6:25-cv-00002
Redwood Tech LLC v. Broadcom Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Redwood Technologies, LLC (Texas)
- Defendant: Broadcom, Inc. and Broadcom Corporation (Delaware & California)
- Plaintiff’s Counsel: Nelson Bumgardner Conroy PC
- Case Identification: 6:25-cv-00002, W.D. Tex., 01/02/2025
- Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because Defendants maintain a regular and established place of business in the district, specifically an office in Austin, and have committed acts of infringement within the district.
- Core Dispute: Plaintiff alleges that Defendant’s Wi-Fi compliant devices, components, and related processes infringe eight U.S. patents related to wireless communication systems and methods.
- Technical Context: The technology at issue concerns methods for managing wireless data transmission in networks, such as those compliant with IEEE 802.11 (Wi-Fi) standards, to improve efficiency, avoid interference, and enhance signal quality.
- Key Procedural History: The complaint alleges that Plaintiff first notified Defendant of its infringement of the asserted patents via a letter sent on November 3, 2021, and that subsequent licensing discussions were unsuccessful. Plaintiff also alleges Defendant had knowledge of certain patents because they were cited during the prosecution of Defendant's own patent applications.
Case Timeline
| Date | Event |
|---|---|
| 2001-11-13 | Earliest Priority Date for ’901, ’371, ’224, ’005, and ’300 Patents |
| 2003-08-07 | Earliest Priority Date for ’102 Patent |
| 2004-03-01 | Earliest Priority Date for ’130 and ’517 Patents |
| 2010-02-16 | Issue Date for U.S. Patent No. 7,664,130 |
| 2010-03-30 | Issue Date for U.S. Patent No. 7,688,901 |
| 2011-03-29 | Issue Date for U.S. Patent No. 7,917,102 |
| 2011-07-05 | Issue Date for U.S. Patent No. 7,974,371 |
| 2012-04-10 | Issue Date for U.S. Patent No. 8,155,224 |
| 2014-06-03 | Issue Date for U.S. Patent No. 8,744,005 |
| 2014-10-28 | Issue Date for U.S. Patent No. 8,873,517 |
| 2017-04-18 | Issue Date for U.S. Patent No. 9,628,300 |
| 2021-11-03 | Redwood sends first notice letter to Broadcom |
| 2022-01-04 | Redwood sends follow-up letter to Broadcom |
| 2022-03-02 | Redwood sends follow-up letter to Broadcom |
| 2022-05-12 | Redwood sends second notice letter to Broadcom |
| 2022-09-13 | Redwood sends follow-up letter to Broadcom |
| 2022-09-14 | Redwood sends two follow-up letters to Broadcom |
| 2022-09-19 | Broadcom replies and is given access to infringement charts |
| 2022-12-02 | Redwood emails Broadcom regarding fulfillment of RAND obligations |
| 2025-01-02 | 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"
The Invention Explained
- Problem Addressed: In autonomous, distributed wireless networks (such as ad-hoc Wi-Fi networks), communication stations must contend for access to the wireless medium, creating a risk of mutual interference and data collisions, which degrades network performance (’130 Patent, col. 1:35-41).
- The Patented Solution: The patent describes a system where each station can secure a "prioritized utilization region" to transmit frames with priority. To avoid collisions, stations gather information about the "transmission-reception dangerous zones" of neighboring stations by receiving timing information from them. A station can then perform its frame transmissions in a way that avoids these recorded dangerous zones, thereby preventing collisions. (’130 Patent, col. 14:30-41; Abstract).
- Technical Importance: This decentralized approach to scheduling and collision avoidance allows for the implementation of quality of service (QoS) and prioritized traffic in networks without a central controller. (’130 Patent, col. 1:39-41).
Key Claims at a Glance
- The complaint asserts independent claim 10 (Compl. ¶65).
- Claim 10 requires a wireless communication station comprising:
- a transmitter configured to transmit beacons with network information;
- a receiver configured to receive timing information concerning priority transmission from other stations; and
- the transmitter is further configured to transmit a message requesting a report of said timing information from a neighborhood station.
U.S. Patent No. 7,917,102 - "Radio Transmitting Apparatus and Radio Transmission Method"
The Invention Explained
- Problem Addressed: In multi-antenna wireless systems where the number of simultaneously transmitted signals changes based on channel conditions, the received signal level fluctuates. This can lead to "quantization error" at the receiver's analog-to-digital converter, which in turn degrades the quality of channel estimation and overall data reception. (’102 Patent, col. 2:12-18).
- The Patented Solution: The patent proposes two related solutions. The first is to change the transmit power of the signal from each antenna according to the number of antennas simultaneously transmitting signals (’102 Patent, col. 2:19-22). The second, recited in the asserted claim, is a specific transmission frame structure that includes a first gain control signal, a frequency offset estimation signal, and then a second gain control signal, arranged in that sequence to improve reception quality. (’102 Patent, col. 17:34-50, Claim 3).
- Technical Importance: The invention provides a method to improve reception quality in adaptive multi-antenna (MIMO) systems, which are foundational to modern high-speed Wi-Fi standards that vary the number of spatial streams based on signal quality. (’102 Patent, col. 2:12-18).
Key Claims at a Glance
- The complaint asserts independent claim 3 (Compl. ¶87).
- Claim 3 requires a radio transmitting apparatus comprising circuitry that:
- forms a transmission frame including a frequency offset estimation signal, a channel fluctuation estimation signal, and a gain control signal;
- transmits the frame;
- wherein the frame includes a first gain control signal and a second gain control signal;
- the first gain control signal is arranged prior to the frequency offset estimation signal; and
- the second gain control is arranged subsequent to the frequency offset estimation signal and prior to the channel fluctuation estimation signal.
U.S. Patent No. 7,688,901 - "Transmission Method, Transmission Apparatus, and Reception Apparatus"
Technology Synopsis
The patent addresses the difficulty of accurately estimating communication channels when multiple modulation signals are multiplexed and transmitted simultaneously, especially in the presence of frequency offsets ('901 Patent, col. 1:41-52). The proposed solution involves generating multiple modulation signals that each include one or more "preamble symbol groups," which are inserted at the same temporal points and are orthogonal to each other, allowing a receiver to more easily isolate the symbols and estimate the channels ('901 Patent, col. 2:16-22).
Asserted Claims
At least independent claim 1 (Compl. ¶109).
Accused Features
The complaint alleges that Broadcom devices, such as the BCM6726 series, infringe by generating and transmitting multiple modulation signals (e.g., HT-mixed format PPDUs) with orthogonal pilot symbol sequences for demodulation, in compliance with IEEE 802.11 standards (Compl. ¶¶110-112).
U.S. Patent No. 7,974,371 - "Communication Method and Radio Communication Apparatus"
Technology Synopsis
The patent describes a communication method that adaptively switches between two transmission modes: transmitting multiple multiplexed modulation signals from multiple antennas, or transmitting a single modulation signal from one antenna ('371 Patent, col. 4:27-31). The transmitter selects the appropriate method based on information it receives from a communication partner regarding the estimated radio-wave propagation environment, enabling an increase in data rate when channel conditions are favorable ('371 Patent, col. 5:4-16).
Asserted Claims
At least independent claim 14 (Compl. ¶129).
Accused Features
The accused functionality involves Broadcom devices (e.g., BCM6726 series) selecting a transmission method, such as a Modulation and Coding Scheme (MCS) that determines the number of spatial streams, based on received channel quality information, and then generating either a single modulation signal or a plurality of signals for spatial multiplexing (Compl. ¶¶130-132).
U.S. Patent No. 8,155,224 - "Transmission Method, Transmission Apparatus, and Reception Apparatus"
Technology Synopsis
The patent discloses a transmission method to improve the accuracy of channel estimation when demultiplexing signals. The method involves generating a plurality of modulation signals for transmission from different antennas, where each signal includes pilot symbol sequences used for demodulation ('224 Patent, Abstract). These pilot symbol sequences are inserted at the same temporal point in each signal and are orthogonal to each other, allowing a reception apparatus to more easily isolate them to estimate the channels ('224 Patent, col. 2:28-34).
Asserted Claims
At least independent claim 1 (Compl. ¶151).
Accused Features
The complaint accuses Broadcom devices (e.g., BCM6726 series) that generate and transmit multiple modulation signals (e.g., HT-mixed format PPDUs) from multiple antennas, where the signals contain orthogonal pilot symbol sequences inserted at the same temporal point, as required by IEEE 802.11 standards (Compl. ¶¶152-154).
U.S. Patent No. 8,744,005 - "Method and Apparatus for Generating Modulation Signals"
Technology Synopsis
The patent describes a method for generating modulation signals to facilitate accurate channel estimation. The method involves generating multiple modulation signals for different antennas, each including a pilot symbol sequence ('005 Patent, Abstract). The pilot symbol sequences are orthogonal, inserted at the same temporal point, and have a quantity of pilot symbols that is greater than the quantity of modulation signals to be transmitted, which aids in demodulation ('005 Patent, Claim 9).
Asserted Claims
At least independent claim 9 (Compl. ¶174).
Accused Features
Infringement is alleged against Broadcom devices (e.g., BCM6726 series) that generate multiple spatial streams for transmission from fewer than four antennas, where each stream includes a pilot sequence containing four pilot symbols, thus satisfying the requirement that the quantity of pilot symbols (four) is greater than the quantity of modulation signals (e.g., two or three) (Compl. ¶¶175-180).
U.S. Patent No. 8,873,517 - "Wireless Communication System, Wireless Communication Apparatus, Wireless Communication Method and Computer Program"
Technology Synopsis
The patent addresses the problem of mutual interference among communication stations in a mesh network ('517 Patent, col. 1:40-46). The invention provides for a communication station to set a "duration of transmission opportunity" and an "offset" that indicates the beginning of that opportunity relative to a transmission interval. This information is transmitted to other stations to shift beacon transmission times away from each other and evade overlapping transmissions. ('517 Patent, col. 21:50-60; Claim 1).
Asserted Claims
At least independent claim 1 (Compl. ¶203).
Accused Features
The complaint alleges infringement by Broadcom's mesh-compliant devices (e.g., BCM6726 series) that implement features of the IEEE 802.11 mesh standard, such as setting a "Mesh Awake Window" (duration) and performing a "Target Beacon Transmission Time (TBTT)" adjustment (offset) to coordinate transmissions (Compl. ¶¶204-205).
U.S. Patent No. 9,628,300 - "Method and Signal Generating Apparatus for Generating Modulation Signals"
Technology Synopsis
The patent discloses a method and apparatus for generating modulation signals to enable accurate channel estimation from multiplexed signals. The invention involves generating a plurality of modulation signals, each for a different antenna, and inserting into each signal pilot symbol sequences and/or pilot subcarriers ('300 Patent, Abstract). These pilot sequences/subcarriers are inserted at the same temporal point, are orthogonal to each other, and the quantity of pilot symbols is greater than the quantity of modulation signals, thereby improving the ease of demultiplexing ('300 Patent, Claim 8).
Asserted Claims
At least independent claim 8 (Compl. ¶227).
Accused Features
The accused functionality involves Broadcom devices (e.g., BCM6726 series) that generate and transmit multiple modulation signals (e.g., HT-mixed format PPDUs) containing orthogonal pilot sequences/subcarriers where the number of pilot symbols per sequence (e.g., four or six) is greater than the number of modulation signals, as implemented in IEEE 802.11 standards (Compl. ¶¶228-230).
III. The Accused Instrumentality
Product Identification
The accused instrumentalities are broadly identified as "Broadcom Wi-Fi compliant devices," which include components compliant with various IEEE 802.11 standards (n, ac, ax, be) and Broadcom's mesh devices (Compl. ¶4). The complaint repeatedly uses the BCM6726 series of chips as an exemplary accused product (Compl. ¶¶58, 65, 87).
Functionality and Market Context
The accused products are described as MAC/PHY/radio devices that form the core of wireless communication systems such as Wi-Fi access points and mesh network nodes (Compl. ¶¶65, 87, 203). The complaint provides a product brief diagram for the BCM67263/BCM6726, identifying it as a Wi-Fi 7 compliant, quad-stream 4x4 device for Wi-Fi mesh applications (Compl. p. 23). The allegations focus on the products' implementation of specific functionalities mandated by the IEEE 802.11 standards, such as the formation and transmission of beacon frames, probe requests, and High Throughput (HT)-mixed format Protocol Packet Data Units (PPDUs) containing specific subframes (e.g., L-STF, L-LTF, HT-STF) used for synchronization, channel estimation, and gain control (Compl. ¶¶66-68, 88-90). The complaint positions Broadcom as a "global technology leader" in semiconductor and infrastructure software solutions, suggesting the accused products are of significant commercial importance (Compl. ¶11).
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 transmit beacons containing a Mesh Configuration element that advertises the services of a mesh network. | ¶66 | col. 33:1-10 |
| 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 information fields used to prioritize transmissions and avoid collisions. | ¶67 | col. 54:1-15 |
| the transmitter further configured to transmit a message to the neighborhood communication station, the message requesting a report of timing information... | The Accused Products transmit a Probe Request frame to request Beacon Timing Information from a neighborhood station. | ¶68 | col. 51:27-32 |
Identified Points of Contention:
- Scope Questions: A central question may be whether the term "timing information concerning priority transmission" reads on the "Beacon Timing element" as defined in the IEEE 802.11 standard. The analysis may focus on whether the standard element's function of avoiding "Beacon frame collisions" (Compl. ¶67) is equivalent to managing "priority transmission" as described in the patent.
- Technical Questions: The court may need to determine if a standard "Probe Request frame" (Compl. ¶68) functions as a "message requesting a report of timing information" as required by the claim. The dispute could turn on whether the primary purpose of a probe request is to discover networks, with the receipt of timing information being an incidental result, or if it meets the claim's requirement of an explicit request for such information.
U.S. Patent No. 7,917,102 Infringement Allegations
| Claim Element (from Independent Claim 3) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A radio transmitting apparatus...comprising circuitry that forms a transmission frame which includes a frequency offset estimation signal...a channel fluctuation estimation signal for estimating channel fluctuation...and a gain control signal for performing gain control...and transmits the transmission frame | The Accused Products form and transmit an HT-mixed format PPDU frame. This frame allegedly comprises an L-LTF subframe as a frequency offset estimation signal, an HT-LTF subframe as a channel fluctuation estimation signal, and an L-STF subframe as a gain control signal. This functionality is depicted in a product brief for an accused device series (Compl. p. 33). | ¶¶88, 89 | col. 17:34-40 |
| wherein the transmission frame includes a first gain control signal and a second gain control signal | The HT-mixed format PPDU allegedly comprises a first gain control signal in the L-STF subframe and a second gain control signal in the HT-STF subframe. | ¶90 | col. 17:41-42 |
| the first gain control signal is arranged prior to the frequency offset estimation signal | The L-STF subframe (alleged first gain control signal) is arranged prior to the L-LTF subframe (alleged frequency offset estimation signal). | ¶90 | col. 17:43-45 |
| the second gain control is arranged subsequent to the frequency offset estimation signal and prior to the channel fluctuation estimation signal | The HT-STF subframe (alleged second gain control signal) is arranged subsequent to the L-LTF subframe (alleged frequency offset estimation signal) and prior to the HT-LTF subframe (alleged channel fluctuation estimation signal). | ¶90 | col. 17:46-50 |
Identified Points of Contention:
- Scope Questions: The infringement theory relies on mapping specific IEEE 802.11 subframes (L-STF, HT-STF) to the functional term "gain control signal." A likely point of contention will be whether the primary technical purpose of these standardized subframes is in fact "gain control," as opposed to other functions like synchronization or packet detection, which are also critical at the start of a transmission.
- Technical Questions: The analysis will raise the question of whether there is a functional distinction between the claimed signals. The claim separately recites a "gain control signal" and a "frequency offset estimation signal." If a defendant can show that the accused L-STF and L-LTF fields perform overlapping or indistinct functions, it may challenge the allegation that they satisfy separate and distinct claim limitations.
V. Key Claim Terms for Construction
For the ’130 Patent:
- The Term: "timing information concerning priority transmission"
- Context and Importance: The infringement allegation hinges on mapping this term to the standardized "Beacon Timing element." The construction of this term will determine whether standard mechanisms for collision avoidance in mesh networks fall within the scope of the claim, which is directed at enabling "priority transmission." Practitioners may focus on this term because it links the patent's core concept of prioritization to the accused product's standards-based functionality.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification discusses the overall goal of enabling "each communication station to evade mutual interference while performing communication securing a band by providing a prioritized utilization region" (’130 Patent, col. 1:35-41). This could support a reading where any timing data that helps a station secure a transmission slot without interference qualifies.
- Evidence for a Narrower Interpretation: The patent describes specific embodiments involving a "Transmission Prioritized Period (TPP)" that begins after a beacon is transmitted (’130 Patent, col. 22:35-44, FIG. 5). A narrower construction might limit the term to information that explicitly defines the start, end, or rules of such a formally designated priority period, as opposed to more general collision avoidance timing.
For the ’102 Patent:
- The Term: "gain control signal"
- Context and Importance: Claim 3 requires a specific sequence of signals, including two distinct "gain control signals." The complaint maps the IEEE 802.11 L-STF and HT-STF fields to these limitations. The viability of the infringement claim depends on whether these fields, which are known to have multiple functions (including synchronization), are properly construed as "gain control signals" in the context of this claim.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent's background explains that the invention aims to solve problems of "quantization error" (’102 Patent, col. 2:15), a problem directly related to receiver gain. This context may support interpreting any signal used by the receiver to adjust its gain as a "gain control signal."
- Evidence for a Narrower Interpretation: The claim itself distinguishes the "gain control signal" from the "frequency offset estimation signal" and "channel fluctuation estimation signal." A defendant may argue that since the L-STF is also used for synchronization and frequency offset correction, it cannot be solely a "gain control signal" as distinct from the other claimed signals, suggesting a narrower definition is required to preserve the distinctions made in the claim.
VI. Other Allegations
- Indirect Infringement: The complaint alleges induced infringement across all asserted patents, stating that Broadcom provides user manuals, advertisements, and technical support that instruct and encourage customers and end-users to operate the accused devices in an infringing manner. Contributory infringement is alleged on the basis that the accused components are especially made to practice the IEEE 802.11 standards, are a material part of the claimed inventions, and have no substantial non-infringing uses. (Compl. ¶¶74-76, 96-98).
- Willful Infringement: Willfulness is alleged based on Broadcom's purported knowledge of the asserted patents since at least November 3, 2021, via a notice letter from Redwood. The complaint also alleges knowledge based on the citation of asserted patents during the prosecution of Broadcom's own patent portfolio. The allegations state that Broadcom's continued infringement despite this knowledge is objectively reckless and constitutes willful infringement. (Compl. ¶¶73, 79, 95, 101).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional mapping and claim scope: can the functional language of the patent claims, such as "timing information concerning priority transmission" and "gain control signal," be construed to read on the specific, multi-purpose fields and protocols defined in the IEEE 802.11 standards (e.g., "Beacon Timing element," "L-STF")? The outcome may depend on whether the primary purpose of the standardized features aligns with the specific functions required by the claims.
- A key evidentiary question will be one of technical function versus standardization: given that the accused products operate by complying with public standards, the case will likely explore the relationship between the patented inventions and the standards themselves. The court may need to assess whether the patents claim novel technical solutions that were later adopted by the standard, or whether they claim methods that were already known or obvious contributions within the standard-setting process at the time of invention.
- A central validity question may revolve around enablement and written description for a broad range of technologies: the complaint accuses products compliant with standards from 802.11n through 802.11be. A question for the court could be whether the patent specifications, with priority dates as early as 2001, provide sufficient written description and enablement to cover the technical implementations in later, more advanced standards like Wi-Fi 6E and Wi-Fi 7.