DCT
2:21-cv-00242
KMizra LLC v. T-Mobile
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: K.Mizra LLC (Delaware)
- Defendant: T-Mobile US, Inc., T-Mobile USA, Inc., and Sprint Corp. (Delaware)
- Plaintiff’s Counsel: Folio Law Group PLLC
- Case Identification: 2:21-cv-00242, E.D. Tex., 06/30/2021
- Venue Allegations: Plaintiff alleges venue is proper in the Eastern District of Texas because Defendant T-Mobile maintains multiple regular and established places of business in the district, including retail stores and research facilities, and has committed acts of infringement there.
- Core Dispute: Plaintiff alleges that Defendant’s mobile location services infrastructure, used in its 4G LTE and 5G networks, infringes a patent related to using information from both macro and femto base stations to improve mobile device location accuracy.
- Technical Context: The technology addresses the challenge of accurately locating mobile devices in environments where GPS signals are weak, such as indoors, by combining signals from different types of cellular base stations.
- Key Procedural History: An inter partes review (IPR) was filed against the patent-in-suit after the complaint was filed. In that proceeding (IPR2022-00730), the Patent Trial and Appeal Board confirmed the patentability of all asserted claims in this case, including independent claim 30. This finding may strengthen the patent's presumption of validity and focus the litigation primarily on questions of infringement.
Case Timeline
| Date | Event |
|---|---|
| 2012-12-11 | ’819 Patent Priority Date |
| 2015-02-17 | ’819 Patent Issue Date |
| 2021-06-30 | Complaint Filing Date |
| 2022-03-23 | IPR Filed Against ’819 Patent |
| 2024-04-09 | IPR Certificate Issued Confirming Patentability of Asserted Claims |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,958,819 - Femto-Assisted Location Estimation in Macro-Femto Heterogeneous Networks
- Patent Identification: U.S. Patent No. 8,958,819, Femto-Assisted Location Estimation in Macro-Femto Heterogeneous Networks, issued February 17, 2015.
The Invention Explained
- Problem Addressed: The patent addresses the failure of Global Positioning System (GPS) technology to provide accurate location estimates for mobile devices in non-line-of-sight (NLOS) conditions, such as inside buildings or in urban areas with tall structures (Compl. ¶24; ’819 Patent, col. 1:30-40).
- The Patented Solution: The invention proposes a "femto-assisted location estimation" (FALE) method that improves location accuracy by using data from both large, powerful macro base stations (mBS) and small, low-power femto base stations (fBS) often deployed indoors (’819 Patent, col. 5:3-6). The method uses a particle filtering technique—a statistical method for estimation—to process the various data inputs and account for uncertainties, such as the imprecise location of a consumer-deployed femto base station, to generate a more accurate position for the mobile device (’819 Patent, col. 9:49-65).
- Technical Importance: By leveraging femto base stations, which are closer to the user and suffer from less signal attenuation, the invention claims to achieve improved accuracy compared to older 2G/3G cellular networks or systems relying only on macro base stations, thereby enabling better performance for applications like indoor location-based services (LBS) (Compl. ¶26; ’819 Patent, col. 5:22-33).
Key Claims at a Glance
- The complaint asserts infringement of at least independent claim 30 (Compl. ¶33).
- Independent Claim 30 (Method):
- receiving femto base station timing information related to a user equipment;
- receiving macro base station timing information related to the user equipment;
- receiving particle information for a first set of particles corresponding to possible user equipment locations;
- receiving femto base station position information; and
- determining user equipment location information based on a first particle filtering for particle filtering the first set of particles based on the base station information.
- The complaint does not explicitly reserve the right to assert dependent claims.
III. The Accused Instrumentality
Product Identification
- The T-Mobile LTE and 5G Networks, and more specifically, the "mobile location services infrastructure" within those networks (Compl. ¶31). This infrastructure is alleged to include location server equipment and software such as T-Mobile's Enhanced Serving Mobile Location Center (“E-SMLC”), Serving Mobile Location Centers (“SMLC”), Secure User Plane Location Platform (“SLP”), and Location Management Function (“LMF”) (Compl. ¶32).
Functionality and Market Context
- The accused infrastructure is alleged to pinpoint a mobile user's location to provide various location-based services, including E911, proximity-based marketing, and consumer applications like the T-Mobile FamilyWhere® service (Compl. ¶¶31, 35). The complaint alleges these location servers operate in accordance with industry standards from the 3rd Generation Partnership Project (3GPP) and the Open Mobile Alliance (OMA), and that they communicate with both macro and femto base stations (femtocells) in the T-Mobile network to determine a device’s location (Compl. ¶¶33, 37). The complaint references an ASN.1 data structure from a 3GPP standard to illustrate the types of location data exchanged. This visual presents an ASN.1 data structure definition for a "ProvideLocationInformation" message, which enumerates various optional location-related information elements (Compl. p. 11).
IV. Analysis of Infringement Allegations
’819 Patent Infringement Allegations
| Claim Element (from Independent Claim 30) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| receiving femto base station timing information related to a user equipment; | T-Mobile's location servers (e.g., E-SMLCs) communicate with and receive timing information from femtocells deployed in its network. | ¶37 | col. 26:56-59 |
| receiving macro base station timing information related to the user equipment; | T-Mobile's E-SMLCs communicate with and receive timing information from reachable macro base stations. | ¶38 | col. 26:50-55 |
| receiving particle information for a first set of particles corresponding to possible user equipment locations; | T-Mobile's location servers receive "possible locations" for a mobile device, for example, within the ProvideLocationInformation message defined by 3GPP standards. |
¶39 | col. 2:7-10 |
| receiving femto base station position information; | T-Mobile's location servers receive femtocell position information either directly from the femtocell (which may have a GPS receiver) or from a T-Mobile database of known base station positions. | ¶¶40-41 | col. 26:62-65 |
| determining user equipment location information based on a first particle filtering for particle filtering the first set of particles based on the base station information. | T-Mobile's location server is alleged to determine a mobile device's location by filtering a "spread of estimates" (particles) that are continuously accumulated over time, based on the base station information received. | ¶42 | col. 9:49-54 |
- Identified Points of Contention:
- Technical Question: The complaint alleges that T-Mobile's system performs "particle filtering" by accumulating and filtering a "spread of estimates" (Compl. ¶42). A central question will be whether T-Mobile's accused "mobile positioning algorithms" (Compl. ¶33) actually implement the specific steps of a particle filter as taught in the patent—which include importance sampling, weighting, and resampling (’819 Patent, col. 10:5-11:15)—or if they use a different type of statistical estimation that Plaintiff has characterized as particle filtering.
- Scope Question: Does the receipt of "possible locations" within a standardized "ProvideLocationInformation" message (Compl. ¶39) constitute "particle information for a first set of particles" as that term is used in the context of the claimed particle filtering method? The analysis may hinge on whether this standard data transfer meets the specific functional requirements of providing inputs to a particle filter algorithm.
V. Key Claim Terms for Construction
Term: "particle filtering"
- Context and Importance: This term describes the core computational process of the claimed invention. The outcome of the case may depend on whether T-Mobile’s method of calculating a user's location is found to be a "particle filtering" method. Practitioners may focus on this term because the patent provides a detailed, multi-step technical definition, whereas the complaint's allegations are more general.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent abstract describes the invention more generally as using "Bayesian estimation based on TDOA and utilization of a particle filter" without limiting it to one specific type of filter (’819 Patent, Abstract). This could support an argument that the term covers a class of similar statistical methods.
- Evidence for a Narrower Interpretation: The detailed description explains a specific algorithm, a Sampling Importance Resampling (SIR) particle filter, complete with equations for state updates, weight calculations, and resampling to "avoid degeneracy" (’819 Patent, col. 10:5-11:15). This detailed embodiment may be used to argue that "particle filtering" requires these specific sub-steps.
Term: "particle information"
- Context and Importance: This term defines a key input to the "particle filtering" step. The dispute may turn on what type of data qualifies as "particle information."
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent states that the system receives "particle information for a first set of particles corresponding to possible user equipment locations" (’819 Patent, col. 2:7-10). This language could support an interpretation that any set of data representing multiple possible locations qualifies.
- Evidence for a Narrower Interpretation: The patent describes particles in a specific context: as a "sample-based or particle-based representation of a posterior probability distribution function" within a filter designed to "approximate a posterior PDF for UE position" (’819 Patent, col. 4:30-34, col. 9:49-54). This suggests "particle information" is not just any set of possible locations, but a set specifically structured for use in a recursive Bayesian estimation process.
VI. Other Allegations
- Willful Infringement: The complaint alleges that T-Mobile has had notice of its infringement "at least as of the service of this complaint" and that its continued infringement is therefore willful (Compl. ¶45). The prayer for relief requests that the court adjudge the infringement to be willful (Compl. Prayer for Relief ¶D).
VII. Analyst’s Conclusion: Key Questions for the Case
Given that the asserted claim has survived an inter partes review, suggesting its validity is robust, the case will likely center on infringement. The key questions will be:
A core issue will be one of technical equivalence: Does T-Mobile’s proprietary method for calculating device locations, which is alleged to operate according to 3GPP standards, perform the specific computational steps of "particle filtering" as described in the ’819 patent’s detailed embodiment, or does it utilize a fundamentally different statistical algorithm?
A second issue will be one of evidentiary proof: Beyond referencing industry standards, what specific evidence will show that T-Mobile’s infrastructure actually implements each step of the claimed method, particularly the generation and processing of what the patent defines as "particle information" as an input for a "particle filtering" algorithm?