Wifidelity LLC v. Ubisense Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: WiFidelity LLC (New Mexico)
  • Defendant: Ubisense Limited (United Kingdom)
  • Plaintiff’s Counsel: Rabicoff Law LLC
• Case Identification: 2:25-cv-1141, E.D. Tex., 11/19/2025
• Venue Allegations: Plaintiff alleges venue is proper because the Defendant is a foreign corporation and has committed acts of patent infringement in the district.
• Core Dispute: Plaintiff alleges that Defendant infringes a patent related to systems and methods for gathering information about and locating discrete wireless terminals within a defined three-dimensional space.
• Technical Context: The technology concerns passive, real-time location systems that use an array of receivers to determine the precise position of standard wireless devices by analyzing signal time-of-arrival data.
• Key Procedural History: The patent-in-suit claims priority back to an application filed in 2009. The complaint does not reference any prior litigation, inter partes review proceedings, or licensing history involving the patent.

Case Timeline

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

U.S. Patent No. 9,002,376 - Systems and methods for gathering information about discrete wireless terminals

• Patent Identification: U.S. Patent No. 9,002,376, "Systems and methods for gathering information about discrete wireless terminals," issued April 7, 2015 (the "’376 Patent"). (Compl. ¶¶8, 9).

The Invention Explained

• Problem Addressed: The patent’s background section describes the limitations of prior art radio location techniques, such as radio direction finding ("RDF"). These methods are noted to be imprecise, susceptible to multipath signal reflection errors, and unable to define clear boundaries for the monitored area, particularly in three dimensions. (’376 Patent, col. 1:24-60). The patent also notes that active "jamming" to control wireless devices in a given area is often illegal and can block critical communications for emergency personnel. (’376 Patent, col. 2:42-60).
• The Patented Solution: The invention proposes a system that uses an array of four or more synchronized receivers to passively intercept administrative signals from wireless terminals (e.g., cell phones) within a "defined local space" ("DLS"). (’376 Patent, Abstract). A processor then calculates the relative time of arrival ("RTOA") of a signal at the different receivers to determine the precise three-dimensional coordinates of the terminal. (’376 Patent, col. 6:31-54; Fig. 2a). This allows for the tracking and monitoring of devices within specifically defined volumes without requiring special hardware on the terminals themselves.
• Technical Importance: The described method purports to offer a precise and passive way to locate and track unmodified wireless devices in three dimensions, overcoming the imprecision of older methods and providing a legal alternative to signal jamming for managing device use in sensitive locations like theaters or secure facilities. (’376 Patent, col. 3:1-15).

Key Claims at a Glance

• The complaint alleges infringement of "one or more claims" and references "exemplary claims" in an exhibit not provided with the complaint. (Compl. ¶11). Claim 1 is the first independent method claim.
• Independent Claim 1 includes the following essential elements:
  • Determining positioning of a plurality of receivers capturing a wireless signal.
  • Determining a plurality of "defined local spaces (DLSs)," with each DLS defining a volume among four of the receivers.
  • Determining a plurality of points within each DLS and relating each point to the receiver positions.
  • Determining theoretical "travel times" for a signal to go from each point to each of the four corresponding receivers.
  • Determining a plurality of measured "arrival times" for the actual wireless signal at the receivers.
  • Determining the terminal is positioned within the DLS that contains the point whose theoretical travel times are "most closely correlated" with the measured arrival times. (’376 Patent, col. 13:21 - col. 14:1).

III. The Accused Instrumentality

Product Identification

The complaint does not identify the accused products or services by name in the body of the complaint, instead referring to "Exemplary Defendant Products" detailed in an "Exhibit 2" that was not publicly filed with the complaint. (Compl. ¶¶11, 16). The complaint therefore does not provide sufficient detail for analysis of the accused instrumentality's specific functionality or market context.

IV. Analysis of Infringement Allegations

No probative visual evidence provided in complaint.

The complaint alleges direct and induced infringement but relies entirely on claim charts in an unfiled "Exhibit 2" to substantiate these claims. (Compl. ¶¶14, 17). The narrative allegations are conclusory, stating that the accused products "practice the technology claimed by the '376 Patent" and "satisfy all elements of the Exemplary '376 Patent Claims." (Compl. ¶16). Without the referenced claim charts, a detailed analysis of the infringement theory is not possible.

• Identified Points of Contention: Based on the language of Claim 1 of the ’376 Patent, the infringement analysis may raise several technical and legal questions once the accused product's functionality is known:
  • Scope Questions: Claim 1 requires "determining a plurality of defined local spaces (DLSs)." A potential question is whether the accused system defines and utilizes multiple, discrete, four-receiver volumes as required by the claim, or if it operates within a single, undifferentiated monitored space. The construction of "DLS" will be critical to this inquiry.
  • Technical Questions: The claim recites a specific method for locating a terminal: determining that it is within a DLS associated with a point whose theoretical "travel times" are "most closely correlated with the first arrival times." A central question will be whether the accused system's location algorithm actually performs this specific correlation of theoretical data against measured data, or if it employs a different computational method (e.g., direct trilateration, signal fingerprinting) that does not map onto the claimed steps.

V. Key Claim Terms for Construction

• The Term: "defined local spaces (DLSs)"

  • Context and Importance: This term appears in nearly every independent claim and is foundational to the patent's architecture. The outcome of the case may hinge on whether the accused system's monitored areas constitute "DLSs" as claimed, which require a "volume among four receivers." (’376 Patent, col. 13:26-28).
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification illustrates DLSs in highly varied applications, including shopping mall corridors (Fig. 7), airport glide paths (Fig. 16), and sections of a roadway (Fig. 17), which may suggest the term is meant to be applied flexibly to different environments and shapes.
    • Evidence for a Narrower Interpretation: The patent repeatedly describes a DLS as a geometric volume defined by the physical position of four receivers, specifically a "single tetrahedron determined by the position of 4 receivers." (’376 Patent, col. 10:63-66). Claim 1 explicitly requires "each DLS defining a volume among four receivers," which could be interpreted to limit the term to such four-point geometric constructs. (’376 Patent, col. 13:26-28).

• The Term: "point having travel times most closely correlated with the first arrival times"

  • Context and Importance: This phrase describes the core computational step for determining the terminal's location. Practitioners may focus on this term because the infringement analysis will depend on whether the accused system's algorithm performs this specific type of correlation or uses a fundamentally different calculation.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent does not provide a specific mathematical formula for "correlation," which may support an argument that the term should be given its plain and ordinary meaning, covering any algorithm that finds the best match between theoretical and measured timing data.
    • Evidence for a Narrower Interpretation: The specification consistently frames the process as a comparison between two distinct sets of data: measured "arrival times" and pre-determined "travel times" associated with points in space. (’376 Patent, col. 11:15-34). This could support an interpretation that requires a direct comparison or look-up process, potentially excluding other mathematical location-solving techniques that do not rely on a pre-defined set of points and associated "travel times."

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement, asserting that Defendant provides "product literature and website materials" that instruct customers to use the accused products in an infringing manner. (Compl. ¶14).
• Willful Infringement: The complaint does not use the term "willful." It pleads "Actual Knowledge of Infringement," but bases this allegation solely on the act of serving the complaint and its associated (unfiled) claim charts. (Compl. ¶13). This allegation appears directed at potential post-filing conduct.

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

Based on the complaint and the patent, the dispute appears poised to center on the following key questions:

1. A core issue will be one of technical operation and evidence: What is the precise algorithm used by the accused system to calculate a device's location? Does it, as the patent claims, function by comparing measured signal arrival times against a model of theoretical travel times from discrete points within a defined space, or does it rely on an alternative computational method?

2. A second central issue will be one of definitional scope: Can the claim term "defined local spaces (DLSs)," which is described in the patent as a tetrahedral volume formed by four receivers, be construed to cover the architecture and monitored areas of the accused system? The resolution of this claim construction dispute may be dispositive of infringement.