DCT

2:23-cv-08949

GenghisComm Holdings LLC v. TCL Communication Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:23-cv-08949, C.D. Cal., 10/24/2023
  • Venue Allegations: Plaintiff alleges venue is proper in the Central District of California because Defendant is a California corporation with a regular and established place of business in Irvine, California.
  • Core Dispute: Plaintiff alleges that Defendant’s 4G LTE and 5G-capable mobile devices, tablets, and hotspots infringe eight U.S. patents related to wireless communication signal processing techniques, such as precoding in Orthogonal Frequency-Division Multiplexing (OFDM) and Single-Carrier Frequency-Division Multiple Access (SC-FDMA) systems.
  • Technical Context: The technology concerns fundamental signal processing methods used in modern cellular standards like 4G LTE and 5G to manage signal power and interference, which is critical for efficient and reliable high-speed data transmission in mobile devices.
  • Key Procedural History: The complaint alleges pre-suit knowledge based on a letter sent to TCL on November 11, 2020, identifying the ’842, ’227, and ’568 patents and providing claim charts. A subsequent letter on June 29, 2022, identified the ’786 and ’508 patents. Plaintiff alleges that despite this notice and a response from TCL indicating a willingness to negotiate a license, TCL continued its accused activities, forming the basis for a willfulness allegation.

Case Timeline

Date Event
2002-05-14 Earliest Priority Date for ’842, ’227, ’568 Patents
2004-08-02 Earliest Priority Date for ’786, ’508, ’005, ’285 Patents
2007-01-08 Earliest Priority Date for ’792 Patent
2017-09-19 ’842 Patent Issued
2017-09-19 ’508 Patent Issued
2019-02-05 ’227 Patent Issued
2019-08-20 ’568 Patent Issued
2020-11-11 Plaintiff's counsel sent letter to TCL identifying ’842, ’227, and ’568 Patents
2021-07-27 ’786 Patent Issued
2022-02-15 ’005 Patent Issued
2022-04-19 TCL responded to Plaintiff indicating willingness to negotiate a license
2022-06-29 Plaintiff's counsel sent letter to TCL identifying ’786 and ’508 Patents
2022-07-05 ’285 Patent Issued
2022-08-23 ’792 Patent Issued
2023-10-24 Complaint Filed

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

U.S. Patent No. 9,768,842 - "Pre-coding in multi-user MIMO"

The Invention Explained

  • Problem Addressed: The patent family addresses the technical challenge of high peak-to-average power ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) communication systems, which can lead to inefficient power amplifier usage and reduced battery life in mobile devices (’227 Patent, col. 9:9-11). It also addresses the broader problem of inter-cell interference limiting system capacity in wireless networks (’227 Patent, col. 2:24-25).
  • The Patented Solution: The invention describes an OFDM transmitter that uses a pre-coder, specifically a Discrete Fourier Transform (DFT) spreader, to spread data symbols with Fourier coefficients before modulation (’842 Patent, Claim 1). This DFT-spreading process generates a signal with a reduced PAPR, which is a key characteristic of the Single-Carrier Frequency-Division Multiple Access (SC-FDMA) transmission scheme used in 4G LTE uplinks (’227 Patent, Fig. 30A; col. 29:21-34).
  • Technical Importance: This technique allows mobile devices to gain the multipath resilience benefits of a multi-carrier system like OFDM while maintaining the low PAPR properties of a single-carrier system, enabling the use of more power-efficient and cost-effective amplifiers (Compl. ¶17).

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 2-4 and 7-9 (Compl. ¶¶32, 45, 56, 64, 73, 81, 89).
  • Independent Claim 1 requires:
    • An OFDM transmitter, comprising:
    • an OFDM spreader configured to spread a plurality of data symbols with Fourier coefficients to generate a discrete Fourier Transform (DFT)-spread data signal;
    • a mapper configured to map the DFT-spread data signal to a plurality of OFDM subcarriers; and
    • an OFDM modulator configured to modulate the DFT-spread data signal onto the plurality of OFDM subcarriers to produce an OFDM transmission signal comprising a superposition of the OFDM subcarriers, wherein the OFDM spreader is configured to provide the superposition with a reduced peak-to-average power ratio.

U.S. Patent No. 10,200,227 - "Pre-coding in multi-user MIMO"

The Invention Explained

  • Problem Addressed: The patent addresses the need for increased capacity and spectral efficiency in cellular networks, which is often limited by inter-cell interference and the high peak-to-average power ratio (PAPR) inherent in traditional OFDM systems (’227 Patent, col. 1:47-51; col. 9:9-11).
  • The Patented Solution: The invention is an apparatus, comprising a processor and memory, that executes instructions to perform signal processing steps functionally equivalent to SC-FDMA (’227 Patent, Claim 22). It uses an invertible transform (like a DFT) to spread data symbols, maps them to subcarriers, and then uses a larger inverse transform (an IDFT) to generate a time-domain signal. This process is designed to create a signal with a reduced PAPR, making it suitable for power-constrained user equipment (’227 Patent, col. 9:11-20). The patent’s Figure 31 flow chart illustrates this process of spreading, mapping, and inverse transforming data. (’227 Patent, Fig. 31).
  • Technical Importance: This method provides a blueprint for implementing the power-efficient SC-FDMA uplink transmission scheme, which became a cornerstone of the 4G LTE standard, in the processors of mobile devices.

Key Claims at a Glance

  • The complaint asserts independent claim 22 and dependent claims 24-26 and 28 (Compl. ¶¶98, 114, 122, 131, 139).
  • Independent Claim 22 requires:
    • An apparatus comprising a processor and non-transitory memory with instructions to:
    • perform an invertible transform on a set of data symbols to generate N spread data symbols, the transform comprising complex-valued spreading codes;
    • map the N spread data symbols to at least N subcarriers of a plurality M of OFDM subcarriers to generate complex subcarrier amplitudes; and
    • perform an M-point inverse discrete Fourier transform (IDFT) on the complex subcarrier amplitudes to generate a time-domain sequence comprising a superposition of the OFDM subcarriers, wherein the invertible transform is configured to provide the superposition with a reduced PAPR.

Multi-Patent Capsules

  • Patent Identification: U.S. Patent No. 10,389,568, “Single carrier frequency division multiple access baseband signal generation,” issued August 20, 2019.

  • Technology Synopsis: This patent describes a processor-based apparatus for generating an SC-FDMA signal. The technology involves dividing a block of symbols, transform precoding them to create orthogonal spreading codes, and generating an OFDM signal with a reduced PAPR. This is central to the uplink signal generation in 4G LTE. (Compl. ¶¶148, 153-156).

  • Asserted Claims: Independent claim 24 and dependent claims 25, 26, 29, 32-34, and 44. (Compl. ¶¶147, 161, 171, 179, 188, 198, 207, 215).

  • Accused Features: The accused features are the processors and memory in the Accused TCL LTE Devices that are alleged to perform the steps of scrambling, modulation, transform precoding, and mapping of symbols as required by the LTE standard for uplink transmissions. (Compl. ¶¶151-156).

  • Patent Identification: U.S. Patent No. 11,075,786, “Multicarrier sub-layer for direct sequence channel and multiple-access coding,” issued July 27, 2021.

  • Technology Synopsis: The patent claims an apparatus for wireless communication that uses a first set of complex-valued codes (e.g., a DFT) to encode data symbols and a second set (the inverse) to recover them. The process involves selecting subcarriers, encoding data symbols, and applying them to the subcarriers to produce a spread-OFDM signal, consistent with SC-FDMA operations. (Compl. ¶¶224, 227, 231).

  • Asserted Claims: Independent claim 10 and dependent claims 11, and 15-18. (Compl. ¶¶223, 240, 247, 254, 261, 268).

  • Accused Features: The processors and memory in the Accused TCL LTE Devices are accused of infringing by performing transform precoding for uplink SC-FDMA transmissions, where the DFT used for encoding is the inverse of the DFT used by the base station for decoding. (Compl. ¶¶227-236).

  • Patent Identification: U.S. Patent No. 11,223,508, “Wireless communications using flexible channel bandwidth,” issued September 19, 2017.

  • Technology Synopsis: This patent describes an apparatus with transceiver-control circuitry that provisions a series of OFDM subcarriers with different selectable subcarrier spacings. This flexibility allows the system to generate a single-carrier (SC-FDMA) signal with different symbol periods, adapting to various deployment scenarios and channel characteristics as seen in 5G networks. (Compl. ¶¶276, 281, 311).

  • Asserted Claims: Independent claim 17 and dependent claims 18-22. (Compl. ¶¶275, 287, 294, 301, 308, 316).

  • Accused Features: The Accused TCL 5G Devices are alleged to infringe by implementing the flexible numerologies of the 5G standard, which allows for selectable subcarrier spacings (e.g., 15, 30, 60 kHz) that result in different symbol periods to suit different frequency ranges and channel conditions. (Compl. ¶¶280-281, 311).

  • Patent Identification: U.S. Patent No. 11,252,005, “Spreading and precoding in OFDM,” issued February 15, 2022.

  • Technology Synopsis: This patent claims a processor-based apparatus that produces subcarrier values by multiplying a code matrix with a data matrix. The resulting values are modulated onto selected subcarriers to create a time-domain waveform. The process uses complex-valued codes to shape interference patterns, creating cyclic-shifted waveforms, a technique for managing signal transmission in multi-carrier systems. (Compl. ¶¶327, 331, 336).

  • Asserted Claims: Independent claim 13 and dependent claims 18 and 19. (Compl. ¶¶326, 340, 348).

  • Accused Features: The Accused TCL 5G Devices are accused of infringing by using a DFT in their transform precoding step, which is alleged to be a complex matrix transform that multiplies a matrix of complex codes with a matrix of data symbols to shape interference patterns. (Compl. ¶¶331-336).

  • Patent Identification: U.S. Patent No. 11,381,285, “Transmit pre-coding,” issued July 5, 2022.

  • Technology Synopsis: The patent describes a processor-based apparatus that encodes data symbols using "polyphase codes." These codes are alleged to cause constructive and destructive interference among subcarriers to produce periodic pulse waveforms at different, distinct times within an OFDM symbol interval, a method for time-division multiplexing of signals. (Compl. ¶¶356, 361, 365).

  • Asserted Claims: Independent claim 11 and dependent claims 17 and 19. (Compl. ¶¶355, 369, 376).

  • Accused Features: The Accused TCL 5G Devices are accused of infringing by using a DFT for transform precoding, where the exponential term of the DFT allegedly defines polyphasic codes that create pulse waveforms at specific times within a symbol period. (Compl. ¶¶361, 365).

  • Patent Identification: U.S. Patent No. 11,424,792, “Coordinated multipoint systems,” issued August 23, 2022.

  • Technology Synopsis: This patent claims an apparatus for providing flexible channel bandwidth by encoding data with polyphase codes from a DFT and modulating them onto OFDM subcarriers. The system allows for selecting from different subcarrier spacings to produce a single-carrier signal with one of a plurality of different symbol durations. (Compl. ¶¶384, 389).

  • Asserted Claims: Independent claim 8 and dependent claims 9 and 10. (Compl. ¶¶383, 397, 404).

  • Accused Features: The Accused TCL 5G Devices are accused of infringing by implementing the flexible numerologies of the 5G standard, where selecting a specific subcarrier spacing (e.g., 15 kHz vs 30 kHz) results in a different OFDM symbol duration (e.g., 66.6 µs vs 33.3 µs). (Compl. ¶¶388-389).

III. The Accused Instrumentality

Product Identification

  • The accused instrumentalities are broadly categorized as "Accused TCL LTE Devices" and "Accused TCL 5G Devices" (Compl. ¶¶24, 25). These categories encompass a wide range of TCL and Alcatel-branded smartphones, tablets, and mobile hotspots that offer 4G LTE and/or 5G network connectivity (Compl. ¶24). Specific product examples cited include the TCL 40 XL and the TCL 40 X 5G (Compl. ¶¶36, 279).

Functionality and Market Context

  • The complaint alleges that the accused devices implement the 4G LTE and 5G wireless standards, specifically the 3GPP technical specifications for the physical channel (Compl. ¶¶34, 100, 277). The relevant functionality is the devices' uplink transmitter, which is alleged to generate SC-FDMA signals for 4G LTE and a variant for 5G (Compl. ¶¶37, 279, 282). This process involves a processor executing instructions stored in memory to perform steps including transform precoding of data symbols using a DFT, mapping the resulting symbols to subcarriers, and generating the final time-domain signal using an inverse DFT (Compl. ¶¶38-40, 103-108). The complaint asserts TCL is a significant market participant, identifying it as the "fifth largest handset manufacturer in North America" (Compl. ¶5).

IV. Analysis of Infringement Allegations

’842 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
An OFDM transmitter, comprising: The Accused TCL LTE Devices contain a transmitter for LTE network communications, which relies on SC-FDMA, a form of OFDM. ¶36-37 col. 9:11-20
an OFDM spreader configured to spread a plurality of data symbols with Fourier coefficients to generate a discrete Fourier Transform (DFT)-spread data signal; The transmitter performs "Transform Precoding" on data symbols consistent with the LTE Specification, which uses a DFT to spread the data symbols across multiple subcarriers. A screenshot from the 3GPP specification shows the DFT equation used for this step. (Compl. p. 16). ¶38 col. 9:11-20
a mapper configured to map the DFT-spread data signal to a plurality of OFDM subcarriers; The transmitter includes a mapper that maps the spread data signals to physical resource elements (subcarriers) as required by the LTE Specification's "Mapping to Physical Resources" section. ¶39 col. 10:20-25
an OFDM modulator configured to modulate the DFT-spread data signal onto the plurality of OFDM subcarriers to produce an OFDM transmission signal comprising a superposition of the OFDM subcarriers, wherein the OFDM spreader is configured to provide the superposition with a reduced peak-to-average power ratio. The transmitter performs "SC-FDMA baseband signal generation" per the LTE Specification, which uses an inverse DFT to modulate the spread data onto subcarriers, creating a superposition signal that mimics a single carrier and has a lower PAPR than standard OFDM. ¶17, 40 col. 9:21-34

Identified Points of Contention

  • Scope Questions: The case may turn on whether the term "OFDM transmitter" is construed to cover transmitters that implement SC-FDMA. While SC-FDMA is a variant of OFDM, a defendant could argue for a narrower construction that excludes it. The complaint anticipates this by asserting that an "SC-FDMA signal is a modulated OFDM signal" (Compl. ¶37).
  • Technical Questions: A central question will be whether compliance with the cited 3GPP LTE standard sections inherently results in a device that meets every limitation of Claim 1. A potential defense could argue that the standard allows for non-infringing implementations or that the accused devices' specific hardware (e.g., MediaTek chipsets) operates in a way that deviates from the claim requirements, even while being standard-compliant.

’227 Patent Infringement Allegations

Claim Element (from Independent Claim 22) Alleged Infringing Functionality Complaint Citation Patent Citation
An apparatus comprising: a processor; and a non-transitory memory...including a set of instructions...executable by the processor to: The Accused TCL LTE Devices contain processors (e.g., MediaTek G37 Octa-core chip) and non-transitory memory (RAM and flash) that stores instructions for LTE physical channel processing. ¶102 col. 28:15-19
perform an invertible transform on a set of data symbols to generate a plurality N of spread data symbols, the invertible transform comprising complex-valued spreading codes; The memory includes instructions for performing "transform precoding" according to the LTE specification. This process uses a DFT, which is an invertible transform that acts on data symbols and is comprised of complex-valued basis functions (alleged to be "spreading codes"). ¶103 col. 9:11-20
map the N spread data symbols to at least N subcarriers of a plurality M of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers to generate a set of complex subcarrier amplitudes; The memory includes instructions to map the N spread data signals to N subcarriers, which are a subset of the M total subcarriers available in the uplink bandwidth, as specified in the LTE standard's mapping section. ¶105-106 col. 10:20-25
perform an M-point inverse discrete Fourier transform (IDFT) on the set of complex subcarrier amplitudes to generate a time-domain sequence...comprising a superposition of the OFDM subcarriers, wherein the invertible transform is configured to provide the superposition with a reduced peak-to-average power ratio. The memory includes instructions for SC-FDMA baseband signal generation, which uses an M-point IDFT to create the final time-domain signal. The combination of the initial N-point DFT spreading and the M-point IDFT modulation results in a signal with a reduced PAPR. A screenshot from the 3GPP specification shows the IDFT equation used for this step. (Compl. p. 32). ¶104, 107-108 col. 9:21-34

Identified Points of Contention

  • Scope Questions: A key point of contention may be the construction of "complex-valued spreading codes." Defendant could argue this term requires specific, predefined code sequences (like Walsh codes) and does not read on the basis functions of a DFT, which are mathematical constructs rather than stored codes.
  • Technical Questions: The infringement theory hinges on the processor and memory of the accused devices executing instructions that perfectly mirror the steps of the LTE standard. What evidence does the complaint provide that the software running on the MediaTek G37 chip actually performs the specific function of generating an "invertible transform" for the purpose of reducing PAPR, as required by the claim's "wherein" clause?

V. Key Claim Terms for Construction

  • The Term: "OFDM spreader" (’842 Patent, Claim 1)

  • Context and Importance: This term is central to the infringement allegation, as the complaint equates it with the "Transform Precoding" block in the LTE uplink process. The viability of the infringement claim depends on this term being construed broadly enough to cover a DFT operation applied to data symbols before they are mapped to OFDM subcarriers.

  • Intrinsic Evidence for Interpretation (from ’227 Patent as a related patent):

    • Evidence for a Broader Interpretation: The abstract describes a "Discrete Fourier Transform (DFT) spreader" that "provides data symbols spread with Fourier coefficients" (’227 Patent, Abstract). Figure 30A explicitly labels a block performing this function as a "DFT Spreader (CI Coder)," directly supporting the interpretation that a DFT operation for this purpose is an "OFDM spreader." (’227 Patent, Fig. 30A).
    • Evidence for a Narrower Interpretation: A defendant might argue that the patent's repeated references to "Carrier Interferometry" (CI) and "CI Coder" (’227 Patent, Fig. 30A) suggest that an "OFDM spreader" is limited to the specific CI techniques described in the specification, potentially distinguishing it from the generic DFT defined in the 3GPP standard.

  • The Term: "invertible transform comprising complex-valued spreading codes" (’227 Patent, Claim 22)

  • Context and Importance: The infringement theory relies on this term covering the DFT used in the LTE standard's "Transform Precoding" step. Practitioners may focus on this term because if "spreading codes" is construed narrowly to mean something other than the basis functions of a DFT, the infringement argument could fail.

  • Intrinsic Evidence for Interpretation (’227 Patent):

    • Evidence for a Broader Interpretation: The specification describes the invention as a "pre-coder" that "comprises a Discrete Fourier Transform (DFT) spreader provides data symbols spread with Fourier coefficients" (’227 Patent, Abstract). This language suggests that the Fourier coefficients (the basis functions of the DFT) are the "complex-valued spreading codes."
    • Evidence for a Narrower Interpretation: A defendant could argue that the term "spreading codes" has a specific meaning in the art that implies sequences distinct from the inherent basis functions of a mathematical transform. They might point to sections discussing other types of codes to argue that if the patentee meant the basis functions of a DFT, they would not have used the term "spreading codes."

VI. Other Allegations

  • Indirect Infringement: The complaint includes a general allegation that Defendant continued to "induce the infringement" (Compl. ¶31), but it does not plead specific facts, such as instructing users via manuals, to support a claim for indirect infringement under 35 U.S.C. § 271(b). The formal counts are for direct infringement under § 271(a).
  • Willful Infringement: The complaint alleges willful infringement based on both pre-suit and post-suit knowledge (Compl. ¶¶411-413). The basis for pre-suit knowledge is a detailed notice letter with claim charts sent on November 11, 2020, for the ’842, ’227, and ’568 patents, and a second letter on June 29, 2022, for the ’786 and ’508 patents (Compl. ¶¶26, 28, 42, 111). Post-suit knowledge for all patents is based on the filing of the complaint itself (Compl. ¶30).

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

  • A core issue will be one of definitional scope: can terms such as "OFDM spreader" and "complex-valued spreading codes," which are rooted in the patent's specific disclosure, be construed broadly enough to read on the functional blocks ("Transform Precoding") and mathematical operations (DFT) defined in the public 3GPP standards for 4G LTE and 5G?
  • A key evidentiary question will be one of standard-essentiality: does compliance with the cited sections of the 3GPP standards necessarily require practicing every element of the asserted claims? The case will likely involve a technical deep-dive into whether the standards allow for non-infringing alternatives that the accused products might use.
  • A central question for damages will be willfulness: given the allegations of early and detailed pre-suit notice, including the provision of claim charts, the court will need to determine whether TCL’s alleged continued infringement after these dates was objectively reckless, potentially leading to enhanced damages.