CommPlex Systems LLC v. D Link Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: CommPlex Systems LLC (NM)
  • Defendant: D-Link Corporation (Taiwan)
  • Plaintiff’s Counsel: Rabicoff Law LLC
• Case Identification: 2:25-cv-00343, 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 in the district.
• Core Dispute: Plaintiff alleges that certain unidentified D-Link products infringe a patent related to communication systems for transmitting digital data using multiple orthogonal frequencies.
• Technical Context: The technology concerns methods for increasing the rate and efficiency of digital data transmission over wireless or wired channels, a foundational element in modern networking and telecommunications.
• Key Procedural History: The complaint asserts that its filing and service constitute actual knowledge of infringement for the purpose of willfulness allegations. No prior litigation or other procedural events are mentioned.

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," issued January 4, 2011

The Invention Explained

• Problem Addressed: The patent describes challenges with conventional Frequency Shift Keying (FSK) modulation, where inaccuracies in determining the center frequency can lead to a "distorted mark/space ratio in the demodulated data," causing transmission errors (’900 Patent, col. 2:1-6). The background also implies a general need to increase data transmission rates and capacity within a given bandwidth (’900 Patent, col. 3:3-8).
• The Patented Solution: The invention proposes a communication system using a "Multiple Orthogonal locked frequencies Narrow Band Frequency Shift Keying (Mary-NBFSK)" scheme (’900 Patent, col. 4:9-11). Instead of transmitting a single frequency to represent one or two states (e.g., a '0' or '1'), the system encodes a block of multiple data bits into a combination of multiple frequencies selected from a larger set of available orthogonal frequencies, which are then transmitted simultaneously (’900 Patent, Abstract). This is intended to increase the "code density and data rate per Hz of bandwidth" by using a look-up table to map data to specific frequency combinations (’900 Patent, col. 8:61-68; col. 6:61-68).
• Technical Importance: The described technique aims to provide a system with higher data throughput and reduced hardware complexity compared to using multiple, separate FSK systems in parallel (’900 Patent, col. 4:19-23).

Key Claims at a Glance

The complaint does not specify which claims are asserted, instead referring to the "Exemplary '900 Patent Claims" identified in an unattached exhibit (Compl. ¶11). Independent claim 1 is the broadest claim and is analyzed here.

• 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 states that Plaintiff may assert infringement of other claims, including dependent claims (Compl. ¶11).

III. The Accused Instrumentality

Product Identification

The complaint does not identify any specific accused products by name or model number. It refers generally to "Exemplary Defendant Products" that are purportedly identified in an unattached exhibit (Compl. ¶11).

Functionality and Market Context

The complaint does not provide sufficient detail for analysis of the accused products' specific functionality or market context. It makes only a conclusory allegation that the products "practice the technology claimed by the '900 Patent" (Compl. ¶16). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint alleges infringement by incorporating by reference claim charts in an unattached "Exhibit 2" (Compl. ¶16, ¶17). As this exhibit was not provided, a detailed element-by-element analysis of the infringement allegations is not possible. The complaint offers only a conclusory allegation that the "Exemplary Defendant Products" satisfy all elements of the asserted claims (Compl. ¶16).

Identified Points of Contention

Based on the language of claim 1 of the ’900 Patent, the infringement analysis may raise several technical and legal questions:

• Scope Questions: Claim 1 recites specific numerical performance metrics, such as a "bandwidth of the order of 3.2 MHz for 32 carriers" and transmission of "at least 6 Mbps." A central question will be whether the accused products meet these quantitative limitations, and how broadly the term "of the order of" can be interpreted.
• Technical Questions: The claim requires a "general binary coded Orthogonal Frequency-Division Multiplexing carrier scheme" (’900 Patent, col. 8:62-65). A likely point of dispute will be whether the modulation technique used in the accused products constitutes such a scheme as understood in the patent, or if it represents a different, non-infringing technology (e.g., Quadrature Amplitude Modulation (QAM) or a different FSK variant).

V. Key Claim Terms for Construction

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

Context and Importance

This term defines the core technology of the asserted claim. Its construction will be critical, as the accused products' classification as using or not using an "OFDM" scheme will likely be determinative of infringement. Practitioners may focus on this term because the patent's specification heavily describes specific FSK-based systems, which could be used to argue for a narrow construction that excludes more common forms of OFDM.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: The claim itself uses the qualifier "general binary coded," suggesting the term is not limited to a single specific embodiment (’900 Patent, col. 8:62-63). The Summary of the Invention also broadly contemplates 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 detailed description repeatedly refers to the invention as a "Multiple Orthogonal locked frequencies Narrow Band Frequency Shift Keying (Mary-NBFSK)" system (’900 Patent, col. 4:9-11). A defendant may argue that this specific implementation defines the scope of the claimed "scheme," limiting it to FSK-based systems rather than encompassing other modulation techniques commonly associated with OFDM.

The Term: "of the order of"

Context and Importance

This phrase qualifies three distinct numerical limitations in claim 1: a carrier separation "of the order of 0.1 MHz," a bandwidth "of the order of 3.2 MHz," and a data rate of "at least 6 Mbps" (’900 Patent, col. 9:7-10). The degree of numerical flexibility this term provides will be central to determining whether the performance characteristics of an accused product fall within the literal scope of the claim.

Intrinsic Evidence for Interpretation

• Evidence for a Broader Interpretation: The patent does not explicitly define the term, which may support an argument that it should be given its plain and ordinary meaning of "approximately" or "about," allowing for significant deviation from the stated values.
• Evidence for a Narrower Interpretation: A party could argue that the term must be interpreted in light of the specific examples provided in the specification, such as those in Table 1, which show specific bandwidths and data rates for different channel configurations (’900 Patent, col. 5-6). This could suggest the term covers a range of values consistent with the disclosed embodiments but does not permit unbounded variation.

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). It notes that an unattached exhibit references these materials (Compl. ¶14).

Willful Infringement

Willfulness is alleged based on post-suit knowledge. The complaint asserts that its service "constitutes actual knowledge of infringement" and that Defendant's continued infringement thereafter is willful (Compl. ¶13-14).

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

• A core issue will be one of definitional scope: can the term "Orthogonal Frequency-Division Multiplexing carrier scheme," which is described in the patent primarily through specific "Mary-NBFSK" embodiments, be construed broadly enough to read on the modulation techniques used in the unidentified accused products?
• A key evidentiary question will be one of factual compliance: assuming the accused products are identified, will their measured performance characteristics—such as carrier separation, total bandwidth, and data rate—meet the specific numerical limitations recited in claim 1, particularly given the ambiguity inherent in the phrase "of the order of"?
• An initial procedural question will be the sufficiency of the pleadings: the complaint's reliance on unattached exhibits to identify the accused products and provide the basis for its infringement allegations may be subject to challenge under federal pleading standards.