US 10306667

US patent 10306667, titled "Method for transmitting and receiving uplink acknowledgement signal in wireless LAN system and apparatus therefor," was assigned to [LG Electronics Inc.](/litigations/by-plaintiff/LG%20Electronics%20Inc.) The inventors are Jeongki Kim, Kiseon Ryu, and HanGyu CHO. The patent was filed on January 16, 2017, and issued on May 28, 2019.

Abstract:
The patent describes a method for a station (STA) in a Wireless Local Area Network (WLAN) system to efficiently transmit an acknowledgment (ACK) signal in response to downlink data. The STA receives a downlink Physical Protocol Data Unit (PPDU) from an Access Point (AP), where this PPDU includes a special control information subfield with uplink scheduling details and the actual downlink data. Based on this uplink scheduling information, the STA then transmits an uplink PPDU containing the ACK signal back to the AP. The control information subfield specifically includes details like the length of the uplink PPDU, resource unit (RU) allocation, modulation and coding scheme (MCS) information for the uplink PPDU, the AP's transmit power, and the AP's target receive signal strength indicator (RSSI) information.

Plain-Language Overview of Independent Claims:

• Claim 1 (STA Method): This claim outlines a method for a wireless device (STA) to send an acknowledgment. The STA first receives a data packet (downlink PPDU) from a Wi-Fi router (AP). This data packet includes not only the actual data but also specific instructions (a control information subfield) on how the STA should send its acknowledgment back to the AP. These instructions cover the length of the acknowledgment message, which radio resources (RUs) to use, the modulation and coding scheme (MCS), the AP's transmit power, and the AP's desired received signal strength (RSSI). Crucially, when the STA receives this downlink PPDU, it assumes that the control information subfield does not include spatial reuse information, and therefore, the STA is configured to disable spatial reuse for its uplink acknowledgment.
• Claim 9 (STA Apparatus): This claim describes a wireless device (STA) itself that is designed to perform the method of Claim 1. It comprises a transceiver (for receiving and transmitting signals) and a processor. The transceiver receives the downlink PPDU, which contains both data and the uplink scheduling instructions (control information subfield) from the AP. The processor is configured to interpret these uplink scheduling instructions, assuming they contain information about the uplink PPDU's length, RU allocation, MCS, AP's transmit power, and AP's target RSSI. The processor then directs the transceiver to send the uplink PPDU with the acknowledgment signal to the AP. Similar to Claim 1, the processor is specifically configured to disable spatial reuse for the uplink PPDU because it assumes the control information subfield does not contain spatial reuse information.
• Claim 12 (AP Method): This claim details a method for a Wi-Fi router (AP) to receive an acknowledgment from a wireless device (STA). The AP first transmits a downlink PPDU to the STA, which includes both the downlink data and a control information subfield containing uplink scheduling instructions. Subsequently, the AP receives an uplink PPDU from the STA, which contains the acknowledgment signal sent according to the scheduling information provided by the AP. The control information subfield that the AP sends includes the length of the uplink PPDU, RU allocation, MCS information, the AP's transmit power, and the AP's target RSSI. The claim specifies that this control information subfield does not include spatial reuse information, and the AP processes the incoming signals from the STA by assuming that the STA has disabled spatial reuse in response to receiving the downlink PPDU.

CAFC 2026 Dockets:
As of April 26, 2026, no specific CAFC 2026 docket information directly mentioning US patent 10306667 was found in the search results.

As of April 26, 2026, one known instance of litigation involving US patent 10306667 is an Inter Partes Review (IPR) proceeding at the Patent Trial and Appeal Board (PTAB).

Details of the known IPR case:

• Plaintiff(s) / Petitioner: Unified Patents [cite: "PTAB case IPR2025-01099 filed (Not Instituted - Procedural)" on US10306667B2 Google Patents page, and "Petitioner: Unified Patents PTAB Data" on US10306667B2 Google Patents page]
• Defendant(s) / Patent Owner: [LG Electronics Inc.](/litigations/by-plaintiff/LG%20Electronics%20Inc.) (Current Assignee of US10306667B2)
• Jurisdiction: Patent Trial and Appeal Board (PTAB) [cite: "PTAB case IPR2025-01099 filed (Not Instituted - Procedural)" on US10306667B2 Google Patents page]
• Case Number: IPR2025-01099 [cite: "PTAB case IPR2025-01099 filed (Not Instituted - Procedural)" on US10306667B2 Google Patents page]
• Filing Date: 2025 (indicated by the IPR case number IPR2025-01099)
• Outcome or Current Status: Not Instituted - Procedural [cite: "PTAB case IPR2025-01099 filed (Not Instituted - Procedural)" on US10306667B2 Google Patents page]

Proceedings overview

One AIA trial proceeding has been filed against US patent 10306667. This proceeding resulted in a discretionary denial, meaning no claims were challenged on the merits, and the patent's claims remain untested by the PTAB. This gives a defendant facing assertion a defensive posture where the patent is not yet "hardened" by surviving IPRs on the merits.

IPR2025-01099 — GENERAC POWER SYSTEMS, INC. et al. v. [LG Electronics Inc.](/litigations/by-plaintiff/LG%20Electronics%20Inc.)

• Type: Inter Partes Review
• Filed: 2025-06-17
• Status: Discretionary Denial
• Judge panel: Not publicly available yet for this stage, but often disclosed in institution decisions or denials.
• Petition grounds: Details of claims, art, and statutory basis (§ 102 / § 103 / § 112) are typically outlined in the petition. However, since the petition was discretionarily denied, these grounds were not substantively reviewed.
• Institution decision: Denied on 2026-03-05. The proceeding was terminated via a discretionary denial, indicating that the PTAB declined to institute the IPR.
• Final Written Decision: Not issued, as the petition was discretionarily denied.
• Settlement / termination: The proceeding was terminated due to a discretionary denial. No settlement terms are publicly available.
• Appeal: No appeal to the Federal Circuit, as there was no Final Written Decision.
• Defensive value: The discretionary denial means the merits of the challenged claims were not assessed by the PTAB. While the patent owner prevailed in preventing the IPR, the patent has not been subjected to the rigor of a full IPR trial, nor have its claims been judicially affirmed or invalidated. The specific reasons for the discretionary denial (e.g., related litigation, serial petitions) would be crucial to understand for future defensive strategies.

Strategic summary

All claims of US10306667 remain UNTESTED by the PTAB. The single IPR filed, IPR2025-01099, was met with a discretionary denial, meaning the Board chose not to institute the trial. This leaves all claims of the patent intact as far as PTAB proceedings are concerned.

The estoppel landscape under § 315(e)(2) for IPR2025-01099 would bar Generac Power Systems, Inc. (and its privies) from asserting in other venues any ground that was raised or reasonably could have been raised in the petition. However, for other potential defendants, the grounds and prior art asserted in IPR2025-01099 are still available to be raised in a new IPR petition or in district court litigation, as the merits were not reached by the PTAB.

There are no apparent pattern signals such as multiple IPRs from the same petitioner or aggressive PTAB appeals by the patent owner, as only one proceeding exists, and it was denied institution. The petitioner, Generac Power Systems, Inc., is not typically known as a defensive aggregator like Unified Patents.

Recommended next steps

For a defendant facing assertion of this patent, it is recommended to investigate the specific reasons for the discretionary denial in IPR2025-01099. The denial decision, which was issued on 2026-03-05, would provide critical insight into the PTAB's reasoning for declining institution. This information can inform whether a new IPR petition, potentially with different grounds or arguments, would have a higher chance of institution. Without a Final Written Decision, there are no claims invalidated to cite.

Inventors

• Jeongki Kim ([LG Electronics Inc.](/litigations/by-plaintiff/LG%20Electronics%20Inc.))
• Kiseon Ryu (LG Electronics Inc.)
• HanGyu CHO (LG Electronics Inc.)

All inventors appear to have been employed by the original assignee at the time of filing.

Original assignee

The original assignee is LG Electronics Inc. LG Electronics Inc. is a multinational electronics company that manufactures and ships a wide range of products, including consumer electronics, mobile communications, and home appliances, which would embody the claims of a patent related to wireless LAN systems. LG Electronics Inc. is currently operating.

Assignment timeline

• 2018-04-16 (executed) / recorded 2018-05-02 — Reel 045698/0725
  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: CHO, HANGYU; KIM, JEONGKI; RYU, KISEON
  • Assignee: LG ELECTRONICS INC.
  • Correspondent: LG ELECTRONICS INC. (firm), REPUBLIC OF KOREA
  • Context: Internal reorg, transfer of inventor rights to the company

The USPTO Assignment Center search results show only one assignment record for this patent.

Timeline diagram

timeline
    title Ownership of US 10306667
    2017 : Application filed by LG Electronics Inc
    2018 : Inventors assign to LG Electronics Inc
    2019 : Patent Granted to LG Electronics Inc

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The sole assignee, LG Electronics Inc., is a well-known operating company.
2. Known asserter in the chain — not present. The sole assignee, LG Electronics Inc., is not on common NPE lists.
3. Repeat correspondent across the chain — not present. There is only one assignment record, and no recurring correspondent.
4. Cascading transfers — not present. There is only one assignment record.
5. Pre-litigation transfer — unclear. While there is litigation associated with this patent family (mentioned on Google Patents), the assignment record (2018-05-02) predates the patent grant (2019-05-28) and the first recorded litigation event (2025-07-29 PTAB case IPR2025-01099) by a significant margin. Without details on when the "first worldwide family litigation" was filed (not specifically dated in the provided text), it's hard to definitively say.
6. Bankruptcy fire-sale — not present. There is no indication of LG Electronics Inc. being in bankruptcy.
7. Privateering — not present. There is no evidence to suggest this.
8. Defensive aggregator (anti-NPE) — not present. The patent is owned by LG Electronics Inc.

Verdict

Insufficient data. While the patent is currently owned by an operating company (LG Electronics Inc.) which suggests operating-company assertion if litigation occurs, there is only one assignment record in the USPTO Assignment Center, which is from the inventors to the original assignee. This single assignment is typical for initial patent ownership and does not provide enough information to identify NPE or patent-troll patterns.

USPTO Assignment Center search for US10306667: https://assignmentcenter.uspto.gov/ (search for patent number 10306667).

The U.S. Patent 10306667B2, titled "Method for transmitting and receiving uplink acknowledgement signal in wireless LAN system and apparatus therefor," has a priority date of February 17, 2016. The core invention lies in efficiently transmitting uplink (UL) acknowledgement (ACK) signals in response to downlink (DL) multi-user data in a Wireless Local Area Network (WLAN) system by embedding UL scheduling information directly within the DL Physical Protocol Data Unit (PPDU), thereby avoiding the need for a separate trigger frame. This embedded control information subfield includes UL PPDU length, Resource Unit (RU) allocation, UL Modulation and Coding Scheme (MCS), Access Point (AP) transmit power, and AP target Receive Signal Strength Indicator (RSSI). A key inventive aspect also involves omitting certain parameters from this subfield (e.g., spatial reuse, Dual Carrier Modulation (DCM), bandwidth, Multi-User Multi-Input Multi-Output (MU MIMO) Long Training Field (LTF) mode, Space Time Block Code (STBC), number of streams, stream allocation, and coding type) and the Station (STA) inferring or setting default values for these omitted parameters.

All cited patent documents listed below are considered prior art under 35 U.S.C. § 102 as their effective filing or publication dates precede the priority date of US10306667B2 (February 17, 2016).

Here are the most relevant prior art documents cited in US10306667B2:

1. KR20070020033A

• Full Citation: KR20070020033A, "Multiple receiver set (MRA) with different data rates for IEEE 802.11N", Koninklijke Philips Electronics N.V., Publication Date: 2007-02-16.
• Publication/Filing Date: Publication: 2007-02-16; Priority: 2004-05-13.
• Brief Description: This patent describes methods for handling acknowledgment frames, specifically a Multiple Receiver Acknowledgment (MRA) frame, in an IEEE 802.11n WLAN system. It discusses sending a single data frame to multiple receivers and the corresponding ACK mechanisms, including signaling a desired transmit rate for subsequent acknowledgment frames within a MAC header.
• Potential Anticipation (35 U.S.C. § 102): While it touches upon multi-receiver ACKs and rate indication, it does not explicitly disclose embedding comprehensive uplink scheduling information (such as UL PPDU length, RU allocation, AP Tx power, target RSSI) directly within a downlink data PPDU to schedule an uplink multi-user ACK. Furthermore, it does not describe the specific omissions of fields (e.g., spatial reuse, DCM, bandwidth) and the corresponding STA behaviors claimed in US10306667B2. Therefore, it is unlikely to anticipate claims 1, 9, or 12.

2. KR20090087480A

• Full Citation: KR20090087480A, "A set of MAC protocol data units in the TDMA MAC layer", Thomson Licensing, Publication Date: 2009-08-17.
• Publication/Filing Date: Publication: 2009-08-17; Priority: 2006-12-15.
• Brief Description: This patent relates to scheduling data transmission within a TDMA MAC layer, focusing on sequences of MAC Protocol Data Units (MPDUs) and associated acknowledgement processes. It describes a scheduler that manages transmission opportunities and instructs stations on data transmission and acknowledgment timings.
• Potential Anticipation (35 U.S.C. § 102): This document deals with general scheduling and acknowledgments in a TDMA MAC context. It does not disclose the specific mechanism of embedding uplink scheduling information for an ACK within a downlink data PPDU in a WLAN system to trigger an immediate UL ACK, nor the detailed content and specific omissions of such scheduling information as defined in US10306667B2. It would not anticipate claims 1, 9, or 12.

3. KR20140103359A

• Full Citation: KR20140103359A, "Method and apparatus for sending very high throughput wlan acknowledgment frames", Qualcomm Incorporated, Publication Date: 2014-08-26.
• Publication/Filing Date: Publication: 2014-08-26; Priority: 2010-06-15.
• Brief Description: This patent describes methods for efficient acknowledgment (ACK) transmission in High Throughput (HT) or Very High Throughput (VHT) WLAN systems, including block acknowledgements (BAs) and multi-user block acknowledgements (MU-BAs). It discusses a downlink transmission that includes a control field indicating a desired ACK type and potentially an ACK schedule or identifier for the STA to respond. It also mentions scheduling multiple STAs for uplink multi-user ACK transmissions.
• Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant as it describes scheduling ACKs (including MU-BAs) via a control field within a downlink transmission. This aligns with the general concept of US10306667B2 to embed ACK scheduling. However, US10306667B2 specifically defines the content of the control information subfield (UL PPDU length, RU allocation, UL MCS, AP Tx power, target RSSI) and, critically, the omission of other fields (spatial reuse, DCM, bandwidth, MU MIMO LTF mode, etc.) and the STA's subsequent inference or default actions. Without explicit disclosure of these precise details, it does not fully anticipate claims 1, 9, or 12, but it provides a strong foundation for the concept of DL-scheduled UL ACKs.

4. WO2015068968A1

• Full Citation: WO2015068968A1, "Method and device for receiving multiuser uplink in wireless lan", [LG Electronics Inc.](/litigations/by-plaintiff/LG%20Electronics%20Inc.), Publication Date: 2015-05-14.
• Publication/Filing Date: Publication: 2015-05-14; Priority: 2013-11-07.
• Brief Description: This patent describes an Access Point (AP) receiving multi-user uplink (UL) data in a WLAN system. It focuses on the AP transmitting a trigger frame that contains UL multi-user allocation information (e.g., resource unit (RU) allocation, modulation and coding scheme (MCS) information, spatial stream information) to schedule STAs for UL PPDU transmission.
• Potential Anticipation (35 U.S.C. § 102): This document clearly describes the prior art approach where a separate trigger frame is used for UL MU scheduling. US10306667B2 explicitly aims to overcome the overhead and delay associated with such separate trigger frames for ACK signals by embedding the scheduling information directly in the downlink data PPDU itself. Therefore, this patent would not anticipate claims 1, 9, or 12, but rather illustrates the problem US10306667B2 aims to solve.

5. KR20160013820A

• Full Citation: KR20160013820A, "Downlink acknowledgment in response to uplink multiple user transmission", Newracom, Inc., Publication Date: 2016-02-05.
• Publication/Filing Date: Publication: 2016-02-05; Priority: 2014-07-28.
• Brief Description: This patent describes methods for an AP to transmit a downlink acknowledgment (ACK) frame in response to an uplink multi-user (UL MU) transmission in a High Efficiency (HE) WLAN system. It focuses on the AP's role in sending ACKs (e.g., MU-BAs) after receiving UL MU data.
• Potential Anticipation (35 U.S.C. § 102): The subject of this patent is downlink acknowledgments for uplink multi-user transmissions, which is the inverse communication direction compared to US10306667B2 (uplink acknowledgments for downlink multi-user data). While it deals with multi-user ACKs in HE WLAN, its application context and specific technical problem are different. Thus, it does not anticipate claims 1, 9, or 12.

6. WO2016021831A1

• Full Citation: WO2016021831A1, "Multi-user transmission method in wireless communication system and device therefor", LG Electronics Inc., Publication Date: 2016-02-11.
• Publication/Filing Date: Publication: 2016-02-11; Priority: 2014-08-07.
• Brief Description: This patent, also by LG Electronics, describes a multi-user transmission method focusing on UL MU transmissions initiated by a trigger frame. It details the trigger frame's structure and includes various UL scheduling parameters such as bandwidth, duration, RU allocation, MCS, and Cyclic Prefix (CP)/LTF type. The AP receives UL MU PPDUs in response to the trigger frame and then sends a block acknowledgment (BA) or multi-user block acknowledgment (MU-BA).
• Potential Anticipation (35 U.S.C. § 102): Similar to WO2015068968A1, this patent describes the use of a separate trigger frame for UL MU scheduling, which is the problem US10306667B2 aims to overcome for ACK signaling. Although it lists specific UL scheduling parameters, it does not disclose embedding this information directly into a DL data PPDU for ACK scheduling, nor the specific field omissions and STA inferences that are central to US10306667B2. Therefore, it does not anticipate claims 1, 9, or 12.

7. US20160043855A1

• Full Citation: US20160043855A1, "Dynamic inter-frame space processing in high efficiency wireless lan", Newracom, Inc., Publication Date: 2016-02-11.
• Publication/Filing Date: Publication: 2016-02-11; Priority: 2014-08-08.
• Brief Description: This patent focuses on methods for dynamic inter-frame space (IFS) processing in High Efficiency (HE) WLAN systems to schedule subsequent transmissions. It describes an AP transmitting a PPDU that includes signaling for a subsequent UL MU transmission, potentially a trigger frame, and focuses on the timing and IFS settings for these transmissions and responses.
• Potential Anticipation (35 U.S.C. § 102): This reference broadly discusses scheduling and responses in HE WLAN, often involving trigger frames for UL MU transmissions. It emphasizes timing and IFS adjustments. However, it does not explicitly disclose embedding comprehensive UL ACK scheduling information (including specific fields and omissions) directly within a DL data PPDU, which is the inventive step of US10306667B2. It is unlikely to anticipate claims 1, 9, or 12.

8. US20180288800A1

• Full Citation: US20180288800A1, "Parallel data transmission method and apparatus", Huawei Technologies Co., Ltd., Publication Date: 2018-10-04.
• Publication/Filing Date: Publication: 2018-10-04; Priority: 2015-12-07.
• Brief Description: This patent describes methods for parallel data transmission in wireless communication systems, including MU-MIMO and OFDMA. It mentions transmitting a trigger frame carrying uplink (UL) resource allocation information for multiple user equipment (UEs) to transmit UL data.
• Potential Anticipation (35 U.S.C. § 102): Similar to other references, this patent describes UL resource allocation using a trigger frame. It does not describe embedding UL ACK scheduling information directly within a DL data PPDU for immediate response, which is the distinguishing feature of US10306667B2. Therefore, it does not anticipate claims 1, 9, or 12.

9. US20170255659A1

• Full Citation: US20170255659A1, "Basic service set identifications for using non-default spatial reuse parameters", Intel IP Corporation, Publication Date: 2017-09-07.
• Publication/Filing Date: Publication: 2017-09-07; Priority: 2016-01-29.
• Brief Description: This patent describes methods and apparatuses related to spatial reuse in WLAN systems, specifically for identifying basic service sets (BSSs) that utilize non-default spatial reuse parameters. It focuses on how BSSs manage frame transmissions based on channel conditions and spatial reuse rules.
• Potential Anticipation (35 U.S.C. § 102): This patent addresses the concept of spatial reuse, which is a specific element referenced in US10306667B2's claims. US10306667B2 specifically claims that its control information subfield may not include spatial reuse information, leading the STA to disable spatial reuse. While US20170255659A1 covers spatial reuse generally, it does not disclose the specific combination of embedding UL ACK scheduling within a DL data PPDU, the omission of spatial reuse information from this embedded scheduling, and the resulting default behavior of disabling spatial reuse for the UL ACK. Thus, it is unlikely to anticipate claims 1, 9, or 12 in their entirety, but it is relevant for the state of the art concerning spatial reuse.

Obviousness Analysis under 35 U.S.C. § 103 for US Patent 10306667

This analysis assesses the obviousness of US patent 10306667, focusing on its independent claims (Claims 1, 9, and 12), by identifying combinations of prior art references that would render the claims obvious to a Person Having Ordinary Skill in the Art (PHOSITA) at the time of the invention (priority date: February 17, 2016).

Identified Problem and Proposed Solution

US patent 10306667 addresses a problem in Wireless Local Area Network (WLAN) systems, particularly within the context of IEEE 802.11ax (High Efficiency, HE) standards, which support multi-user (MU) transmissions. According to the patent, while uplink (UL) multi-user transmissions are typically scheduled by an Access Point (AP) using a dedicated "trigger frame," using a separate trigger frame to receive acknowledgment (ACK) signals in response to downlink (DL) multi-user data causes "delay in the process or unnecessary signaling overhead." [cite: 'if the AP transmits a PPDU for downlink multi-user transmission and a separate trigger frame to receive an acknowledgement signal in response to the PPDU in a multi-user manner as well, it may cause a delay in the process or unnecessary signaling overhead.']

To solve this, the patent proposes transmitting uplink scheduling information (UL trigger information) by including it directly in the downlink Physical Protocol Data Unit (DL PPDU) when data is transmitted in a DL MU manner. [cite: 'To solve this problem, it is proposed in an embodiment of the present invention to transmit UL trigger information by including it in a DL PPDU when data is transmitted in a DL MU manner as shown in FIG. 6.']

Prior Art References for Combination

The following prior art references, as cited in US10306667, are relevant for an obviousness analysis:

• US10306667 (the patent itself): Provides comprehensive background on WLAN operation (FIG. 1), the multi-user transmission scheme in HE systems (FIG. 2), and detailed descriptions of trigger frame formats for uplink scheduling (FIGS. 3-5). Crucially, it explicitly identifies the problem (signaling overhead/delay) and the motivation for improvement. [cite: 'FIG. 1 is a diagram for explaining a general data transmission method for STAs in a WLAN system.', 'FIG. 2 is a diagram for explaining an example of uplink multi-user transmission in an HE system.', 'FIGS. 3 to 5 are diagrams for explaining trigger frame formats used in an HE system.', 'if the AP transmits a PPDU for downlink multi-user transmission and a separate trigger frame to receive an acknowledgement signal in response to the PPDU in a multi-user manner as well, it may cause a delay in the process or unnecessary signaling overhead.']
• Stacey, R., "Specification Framework for TGax", IEEE P802.11 Wireless LANs, doc.: IEEE 80211-15/0132r15, Jan. 2016: This non-patent literature (NPL) outlines the specification framework for the IEEE 802.11ax standard (TGax/HE system), confirming the state of the art regarding multi-user operations and frame structures.
• Porat, R. et al., "SIG-A Fields and Bitwidths", doc.: IEEE 802.11-15/1354r1, Nov. 2015: This NPL likely details the structure and use of the HE-SIG-A field, a critical control information subfield within PPDUs in 802.11ax, which is relevant to embedding scheduling information.
• US20170255659A1 (Intel IP Corp.), filed Jan 29, 2016: Titled "Basic service set identifications for using non-default spatial reuse parameters," this patent application indicates that spatial reuse and its associated signaling were known and actively being optimized in WLAN systems around the priority date of US10306667. [cite: 'Basic service set identifications for using non-default spatial reuse parameters']

Obviousness Argument

A PHOSITA in the field of WLAN systems, particularly those working on the IEEE 802.11ax standard, would have possessed the following knowledge at the time of the invention:

1. Downlink Multi-User (DL MU) Transmissions: It was known that APs transmit data to multiple STAs in a downlink multi-user manner in HE systems. [cite: 'an IEEE 802.11 ax system (hereinafter referred to as a high efficiency (HE) system) uses a multi-user transmission scheme where a plurality of STAs transmit data to an access point (AP) in uplink and the AP transmits data to the plurality of STAs in downlink']
2. Uplink Multi-User (UL MU) Scheduled by Trigger Frames: It was established that APs initiate and schedule UL MU transmissions from multiple STAs using dedicated "trigger frames," which contain essential scheduling information such as Resource Unit (RU) allocation, Modulation and Coding Scheme (MCS), and other parameters. [cite: 'An uplink (UL) multi-user (MU) transmission scheme can be used in the HE system as described above, and an AP can transmit trigger frames to a plurality of STAs (e.g., STA 1 to STA 4 ) to initiate the UL MU transmission.', 'the trigger frame may include UL MU allocation information (e.g., resource location and size, STA IDs, MCS, MU type (e.g., MIMO, OFDMA, etc.)).', 'FIGS. 3 to 5 are diagrams for explaining trigger frame formats used in an HE system.'] These trigger frame mechanisms are explicitly described in US10306667 (FIGS. 2-5) and would be detailed in NPLs like Stacey (2016).
3. Acknowledgement (ACK) for Reliability: ACKs are fundamental to WLAN reliability, with STAs sending ACKs for received data (e.g., FIG. 1 of US10306667). [cite: 'the second STA may transmit an acknowledgement (ACK) frame after receiving the data transmitted from the first STA.']
4. Control Information Subfields in PPDUs: PPDUs are known to contain various control information subfields, such as the HE-SIG-A field in 802.11ax. NPLs like Porat (2015) would describe the structure and function of such fields. The patent also notes the use of an "A-control subfield, which is currently used in the WLAN system." [cite: 'However, embodiments of the present invention are described based on the method of using an A-control subfield, which is currently used in the WLAN system.']

Motivation for Combination

The patent itself provides the explicit motivation for a PHOSITA to combine these known elements: to overcome the "delay in the process or unnecessary signaling overhead" caused by sending a separate trigger frame for scheduling ACK signals in response to DL MU data. [cite: 'if the AP transmits a PPDU for downlink multi-user transmission and a separate trigger frame to receive an acknowledgement signal in response to the PPDU in a multi-user manner as well, it may cause a delay in the process or unnecessary signaling overhead.'] A PHOSITA would inherently be motivated to reduce such inefficiencies.

Combination Rationale for Independent Claims

Claims 1 (STA Method) and 12 (AP Method):
Given the recognized problem and the existing mechanism for UL scheduling via trigger frames (known from US10306667 FIGS. 2-5, and NPLs like Stacey), a PHOSITA would find it obvious to integrate the uplink scheduling information required for ACK responses directly into the downlink PPDU that carries the data being acknowledged. This would eliminate the need for a separate trigger frame and thereby reduce overhead and delay.

The specific parameters listed in the control information subfield (length information of the UL PPDU, RU allocation, MCS information, AP transmit power, and target RSSI of the AP) are all standard scheduling parameters already present in or inferable from trigger frames used for general UL MU transmissions (e.g., as described in US10306667 FIGS. 4 and 5 for trigger frames). Embedding these parameters into an existing control subfield within the DL PPDU (e.g., an A-Control subfield or HE-SIG-A field, as discussed in the patent and by Porat) would be a straightforward engineering adaptation to achieve the desired efficiency gains.

The "disabling spatial reuse" limitation:
Claim 1 and 12 also specify that the control information subfield does not include spatial reuse information, and the STA (or AP processing) is configured to disable spatial reuse for the uplink PPDU. The patent itself explains the rationale: "the gain obtained by applying the spatial reuse to ACK/BA-M-BA transmission for UL MU data transmission is not greater than that obtained by saving the space for signaling." [cite: 'However, the gain obtained by applying the spatial reuse to ACK/BA-M-BA transmission for UL MU data transmission is not greater than that obtained by saving the space for signaling.'] This indicates that spatial reuse and the trade-offs involved were known in the art. US20170255659A1, prior to the priority date, confirms active work on spatial reuse parameters. A PHOSITA, striving for efficiency, would readily understand and implement such a trade-off for short, critical messages like ACKs, deciding to omit spatial reuse signaling and disable the feature to save bits, especially when the benefits are marginal for such traffic.

Claim 9 (STA Apparatus):
Claim 9 describes an STA apparatus comprising a transceiver and a processor configured to perform the method of Claim 1. Given that the method described in Claim 1 is deemed obvious, configuring a standard STA processor and transceiver (components widely known in the art, as illustrated generally in US10306667 FIG. 11) to implement this obvious method would also be an obvious step for a PHOSITA. No specialized hardware beyond standard WLAN components is required, only a reprogramming or configuration of existing elements.

Conclusion

The independent claims of US patent 10306667, particularly the core invention of embedding uplink scheduling information for acknowledgements directly within a downlink PPDU, would have been obvious to a PHOSITA. The motivation for this combination is explicitly stated in the patent itself: to reduce the signaling overhead and delay associated with using a separate trigger frame for ACK responses in a multi-user WLAN environment. The specific elements of the scheduling information and the decision to disable spatial reuse are either standard parameters from existing trigger frame mechanisms or known engineering trade-offs in WLAN optimization. Combining the knowledge of existing multi-user transmission schemes, trigger frame functionality (as described in US10306667 and NPLs like Stacey), and the purpose and structure of PPDU control subfields (as discussed in US10306667 and NPLs like Porat), with the clear motivation to improve efficiency, would lead a PHOSITA to the claimed invention.

To find the detailed information regarding US patent 10306667, including patent term adjustments (PTA), patent term extensions (PTE), continuation/divisional applications, related family members, and the projected expiration date, a direct search on the USPTO Patent Center or Patent Public Search is required. While the provided text offers general definitions and mechanisms for these aspects, it does not contain the specific data for patent 10306667 itself.

As a general rule, a U.S. utility patent filed on or after June 8, 1995, expires 20 years from its earliest effective filing date, subject to any patent term adjustments or extensions.

Without direct access to the USPTO Patent Center or Patent Public Search live data for patent 10306667, I cannot provide the exact PTA, PTE, or a definitive projected expiration date. However, based on the information provided in the prompt:

• Filing Date: January 16, 2017.
• Issue Date: May 28, 2019.
• Anticipated Expiration (without adjustments): The standard patent term is 20 years from the filing date. Therefore, without any adjustments, the patent would expire on January 16, 2037.

Patent Term Adjustments (PTA):
PTA compensates applicants for certain delays by the USPTO during patent prosecution. These delays can include:
* Failure to issue a first Office Action or notice of allowance within 14 months of filing.
* Failure to respond to an applicant's reply within 4 months.
* Failure to issue a patent within 4 months of the issue fee payment.
* Prosecution exceeding three years from the filing date.

The USPTO automatically calculates PTA, and the amount can be reduced by delays caused by the applicant. This information is typically provided on the patent's front page or in the Patent Center.

Patent Term Extensions (PTE):
PTE is distinct from PTA and is available for patents covering certain products (e.g., human drugs, medical devices, food additives) to restore patent term lost due to regulatory review periods before commercial marketing. There is no indication in the provided patent text or metadata that US10306667 is subject to a PTE.

Continuation and Divisional Applications:
The prompt states the patent's application number is US15/772,799 and lists "Priority to US15/772,799" as a critical event, and also lists "US201715772799A" as an application number. The priority date is listed as February 17, 2016. The patent also claims benefit of U.S. Provisional Application Nos. 62/296,082, filed on Feb. 17, 2016, and 62/239,172, filed on Apr. 28, 2016. For patents granted on continuation or divisional applications, the term typically expires 20 years from the filing date of the earliest application for which a benefit is claimed.

Related Family Members:
The provided text identifies several related applications and publications:

• Priority Applications: US Provisional Application Nos. 62/296,082 (filed Feb. 17, 2016) and 62/239,172 (filed Apr. 28, 2016).
• International Application: PCT/KR2017/000527 (filed Jan. 16, 2017), which resulted in WO2017142210A1.
• Other versions/publications: US20180324840A1.
• Other family members listed under "Also Published As": EP4262131A3, EP3419203A4, EP3419203B1, KR101966132B1, EP4262131B1, EP3419203A1, EP4262131A2, KR20180098405A, WO2017142210A1, EP4262131C0. These are international and foreign counterparts, part of the broader patent family.

Projected Expiration Date:
Based on the filing date of the earliest priority application, US Provisional Application No. 62/296,082 on February 17, 2016, the base 20-year patent term would extend to February 17, 2036. This date would then be adjusted by any PTA. Without specific PTA data from the USPTO for patent 10306667, the anticipated expiration date is February 17, 2036, plus any applicable Patent Term Adjustment. The Google Patents page for US10306667 also indicates an "Anticipated expiration" date of 2037-01-16. This discrepancy might be due to the difference in how the "earliest filing date" is interpreted for the 20-year term calculation or the inclusion of PTA. To confirm, direct access to the USPTO's Patent Center for the specific patent number would be necessary.

Defensive Disclosure: Derivative Variations of US Patent 10306667

This document outlines several derivative variations of the inventions described in US Patent 10306667, "Method for transmitting and receiving uplink acknowledgement signal in wireless LAN system and apparatus therefor." These disclosures aim to establish prior art for future incremental improvements by competitors, focusing on making such improvements obvious or non-novel. The core inventive concept of US10306667 revolves around an Access Point (AP) embedding uplink (UL) acknowledgment (ACK) scheduling information directly into a downlink (DL) Physical Protocol Data Unit (PPDU) carrying DL data, thereby eliminating the need for a separate trigger frame. A key aspect is the explicit exclusion of spatial reuse information from this embedded scheduling, leading the Station (STA) to disable spatial reuse for the subsequent UL ACK transmission. The UL scheduling information minimally includes UL PPDU length, Resource Unit (RU) allocation, Modulation and Coding Scheme (MCS) for the UL PPDU, AP transmit power, and AP target Receive Signal Strength Indicator (RSSI).

---

Derivative Variations

1. Material & Component Substitution

Derivative 1.1: Quantum Dot-Enhanced Transceiver for mmWave Frequencies

• Enabling Description: The conventional transceivers (130/180 in FIG. 11) for AP and STA are replaced with quantum dot (QD)-enhanced millimeter-wave (mmWave) transceivers operating in the 60 GHz band (e.g., IEEE 802.11ad/ay spectrum). These QDs are integrated into the antenna arrays and phase shifters to improve beamforming precision and energy efficiency. The AP (100) embeds UL scheduling information (UL PPDU length, RU allocation, UL MCS, AP Tx power, AP target RSSI) within the DL PPDU transmitted via highly directive mmWave beams. The STA (150) receives this DL PPDU, and its QD-enhanced processor (160) interprets the scheduling and directs its QD-enhanced transceiver (180) to transmit the UL ACK PPDU using spatially precise beams. The absence of spatial reuse information in the control subfield simplifies beam management, as no explicit coordination for overlapping basic service sets is attempted at the PHY layer, optimizing for high-gain, point-to-point-like mmWave links. The QD material ensures robust performance under varying environmental conditions typical for mmWave.

classDiagram
    class AP {
        +Processor 110
        +Memory 120
        +QD-Enhanced Transceiver 130_QD_mmWave
        +transmitDLPPDUMmWave()
        +receiveULACKMmWave()
    }
    class STA {
        +Processor 160
        +Memory 170
        +QD-Enhanced Transceiver 180_QD_mmWave
        +receiveDLPPDUMmWave()
        +transmitULACKMmWave()
    }
    class DLPPDUSubfield {
        +UL_PPDU_Length
        +RU_Allocation
        +UL_MCS
        +AP_Tx_Power
        +AP_Target_RSSI
        -Spatial_Reuse_Info // Excluded
    }
    AP "1" -- "1" QD-Enhanced Transceiver 130_QD_mmWave : controls
    STA "1" -- "1" QD-Enhanced Transceiver 180_QD_mmWave : controls
    QD-Enhanced Transceiver 130_QD_mmWave -- DLPPDUSubfield : includes
    QD-Enhanced Transceiver 180_QD_mmWave -- DLPPDUSubfield : receives
    Processor 110 -- DLPPDUSubfield : configures
    Processor 160 -- DLPPDUSubfield : processes

Derivative 1.2: Photonic Integrated Circuit (PIC) based Transceiver

• Enabling Description: In a data center or high-density campus environment, the wireless transceivers (130/180) are implemented using Photonic Integrated Circuits (PICs) for enhanced bandwidth and reduced electromagnetic interference, operating in optical wireless communication bands (e.g., visible light communication or free-space optics). The AP utilizes a PIC-based transmitter to send DL PPDUs, where the control information subfield for UL scheduling is encoded using optical modulation. The STA's PIC-based receiver demodulates the optical signal, extracts the UL scheduling information (UL PPDU length, RU allocation, UL MCS, AP Tx power, AP target RSSI), and disables spatial reuse as indicated by the absence of related fields. The UL ACK PPDU is then transmitted via a PIC-based optical transmitter using pre-configured beam steering or diffuse IR/visible light, leveraging the inherent directionality of optical links to minimize interference and implicitly negate the need for explicit spatial reuse signaling.

flowchart TD
    AP_PIC_Tx(AP PIC Transmitter) --> Optical_DL_PPDU(Optical DL PPDU)
    Optical_DL_PPDU --> STA_PIC_Rx(STA PIC Receiver)
    STA_PIC_Rx -- Demodulate --> STA_Processor(STA Processor)
    STA_Processor -- Extract UL Scheduling --> UL_Scheduling_Data{UL PPDU Length, RU, MCS, AP Tx Power, AP Target RSSI}
    STA_Processor -- Assume No Spatial Reuse --> Disable_Spatial_Reuse(Disable Spatial Reuse)
    STA_Processor -- Configure UL ACK PPDU --> STA_PIC_Tx(STA PIC Transmitter)
    STA_PIC_Tx --> Optical_UL_ACK(Optical UL ACK PPDU)
    Optical_UL_ACK --> AP_PIC_Rx(AP PIC Receiver)
    AP_PIC_Rx -- Demodulate --> AP_Processor(AP Processor)

2. Operational Parameter Expansion

Derivative 2.1: Ultra-Low Latency, Deterministic Acknowledgment for Industrial IoT

• Enabling Description: The system is optimized for ultra-low latency, deterministic communication in an Industrial Internet of Things (IIoT) environment where ACK signals are critical for real-time control loops (e.g., robotics, automated guided vehicles). The "UL PPDU length" is reduced to a minimal fixed size (e.g., 2 OFDM symbols) to minimize airtime. "RU allocation" is pre-determined or semi-static, assigned via higher-layer configuration to specific time-frequency slots within a Time Sensitive Network (TSN) schedule, rather than dynamic signaling in the control subfield. The "UL MCS" is locked to the most robust scheme (e.g., BPSK, rate 1/2) to ensure high reliability. "AP Tx power" and "AP target RSSI" are configured for guaranteed reception within a tight operational range. The exclusion and disabling of spatial reuse are paramount to avoid any potential interference or retransmission delays that could arise from complex spatial coordination, ensuring predictable and low-jitter ACK delivery. The control information subfield's granularity for length and RU is adjusted to microsecond and subcarrier group levels, respectively.

sequenceDiagram
    AP->>STA: DL PPDU (Data + UL Scheduling)
    note over STA: UL Scheduling:
    note over STA: Fixed UL PPDU Length (e.g., 2 symbols)
    note over STA: Pre-allocated RU (TSN sync)
    note over STA: Robust MCS (e.g., BPSK 1/2)
    note over STA: AP Tx Power (Fixed for range)
    note over STA: AP Target RSSI (Fixed for reliability)
    note over STA: NO Spatial Reuse Info
    STA->>STA: Disable Spatial Reuse
    STA->>AP: UL ACK PPDU (Ultra-low latency)
    AP->>AP: Process UL ACK (Deterministic)

Derivative 2.2: Extreme-Range, LoRa-like Acknowledgment for Environmental Sensing

• Enabling Description: The system is adapted for extreme-range (e.g., several kilometers) acknowledgment in sparse environmental sensing networks, where STAs are low-power, battery-operated devices (e.g., sensors monitoring agricultural conditions). The "UL PPDU length" information is constrained to a few predefined, very long duration options, leveraging spread spectrum techniques (e.g., LoRa-like chirp spread spectrum) within the UL PPDU for robust reception over distance. "RU allocation" would correspond to broad frequency hopping channels rather than fine-grained OFDMA RUs. "UL MCS" uses extremely low data rates (e.g., CSS with high spreading factors) to maximize link budget. "AP Tx power" is maximized for range, and "AP target RSSI" is set to a very low threshold to capture weak signals. The absence of spatial reuse information is beneficial as large geographic separations between APs naturally minimize co-channel interference, allowing for simpler, single-channel or wide-channel operation without complex spatial coordination. The control subfield might include additional parameters like spreading factor and coding rate for the CSS.

graph TD
    A[AP Transmits DL PPDU] -- Data & UL Scheduling (Long Range) --> B(STA Receives DL PPDU)
    B -- Extracts UL Scheduling --> C{UL PPDU Length: Long, Predefined; RU: Wideband/FH; MCS: CSS/Low Rate; AP Tx Power: Max; AP Target RSSI: Low Threshold; No Spatial Reuse}
    C --> D[STA Disables Spatial Reuse]
    D --> E[STA Configures UL ACK PPDU (CSS)]
    E --> F[STA Transmits UL ACK PPDU (Extreme Range)]
    F --> G[AP Receives & Processes UL ACK]

3. Cross-Domain Application

Derivative 3.1: Autonomous Logistics Robot Communication

• Enabling Description: In an automated warehouse or logistics hub, autonomous mobile robots (STA) communicate with a central control unit (AP). The AP sends control commands (DL data) to robots via DL PPDU. The control information subfield embedded in this DL PPDU specifies the UL ACK scheduling for the robot to confirm receipt and execution. This includes the required UL PPDU length, the specific RU within the high-density Wi-Fi 6E spectrum to avoid interference with other robots, the UL MCS adjusted for the robot's current line-of-sight and speed, the AP's transmit power for range, and the AP's target RSSI for reliable feedback. Spatial reuse is disabled to ensure that ACK signals from adjacent robots do not interfere, simplifying the communication overhead in a busy, multi-robot environment where deterministic responses are critical.

stateDiagram
    state "Warehouse Operational" as WH_OP
    WH_OP --> Robot_Receive_DL_PPDU: AP_sends_DL_Command
    Robot_Receive_DL_PPDU --> Extract_UL_Scheduling: UL_PPDU_Length, RU, MCS, AP_Tx_Power, AP_Target_RSSI
    Extract_UL_Scheduling --> Disable_Spatial_Reuse: No_Spatial_Reuse_Flag
    Disable_Spatial_Reuse --> Robot_Transmit_UL_ACK: Robot_sends_ACK_PPDU
    Robot_Transmit_UL_ACK --> AP_Receive_UL_ACK: Confirm_Command_Received
    AP_Receive_UL_ACK --> WH_OP: Continue_Operations

Derivative 3.2: Smart Agriculture Drone Fleet Management

• Enabling Description: A fleet of agricultural drones (STA) communicates with a ground-based control station (AP) for tasks like crop monitoring or spraying. The AP transmits flight path updates or sensor configuration commands (DL data) to the drones via DL PPDU. The embedded control information subfield dictates how each drone should send its ACK for these commands. This includes the UL PPDU length for the ACK, specific RU allocations within a licensed or unlicensed band (e.g., 5 GHz or CBRS) to manage concurrent drone communications, UL MCS tailored to the drone's altitude and atmospheric conditions, AP Tx power, and target RSSI. Spatial reuse is disabled to prioritize clear, unambiguous ACK signals from each drone, preventing potential misinterpretations or collisions in a multi-drone operational area, ensuring precise command execution and safety.

flowchart LR
    A[Ground Station AP] -- Transmit DL PPDU (Flight Commands + UL Schedule) --> B(Agricultural Drone STA)
    B -- Process DL PPDU --> C{Extract UL Scheduling: UL PPDU Length, RU, MCS, AP Tx Power, AP Target RSSI, No Spatial Reuse}
    C --> D[Disable Spatial Reuse on Drone]
    D --> E[Configure UL ACK PPDU]
    E --> F[Transmit UL ACK PPDU]
    F -- ACK for Flight Commands --> A

Derivative 3.3: Emergency Response Body Camera Network

• Enabling Description: In a public safety scenario, body cameras worn by first responders (STA) form an ad-hoc mesh network or communicate with a central incident command vehicle (AP). The AP broadcasts critical incident updates or configuration changes (DL data) to multiple body cameras via a DL PPDU. The control information subfield in this PPDU instructs each camera on how to transmit its ACK, specifying UL PPDU length, RU allocation within a public safety band (e.g., 4.9 GHz), UL MCS adapted to urban clutter and range, AP Tx power, and target RSSI. Spatial reuse is deliberately disabled to guarantee that each responder's ACK is distinctly received by the AP, preventing "hidden node" issues or ambiguity in confirming vital information delivery, crucial for coordinating emergency efforts.

sequenceDiagram
    AP_ICV(Incident Command Vehicle AP)->>BC_STA(Body Camera STA): DL PPDU (Incident Update + UL Scheduling)
    note over BC_STA: UL Scheduling contains:
    note over BC_STA: - UL PPDU Length
    note over BC_STA: - RU Allocation (Public Safety Band)
    note over BC_STA: - UL MCS (Urban)
    note over BC_STA: - AP Tx Power
    note over BC_STA: - AP Target RSSI
    note over BC_STA: - NO Spatial Reuse Info
    BC_STA->>BC_STA: Disable Spatial Reuse
    BC_STA->>AP_ICV: UL ACK PPDU (Update Confirmed)

4. Integration with Emerging Technologies

Derivative 4.1: AI-Optimized Adaptive Scheduling

• Enabling Description: The AP (100) incorporates an AI/ML inference engine (integrated into processor 110) that dynamically optimizes the parameters within the control information subfield. Based on real-time channel conditions, predicted traffic loads, STA mobility patterns, and historical performance data, the AI agent determines the optimal "UL PPDU length," "RU allocation," "UL MCS," "AP Tx power," and "AP target RSSI" for each STA's ACK. This information is then embedded in the DL PPDU. The STA (150) still processes this explicit scheduling, disables spatial reuse as before, and transmits its ACK. The AI's role is to ensure that even without spatial reuse, the ACK efficiency is maximized by adaptively choosing the most robust and resource-efficient UL parameters for each ACK, learning from past successful and failed ACK transmissions. For example, if an STA is consistently experiencing high interference, the AI might schedule a lower MCS and longer PPDU length.

graph TD
    A[AP Processor with AI Engine] --> B{AI Model Infers Optimal UL Schedule Parameters: Length, RU, MCS, Tx Power, Target RSSI}
    B --> C[Configure Control Info Subfield in DL PPDU]
    C --> D[AP Transceiver Transmits DL PPDU]
    D --> E[STA Transceiver Receives DL PPDU]
    E --> F[STA Processor Extracts UL Schedule]
    F --> G[STA Disables Spatial Reuse]
    G --> H[STA Transceiver Transmits UL ACK PPDU]
    H --> I[AP Transceiver Receives UL ACK PPDU]
    I --> J[AP Processor with AI Engine: Feedback Loop for Model Retraining/Refinement]

Derivative 4.2: IoT Sensor-Triggered Acknowledgment with Real-time Monitoring

• Enabling Description: In a large-scale IoT deployment, numerous sensors (STA) are deployed. An AP (100) centrally manages these sensors. When the AP pushes a firmware update or a new configuration (DL data) to a group of sensors, the DL PPDU includes the embedded UL scheduling information for their ACKs. This ACK signal itself isn't just a confirmation; it also contains real-time diagnostic data from the sensor, monitored by an integrated IoT sensor management module within the STA (150). The "UL PPDU length" is dynamically adjusted to accommodate both the ACK and the short diagnostic payload. "RU allocation" is managed to prevent collisions among many simultaneous sensor ACKs. "UL MCS" and power settings ensure reliable transmission of both the ACK and diagnostic data. The absence of spatial reuse simplifies the ACK process for these low-power IoT devices, ensuring their limited processing power isn't burdened by complex spatial awareness protocols. The real-time monitoring of ACK receipt and diagnostic data at the AP allows for immediate identification of unresponsive or faulty sensors.

sequenceDiagram
    AP->>IoT_Sensors: DL PPDU (Config Update + UL Scheduling)
    note over IoT_Sensors: UL Scheduling includes:
    note over IoT_Sensors: - Dynamic UL PPDU Length (ACK + Diag Data)
    note over IoT_Sensors: - RU Allocation (Multi-sensor)
    note over IoT_Sensors: - UL MCS
    note over IoT_Sensors: - AP Tx Power
    note over IoT_Sensors: - AP Target RSSI
    note over IoT_Sensors: - NO Spatial Reuse Info
    IoT_Sensors->>IoT_Sensors: Gather Real-time Diagnostic Data
    IoT_Sensors->>IoT_Sensors: Disable Spatial Reuse
    IoT_Sensors->>AP: UL ACK PPDU (ACK + Diagnostic Data)
    AP->>AP: Monitor Sensor Health & Update Status

Derivative 4.3: Blockchain-Verified Acknowledgment of Critical Data Delivery

• Enabling Description: For applications requiring immutable proof of data delivery, such as financial transactions over a local network or secure content distribution, the ACK mechanism is integrated with blockchain technology. After receiving critical "DL data" in a DL PPDU, the STA (150) processes the embedded UL scheduling information. The UL ACK PPDU then includes not just the standard ACK, but also a cryptographic hash of the received data and potentially a digital signature, forming a transaction that is transmitted according to the AP's (100) scheduling. This "hashed ACK" is then relayed by the AP to a local blockchain ledger. The "UL PPDU length" must accommodate the cryptographic overhead. "RU allocation" and "UL MCS" are chosen for maximum reliability to ensure the integrity of the blockchain transaction. The disabling of spatial reuse contributes to a simpler, more robust, and less variable PHY layer for these critical ACK transactions, where any uncertainty from complex spatial coordination is undesirable. The AP processes incoming signals from the STA, assuming disabled spatial reuse for consistent transaction handling.

flowchart TD
    A[AP Transmits DL PPDU (Critical Data + UL Schedule)] --> B(STA Receives DL PPDU)
    B -- Extracts UL Scheduling --> C{UL PPDU Length, RU, MCS, AP Tx Power, AP Target RSSI, No Spatial Reuse}
    C --> D[STA Disables Spatial Reuse]
    D -- Hashes Received Data + Signs --> E[Configure UL ACK PPDU (ACK + Cryptographic Hash)]
    E --> F[STA Transmits UL ACK PPDU]
    F --> G[AP Receives UL ACK PPDU]
    G -- Validate Hash + Sign --> H[AP Relays Hashed ACK to Local Blockchain]
    H --> I[Blockchain Ledger Updates with Verified Data Receipt]

5. The "Inverse" or Failure Mode

Derivative 5.1: Graceful Degradation to "Basic ACK" Mode

• Enabling Description: In situations of severe channel degradation (e.g., high interference, extreme distance, low battery on STA), the system is designed to gracefully degrade its ACK mechanism. If the STA (150) fails to properly decode certain fields within the control information subfield (e.g., RU allocation, MCS) after receiving the DL PPDU, or if its internal link quality metrics fall below a threshold, it defaults to a "Basic ACK" mode. In this mode, the STA ignores the detailed UL scheduling information and instead transmits a minimal, robust individual ACK (not BA or MU-BA) using a pre-defined, lowest-rate MCS (e.g., MCS0), a fixed, shortest UL PPDU length, and a default, narrowest RU. Spatial reuse remains disabled, as per the patent, which simplifies the fallback procedure. The AP (100), expecting a scheduled ACK, implements a timeout mechanism. If no scheduled ACK is received, it scans for a "Basic ACK" on the default parameters. This ensures at least a basic level of acknowledgment even under challenging conditions.

stateDiagram
    state "Normal ACK Mode" as Normal
    state "Basic ACK Mode" as BasicACK
    Normal --> BasicACK : STA Fails Decode UL Schedule OR Link Quality Low
    BasicACK --> BasicACK : (STA) Transmit Fixed/Robust UL ACK PPDU
    BasicACK --> Normal : (STA) Link Quality Improves OR Schedule Decoded
    state "AP Waiting" as AP_Waiting
    AP_Waiting --> Normal_ACK_Received : Scheduled ACK Rx
    AP_Waiting --> Basic_ACK_Detected : Timeout and Basic ACK Rx
    Normal_ACK_Received --> AP_Waiting
    Basic_ACK_Detected --> AP_Waiting
    AP_Waiting --> AP_Timeout_No_ACK : Timeout, No ACK

Derivative 5.2: Low-Power, Asynchronous ACK for Sleepy STAs

• Enabling Description: For energy-constrained STAs (150) that frequently enter deep sleep states (e.g., battery-powered IoT devices), the ACK mechanism supports a low-power, asynchronous mode. When the AP (100) transmits a DL PPDU with data for a sleepy STA, the control information subfield contains not just the UL scheduling, but also a "Wake-up Indication" and a short "ACK Window" duration. The STA, upon partial wake-up and detection of the DL PPDU, decodes the wake-up indication and ACK window. If it cannot fully decode the detailed UL scheduling (e.g., RU, MCS) due to power constraints or limited processing, it performs a minimal wake-up to transmit a simple, short ACK within the specified ACK window. This "limited functionality" ACK could be a basic ACK-frame transmitted on a contention basis (e.g., using EDCA) on a narrow, pre-assigned common channel, rather than a scheduled UL MU PPDU. Spatial reuse is still not explicitly enabled by the AP's signaling, aligning with the patent, and the STA's low-power mode ensures minimal overhead. The AP proactively listens for these asynchronous ACKs within the window.

sequenceDiagram
    AP->>Sleepy_STA: DL PPDU (Data + UL Scheduling + Wake-up + ACK Window)
    Sleepy_STA->>Sleepy_STA: Partial Wake-up
    Sleepy_STA->>Sleepy_STA: Detect DL PPDU & Decode Wake-up/ACK Window
    alt Cannot fully decode UL Scheduling
        Sleepy_STA->>Sleepy_STA: Enter Low-Power ACK Mode
        Sleepy_STA->>AP: Transmit Basic ACK (Contention-based on common channel)
    else Fully decode UL Scheduling
        Sleepy_STA->>Sleepy_STA: Disable Spatial Reuse
        Sleepy_STA->>AP: Transmit Scheduled UL ACK PPDU
    end
    AP->>AP: Monitor for Scheduled ACK or Basic ACK within Window

Combination Prior Art Scenarios

1. US10306667 + IEEE 802.11ax Standard (High Efficiency WLAN):
   The patent explicitly describes its application within the context of IEEE 802.11ax (HE system) to address the overhead of separate trigger frames for UL ACKs in multi-user downlink transmissions. Combining the specific method of embedding UL scheduling information (UL PPDU length, RU allocation, UL MCS, AP Tx power, AP target RSSI, without spatial reuse information) directly within a DL PPDU (as per claims 1, 9, 12) with the general OFDMA and MU-MIMO multi-user transmission mechanisms defined in the 802.11ax standard, particularly how HE PPDUs are structured and processed by HE STAs. This combination makes explicit the integration of this ACK signaling optimization into the broader HE physical layer and MAC operations, potentially defining how an "A-Control subfield" is used within an HE-SIG-A field for UL scheduling in 802.11ax.

   • Prior Art: IEEE 802.11ax-2019 (Standard for Information technology--Telecommunications and information exchange between systems Local and metropolitan area networks--Specific requirements--Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 1: Enhancements for High-Efficiency WLAN).

2. US10306667 + IEEE 802.11ba Standard (Wake-up Radio):
   Integrating the core method with IEEE 802.11ba Wake-up Radio (WUR) capabilities. An AP (100) could transmit a DL PPDU containing data and UL scheduling information to an 802.11ba-enabled STA (150). The WUR module on the STA, operating in a very low-power state, would first detect a WUR preamble from the AP. Upon full wake-up, the STA's main transceiver (180) receives the DL PPDU with the embedded UL ACK scheduling. The method described in the patent (disabling spatial reuse) then applies for the UL ACK PPDU. This combination extends the efficiency gains to power-constrained devices, allowing them to remain in deep sleep until a DL PPDU with embedded ACK scheduling is specifically directed at them, without incurring extra overhead from separate trigger frames. The WUR could also signal the presence of such an embedded control subfield.

   • Prior Art: IEEE 802.11ba-2021 (Standard for Information technology--Telecommunications and information exchange between systems Local and metropolitan area networks--Specific requirements--Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 3: Wake-up Radio).

3. US10306667 + Open-source Network Monitoring Tools (e.g., Wireshark/Scapy):
   Applying the principles of the patent to network analysis and debugging. The specific structure of the "control information subfield" within the DL PPDU, including the absence of spatial reuse information and the explicit presence of UL PPDU length, RU allocation, UL MCS, AP Tx power, and AP target RSSI, could be formally defined and parsed by open-source network protocol analyzers like Wireshark or packet crafting libraries like Scapy. This enables network administrators or researchers to monitor and analyze the efficiency of UL ACK scheduling in real-time, verifying that spatial reuse is indeed disabled and that the other UL parameters are correctly signaled and applied by STAs. Tools could generate alerts if a separate trigger frame is observed for ACKs, indicating a deviation from this optimized scheme.

   • Prior Art: Wireshark (open-source network protocol analyzer, available at wireshark.org); Scapy (Python-based packet manipulation program, available at scapy.net).