DCT

4:25-cv-00428

Freedom Patents LLC v. Renesas Electronics Corp

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 4:25-cv-00428, E.D. Tex., 04/24/2025
  • Venue Allegations: Venue is alleged to be proper because the Defendant is a foreign corporation, which may be sued in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendant’s Wi-Fi 6 integrated circuits infringe three patents related to methods for selecting antennas in multiple-input, multiple-output (MIMO) wireless networks.
  • Technical Context: The technology concerns antenna selection in MIMO systems, a foundational technique for improving the performance and efficiency of modern wireless standards like Wi-Fi.
  • Key Procedural History: The complaint notes that the patented technology was developed by engineers at Mitsubishi Electric Research Laboratories (MERL) and that the patents have been cited during the prosecution of patent applications by numerous major electronics companies. No prior litigation or post-grant proceedings are mentioned.

Case Timeline

Date Event
2005-09-30 Earliest Priority Date for ’096 and ’815 Patents
2005-11-21 Earliest Priority Date for ’686 Patent
2012-10-09 U.S. Patent No. 8,284,686 Issues
2013-02-12 U.S. Patent No. 8,374,096 Issues
2013-08-20 U.S. Patent No. 8,514,815 Issues
2025-04-24 Complaint Filed

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

U.S. Patent No. 8,284,686 - "Antenna/Beam Selection Training in MIMO Wireless LANS with Different Sounding Frames," issued October 9, 2012

The Invention Explained

  • Problem Addressed: The patent’s background section describes that while using multiple antennas in MIMO wireless systems can increase capacity, it also increases hardware cost and complexity. Conventional methods for selecting a smaller, optimal subset of antennas to use at any given time were said to create undesirable overhead due to their signaling requirements. (’686 Patent, col. 1:19-52).
  • The Patented Solution: The invention provides a method where a wireless station receives a series of "sounding packets" to test different antenna subsets. The process is initiated and defined by a "high throughput (HT) control field" within a packet, which signals the start of the selection process and specifies the number of sounding packets to follow. The receiving station uses these packets to estimate the wireless channel's characteristics, creates a "channel matrix," and selects the best subset of antennas based on that matrix. (’686 Patent, Abstract; col. 4:1-17).
  • Technical Importance: This MAC-layer control mechanism was designed to make antenna selection more efficient in the context of emerging high-throughput Wi-Fi standards. (’686 Patent, col. 2:52-60).

Key Claims at a Glance

  • The complaint asserts independent claims 1 and 21 (Compl. ¶17).
  • Independent Claim 1 recites a method with the essential elements:
    • Receiving plural consecutive packets that include plural "sounding packets," where each corresponds to a different antenna subset.
    • At least one packet must include a "high throughput (HT) control field" containing a signal to initiate antenna selection and a number N indicating how many sounding packets will follow for the selection process.
    • Estimating a "channel matrix" based on the received N sounding packets.
    • Selecting a subset of antennas based on the channel matrix.
    • The claim further specifies receiving a "non-ZLF+HTC packet" followed by plural "zero length frame (ZLF) sounding packets" to carry out the process.

U.S. Patent No. 8,374,096 - "Method for Selecting Antennas and Beams in MIMO Wireless LANS," issued February 12, 2013

The Invention Explained

  • Problem Addressed: Similar to the ’686 Patent, this patent addresses the need for an efficient antenna selection mechanism in MIMO systems to reduce cost and complexity without incurring significant overhead from training procedures. (’096 Patent, col. 1:21-54).
  • The Patented Solution: The invention describes a method where a station receives multiple sounding packets, estimates the channel matrix for each corresponding antenna subset, and then sends a frame containing a high throughput (HT) control field. This control field initiates the final selection of an antenna subset based on the previously estimated channel matrices. The HT control field is also used to convey information such as the number of sounding packets used in the training. (’096 Patent, Abstract; col. 4:21-41).
  • Technical Importance: This method provides a MAC-layer framework for coordinating the estimation and selection phases of antenna training, allowing a station to trigger the selection after it has gathered the necessary channel information. (’096 Patent, col. 2:55-62).

Key Claims at a Glance

  • The complaint asserts independent claim 1 (Compl. ¶27).
  • Independent Claim 1 recites a method with the essential elements:
    • Receiving multiple transmitted "sounding packets," each for a different antenna subset.
    • Estimating a "channel matrix" for each antenna subset.
    • Sending a frame with a "high throughput (HT) control field" to initiate the selection of antennas based on the estimated matrices.
    • The claim further specifies that the HT control field includes a specific type of feedback field (MFB/ASBFC) that indicates the number of sounding packets.

Multi-Patent Capsule: U.S. Patent No. 8,514,815

  • Patent Identification: U.S. Patent No. 8,514,815, "Training Signals for Selecting Antennas and Beams in MIMO Wireless LANs," issued August 20, 2013.
  • Technology Synopsis: This patent discloses a computer-implemented method for antenna selection in a MIMO network. The method involves a first station sending a predetermined number of "sounding packets" to a second station, which receives them to perform the antenna selection training. The second station estimates a channel matrix from these packets and selects an optimal antenna subset accordingly. (’815 Patent, Abstract).
  • Asserted Claims: The complaint asserts independent claim 1 (Compl. ¶37).
  • Accused Features: The accused products are alleged to infringe by implementing the claimed method of transmitting and receiving sounding packets for antenna selection training in compliance with MIMO Wi-Fi standards (Compl. ¶¶ 36, 40).

III. The Accused Instrumentality

  • Product Identification: The complaint names the Renesas CL8040 Wi-Fi 6 Concurrent Dual Band 4T4R PCIe Chip as an exemplary accused product, along with other similar Renesas products that comply with the IEEE 802.11ax-2021 standard and implement MIMO Wi-Fi capabilities (Compl. ¶¶ 16, 26, 36).
  • Functionality and Market Context: The accused products are alleged to be highly integrated Wi-Fi 6 chips featuring a "4T4R MIMO architecture," meaning four transmit and four receive antennas (Compl. ¶6). A screenshot from the Defendant's website, included in the complaint, describes the CL8040 as a "high-performing, highly integrated Wi-Fi 6 (802.11ax) R2 single PCIe chip" (Compl. p. 5). The complaint alleges that Renesas is a major supplier of advanced semiconductors and that its Wi-Fi 6 technology provides advancements in efficiency and reduced congestion, which aligns with the stated goals of the patents-in-suit (Compl. ¶¶ 3, 19).

IV. Analysis of Infringement Allegations

The complaint references claim chart exhibits for each asserted patent but does not attach them (Compl. ¶¶ 17, 27, 37). The infringement theory is therefore based on the narrative allegations. The core of the Plaintiff's theory is that the accused products, by making, using, or selling products compliant with the IEEE 802.11ax standard, necessarily practice the methods claimed in the patents-in-suit (Compl. ¶¶ 16, 20, 26, 30). The complaint alleges that the products contain hardware and software components that cause them to perform the claimed steps—such as receiving sounding packets, estimating channel matrices, and selecting antennas—during testing and normal end-user operation (Compl. ¶¶ 20, 30, 40).

  • Identified Points of Contention:
    • Scope Questions: The patents were filed during the development of the IEEE 802.11n standard and use terminology specific to that context, such as "high throughput (HT) control field." A central legal question will be whether this term, as defined and used in the patents, can be construed to read on the different control field structures (e.g., "High Efficiency" or "HE" control fields) used in the later IEEE 802.11ax standard implemented by the accused products.
    • Technical Questions: The complaint alleges infringement based on standards compliance. This raises the technical question of whether the specific antenna selection protocols mandated or optionally implemented in the 802.11ax standard perform the exact sequence of steps required by the asserted claims. For example, the court will have to determine if the 802.11ax protocols require the specific packet exchange sequences detailed in claims like claim 1 of the ’686 Patent.

V. Key Claim Terms for Construction

  • The Term: "high throughput (HT) control field" (present in independent claims of both the ’686 and ’096 Patents)
  • Context and Importance: This term is critical because the claims require specific signaling for antenna selection to be carried within this field. The patents are rooted in the 802.11n standard, which introduced "High Throughput" (HT). The accused products implement the subsequent 802.11ax standard, which uses "High Efficiency" (HE) terminology. The case may turn on whether the accused HE control fields fall within the scope of the claimed "HT control field."
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification provides a functional description, stating the field "controls the fast link adaptation training process" and can be "incorporated into any MAC layer frame." (’686 Patent, col. 2:20-24). A party could argue this functional language is not limited to a specific standard.
    • Evidence for a Narrower Interpretation: The specification repeatedly links the term to the IEEE 802.11n standard, citing specific 802.11n draft proposals like "IEEE 802.11-05/1095r3." (’686 Patent, col. 2:29-33). A party could argue this explicitly tethers the term's meaning to the specific structures defined within the 802.11n development context.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges induced infringement, stating that Renesas took active steps with the specific intent to cause infringement by, among other things, "distributing instructions that guide users to use the accused products in an infringing manner" (Compl. ¶47). It also alleges inducement of affiliates and third-party manufacturers to infringe by importing and selling the accused products (Compl. ¶50).
  • Willful Infringement: The complaint alleges willfulness based on knowledge acquired "at least as of the date when it was notified of the filing of this action," supporting a theory of post-suit willfulness (Compl. ¶¶ 21, 31, 41). It also alleges pre-suit willful blindness, asserting that Renesas has a "policy or practice of not reviewing the patents of others" (Compl. ¶70).

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

  1. A core issue will be one of definitional scope: Can the term "high throughput (HT) control field," which is rooted in the lexicon of the IEEE 802.11n wireless standard, be construed to cover the "High Efficiency (HE)" control field structures implemented in the accused products, which operate under the later IEEE 802.11ax standard? The outcome of this claim construction dispute may be dispositive for infringement.

  2. A key evidentiary question will be one of standards mapping: The complaint's infringement theory rests on the accused products' compliance with the 802.11ax standard. The case will require a detailed technical analysis to determine if the mandatory or optional antenna selection procedures within the 802.11ax standard, as implemented by Renesas, align with the specific, multi-step methods recited in the asserted claims, or if there is a fundamental mismatch in technical operation.