CommPlex Systems LLC v. Zyxel Communications Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: CommPlex Systems LLC (NM)
  • Defendant: Zyxel Communications Corporation (Taiwan)
  • Plaintiff’s Counsel: Rabicoff Law LLC
• Case Identification: 2:25-cv-00349, E.D. Tex., 04/07/2025
• Venue Allegations: Plaintiff alleges venue is proper because Defendant has an established place of business in the Eastern District of Texas and has committed acts of patent infringement within the district.
• Core Dispute: Plaintiff alleges that Defendant’s unspecified communication products infringe a patent related to systems for transmitting digital data using multiple orthogonal frequencies.
• Technical Context: The technology at issue involves methods for increasing data transmission rates and spectral efficiency in digital communications by encoding data onto combinations of simultaneously transmitted frequencies.
• Key Procedural History: The complaint is the initial pleading in this action. It asserts that its service provides Defendant with actual knowledge of infringement for the purpose of ongoing and future infringing conduct.

Case Timeline

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

U.S. Patent No. 7,864,900 - Communication system for sending and receiving digital data

• Patent Identification: U.S. Patent No. 7,864,900, "Communication system for sending and receiving digital data," issued Jan. 4, 2011.

The Invention Explained

• Problem Addressed: The patent’s background section describes challenges in conventional Frequency Shift Keying (FSK) systems, where inaccuracies in determining the center frequency—due to component tolerances, aging, or temperature changes—can produce a "distorted mark/space ratio in the demodulated data," leading to transmission errors (Compl. ¶9; ’900 Patent, col. 1:56-65).
• The Patented Solution: The invention proposes a communication system using "Multiple Orthogonal locked frequencies Narrow Band Frequency Shift Keying (Mary-NBFSK)" to increase data throughput and spectral efficiency (’900 Patent, col. 4:9-12). Instead of transmitting a single frequency to represent a bit, the system encodes data by transmitting a combination of multiple orthogonal frequencies simultaneously from a larger available set, with a transmitter and receiver using a look-up table to map data to specific frequency combinations (’900 Patent, Abstract; col. 5:62-68). The patent describes, for example, a "2 of 32 code transmitter system" as depicted in Figure 7 (’900 Patent, col. 4:33-35).
• Technical Importance: The described technique aims to "increase code density and data rate per Hz of bandwidth," a fundamental objective in the field of digital wireless communications (’900 Patent, col. 3:13-15).

Key Claims at a Glance

• The complaint does not identify specific claims, instead referring to "Exemplary '900 Patent Claims" in an un-provided exhibit (Compl. ¶11, ¶16). Independent Claim 1 is representative of the patent's core subject matter.
• Independent Claim 1:
  • A communication system for sending and receiving data, said system 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.

III. The Accused Instrumentality

Product Identification

• The complaint does not name any specific accused products in its body. It refers to "Exemplary Defendant Products" that are identified in charts within "Exhibit 2," which was not publicly filed with the complaint (Compl. ¶11, ¶16).

Functionality and Market Context

• The complaint does not provide sufficient detail for analysis of the accused products' functionality. It alleges in general terms that the "Exemplary Defendant Products practice the technology claimed by the '900 Patent" (Compl. ¶16). No allegations are made regarding the products' specific market context or commercial importance.

IV. Analysis of Infringement Allegations

The complaint alleges infringement through claim charts contained in an external "Exhibit 2," which was not provided with the pleading (Compl. ¶16-17). As such, a detailed claim-by-claim analysis based on the complaint is not possible. The infringement theory is summarily stated: the "Exemplary Defendant Products incorporated in these charts satisfy all elements of the Exemplary '900 Patent Claims" (Compl. ¶16).

No probative visual evidence provided in complaint.

• Identified Points of Contention: Based on the language of Claim 1 of the ’900 Patent and the general nature of the allegations, the infringement analysis raises several questions:
  • Scope Questions: Claim 1 recites a specific "2 of 32 Orthogonal Frequency-Division Multiplexing" scheme capable of transmitting "at least 6 Mbps" within a "3.2 MHz" bandwidth (’900 Patent, col. 10:1-10). A central question will be whether Defendant's commercial products, which may implement standardized communication protocols, practice this highly specific combination of parameters, or if there is a technical mismatch.
  • Technical Questions: The infringement case will depend on whether Plaintiff can demonstrate that the accused products implement the specific mapping of data bits to a combination of two simultaneously transmitted frequencies selected from a set of 32, as the claim requires. This raises the question of what evidence the complaint provides that the accused products perform this specific "2 of 32" encoding, as opposed to a more conventional OFDM implementation where data is modulated onto all subcarriers.

V. Key Claim Terms for Construction

The complaint does not provide sufficient detail for analysis of specific disputed claim terms. However, based on the language of Claim 1, certain terms are likely to be central to the dispute.

• The Term: "a 2 of 32 Orthogonal Frequency-Division Multiplexing" (’900 Patent, col. 10:8-10).
• Context and Importance: This term appears in the final wherein clause of Claim 1 and recites a very specific technical implementation. The viability of the infringement claim will likely depend on whether this term is construed as a strict limitation requiring the selection of two frequencies out of a set of 32, or if it can be read more broadly as an example. Practitioners may focus on this term because it appears to be a primary point of novelty and a potential narrowing feature of the claim.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: A party seeking a broader interpretation may argue that the term is an exemplary embodiment of the more "general binary coded Orthogonal Frequency-Division Multiplexing carrier scheme" recited earlier in the claim (’900 Patent, col. 9:54-58).
  • Evidence for a Narrower Interpretation: The specification provides detailed descriptions and figures for systems that map data to a specific number of transmitted frequencies from a larger set, such as a "2 of 7" system or a "2 of 32 code transmitter system" (’900 Patent, col. 4:28-35; Fig. 7). This explicit disclosure may support a narrower construction limited to systems that select and transmit only two frequencies at a time to represent a block of data bits.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement, asserting that since the filing of the suit, Defendant has knowingly induced infringement by distributing "product literature and website materials" that instruct end users on how to use the accused products in an infringing manner (Compl. ¶14-15).
• Willful Infringement: The complaint does not use the term "willful." However, it alleges that service of the complaint constitutes "actual knowledge of infringement" and that Defendant's continued sales despite this knowledge constitute post-suit infringement, which could form a basis for enhanced damages under 35 U.S.C. § 284 (Compl. ¶13-14).

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

• A core issue will be one of claim scope: can the asserted claims, which recite specific performance metrics and a "2 of 32" transmission scheme, be construed to cover Defendant’s accused products? Or are the claims limited to the particular "Mary-NBFSK" architecture described in the patent's specification, potentially distinguishing them from standardized commercial technologies?
• A key evidentiary question will be one of technical proof: as the litigation proceeds beyond the pleading stage, the case will turn on whether Plaintiff can produce sufficient technical evidence to show that Defendant’s products actually perform the specific function of selecting and transmitting two frequencies from a set of thirty-two to encode data, as required by the limitations of Claim 1.