DCT

5:25-cv-00091

Pantech Corp v. TCL Industries Holdings Co Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 5:25-cv-00091, E.D. Tex., 07/03/2025
  • Venue Allegations: Plaintiff alleges venue is proper because Defendants are not resident in the United States and may be sued in any judicial district. Additionally, Plaintiff alleges that TCL products have been sold in physical retail stores within the Eastern District of Texas.
  • Core Dispute: Plaintiff alleges that Defendant’s LTE, LTE-A, and 5G-capable mobile phones and tablets infringe four patents related to fundamental aspects of cellular communication technology, including channel mapping, uplink synchronization, and random access procedures.
  • Technical Context: The patents address core technical challenges in modern cellular networks (4G/LTE and 5G), focusing on ensuring reliable and efficient communication between mobile devices and base stations in crowded radio environments.
  • Key Procedural History: The complaint details a multi-year history of licensing negotiations, beginning with an initial outreach by Plaintiff’s predecessor, Goldpeak Innovations, Inc., on March 6, 2018. Plaintiff alleges that it and its predecessors provided TCL with notice of the asserted patent families, technical details, claim charts, and licensing proposals on multiple occasions between 2018 and 2025, but that TCL failed to engage in good faith negotiations. The complaint also asserts that the patents-in-suit are, or are essential to, the 3GPP cellular standards.

Case Timeline

Date Event
2008-01-01 U.S. Patent Nos. 11,051,344 and 12,267,876 Priority Date
2008-12-08 U.S. Patent No. 9,548,839 Priority Date
2010-02-10 U.S. Patent No. 11,659,503 Priority Date
2017-01-17 U.S. Patent No. 9,548,839 Issues
2018-03-06 Initial licensing outreach to TCL by Plaintiff's predecessor
2020-06-19 Pantech follows up with TCL, provides notice of patent families
2021-06-29 U.S. Patent No. 11,051,344 Issues
2022-02-15 Pantech provides specific notice of the '344 Patent to TCL
2023-05-23 U.S. Patent No. 11,659,503 Issues
2025-04-01 U.S. Patent No. 12,267,876 Issues
2025-07-03 Complaint Filed

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

U.S. Patent No. 9,548,839 - "Method for mapping physical hybrid automatic repeat request indicator channel"

The Invention Explained

  • Problem Addressed: In a cellular network, a mobile device (user equipment or "UE") needs to know if the data it sent to a base station (uplink transmission) was successfully received. The base station sends back a signal on a specific channel—the physical hybrid automatic repeat request indicator channel (PHICH)—to confirm receipt. The patent notes that efficiently mapping this PHICH onto the available radio resources is a key challenge, especially as resource availability can vary across different transmission symbols.
  • The Patented Solution: The invention provides a method for mapping the PHICH to resource element groups within an Orthogonal Frequency Division Multiplexing (OFDM) symbol, which is a fundamental unit of transmission in LTE. The specific location (index) for the mapping is determined based on a ratio calculated from the number of available resource element groups in different OFDM symbols (Compl. ¶50; ’839 Patent, Abstract). This method is designed to be efficient and avoid interference between neighboring cells by considering the actual resources available at any given moment (’839 Patent, col. 2:39-44).
  • Technical Importance: This dynamic mapping approach allows for more robust and efficient use of the radio spectrum for critical control signaling, which is essential for maintaining reliable data connections in a cellular network (Compl. ¶50).

Key Claims at a Glance

  • The complaint asserts claims 9-12 (Compl. ¶52). The lead independent claim appears to be claim 9, a method claim directed to a mobile station.
  • Essential elements of independent claim 9 include:
    • Decoding a PHICH mapped to at least one OFDM symbol.
    • Wherein each OFDM symbol comprises a plurality of resource element groups.
    • Wherein indexes of the resource element groups are determined according to a ratio (n'₂/n'₁) in an OFDM symbol.
    • Wherein n'₂ is the number of available resource element groups in one OFDM symbol and n'₁ is the number of available resource element groups in a different OFDM symbol of the sub-frame.
  • The complaint reserves the right to assert additional claims, including dependent claims (Compl. ¶52).

U.S. Patent No. 11,659,503 - "Apparatus and method for establishing uplink synchronization in a wireless communication system"

The Invention Explained

  • Problem Addressed: In modern cellular systems that use "carrier aggregation" (bundling multiple frequency bands together for higher speed), it is critical that all uplink transmissions from a mobile device arrive at the base station at the same time. Different frequency bands can have different signal propagation characteristics, making synchronization a complex technical problem (’503 Patent, col. 1:41-48).
  • The Patented Solution: The patent describes a system for managing uplink synchronization across multiple component carriers (CCs) by grouping them into "uplink timing groups." The mobile device receives control messages that define these groups. For each group, a "delegate CC" is used to perform the random access procedure and receive a "timing advance" (TA) value from the base station. This single TA value is then applied to all other secondary CCs within that same timing group, ensuring all carriers in the group are synchronized (Compl. ¶65; ’503 Patent, Abstract, col. 4:1-12). Figure 5 of the '503 Patent, attached as Exhibit 2, provides a process flow diagram illustrating this interaction, including the selection of a delegate CC (S534) and the subsequent updating of the TA for the group (S570) (Compl. ¶63).
  • Technical Importance: This method provides an efficient and scalable way to maintain uplink synchronization in complex, multi-carrier environments, which is a foundational requirement for LTE-Advanced and 5G networks (Compl. ¶65).

Key Claims at a Glance

  • The complaint asserts claims 5, 7, and 8 (Compl. ¶66). Claim 5 is an independent claim directed to a communication apparatus (e.g., a UE).
  • Essential elements of independent claim 5 include:
    • A processor configured to cause the apparatus to receive a Radio Resource Control (RRC) message through a primary Component Carrier (CC) belonging to a first uplink timing group, the message comprising information related to a second uplink timing group.
    • Transmit a random access preamble through one or more uplink CCs, each set as a delegate CC for a respective second uplink timing group.
    • Receive a random access response including a timing advance (TA) value.
    • Apply each TA value to the secondary CC for the respective second uplink timing group.
  • The complaint reserves the right to assert additional claims (Compl. ¶66).

Multi-Patent Capsule: U.S. Patent No. 11,051,344

  • Patent Identification: U.S. Patent No. 11,051,344, "Method for transmitting and receiving random access request and transmitting and receiving random access response," issued June 29, 2021.
  • Technology Synopsis: The patent addresses a potential ambiguity in the random access (RACH) procedure, where two different devices might transmit the same random access signal at nearly the same time. The invention solves this by having the base station’s response include timing information (e.g., the subframe number) indicating when the original request was transmitted, allowing the device to confirm the response is intended for it and not another device (’344 Patent, Abstract, col. 2:5-15). Figure 4 of the '344 Patent, attached as Exhibit 3, illustrates this process where a base station estimates and includes a subframe number in its response (S440), which the user equipment then uses for verification (S460) (Compl. ¶78).
  • Asserted Claims: At least claims 2 and 6 (Compl. ¶81).
  • Accused Features: LTE-compliant random access procedures, which allegedly require receiving a random access response within a specific time window determined by an offset, as mandated by 3GPP standards (Compl. ¶80, ¶82).

Multi-Patent Capsule: U.S. Patent No. 12,267,876

  • Patent Identification: U.S. Patent No. 12,267,876, "Method for Transmitting and Receiving Random Access Request and Transmitting and Receiving Random Access Response," issued April 1, 2025.
  • Technology Synopsis: This patent is from the same family as the ’344 Patent and addresses the same technical problem of resolving ambiguity in the random access procedure. The complaint states its written description contains the same teachings as the ’344 Patent (Compl. ¶94). The solution involves using timing information within the random access response to ensure a mobile device correctly identifies the response corresponding to its specific request.
  • Asserted Claims: At least claims 4-6 (Compl. ¶96).
  • Accused Features: LTE-compliant random access procedures mandated by 3GPP standards, as described for the ’344 Patent (Compl. ¶95, ¶97).

III. The Accused Instrumentality

Product Identification

The "Accused Instrumentalities" are identified as TCL's mobile phones and tablets that are compliant with LTE, LTE-A, and/or 5G cellular network standards (Compl. ¶19). The complaint provides a non-exhaustive list of over 40 specific models, including the TCL 50 XL NXTPAPER 5G, TCL 40 X 5G, TCL Stylus 5G, and various tablet models (Compl. ¶20).

Functionality and Market Context

  • The complaint alleges that the accused products incorporate chipsets (e.g., MediaTek Dimensity 6100+) and modems that implement the 3GPP standards for LTE and 5G (Compl. ¶53, ¶67). The infringing functionality is alleged to be the devices' standard-compliant operation, which purportedly requires practicing the methods claimed by the patents-in-suit (Compl. ¶51, ¶65, ¶80, ¶95).
  • The complaint alleges that TCL is a major participant in the U.S. market, ranking fourth in smartphone shipments and third in tablet shipments in 2023 (Compl. ¶5). The products are advertised and sold in the U.S. through TCL's website and retail stores such as Best Buy (Compl. ¶12, ¶16).

IV. Analysis of Infringement Allegations

'9,548,839 Infringement Allegations

Claim Element (from Independent Claim 9) Alleged Infringing Functionality Complaint Citation Patent Citation
A method for decoding a physical hybrid automatic repeat request indicator channel (PHICH) mapped to at least one orthogonal frequency division multiplexing (OFDM) symbol... The Accused Instrumentalities are LTE/5G compatible devices that necessarily process the PHICH on OFDM symbols to manage uplink data transmissions as required by 3GPP standards. ¶50, ¶53 col. 4:45-55
wherein each OFDM symbol comprises a plurality of resource element groups... The devices operate according to 3GPP TS 36.211, which defines that OFDM symbols comprise a plurality of resource element groups. ¶51 col. 4:56-58
wherein indexes of the resource element groups in which the PHICH is repeatedly transmitted three times are determined according to a ratio n'₂/n'₁... The devices determine resource element group indexes according to the LTE standard, which mandates the use of a ratio involving the number of available resource groups in different OFDM symbols. ¶50, ¶51 col. 6:45-67
wherein n'₂ is the number of available resource element groups in an OFDM symbol, having index 1'₁, ... and n'₁ is the number of available resource element groups in an OFDM symbol, having index 1, of the sub-frame... The Accused Instrumentalities' standards-compliant chipsets perform this ratio calculation to correctly map and decode the PHICH. ¶51, ¶53 col. 6:50-65
  • Identified Points of Contention:
    • Scope Questions: A central question may be whether compliance with the cited 3GPP standards (e.g., TS 36.211) necessarily results in a device that performs every step of the asserted claims. The defense may argue that the standard allows for non-infringing alternatives or that the claim scope is narrower than the standard's requirements.
    • Technical Questions: The complaint alleges infringement based on standards compliance. A key evidentiary question will be whether the accused products, as implemented with their specific chipsets, actually perform the determination of indexes "according to a ratio" in the precise manner claimed, or if they use a different or simplified method permitted by the standard.

'11,659,503 Infringement Allegations

Claim Element (from Independent Claim 5) Alleged Infringing Functionality Complaint Citation Patent Citation
A communication apparatus, comprising: a processor configured to cause the apparatus to: receive, through a primary Component Carrier (CC) belonging to a first uplink timing group, a Radio Resource Control (RRC) message comprising information related to a second uplink timing group... The Accused Instrumentalities are LTE-A/5G compatible devices that support carrier aggregation and receive RRC messages to configure multiple CCs into distinct timing groups as mandated by the standard. ¶65, ¶67 col. 8:16-30
transmit a random access preamble through one or more uplink CCs, each of the one or more uplink CCs being set as a delegate CC for a respective second uplink timing group... The devices are configured to transmit a random access preamble on a designated "delegate CC" for a given timing group to establish synchronization for that group. ¶65, ¶67 col. 9:8-14
receive a random access response including a timing advance (TA) value... After transmitting the preamble, the devices receive a random access response from the base station containing a TA value, which is critical for synchronization. ¶65 col. 9:15-20
apply each TA value to the secondary CC for the respective second uplink timing group. The processor in the accused devices applies the single TA value received via the delegate CC to all other secondary CCs within the same timing group to achieve synchronization across all carriers in the group. ¶65 col. 9:21-24
  • Identified Points of Contention:
    • Scope Questions: A potential dispute may arise over the definition of "uplink timing group" and "delegate CC." The analysis will question whether the groupings and delegations performed by the accused products under the 3GPP standard align with the specific definitions and functional requirements outlined in the patent's claims and specification.
    • Technical Questions: What evidence does the complaint provide that the accused devices actually "apply each TA value to the secondary CC" for an entire timing group based on a single random access procedure via one delegate CC? The defense may explore whether the products' real-world operation involves more complex or individualized TA adjustments that fall outside the claim scope.

V. Key Claim Terms for Construction

For the ’839 Patent

  • The Term: "indexes of the resource element groups... are determined according to a ratio"
  • Context and Importance: This phrase is the core of the inventive method. The infringement case depends on whether the accused devices, by complying with the LTE standard, perform a determination that falls within the scope of this "according to a ratio" language. Practitioners may focus on whether this requires a specific calculation or merely a result that is consistent with one.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language "according to a ratio" may suggest that any method that produces an index value mathematically dependent on the ratio of available resource groups could infringe, even if not calculated using the exact formula in the embodiments.
    • Evidence for a Narrower Interpretation: The specification provides a specific equation for determining the index nᵢ (e.g., ’839 Patent, col. 6:45-67). A defendant may argue that "according to a ratio" is limited to implementations that use this, or a very similar, explicit calculation.

For the ’503 Patent

  • The Term: "uplink timing group"
  • Context and Importance: The entire claim revolves around managing synchronization for these groups. The scope of this term will define how many and what kind of CCs are covered by a single TA value adjustment. A broad definition could cover more operational modes of the accused devices, while a narrow one could limit the scope of infringement.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification suggests groups can be formed based on a variety of characteristics, such as CCs having a difference in center frequency values within a threshold (’503 Patent, col. 11:5-9). This could support a broad, flexible definition of what constitutes a group.
    • Evidence for a Narrower Interpretation: The specific examples provided, such as grouping based on beamforming schemes or service in a macrocell vs. femtocell, could be argued to limit the term to CCs that share a very specific and predefined set of technical characteristics, rather than just any ad-hoc collection of carriers (’503 Patent, col. 10:45-62).

VI. Other Allegations

  • Indirect Infringement: The complaint alleges inducement by advertising the Accused Instrumentalities as compliant with LTE, LTE-A, and 5G standards, and by providing instruction materials and services, which allegedly encourages and facilitates infringement by end-users (Compl. ¶57-58, ¶72-73). Contributory infringement is alleged on the basis that the devices are material components specifically adapted for infringing use and are not staple articles of commerce suitable for substantial non-infringing use (Compl. ¶60, ¶75).
  • Willful Infringement: Willfulness is alleged based on pre-suit knowledge. The complaint asserts that TCL was made aware of the patent families and their infringement via correspondence beginning on June 19, 2020 (Compl. ¶54, ¶69). For patents that issued after this date ('503, '344, '876), willfulness is alleged from their date of issuance, based on TCL's prior knowledge of the parent applications and related family members (Compl. ¶70, ¶84, ¶99).

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

  • A central issue will be one of standards essentiality and claim scope: does compliance with the relevant 3GPP standards, as alleged by the Plaintiff, necessarily require practicing the specific methods recited in the asserted independent claims, or do the standards permit non-infringing design choices that TCL may have implemented?
  • A key evidentiary question will be one of technical implementation: beyond mere standards compliance, what is the specific operational logic of the accused chipsets? The case will likely require a deep technical analysis to determine if the products' actual methods for PHICH mapping ('839 Patent), carrier synchronization ('503 Patent), and random access response handling ('344 and '876 Patents) align with the functional steps required by the claims.
  • A further question relates to damages and pre-suit knowledge: given the long history of licensing discussions alleged in the complaint, the timing and content of each notice will be scrutinized to establish the period for which willful infringement could apply and to frame the basis for a reasonable royalty.