KMizra LLC v. AT&T Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: KMizra LLC (Delaware)
  • Defendant: T-Mobile US, Inc., et al. (Delaware, Washington, Kansas); Ericsson Inc. (Intervenor-Defendant, Delaware)
  • Plaintiff’s Counsel: Folio Law Group PLLC
• Case Identification: 2:21-cv-00241, E.D. Tex., 03/09/2022
• Venue Allegations: Plaintiff alleges venue is proper in the Eastern District of Texas because T-Mobile operates wireless networks, retail stores, and R&D facilities within the district, and has previously admitted to or not contested venue in the district. Venue over Ericsson is based on its U.S. headquarters being located in Plano, Texas, within the district.
• Core Dispute: Plaintiff alleges that Defendants' 4G LTE and 5G cellular networks, specifically the location server infrastructure supplied by Ericsson and operated by T-Mobile, infringe a patent related to improving mobile device location accuracy by combining data from both large macro cell towers and smaller femto base stations.
• Technical Context: The technology addresses the challenge of accurately locating mobile devices in environments where GPS is unreliable, such as indoors, by leveraging a heterogeneous network architecture to enhance location-based services like E911.
• Key Procedural History: The complaint notes that Ericsson was granted a motion to intervene as a defendant. Subsequent to the filing of this complaint, an Inter Partes Review (IPR) was instituted against the patent-in-suit. The IPR concluded with a certificate issued on April 9, 2024, confirming the patentability of claims 22, 23, 30, 32, and 33. As the complaint asserts infringement of at least claim 30, this outcome strengthens the patent’s presumption of validity against future challenges on the grounds considered in the IPR.

Case Timeline

Date	Event
2012-12-11	U.S. Patent No. 8,958,819 Priority Date
2015-02-17	U.S. Patent No. 8,958,819 Issue Date
2021-09-01	Alleged pre-suit notice date for Ericsson
2022-03-09	First Amended Complaint Filing Date
2022-03-23	IPR2022-00730 Filed against U.S. Patent No. 8,958,819
2024-04-09	IPR Certificate Issued, confirming patentability of Claim 30

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 inability of Global Positioning System (GPS) technology to provide accurate location estimates for mobile devices in non-line-of-sight (NLOS) environments, such as inside buildings or in areas with heavy obstruction from tall structures (Compl. ¶28; ’819 Patent, col. 1:30-36).
• The Patented Solution: The invention proposes a method to improve location accuracy by using data from both large-scale macro base stations (mBS) and small, short-range femto base stations (fBS) in a "heterogeneous network." The system applies a particle filtering technique to combine timing and position information from both sources, even when the exact position of the femto base station is uncertain, to calculate a more precise location for the user equipment (Compl. ¶30, ¶32; ’819 Patent, col. 5:3-15). The particle filter represents a user's possible locations as a collection of weighted data points, or "particles," which are recursively refined.
• Technical Importance: This method was designed to improve the reliability of crucial location-based services (LBS), including Enhanced 911 (E911), by leveraging the growing deployment of femtocells to enhance indoor network coverage in advanced cellular systems like LTE-A (Compl. ¶28; ’819 Patent, col. 1:19-27).

Key Claims at a Glance

• The complaint asserts infringement of at least independent method claim 30 (Compl. ¶37).
• Essential elements of Claim 30 include:
  • 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 also notes that Ericsson knows its activities induce infringement of at least claim 1, but focuses its infringement analysis on claim 30 (Compl. ¶69).

III. The Accused Instrumentality

Product Identification

• The accused instrumentalities are T-Mobile's 4G LTE and 5G wireless telecommunications networks, specifically the infrastructure and methods used for mobile location services (Compl. ¶35). This includes location server equipment and software such as the Enhanced Serving Mobile Location Center (E-SMLC), Serving Mobile Location Center (SMLC), Secure User Plane Location Platform (SLP), and Location Management Function (LMF), which are allegedly deployed, operated, and maintained by Ericsson for T-Mobile (Compl. ¶36, ¶52-53).

Functionality and Market Context

• The accused functionality is the system that pinpoints a mobile user's location for services such as E911, location-based mobile applications, and roadside assistance (Compl. ¶35, ¶52). The complaint alleges this functionality is instrumental to T-Mobile's services and operates in accordance with 3rd Generation Partnership Project (3GPP) and Open Mobile Alliance (OMA) industry standards, which plaintiff contends implement the patented method (Compl. ¶37).

IV. Analysis of Infringement Allegations

The complaint alleges that T-Mobile’s and Ericsson's location services infrastructure and methods meet every limitation of at least claim 30 of the ’819 Patent. The complaint provides an ASN.1 code block snippet from a 3GPP technical specification to illustrate the "ProvideLocationInformation" message, which it alleges constitutes the claimed "particle information" (Compl. ¶43). This visual shows a data structure for communicating various types of location data, including A-GNSS, OTDOA, and ECID measurements (Compl. ¶43, p. 12).

’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-SMLCs) communicate with and receive timing information from femtocells (e.g., Nokia SS2FII, Alcatel Lucent 9961) operating on its network (Compl. ¶41).	¶41	col. 2:15-20
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 (eNodeBs) (Compl. ¶42).	¶42	col. 2:15-20
receiving particle information for a first set of particles corresponding to possible user equipment locations;	T-Mobile's location servers receive a "ProvideLocationInformation" message from the mobile device, which the complaint alleges contains "particle information for a set of particles corresponding to possible locations" (Compl. ¶43).	¶43	col. 2:7-10
receiving femto base station position information;	T-Mobile's location servers receive femtocell position information either from a database or directly from the femtocells, which may be equipped with GPS receivers (Compl. ¶44-45).	¶44, ¶45	col. 6:23-32
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 "determines a mobile device's location based on a first particle filtering of the first set of particles" by filtering the continuously accumulated location samples ("particles") over time (Compl. ¶46).	¶46	col. 2:11-14

• Identified Points of Contention:
  • Scope Questions: The core of the dispute may center on whether the term "particle information", as used in the patent, can be properly construed to cover the standardized "ProvideLocationInformation" message structure. A key question is whether a standard data message conveying location measurements is equivalent to the patent's more specific concept of "particles" as weighted samples in a recursive filtering process.
  • Technical Questions: The complaint alleges that the accused location servers perform "particle filtering" but does not provide specific evidence of how this filtering is implemented. A central question for the court will be whether the defendants' method of processing location data constitutes the specific "particle filtering" technique described in the patent (e.g., involving importance sampling, weight updates, and resampling as detailed in col. 9-11), or if it is a more generic form of statistical filtering that falls outside the claim's scope.

V. Key Claim Terms for Construction

• The Term: "particle information"

• Context and Importance: This term's construction is critical. The plaintiff's infringement theory for element [C] of claim 30 depends on equating this term with a standard 3GPP message format. Practitioners may focus on this term because if it is construed narrowly to mean only weighted data points within a specific Bayesian filtering algorithm, the infringement case may be significantly weakened.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The claim language "particle information for a first set of particles corresponding to possible user equipment locations" is not explicitly defined with a specific data structure (Compl. ¶38; ’819 Patent, col. 34:47-50). A party could argue it broadly covers any set of data points representing possible locations.
  • Evidence for a Narrower Interpretation: The specification's detailed description consistently frames "particles" within the context of a specific computational method: "a particle filter can be introduced in the FALE scheme to approximate a posterior PDF for UE position by associating weights with a set of particles" (’819 Patent, col. 10:50-54). The patent's figures and discussion of importance sampling and resampling further suggest a specific technical meaning tied to Bayesian estimation techniques (’819 Patent, Fig. 5; col. 10:14-41).

• The Term: "particle filtering"

• Context and Importance: This is the central action of the claimed method. Whether the accused system's processing qualifies as "particle filtering" will likely be a primary point of dispute. Practitioners may focus on whether the accused system's alleged "filtering" meets the functional requirements described in the patent's specification.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The claim recites "determining user equipment location information based on a first particle filtering for particle filtering the first set of particles" without detailing the steps of the filtering process itself (’819 Patent, col. 34:51-54). This could support an argument that any process that filters a set of location "particles" is covered.
  • Evidence for a Narrower Interpretation: The specification provides a detailed, multi-step explanation of a "Sampling Importance Resampling (SIR) particle filter," including a state update, a measurement update, weight calculation, and resampling steps (’819 Patent, col. 10:5-11:15; Fig. 5). A party would likely argue that the term "particle filtering" is implicitly limited to this disclosed algorithm or a structurally equivalent one.

VI. Other Allegations

• Indirect Infringement: The complaint alleges that Ericsson induces infringement by supplying T-Mobile with the necessary location server hardware and software and providing instructions on their use for location determination (Compl. ¶67-68). It further alleges contributory infringement, claiming the provided products are especially adapted for this purpose and lack substantial non-infringing uses (Compl. ¶70).
• Willful Infringement: Willfulness is alleged against T-Mobile from the date of the complaint's filing (Compl. ¶49; Prayer ¶D). Against Ericsson, willfulness is alleged based on pre-suit knowledge dating to at least September 2021, when its counsel allegedly communicated its intent to intervene in the lawsuit (Compl. ¶66, ¶71).

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

• A core issue will be one of definitional scope: can the term "particle information," which is rooted in the patent's specific disclosure of Bayesian estimation techniques, be construed broadly enough to read on the standardized "ProvideLocationInformation" message format used in the accused 4G/5G networks?
• A key evidentiary question will be one of technical operation: does the plaintiff possess evidence to demonstrate that the accused T-Mobile and Ericsson location servers perform the specific, multi-step "particle filtering" algorithm described in the ’819 Patent's specification, or do they employ a more generic statistical processing method that falls outside the patent's claimed scope?
• A central strategic question will be the impact of the IPR proceeding: how will the post-complaint confirmation of claim 30's patentability by the USPTO influence settlement negotiations and litigation strategy, given that it significantly strengthens the patent's presumption of validity against certain invalidity defenses?