typically implies approximation in technical parlance. Plaintiff may argue it does not require the exact values of 0.1 MHz and 3.2 MHz, but rather values reasonably close to them. The specification discusses various system configurations with different parameters (e.g., "1 out of 8," "2 of 7," "2 of 32"), suggesting the specific numbers in Claim 1 are exemplary rather than strictly limiting (’900 Patent, col. 5:2-61).
      • Evidence for a Narrower Interpretation: A defendant could argue that "of the order of" should be limited to the specific context provided by the patent's examples and figures. For instance, the specification describes a "band spacing between each two successive carriers is 100 KHz [0.1 MHz]" in a specific example, potentially anchoring the term's meaning to that disclosure (’900 Patent, col. 4:37-39).

VI. Other Allegations

  • Indirect Infringement: The complaint alleges induced infringement, stating that Defendant distributes "product literature and website materials inducing end users and others to use its products in the customary and intended manner that infringes the '900 Patent" (Compl. ¶14). The specific content of this literature is referenced as being in Exhibit 2 (Compl. ¶14). The allegations state this inducement occurred at least since the filing of the complaint (Compl. ¶15).
  • Willful Infringement: The complaint does not use the word "willful." However, it alleges that service of the complaint and its attached claim charts "constitutes actual knowledge of infringement" (Compl. ¶13). It further alleges that "Despite such actual knowledge, Defendant continues to make, use, test, sell, offer for sale, market, and/or import" infringing products, which could form the basis for a claim of post-filing willfulness (Compl. ¶14).

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

Given the limited factual detail in the complaint, the initial phase of this case will likely focus on discovery to identify the accused products and their specific operation. Once those facts are established, the case may turn on the following key questions:

  1. A core issue will be one of definitional scope: Will the term "Orthogonal Frequency-Division Multiplexing carrier scheme" be construed broadly to cover various multi-carrier systems, or will it be limited to the specific "Mary-NBFSK" FSK-based architecture detailed in the patent's specification?

  2. A second key issue will be one of quantitative matching: How will the court interpret the phrase "of the order of" regarding the claimed frequency separation and bandwidth? The degree of flexibility allowed by this term will be critical in determining whether the technical parameters of the accused products fall within the scope of the claims.

  3. An ultimate evidentiary question will be one of technical mapping: Once the accused products are identified, what evidence will Plaintiff present to demonstrate that they utilize a multi-carrier scheme with the specific orthogonal frequency and bandwidth characteristics required by the asserted claims?