DCT
6:25-cv-00111
Redwood Tech LLC v. Realtek Semiconductor Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Redwood Technologies, LLC (Texas)
- Defendant: Realtek Semiconductor Corporation (Taiwan)
- Plaintiff’s Counsel: Nelson Bumgardner Conroy PC
- Case Identification: 6:25-cv-00111, W.D. Tex., 03/25/2025
- Venue Allegations: Venue is alleged to be proper because Defendant is a foreign entity, which may be sued in any judicial district pursuant to 28 U.S.C. § 1391(c)(3).
- Core Dispute: Plaintiff alleges that Defendant’s Wi-Fi compliant semiconductor devices, which are incorporated into a wide range of consumer electronics, infringe seven U.S. patents related to wireless mesh networking and MIMO transmission technologies.
- Technical Context: The patents relate to methods for managing interference, scheduling transmissions, and improving signal quality in wireless networks, particularly those adhering to the IEEE 802.11 (Wi-Fi) standards.
- Key Procedural History: The complaint alleges that Plaintiff sent multiple notice letters and emails to Defendant regarding the asserted patents between November 2021 and July 2024, which Defendant allegedly refused to accept or to which it refused to respond. These allegations form the basis of the willfulness claims.
Case Timeline
| Date | Event |
|---|---|
| 2001-11-13 | Priority Date for ’901, ’371, ’224, ’005, ’300 Patents |
| 2004-03-01 | Priority Date for ’130 and ’517 Patents |
| 2010-02-16 | U.S. Patent No. 7,664,130 Issues |
| 2010-03-30 | U.S. Patent No. 7,688,901 Issues |
| 2011-07-05 | U.S. Patent No. 7,974,371 Issues |
| 2012-04-10 | U.S. Patent No. 8,155,224 Issues |
| 2014-06-03 | U.S. Patent No. 8,744,005 Issues |
| 2014-10-28 | U.S. Patent No. 8,873,517 Issues |
| 2017-04-18 | U.S. Patent No. 9,628,300 Issues |
| 2021-11-02 | Plaintiff alleges first pre-suit notice letter sent to Defendant |
| 2021-12-08 | Plaintiff alleges second pre-suit notice letter sent to Defendant |
| 2022-05-12 | Plaintiff alleges email notice sent to Defendant |
| 2022-05-22 | Plaintiff alleges third pre-suit notice letter sent to Defendant |
| 2023-09-15 | Plaintiff alleges email notice sent to Defendant |
| 2024-07-19 | Plaintiff alleges email notice sent to Defendant |
| 2025-01-01 | Alleged use of BE3600 Accused Product at CES |
| 2025-03-25 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,664,130 - “Wireless Communication System, Wireless Communication Apparatus, Wireless Communication Method, and Computer Program,” Issued February 16, 2010
The Invention Explained
- Problem Addressed: The patent addresses the problem of mutual interference between communication stations in a self-organized, distributed wireless network (like an ad-hoc or mesh network) where there is no central controlling station. The challenge is to enable communication while securing bandwidth for prioritized traffic (Compl. ¶74; ’130 Patent, col. 1:35-41).
- The Patented Solution: The invention proposes a system where each communication station can establish a "prioritized utilization region" to secure bandwidth. To avoid collisions, stations exchange information about their "transmission-reception dangerous zones," allowing them to perform transmissions in a way that avoids these zones and prevents interference with neighboring stations (’130 Patent, col. 14:30-41). This distributed coordination allows for more efficient use of the shared wireless medium.
- Technical Importance: This technology provides a method for decentralized collision avoidance and quality-of-service management, which is critical for the stable operation of ad-hoc and mesh Wi-Fi networks that lack a central access point to coordinate traffic (’130 Patent, col. 1:11-20).
Key Claims at a Glance
- The complaint asserts independent claim 10 (Compl. ¶67).
- Essential elements of Claim 10 (a wireless communication station):
- A transmitter configured to transmit beacons with network information to other stations.
- A receiver configured to receive timing information concerning priority transmission of a neighborhood station from other stations.
- The transmitter further configured to transmit a message to the neighborhood station, requesting a report of that timing information.
- The complaint does not explicitly reserve the right to assert dependent claims.
U.S. Patent No. 7,688,901 - “Transmission Method, Transmission Apparatus, and Reception Apparatus,” Issued March 30, 2010
The Invention Explained
- Problem Addressed: The patent identifies the difficulty of accurately estimating communication channels when multiple modulation signals are multiplexed and transmitted simultaneously, particularly when there is a lack of synchronization and potential frequency offsets between the channels (’901 Patent, col. 1:41-45).
- The Patented Solution: The invention describes a method of inserting special symbols ("preamble symbols" or pilot symbols) used for demodulation into the modulation signals. These preamble symbols are placed at the same time across different channels and are designed to be "orthogonal" to each other. This orthogonality allows a receiving apparatus to easily isolate the symbols for each channel, enabling accurate channel estimation even in a multiplexed environment (’901 Patent, col. 2:16-22).
- Technical Importance: This method provides a robust way to perform channel estimation in Multiple-Input, Multiple-Output (MIMO) systems, a foundational technology for increasing data rates in modern Wi-Fi standards like 802.11n and beyond (’901 Patent, col. 1:50-52).
Key Claims at a Glance
- The complaint asserts independent claim 1 (Compl. ¶89).
- Essential elements of Claim 1 (a transmission method):
- Generating a plurality of modulation signals for transmission from different antennas.
- Each modulation signal includes one or more preamble symbol groups, each consisting of a plurality of preamble symbols for demodulation.
- Inserting the preamble symbol groups at the same temporal point(s) in each modulation signal.
- The preamble symbol groups are orthogonal to each other with zero mutual correlation.
- Each preamble symbol has a non-zero amplitude.
- Each preamble symbol group consists of a quantity of symbols greater than the quantity of modulation signals to be transmitted.
- Transmitting the plurality of modulation signals from the antennas in an identical frequency band.
- The complaint does not explicitly reserve the right to assert dependent claims.
Multi-Patent Capsules for Additional Patents-in-Suit
U.S. Patent No. 7,974,371: "Communication Method and Radio Communication Apparatus," Issued July 5, 2011
- Technology Synopsis: The patent describes a communication apparatus that adaptively switches between two transmission methods: a first method transmitting a single modulation signal from one antenna, and a second method (e.g., MIMO) transmitting multiple modulation signals from multiple antennas. The selection is based on the estimated radio-wave propagation environment to optimize the data transmission rate (’371 Patent, Abstract; col. 4:27-31).
- Asserted Claims: Independent claim 14 (Compl. ¶109).
- Accused Features: The complaint alleges that Realtek's RTL8812BU products, which are compliant with IEEE 802.11n/ac, infringe by using a Modulation and Coding Scheme (MCS) to select between single-stream and multi-stream (spatial multiplexing) transmissions based on channel quality information (Compl. ¶¶110-112).
U.S. Patent No. 8,155,224: "Transmission Method, Transmission Apparatus, and Reception Apparatus," Issued April 10, 2012
- Technology Synopsis: This patent, related to the ’901 Patent, discloses a transmission method for multiplexed signals. A symbol for demodulation is inserted into one channel while, at the same time, the corresponding symbol in another channel is made to be zero, which allows the demodulation symbol to be isolated easily by the receiver (’224 Patent, col. 2:9-21).
- Asserted Claims: Independent claim 1 (Compl. ¶131).
- Accused Features: The complaint alleges infringement by Realtek's RTL8812BU products through their use of orthogonal pilot symbol sequences in MIMO transmissions, consistent with the IEEE 802.11n/ac standards (Compl. ¶¶132-134).
U.S. Patent No. 8,744,005: "Method and Apparatus for Generating Modulation Signals," Issued June 3, 2014
- Technology Synopsis: The patent describes an apparatus for generating multiple modulation signals for transmission from multiple antennas. Each signal includes a pilot symbol sequence for demodulation, where the sequences are orthogonal, and the quantity of pilot symbols in each sequence is greater than the quantity of modulation signals to be transmitted (’005 Patent, Abstract).
- Asserted Claims: Independent claim 9 (Compl. ¶154).
- Accused Features: The complaint accuses Realtek's RTL8812BU products, alleging they generate modulation signals with four-symbol pilot sequences for transmission from two or three antennas, thereby meeting the "greater than" requirement (Compl. ¶¶155-160).
U.S. Patent No. 8,873,517: "Wireless Communication System, Wireless Communication Apparatus, Wireless Communication Method and Computer Program," Issued October 28, 2014
- Technology Synopsis: This patent, related to the ’130 Patent, discloses a method for avoiding interference in a wireless mesh network. The method involves setting a "duration" and an "offset" for a transmission opportunity, with the offset defining the start of the opportunity relative to a larger transmission interval, allowing beacon transmission times to be shifted to avoid conflicts (’517 Patent, col. 21:50-60).
- Asserted Claims: Independent claim 1 (Compl. ¶183).
- Accused Features: The complaint alleges that Realtek's BE3600 mesh devices infringe by implementing the "Mesh Awake Window" (duration) and "Target Beacon Transmission Time (TBTT)" adjustment (offset) features of the IEEE 802.11 standard (Compl. ¶¶184-186).
U.S. Patent No. 9,628,300: "Method and Signal Generating Apparatus for Generating Modulation Signals," Issued April 18, 2017
- Technology Synopsis: This patent discloses a method and apparatus for generating modulation signals that include pilot symbol sequences and/or pilot subcarriers for demodulation. The pilot elements are orthogonal to each other, and the quantity of pilot symbols is greater than the quantity of modulation signals to be transmitted (’300 Patent, Abstract).
- Asserted Claims: Independent claim 8 (Compl. ¶207).
- Accused Features: The complaint alleges infringement by Realtek's RTL8812BU products, which are accused of using four pilot symbols for 20 MHz transmissions and six pilot symbols for 40 MHz transmissions, exceeding the number of modulation signals (Compl. ¶¶208-210).
III. The Accused Instrumentality
Product Identification
- The Accused Products are broadly defined as "Realtek Wi-Fi compliant devices" and products comprising them (Compl. ¶3). Specific exemplary products identified are Realtek's mesh devices compliant with IEEE 802.11 (such as the BE3600 series) and devices compliant with IEEE 802.11n/ac/ax/be (such as the RTL8812BU and various other enumerated chipsets) (Compl. ¶¶60, 67, 89).
Functionality and Market Context
- The Accused Products are semiconductor chips and related components that provide Wi-Fi functionality according to various IEEE 802.11 standards (Compl. ¶3).
- The BE3600 is identified as a "Wi-Fi 7 mesh device" used as a router or extender, which allegedly implements features for coordinating transmissions in a mesh network to avoid interference (Compl. ¶67).
- The RTL8812BU is identified as a "highly integrated single-chip that supports 2-stream 802.11ac solutions with Multi-user MIMO," combining a WLAN MAC, baseband, and RF components (Compl. ¶89).
- The complaint alleges these components are incorporated into downstream consumer products like routers, laptops, TVs, and IoT devices from major manufacturers such as Asus and Lenovo, and sold through retailers like Walmart and Amazon (Compl. ¶¶23, 31-33). No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
U.S. Patent No. 7,664,130 Infringement Allegations
| Claim Element (from Independent Claim 10) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a transmitter configured to transmit beacons with information associated with a network being described therein to other communication stations to construct a network | The Accused Products (e.g., BE3600) transmit a beacon containing a Mesh Configuration element that advertises the mesh services of a mesh network. | ¶68 | col. 13:50-65 |
| a receiver configured to receive timing information concerning priority transmission of a neighborhood communication station from said other communication stations | The Accused Products receive beacons containing a Beacon Timing element, which includes Beacon Timing Information fields that prioritize transmissions to avoid collisions. | ¶69 | col. 14:15-22 |
| said transmitter further configured to transmit a message to the neighborhood communication station, the message requesting a report of timing information concerning priority transmission of the neighborhood communication station | The Accused Products transmit a Probe Request frame to request the Beacon Timing Information from a neighboring station. | ¶70 | col. 14:23-29 |
- Identified Points of Contention:
- Scope Questions: A central question may be whether the functionalities defined by the IEEE 802.11 standard, which the complaint relies on, map directly onto the specific claim language. For example, does the standard "Beacon Timing Information" constitute "timing information concerning priority transmission" as contemplated by the patent? Similarly, does transmitting a standard "Probe Request frame" constitute "requesting a report" as required by the claim?
- Technical Questions: The analysis may require a technical deep dive into how the IEEE 802.11 mesh protocol operates. The court may need to determine if the Beacon Timing element's function of prioritizing transmissions to avoid collisions is the same as the patent's concept of "priority transmission" for a "prioritized utilization region."
U.S. Patent No. 7,688,901 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| generating a plurality of modulation signals each of which is to be transmitted from a different one of a plurality of antennas | The Accused Products (e.g., RTL8812BU) generate modulation signals (e.g., HT-mixed format PPDUs) for transmission from a plurality of antennas. | ¶90 | col. 11:39-43 |
| wherein each modulation signal is to include one or more preamble symbol groups each consisting of a plurality of preamble symbols used for demodulation | Each modulation signal includes OFDM symbols, and each OFDM symbol comprises a pilot symbol sequence of four pilot symbols used for demodulation. | ¶90 | col. 12:40-47 |
| inserting the one or more preamble symbol groups at the same one or more temporal points in each modulation signal | The OFDM symbols containing the pilot sequences are inserted into each modulation signal, and the signals are transmitted simultaneously. | ¶91 | col. 12:48-50 |
| wherein the one or more preamble symbol groups at the one or more temporal points are orthogonal to other preamble symbol groups...with zero mutual correlation | The pilot symbol sequences for different spatial streams are orthogonal with zero mutual correlation. | ¶91 | col. 12:51-56 |
| each preamble symbol having a non-zero amplitude | The pilot symbols are BPSK modulated and have a non-zero amplitude. | ¶91 | col. 12:57-58 |
| and each preamble symbol group consisting of preamble symbols the quantity of which is greater than that of the plurality of modulation signals to be transmitted | Each pilot symbol sequence contains four pilot symbols, which is alleged to be greater than the two or three modulation signals (antennas) used for transmission. | ¶91 | col. 12:59-63 |
| transmitting the plurality of modulation signals...from the plurality of antennas, respectively, in an identical frequency band | The Accused Products transmit the modulation signals from two or three antennas in the same channel (e.g., 20 MHz width). | ¶92 | col. 12:64-67 |
- Identified Points of Contention:
- Scope Questions: A key issue will be the construction of "modulation signals to be transmitted." The complaint appears to equate this with the number of transmit antennas (Compl. ¶91). A defendant may argue it refers to the number of spatial streams, which could be different. The definition of "orthogonal" as used in the patent versus its implementation in the IEEE standard may also be a point of contention.
- Technical Questions: The infringement allegation hinges on a quantitative comparison: is the number of pilot symbols (allegedly four) greater than the number of modulation signals (allegedly two or three)? This raises a factual question that depends on the claim construction of the relevant terms and the specific operating modes of the accused chips.
V. Key Claim Terms for Construction
For U.S. Patent No. 7,664,130
- The Term: "requesting a report of timing information" (Claim 10)
- Context and Importance: This term is critical because the complaint alleges that transmitting a standard "Probe Request frame" meets this limitation (Compl. ¶70). The case may turn on whether a general-purpose probe request, used in Wi-Fi for network discovery, constitutes the specific act of "requesting a report" of "timing information concerning priority transmission" as described in the patent.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: Claim 10 itself does not specify the format of the "message" or "report," which may suggest that any message that elicits the required timing information could suffice.
- Evidence for a Narrower Interpretation: The specification describes a specific investigation and reporting procedure for resolving duplicated transmission periods, involving dedicated "Search," "Report," and "Ask" messages (see, e.g., ’130 Patent, FIG. 16, col. 32:5-30). A defendant could argue this context implies a more specific, targeted request than a general Probe Request.
For U.S. Patent No. 7,688,901
- The Term: "preamble symbol group consisting of preamble symbols the quantity of which is greater than that of the plurality of modulation signals to be transmitted" (Claim 1)
- Context and Importance: This limitation provides a specific, quantitative requirement that is central to the infringement allegation. The complaint alleges that four pilot symbols are greater than two or three "modulation signals" (equated with antennas) (Compl. ¶91). The construction of "quantity of...modulation signals to be transmitted" will be dispositive.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent frequently discusses transmitting signals from a "plurality of antennas," which could support the plaintiff's apparent interpretation that "modulation signals" corresponds to the number of physical antennas used for transmission (’901 Patent, col. 1:15-18).
- Evidence for a Narrower Interpretation: The term "modulation signals" is also used interchangeably with "channels" (e.g., "modulation signals of a plurality of channels" in the abstract). A defendant might argue that in certain MIMO modes, the number of modulation signals (or spatial streams) could equal or exceed the number of pilot symbols, meaning the "greater than" requirement is not always met.
VI. Other Allegations
- Indirect Infringement: The complaint alleges both induced and contributory infringement for all asserted patents. Inducement is primarily based on allegations that Realtek provides instructions, manuals, and technical support that encourage and facilitate the use of the accused functionalities in its Wi-Fi chips (e.g., Compl. ¶¶76, 99). Contributory infringement is based on allegations that the accused components are especially made to be used in an infringing manner (by complying with the IEEE 802.11 standards), are a material part of the invention, and are not staple articles of commerce suitable for substantial noninfringing use (e.g., Compl. ¶¶78, 100).
- Willful Infringement: The complaint alleges willful infringement for all asserted patents based on Defendant’s alleged pre-suit knowledge. Plaintiff alleges it sent multiple notices of infringement via FedEx and email to various Realtek employees between November 2021 and July 2024, and that Realtek refused delivery of the letters and failed to respond to the emails, allegedly demonstrating willful blindness and continued infringement despite an objectively high likelihood of infringement (e.g., Compl. ¶¶17-19, 75, 81, 98, 101).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope and standards-essentiality: The infringement allegations for multiple patents rely heavily on equating the claimed features with functionalities defined in the IEEE 802.11 standards. The case will likely turn on whether claim terms such as "requesting a report" (’130 Patent) and "duration of transmission opportunity" (’517 Patent) can be construed to read on the standard implementations of "Probe Request frames" and "Mesh Awake Windows" as alleged.
- A key evidentiary question will be one of quantitative and functional equivalence: For the MIMO-related patents (’901, ’005, ’300), the dispute will likely focus on a precise technical and numerical analysis. A central question for the court will be whether the accused products' use of a specific number of pilot symbols (e.g., four) for a given number of spatial streams or antennas meets the "quantity... is greater than" limitation of the claims, a determination that is contingent on claim construction.
- A third central issue will be knowledge and intent for willfulness: Given the extensive pre-suit notice alleged in the complaint, including refused deliveries and unanswered emails, a significant question for the court will be whether these actions constitute clear and convincing evidence of willful infringement, potentially exposing the defendant to enhanced damages if infringement is found.