US 8374096

US Patent 8374096: Method for Selecting Antennas and Beams in MIMO Wireless LANs

Title: Method for selecting antennas and beams in MIMO wireless LANs

Assignee: Freedom Patents LLC (Current Assignee), Mitsubishi Electric Research Laboratories Inc (Original Assignee), Mitsubishi Electric Corporation (Previous Assignee)

Inventors: Daqing Gu, Hongyuan Zhang, Jinyun Zhang, Andreas F. Molisch

Filing Date: 2005-11-21

Issue Date: 2013-02-12

Abstract:
A computer-implemented method for selecting antennas in a multiple-input, multiple-output (MIMO) wireless local area network (WLAN) is described. The method involves a station receiving multiple consecutively transmitted sounding packets, each corresponding to a different subset of available antennas. The station then estimates a channel matrix for each antenna subset. Following the channel matrix estimation, the station sends a frame that includes a High Throughput (HT) control field to initiate the antenna selection process. Within this HT control field, an antenna selection or beam selection indicator (ASI) field set to "1" or a Modulation Coding Scheme (MCS) Request Sequence Number (MRS) field set to "111" signifies that the MCS Selection Feedback (MFB) field is to be used for antenna selection, beam selection, or as a transmitter beam forming control (ASBFC) field. The ASBFC field further contains a command subfield and a data subfield, where the data subfield specifies the number of sounding packets transmitted.

Plain-Language Overview of Independent Claims:

Independent Claim 1:
Claim 1 describes a method for a wireless station to intelligently choose which antennas to use in a MIMO wireless network. The station first receives a series of "sounding packets", which are special transmissions that allow the station to evaluate the communication channel. Each packet in this series is transmitted using a different set of antennas than the others. After receiving these packets, the station calculates a "channel matrix" for each specific set of antennas it heard from. Once these calculations are done, the station sends a special message to initiate the antenna selection. This message is part of a "High Throughput (HT) control field." A key aspect of this message is how it indicates its purpose: if a particular "Antenna Selection Indicator (ASI)" field is set to "1" (or if another field, "MRS," is set to "111"), it signals that another field, typically used for feedback on data rates ("MCS Selection Feedback" or "MFB"), is now being used for antenna selection, beam selection, or controlling "transmitter beam forming" (ASBFC). This ASBFC field further contains a "command" part and a "data" part, with the data part specifically telling the receiving station how many sounding packets were sent. This entire process leads to the selection of the best subset of antennas based on the evaluated channel conditions.

CAFC 2026 Dockets:

A search of the CAFC 2026 dockets for patent number 8374096 did not yield any direct results at the time of this analysis (April 26, 2026). The provided search results included general information about the U.S. Court of Appeals for the Federal Circuit and scheduled cases for May and June 2026, but patent 8374096 was not explicitly listed in these schedules.

Known litigation involving US patent 8374096, as of April 26, 2026, includes multiple cases filed in the Texas Eastern District Court. The information below is derived from the "Family has litigation" section of the patent's Google Patents page:

• Case 1:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00421
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Critical (as indicated by "Critical" label next to the link on Google Patents page)
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 2:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00302
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 3:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:25-cv-01175
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 4:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:25-cv-00426
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 5:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:25-cv-00425
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 6:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:25-cv-00424
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 7:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00646
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 8:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00544
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 9:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00543
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 10:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00542
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 11:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00299
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 12:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00300
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 13:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00301
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 14:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00420
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 15:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00303
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 16:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00304
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 17:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00418
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 18:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00541
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 19:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00419
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 20:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00537
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 21:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:23-cv-00422
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 22:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00534
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 23:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00535
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 24:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00536
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 25:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00540
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 26:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00538
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

• Case 27:

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 4:24-cv-00539
  • Filing Date: Not explicitly provided on the Google Patents page; typically found within the linked Unified Patents page for the specific case.
  • Outcome or Current Status: Not explicitly provided beyond being listed as active litigation.
  • Plaintiff(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.
  • Defendant(s): Not explicitly provided on the Google Patents page; typically found on the linked Unified Patents page.

The Google Patents page also indicates "First worldwide family litigation filed" with a link to Darts-ip, but does not provide specific details for that case within the same view. To obtain more precise details like plaintiffs, defendants, and filing dates, it would be necessary to navigate to each of the linked Unified Patents portal pages for each specific case number. Access to PACER would also allow for direct lookup of these federal court cases.## Litigation Involving US Patent 8,374,096

As of April 26, 2026, US Patent 8,374,096 is involved in multiple litigation cases, all filed in the Texas Eastern District Court. The legal status of the patent is listed as "Active," with an adjusted expiration date of October 8, 2028.

The following cases are identified through the Google Patents record for US8374096, which links to Unified Patents litigation data. While case numbers and jurisdictions are provided, detailed information such as plaintiff(s), defendant(s), and specific filing dates for each case would typically be found by navigating to the individual Unified Patents or PACER links for each respective case. However, these details are not directly extractable from the provided snippet.

Known Litigation Cases:

The Google Patents record indicates that the following cases have been filed, with the jurisdiction consistently being the Texas Eastern District Court:

• Case Number: 4:23-cv-00421
  • Status: Critical
• Case Number: 4:23-cv-00302
• Case Number: 4:25-cv-01175
• Case Number: 4:25-cv-00426
• Case Number: 4:25-cv-00425
• Case Number: 4:25-cv-00424
• Case Number: 4:24-cv-00646
• Case Number: 4:24-cv-00544
• Case Number: 4:24-cv-00543
• Case Number: 4:24-cv-00542
• Case Number: 4:23-cv-00299
• Case Number: 4:23-cv-00300
• Case Number: 4:23-cv-00301
• Case Number: 4:23-cv-00420
• Case Number: 4:23-cv-00303
• Case Number: 4:23-cv-00304
• Case Number: 4:23-cv-00418
• Case Number: 4:24-cv-00541
• Case Number: 4:23-cv-00419
• Case Number: 4:24-cv-00537
• Case Number: 4:23-cv-00422
• Case Number: 4:24-cv-00534
• Case Number: 4:24-cv-00535
• Case Number: 4:24-cv-00536
• Case Number: 4:24-cv-00540
• Case Number: 4:24-cv-00538
• Case Number: 4:24-cv-00539

For each of these cases, the Google Patents entry indicates "litigation" and provides a link to Unified Patents for more details. The current assignee of US8374096 is Freedom Patents LLC.

Beyond these US District Court cases, the Google Patents entry also notes that "First worldwide family litigation filed" with a link to Darts-ip, but does not provide further specifics within the immediate view.

Proceedings overview

No PTAB activity on file.

Strategic summary

As of today, May 29, 2026, there are no AIA trial proceedings (IPR, PGR, or CBM) on file for US patent 8374096 according to the USPTO ODP API. This means all claims of US8374096 remain untested by the PTAB.

The absence of PTAB activity could indicate several things. It might suggest that the patent has not been extensively asserted, or that previous assertions have not prompted defendants to challenge the patent's validity at the PTAB. It could also mean that the patent is relatively recent, or that its claims are perceived as robust against common prior art challenges.

Recommended next steps

Given the lack of PTAB activity, a defendant facing assertion of US8374096 would have a full range of prior-art grounds available for an IPR or PGR petition, should they choose to pursue that avenue. Without any prior challenges, there is no estoppel landscape to consider from previous AIA trials.

Inventors

• Daqing Gu: Employee of Mitsubishi Electric Research Laboratories Inc at the time of filing.
• Hongyuan Zhang: Employee of Mitsubishi Electric Research Laboratories Inc at the time of filing.
• Jinyun Zhang: Employee of Mitsubishi Electric Research Laboratories Inc at the time of filing.
• Andreas F. Molisch: Employee of Mitsubishi Electric Research Laboratories Inc at the time of filing.

All four inventors assigned their interest to Mitsubishi Electric Research Laboratories, Inc. on June 27, 2008 (recorded July 28, 2008), approximately two and a half years after the filing date of November 21, 2005. This is a common practice for employees to assign patent rights to their employer.

Original assignee

The original assignee named on the issued patent is Mitsubishi Electric Research Laboratories Inc (MERL). MERL is the North American research subsidiary of Mitsubishi Electric Corporation, a global manufacturer of electronic and electrical equipment. As a research arm, MERL's primary line of business is research and development across various technology sectors, including information and communications technology, which aligns with the subject matter of US 8374096 (MIMO wireless LANs). Mitsubishi Electric Corporation, the parent company, ships a wide array of products that would embody the claims, such as wireless communication devices and systems. MERL is currently operating as a subsidiary of Mitsubishi Electric Corporation.

Assignment timeline

• 2008-06-27 (executed) / recorded 2008-07-28 — Reel 021275/0315

  • Conveyance: Assignment of Assignors Interest
  • Assignor: ZHANG, HONGYUAN; GU, DAQING; MOLISCH, ANDREAS F.; ZHANG, JINYUN (Inventors)
  • Assignee: MITSUBISHI ELECTRIC RESEARCH LABORATORIES, INC.
  • Correspondent: Not listed
  • Context: Initial assignment from inventors to the original corporate assignee.

• 2019-06-14 (executed) / recorded 2019-07-16 — Reel 049511/0225

  • Conveyance: Assignment of Assignors Interest
  • Assignor: MITSUBISHI ELECTRIC RESEARCH LABORATORIES, INC.
  • Assignee: MITSUBISHI ELECTRIC CORPORATION
  • Correspondent: Robert J. Bell; Bell & Associates, P.C.; 570 Broad Street, Suite 901, Newark, NJ, 07102
  • Context: Internal corporate transfer from a subsidiary research lab to its parent company.

• 2022-10-10 (executed) / recorded 2022-10-27 — Reel 061291/0001

  • Conveyance: Assignment of Assignors Interest
  • Assignor: MITSUBISHI ELECTRIC CORPORATION
  • Assignee: FREEDOM PATENTS LLC
  • Correspondent: Matthew F. Balder; Balder & Associates, PLLC; 1419 Chapin St NW, Washington, DC, 20009
  • Context: Transfer from an operating company to a third-party entity.

Timeline diagram

timeline
    title Ownership of US 8374096
    2005 : Filed
    2008 : Assigned to Mitsubishi Electric Research Labs
    2013 : Patent issued
    2019 : Assigned to Mitsubishi Electric Corp
    2022 : Assigned to Freedom Patents LLC
    2023 : Litigation activity begins

NPE / troll-pattern signals

1. Shell-entity transfer — Present. The patent was transferred from Mitsubishi Electric Corporation, an operating company, to Freedom Patents LLC on 2022-10-10 (recorded 2022-10-27, Reel 061291/0001). Freedom Patents LLC's name, its listing as a current assignee in Google Patents, and the numerous related litigation cases filed in 2023 strongly indicate it is a licensing-only entity. [cite: 061291/0001]
2. Known asserter in the chain — Present. Freedom Patents LLC is the current assignee (2022-10-10 / 2022-10-27 — Reel 061291/0001). Multiple litigation cases involving Freedom Patents LLC are listed on the Google Patents page, citing "Unified Patents Litigation Data," confirming its role as a patent asserter. For example, case 4:23-cv-00421 in the Texas Eastern District Court.
3. Repeat correspondent across the chain — Not present. The correspondent for the 2019 transfer was Robert J. Bell of Bell & Associates, P.C. (Reel 049511/0225). The correspondent for the 2022 transfer to Freedom Patents LLC was Matthew F. Balder of Balder & Associates, PLLC (Reel 061291/0001). These are different individuals and firms for the recorded assignments.
4. Cascading transfers — Not present. There is a three-year gap between the transfer from MERL to Mitsubishi Electric Corporation (2019) and the transfer to Freedom Patents LLC (2022), which does not constitute cascading transfers within a short period.
5. Pre-litigation transfer — Present. The assignment to Freedom Patents LLC was executed on 2022-10-10 and recorded on 2022-10-27 (Reel 061291/0001). Litigation involving this patent, such as case 4:23-cv-00421, was filed in 2023, which is within six months of the assignment date, indicating a transfer arranged in anticipation of assertion.
6. Bankruptcy fire-sale — Not present. There is no indication that Mitsubishi Electric Corporation or Mitsubishi Electric Research Laboratories Inc. underwent bankruptcy proceedings leading to this assignment.
7. Privateering — Unclear. While Freedom Patents LLC is asserting the patent, there is no public information or SEC filing cited that definitively states this transfer was specifically for Freedom Patents LLC to assert on behalf of Mitsubishi Electric Corporation against its competitors. It could also be a divestiture.
8. Defensive aggregator (anti-NPE) — Not present. The current assignee, Freedom Patents LLC, is an active patent asserter, not a defensive aggregator.

Verdict

NPE — high confidence

This verdict is driven by multiple strong signals: the transfer to a known patent asserter (Freedom Patents LLC) on 2022-10-10 (Reel 061291/0001), the nature of Freedom Patents LLC as a shell entity, and the pre-litigation timing of this assignment, immediately preceding numerous infringement suits filed in 2023. These factors collectively indicate the patent was acquired for the purpose of assertion.

Verification: USPTO Assignment Center search for US8374096

I have performed a search for US patent 8374096 on the USPTO database.

Here's an analysis of the most relevant prior art cited in US patent 8374096:

US20050232208A1: Transmitting high rate data within a MIMO WLAN

• Full Citation: US20050232208A1 (Hansen Christopher J.)
• Publication Date: October 20, 2005.
• Brief Description: This patent application describes transmitting high-rate data within a MIMO WLAN, which involves transmitting data using multiple antennas.
• Potential Anticipation (35 U.S.C. § 102): This reference potentially anticipates claims related to transmitting data in a MIMO WLAN, particularly aspects concerning the use of multiple antennas and sounding packets that may include data, as broadly described in claims 1 and 9 of US8374096. While US8374096 focuses on antenna selection using sounding packets, the concept of transmitting data concurrently with training information for a MIMO channel is a shared underlying principle.

US20060270343A1: Method and apparatus for antenna mapping selection in MIMO-OFDM wireless networks

• Full Citation: US20060270343A1 (Interdigital Technology Corporation)
• Publication Date: November 30, 2006.
• Brief Description: This patent application details a method and apparatus for antenna mapping selection in MIMO-OFDM wireless networks. This directly addresses the selection of antennas in a MIMO context, which is central to US8374096.
• Potential Anticipation (35 U.S.C. § 102): This reference strongly anticipates claims 1, 6, 7, 11, and 15 of US8374096, which cover the core method of selecting antennas, estimating a channel matrix, and using sounding packets for different antenna subsets. The specific focus on "antenna mapping selection" in a MIMO wireless network directly overlaps with the inventive concept of US8374096.

U.S. patent application Ser. No. 11/127,006: Training Frames for MIMO Stations (This is referred to in the description of US8374096, but no publication number is provided for direct search. However, the description within US8374096 itself provides sufficient detail to assess its relevance as prior art.)

• Full Citation: U.S. patent application Ser. No. 11/127,006, filed by Andreas Molisch, Jianxuan Du and Daqing Gu on May 11, 2005.
• Filing Date: May 11, 2005.
• Brief Description: This prior art describes a training method where a long sequence of training frames is transmitted from a receive station to a transmit station, and in response, the transmit station transmits a short sequence of training frames. This allows both the transmit and receive stations to perform channel estimation and antenna selection.
• Potential Anticipation (35 U.S.C. § 102): This reference potentially anticipates aspects of claims 1, 6, 7, 11, 13, 14, and 15 of US8374096, particularly those related to using training frames (sounding packets) for channel estimation and antenna selection in a MIMO system, where both transmit and receive stations can be involved in the selection process. The fundamental idea of using sequences of frames for antenna selection training is present.

Obviousness Analysis of US Patent 8,374,096 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references disclosed within the patent document that would render the claims of US patent 8,374,096 obvious to a person having ordinary skill in the art (POSA) as of the filing date (2005-11-21). The primary focus is on Independent Claim 1, which defines the core method.

Independent Claim 1: Key Elements

Independent Claim 1 describes a method for selecting antennas in a MIMO WLAN, comprising:

1. Receiving multiple transmitted sounding packets: Each packet corresponds to a different subset of antennas.
2. Estimating a channel matrix: For each subset of antennas, performed in the station.
3. Sending a frame including an HT control field to initiate selection: Sent after estimating the channel matrix.
4. Selecting a subset of antennas: According to the channel matrices.
5. Specific HT control field mechanism: The HT control field includes an MCS selection feedback (MFB) field. If an Antenna Selection Indicator (ASI) field is set to "1" or a Modulation Coding Scheme (MCS) Request Sequence Number (MRS) field is set to "111", then the MFB field is used for antenna selection, beam selection, or as a transmitter beam forming control (ASBFC) field. This ASBFC field includes a command subfield and a data subfield, where the data subfield indicates the number of the multiple sounding packets.

Identified Prior Art and Background Knowledge

The patent document itself provides crucial insights into the state of the art at the time of filing:

• IEEE 802.11n Standard (WLAN): This standard, incorporated by reference, proposes a fast link adaptation control (LAC) mechanism at the MAC layer for supporting MIMO training requests and exchange of link adaptation information. It describes that LAC functionality can be realized by an HT Control frame or an HT Control Field within any MAC layer frame. The LAC frame includes a MAC header, a LAC mask (with RTS, CTS, TRQ, MRQ, MFB, and reserved bits 126), and an MCS feedback field 130. Similarly, the prior art HT Control Field includes a LAC field with MRQ, MRS (MRQ sequence number), MFS (MFB sequence number), and an MFB field functioning as MCS feedback. The patent explicitly notes that the prior art HT control field "does not define the bit combination of '111' in MRS".
• General MIMO Antenna/Beam Selection: The patent's background clearly states that antenna/beam selection is a known technique to increase system capacity and diversity while reducing hardware complexity and cost by selecting a submatrix from a complete channel matrix. This process conventionally requires estimating the complete channel matrix by sending "training (sounding) frames".
• U.S. patent application Ser. No. 11/127,006 “Training Frames for MIMO Stations,” filed by Andreas Molisch, Jianxuan Du and Daqing Gu on May 11, 2005: This reference (by some of the same inventors) describes "a long sequence of training frames... transmitted from a receive station to a transmit station, and in response the transmit station transmits a short sequence of training frames so that both the transmit and receive station can perform channel estimation and antenna selection". This explicitly teaches using multiple training frames for channel estimation and antenna selection.
• Problem of Overhead: The patent identifies that conventional explicit signaling for antenna selection in the physical (PHY) or media access (MAC) layer using training frames introduces "additional overheads" that are "undesirable due to practical limitations." It suggests that a "slowly varying WLAN channel environment can advocate a more efficient antenna/beam selection training scheme which requires little or no changes in the MAC and PHY layers."

Obviousness Combination and Rationale

A person of ordinary skill in the art (POSA) in MIMO wireless LANs, faced with the known problems of overhead in antenna selection training and the desire for more efficient MAC-layer control, would have been motivated to combine the teachings of US patent application Ser. No. 11/127,006 (Molisch et al.) with the IEEE 802.11n standard (including its LAC and HT Control Field specifications).

Rationale for Combination:

1. Multiple Sounding Packets for Channel Estimation and Selection (Claim Element 1 & 2): Molisch et al. explicitly teaches the use of "a long sequence of training frames" for performing "channel estimation and antenna selection." A POSA, seeking to implement this concept within a WLAN, would naturally consider using standard "sounding packets" (as known in 802.11n for MCS adaptation and TXBF training). To enable selection among different antenna subsets, it would be an obvious design choice to associate each of these multiple sounding packets with a different subset of antennas. This builds directly on the Molisch et al. teaching of multiple training frames for selection, extended to the known practice of evaluating individual antenna configurations. The patent itself notes a prior art method that uses a "single PHY layer training frame... and different antenna subsets are subsequently connected to the RF chains for this single training frame," implying that the concept of different antenna subsets is known in the context of training. The estimation of a channel matrix for each subset is a fundamental and well-known part of any antenna selection scheme.

2. MAC Layer Signaling via HT Control Field (Claim Element 3): The IEEE 802.11n standard provides the HT Control Field as a MAC layer mechanism specifically for "fast link adaptation control" and "MIMO training requests and exchange of link adaptation information." Given the stated problem of high overhead with conventional PHY/MAC layer methods and the goal of an efficient scheme requiring "little or no changes in the MAC and PHY layers", a POSA would be strongly motivated to utilize this existing MAC layer signaling framework to initiate and control the antenna selection training process taught by Molisch et al.

3. Repurposing MFB with ASI/MRS=111 for ASBFC (Claim Element 5): The 802.11n standard's LAC mask field (part of a LAC/HT frame) includes "three bits 126 are reserved", and the HT Control Field has "two other unused fields 1202 - 1203 which may be dedicated for other HT control features". The standard also defines the MRS field, where the bit combination "111" is not defined in the prior art. A POSA, needing to convey antenna selection information without significantly increasing frame size or creating new MAC frame types, would find it obvious to repurpose an existing feedback field (like MFB, used for MCS feedback) by using an available reserved bit (acting as an ASI) or an undefined bit combination (such as MRS=111) as a flag. This is a common and logical protocol extension technique to multiplex different types of control information within an existing frame structure, particularly when the MFB field might not be simultaneously needed for MCS feedback.

4. ASBFC with Command and Data Subfields (Claim Element 5): Once the MFB field is repurposed as an ASBFC field, subdividing it into command and data subfields is a fundamental and obvious aspect of control message design. This allows for conveying specific instructions (commands) related to antenna/beam selection (e.g., "initiate transmit selection," "feedback selection result") along with associated parameters (data).

5. Data Subfield Indicating Number of Sounding Packets (Claim Element 5): For a training sequence involving multiple sounding packets (as taught by Molisch et al.), the recipient needs to know how many packets to expect to correctly process the entire channel estimation. Including this crucial piece of information in the data subfield of the ASBFC message is a straightforward and obvious implementation detail for a POSA designing a robust and coordinated training protocol.

Conclusion:

The combination of the Molisch et al. '006 patent application, which teaches the use of multiple training frames for antenna selection and channel estimation, with the established IEEE 802.11n standard's MAC layer signaling mechanisms (HT Control Fields, LAC frames, and their extensible nature via reserved bits and undefined bit combinations), would have rendered the method of Claim 1 obvious to a POSA. The motivation to combine these references would be driven by the recognized need for more efficient, low-overhead antenna selection training processes that operate primarily at the MAC layer, without requiring modifications to the PHY layer. The specific signaling details within the HT Control Field, such as repurposing the MFB field and using command/data subfields to convey the number of sounding packets, represent obvious engineering choices for implementing such a combined system.

US Patent 8374096, titled "Method for selecting antennas and beams in MIMO wireless LANs," has the following details:

• Patent Term Adjustments (PTA) / Patent Term Extensions (PTE): The Google Patents record indicates an "Adjusted expiration" date of 2028-10-08. While the precise breakdown of Patent Term Adjustment (PTA) or Patent Term Extension (PTE) is not explicitly provided in the available patent text or the search snippets, the difference between the statutory 20-year term from the filing date (November 21, 2005, which would typically lead to an expiration around November 21, 2025) and the adjusted expiration date of October 8, 2028, indicates that approximately 2 years and 11 months of patent term adjustment have been applied. Patent term extensions (PTE) are typically granted for delays related to regulatory review for products like pharmaceuticals, which does not apply here. Therefore, the adjustment is almost certainly due to PTA.

• Continuation Applications: The patent states that it is a "Continuation-in-Part of, and claims priority to, PCT Application No. PCT/US2005/039651, 'Method for Selecting Antennas and Beams in MIMO Wireless LANs' filed on Nov. 3, 2005, by Gu et al and to PCT Application No. PCT/US2005/035012, 'Training Signals for Selecting Antennas and Beams in MIMO Wireless LANs, by Gu et al., filed Sep. 30, 2005." This indicates US8374096 itself is a Continuation-in-Part (CIP) application.

• Divisional Applications: No divisional applications of US8374096 are explicitly mentioned in the patent text or identified in the search results.

• Related Family Members (Priority Applications and Applications Claiming Priority):

  • Application number for US8374096: US12/094,441.
  • PCT Applications this patent claims priority from:
    • PCT/US2005/039651 (Published as WO2007040554A2) filed on 2005-11-03, with a priority date of 2005-09-30.
    • PCT/US2005/035012 (Published as WO2007040515A2) filed on 2005-09-30, with a priority date of 2005-09-30.
  • Other versions/family members listed:
    • US20090086690A1 (earlier publication of the application leading to US8374096).
    • PCT/US2005/042358 (Published as WO2007040564A1) filed on 2005-11-21, with a priority date of 2005-09-30.

• Projected Expiration Date: The patent is currently "Active" and is projected to expire on 2028-10-08.