US patent 11516879, titled "Wireless communication method using enhanced distributed channel access, and wireless communication terminal using same," was issued on November 29, 2022, from an application filed on July 23, 2021. The current assignee is Wilus Institute of Standards and Technology Inc, and the inventors are Woojin AHN, Juhyung Son, Geonjung KO, and Jinsam Kwak.

Abstract:
The patent describes a wireless communication method and a terminal that use enhanced distributed channel access. A wireless communication terminal accesses a channel based on data priority and transmits data. This involves switching a channel access parameter set (from a first to a second set) if a base wireless communication terminal triggers its participation in a multi-user uplink transmission. The terminal then accesses the channel using this second set of parameters. After transmitting a trigger-based physical layer protocol data unit (PPDU), the terminal sets a timer (second parameter set timer) when an immediate response to a MAC protocol data unit (MPDU) within the PPDU is received. The application of the second parameter set is terminated when this timer expires.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (Method): This claim describes a method for a wireless communication terminal to wirelessly communicate with a base terminal. The method involves the terminal accessing a channel and transmitting data based on the data's priority. A key aspect is that the terminal switches its channel access parameters (from an initial "first parameter set" to a "second parameter set") if the base terminal instructs it to participate in a multi-user uplink transmission. After the terminal sends a "trigger-based physical layer protocol data unit (PPDU)," it starts a timer (a "second parameter set timer") if it receives an immediate response to a "MAC protocol data unit (MPDU)" that was part of the PPDU. The use of this "second parameter set" stops when the timer expires.

• Independent Claim 6 (Wireless Communication Terminal): This claim outlines a wireless communication terminal that includes a transceiver and a processor. The processor is configured to perform the actions described in Claim 1. Specifically, it's designed to access a channel and transmit data based on priority, and to switch between a first and second set of channel access parameters when triggered by a base terminal for multi-user uplink transmission. The processor also transmits a trigger-based PPDU, sets a timer upon receiving an immediate response to an MPDU within that PPDU, and terminates the application of the second parameter set when the timer expires.

Litigation and Legal Status:
As of April 26, 2026, US patent 11516879 is listed as "Active."
The patent family has ongoing litigation. This includes:

• A PTAB (Patent Trial and Appeal Board) case, IPR2025-01044, which was filed and is currently pending (instituted).
• Two US district court cases filed in the Texas Eastern District Court (case numbers 2:24-cv-00765 and 2:24-cv-00764).

A search for "CAFC 2026 dockets 11516879" did not return any direct results, suggesting that none of the identified litigation has yet reached the Court of Appeals for the Federal Circuit in 2026. However, the IPR was filed in 2025 and the district court cases in 2024, so it is plausible that appeals could arise in the future.

Here is a list of known litigation involving US patent 11516879, based on information available as of April 26, 2026:

1. Case Number: 2:24-cv-00765

   • Jurisdiction: Texas Eastern District Court
   • Plaintiff(s): Wilus Institute of Standards and Technology Inc. (likely, as the current assignee)
   • Defendant(s): Not explicitly stated in the provided text, but district court cases typically list the alleged infringers. A search for this case number is needed to confirm.
   • Filing Date: September 13, 2024
   • Outcome/Current Status: Active litigation

2. Case Number: 2:24-cv-00764

   • Jurisdiction: Texas Eastern District Court
   • Plaintiff(s): Wilus Institute of Standards and Technology Inc. (likely, as the current assignee)
   • Defendant(s): Not explicitly stated in the provided text. A search for this case number is needed to confirm.
   • Filing Date: September 13, 2024
   • Outcome/Current Status: Active litigation

3. Case Number: IPR2025-01044

   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Plaintiff(s): Unified Patents (Petitioner)
   • Defendant(s): Wilus Institute of Standards and Technology Inc. (Patent Owner)
   • Filing Date: July 26, 2024
   • Outcome/Current Status: Pending - Instituted

Proceedings overview

There is one active AIA trial proceeding involving US patent 11516879. IPR2025-01044 has been instituted and is currently in the trial stage. This indicates that the PTAB found a reasonable likelihood that at least one challenged claim of the patent is unpatentable, suggesting a potential vulnerability for the patent owner.

IPR2025-01044 — [[[Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.), Ltd.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%2C%20Ltd.) et al.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%2C%20Ltd.%20et%20al.) v. Wilus Institute of Standards and Technology Inc.

• Type: Inter Partes Review
• Filed: 2025-05-29
• Status: Trial Instituted. This means the PTAB has determined that there is a reasonable likelihood that the petitioner would prevail with respect to at least one challenged claim, and a trial has been initiated.
• Judge panel: The specific panel of Administrative Patent Judges assigned to conduct the trial for IPR2025-01044 is not publicly available from the provided search results. It is known that, effective October 20, 2025, the USPTO Director determines whether to institute IPR and PGR trials, often issuing summary notices for routine decisions, in consultation with at least three PTAB judges.
• Petition grounds: The specific claims challenged, the prior art asserted, and the statutory bases (§ 102 / § 103) for the petition are not publicly available from the search results. IPRs generally challenge patent claims based on anticipation (§ 102) or obviousness (§ 103) using prior art consisting only of patents or printed publications.
• Institution decision: The petition was instituted, meaning a trial has been authorized. The exact date of institution and the detailed reasoning behind the decision are not publicly available from the search results. Given the filing date (2025-05-29) and the current date (2026-05-15), the institution decision would have occurred after October 20, 2025, when the Director began personally making such determinations, likely as a summary notice without extensive explanation.
• Final Written Decision: A Final Written Decision (FWD) has not yet been issued for this proceeding. Under statute, the PTAB typically has one year from the date of institution to issue a FWD.
• Settlement / termination: No information regarding settlement or termination of this proceeding is available from the search results.
• Appeal: No appeal has been filed, as an FWD has not yet been issued.
• Defensive value: The institution of IPR2025-01044 indicates that the challenged claims of US11516879 have been found to have a reasonable likelihood of being unpatentable. While not a final determination, this signals a potential weakness in the patent owner's ability to assert these claims.

Strategic summary

Currently, all claims of US11516879 remain untested by a final written decision. IPR2025-01044, filed by Samsung Electronics Co., Ltd. et al. against Wilus Institute of Standards and Technology Inc., has been instituted, meaning that the PTAB found a reasonable likelihood that at least one of the challenged claims is unpatentable. This proceeding is still active in the trial stage, and no claims have been definitively canceled or sustained through a final decision.

Regarding estoppel, since a Final Written Decision has not yet been issued for IPR2025-01044, no statutory estoppel under 35 U.S.C. § 315(e)(2) currently applies. This means that a petitioner (and their privies) would not yet be barred from raising any ground that was raised or reasonably could have been raised in this IPR. However, if an FWD is eventually issued, estoppel would apply to the grounds asserted in the petition and those that reasonably could have been raised by that petitioner.

The presence of Samsung Electronics Co., Ltd. as the petitioner suggests that this patent is being asserted in commercial contexts against significant industry players. The fact that this is the only IPR identified for US11516879 (as per the canonical list) indicates that while the patent has attracted a challenge, it has not yet faced multiple, overlapping IPRs, which can sometimes be a signal of a widely asserted or particularly vulnerable patent. It is worth noting that Unified Patents has been active in challenging patents against its members, including Samsung and Apple, in other IPRs, sometimes acting as the petitioner on their behalf.

Recommended next steps

For a defendant facing assertion of US patent 11516879, the active IPR2025-01044 is a critical development. While specific claim-level challenges are not publicly available, the institution of the IPR suggests a viable path to invalidity for at least some claims.

• Monitor IPR2025-01044 closely: The proceeding is in the trial phase. The PTAB has a statutory one-year deadline to issue a Final Written Decision from the date of institution. Given the petition was filed on 2025-05-29, the institution decision would likely have been around November/December 2025, placing the FWD due date around November/December 2026. Monitoring the public docket for this IPR will be crucial for obtaining the institution decision details (claims, prior art, and reasoning) and, eventually, the Final Written Decision. Accessing the full record through the USPTO PTAB E2E system would be necessary to get these specific documents.
• Assess asserted claims: If the claims being asserted against a defendant overlap with those challenged in IPR2025-01044, the ongoing IPR provides a potential avenue for invalidity. The grounds presented in the IPR petition could offer insights for a defendant's own invalidity contentions.
• Evaluate settlement options: The pendency of an IPR can influence settlement negotiations. If claims are invalidated in the FWD, the value of the patent to the patent owner will likely decrease significantly.

Inventors

• Woojin AHN (SK Telecom Co Ltd)
• Juhyung Son (SK Telecom Co Ltd)
• Geonjung KO (SK Telecom Co Ltd)
• Jinsam Kwak (SK Telecom Co Ltd)

No unusual patterns were determinable from the provided information.

Original assignee

The original assignee named on the issued patent US11516879B2 is SK Telecom Co Ltd. SK Telecom is a South Korean telecommunications company that provides wireless communication services, broadband internet, and other related services. It is an operating company. Whether they shipped a product embodying the claims is not explicitly stated in the patent text, but as a telecommunications provider, it is highly probable that their services and equipment would implement such wireless communication methods. SK Telecom Co Ltd is currently operating.

Assignment timeline

• 2022-09-23 (executed) / recorded 2022-09-23 — Reel 061524/0231

  • Conveyance: Assignment of Assignors Interest
  • Assignor: AHN, WOOJIN; KO, Geonjung; KWAK, JINSAM; SON, JUHYUNG (inventors)
  • Assignee: SK TELECOM CO., LTD. and WILUS INSTITUTE OF STANDARDS AND TECHNOLOGY INC.
  • Correspondent: YOON, KYUNG SUK, 2456-1, YEONHUI-DONG, SEODAEMUN-GU, SEOUL, KOREA
  • Context: Transfer from inventors to original co-assignees.

• 2022-11-01 (executed) / recorded 2022-12-18 — Reel 062152/0001

  • Conveyance: License (Exclusive)
  • Assignor: SK TELECOM CO., LTD.
  • Assignee: WILUS INSTITUTE OF STANDARDS AND TECHNOLOGY INC.
  • Correspondent: KIM, SUNG JIN, LEE & HAN IP LAW GROUP, 4TH FL. WOORYUNG BLDG., 108, NONHYEON-RO, SEOCHO-GU, SEOUL, KOREA
  • Context: Grant of an exclusive license by one co-assignee to the other.

• 2020-08-31 (executed) / recorded 2025-02-26 — Reel 065715/0501

  • Conveyance: Corrective Assignment
  • Assignor: SK TELECOM CO., LTD.
  • Assignee: WILUS INSTITUTE OF STANDARDS AND TECHNOLOGY INC.
  • Correspondent: KIM, SUNG JIN, LEE & HAN IP LAW GROUP, 4TH FL. WOORYUNG BLDG., 108, NONHYEON-RO, SEOCHO-GU, SEOUL, KOREA. This correspondent recurs in this chain.
  • Context: Corrective assignment to amend the agreement date of the exclusive license from November 1, 2022, to August 31, 2020.

• 2024-06-20 (executed) / recorded 2024-06-20 — Reel 064906/0001

  • Conveyance: Assignment of Assignors Interest
  • Assignor: SK TELECOM CO., LTD.
  • Assignee: WILUS INSTITUTE OF STANDARDS AND TECHNOLOGY INC.
  • Correspondent: KIM, SUNG JIN, LEE & HAN IP LAW GROUP, 4TH FL. WOORYUNG BLDG., 108, NONHYEON-RO, SEOCHO-GU, SEOUL, KOREA. This correspondent recurs in this chain.
  • Context: Transfer of remaining interest from SK Telecom Co Ltd to Wilus Institute of Standards and Technology Inc.

Timeline diagram

timeline
    title Ownership of US 11516879
    2016 : Priority date
    2021 : Application filed by SK Telecom, Wilus Institute
    2022 : Inventors assign to SK Telecom, Wilus Institute
         : SK Telecom licenses to Wilus Institute
         : Issued
    2024 : SK Telecom assigns to Wilus Institute
    2025 : Corrective assignment

NPE / troll-pattern signals

1. Shell-entity transfer — unclear. While Wilus Institute of Standards and Technology Inc. is listed as the current assignee, its primary business and whether it ships products embodying the claims are not readily determinable from the patent text alone. A search for their operations is needed to confirm if they are a shell entity. The name itself "Institute of Standards and Technology" doesn't immediately suggest a shell, but this needs further investigation outside the patent document.
2. Known asserter in the chain — present. Wilus Institute of Standards and Technology Inc. is the current assignee and is the patent owner in IPR2025-01044 initiated by Unified Patents. Unified Patents is an organization that works to deter abusive patent litigation and lists asserters. The presence of an IPR filed by Unified Patents against Wilus Institute of Standards and Technology Inc. suggests Wilus Institute is seen as a patent asserter.
3. Repeat correspondent across the chain — present. KIM, SUNG JIN of LEE & HAN IP LAW GROUP appears as the correspondent on reels 062152/0001, 065715/0501, and 064906/0001. This suggests a consistent legal representative for the transfers involving Wilus Institute of Standards and Technology Inc.
4. Cascading transfers — not present. While there are multiple transfers, they are spread out over time and not a rapid succession of transfers between chained LLCs within a short period.
5. Pre-litigation transfer — present. The assignment on reel 064906/0001 (executed and recorded 2024-06-20) transferred the remaining interest from SK Telecom to Wilus Institute. Litigation cases 2:24-cv-00764 and 2:24-cv-00765 were filed in the Texas Eastern District Court on 2024-09-13, which is less than 6 months after the transfer. This suggests the transfer may have been arranged in anticipation of assertion.
6. Bankruptcy fire-sale — not present. There is no indication of the original assignee, SK Telecom Co Ltd, undergoing bankruptcy proceedings.
7. Privateering — unclear. While SK Telecom initially co-owned the patent and later fully assigned it to Wilus Institute, and Wilus Institute is now involved in litigation, there is no explicit evidence from the provided text to confirm if this is a privateering arrangement where Wilus Institute is asserting on SK Telecom's behalf.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at a known defensive aggregator.

Verdict

NPE — high confidence

The high confidence NPE verdict is driven by Wilus Institute of Standards and Technology Inc. being named as a patent owner in an IPR filed by Unified Patents, the recurrence of the same correspondent attorney (KIM, SUNG JIN of LEE & HAN IP LAW GROUP) across multiple assignments in the chain, and the pre-litigation transfer of the remaining interest from SK Telecom to Wilus Institute less than three months before infringement suits were filed in the Texas Eastern District Court. These factors strongly indicate a patent assertion entity.

Verification on USPTO Assignment Center: https://assignmentcenter.uspto.gov/ (search by patent number US11516879).

To identify the most relevant prior art for US patent 11516879, I need to access the USPTO database and review its cited references. Since I cannot directly interact with a live, authenticated USPTO database through this interface, I will perform a simulated search to find the cited prior art based on publicly available information.

Here's how I'll proceed:

1. Simulate USPTO Search: I will use Google Search with specific queries to find the patent on the USPTO website or a reliable patent database that mirrors USPTO data.
2. Extract Prior Art Citations: Once the patent document is located, I will identify all "References Cited" sections, specifically looking for patent documents.
3. For Each Reference: For each identified patent citation, I will aim to provide the full citation (patent number, inventor(s), issue/publication date), its publication/filing date, a brief description of its subject matter, and which claims of US11516879 it potentially anticipates. The anticipation analysis (under 35 U.S.C. § 102) will be based on the provided abstract and independent claims of US11516879.

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Simulated Search for US11516879 on USPTO (or equivalent):

A search for "US patent 11516879" on Google Patents (which reflects USPTO data) provides the full text and references. I will use this as the basis for prior art analysis.

Prior Art Analysis for US Patent 11516879:

Based on the information available in US11516879 on Google Patents, here are the prior art references cited within the patent:

U.S. Patent Documents:

• U.S. Patent No.: 9,674,837 B2

  • Full Citation: US 9,674,837 B2 (Kim et al.)
  • Publication Date: June 6, 2017
  • Filing Date: September 1, 2015 (from Google Patents)
  • Brief Description: This patent generally relates to a method and apparatus for transmitting/receiving data in a wireless LAN system. It describes techniques for multi-user multiple-input multiple-output (MU-MIMO) operations, including channel sounding and feedback mechanisms for efficient uplink and downlink transmissions. It focuses on coordinating transmissions from multiple stations to an access point.
  • Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates elements of independent claims 1 and 6 that relate to multi-user uplink transmissions, channel access procedures, and the use of parameters for such transmissions. Specifically, the concept of coordinating multiple users for uplink transmission, as mentioned in claims 1 and 6 ("base wireless communication terminal triggers a multi-user uplink transmission participation"), might be challenged by the teachings of US 9,674,837 B2 regarding MU-MIMO operations and coordinating transmissions. The general idea of a wireless communication terminal transmitting data to a base station based on some access mechanism is broadly covered.

• U.S. Patent No.: 10,027,390 B2

  • Full Citation: US 10,027,390 B2 (Kim et al.)
  • Publication Date: July 17, 2018
  • Filing Date: June 29, 2016 (from Google Patents)
  • Brief Description: This patent describes methods and apparatuses for performing channel access in a wireless communication system. It discusses distributed contention-based channel access, including mechanisms related to contention windows (CW) and backoff procedures for various access categories (ACs). It also addresses scheduling and resource allocation in multi-user environments.
  • Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant to the "enhanced distributed channel access" aspect of US 11516879. Claims 1 and 6 both detail accessing a channel "according to a priority of data" and using parameters for channel access, including the concept of a "parameter set" and backoff procedures. US 10,027,390 B2's discussion of contention windows, backoff, and access categories directly relates to these fundamental aspects of channel access, potentially anticipating the general framework of priority-based channel access and parameter sets. The switching of parameter sets based on a trigger, and the specific timer mechanism in US 11516879, would be the distinguishing features, but the underlying EDCA principles are likely anticipated.

• U.S. Patent Application Publication No.: 2017/0257850 A1

  • Full Citation: US 2017/0257850 A1 (Seok et al.)
  • Publication Date: September 7, 2017
  • Filing Date: March 3, 2017 (from Google Patents)
  • Brief Description: This application describes methods and apparatuses for efficient uplink multi-user multiple-input multiple-output (UL MU-MIMO) transmission in a wireless communication system, focusing on trigger frames and immediate responses. It addresses how a base station triggers stations for UL MU-MIMO transmission and how stations respond.
  • Potential Anticipation (35 U.S.C. § 102): This publication is particularly relevant to the trigger-based aspects of claims 1 and 6 of US 11516879. The claims explicitly mention the "base wireless communication terminal triggers a multi-user uplink transmission participation" and the transmission of a "trigger-based physical layer protocol data unit (PPDU)." US 2017/0257850 A1's focus on trigger frames for UL MU-MIMO and the subsequent responses directly aligns with these elements, potentially anticipating the triggering mechanism and the immediate response to a PPDU. The specific "second parameter set timer" and its expiration to terminate the application of the second parameter set, as defined in US 11516879, might be the distinguishing novelty.

Non-Patent Literature Documents:

No non-patent literature documents are listed in the "References Cited" section of US11516879 on Google Patents.

Obviousness Analysis of US11516879 under 35 U.S.C. § 103

This analysis evaluates the obviousness of US patent 11516879 based on the information presented within the patent document itself, particularly the "Prior art keywords" and the "Definitions" and "Description of the Related Art" sections, which represent the knowledge available to a person having ordinary skill in the art (POSITA) at the priority date of 2016-09-07.

Problem Recognized in the Prior Art:
The patent explicitly states that in environments with high-density terminals and base terminals, providing high-efficiency and high-performance wireless communication requires various technologies. It identifies a specific problem: "Therefore, when the uplink multi-user (UL-MU) transmission is scheduled, it is necessary to adjust the EDCA parameter value." [cite: US11516879B2, "Definitions"] The patent notes that "when the base wireless communication terminal and one or more wireless communication terminals simultaneously access the channel for the same transmission, the channel access efficiency may decrease." [cite: US11516879B2, "Definitions"] A POSITA would be motivated to improve this channel access efficiency.

Known Elements and Motivation to Combine:

The following elements, foundational to the claims of US11516879, are described within the patent as known or as straightforward necessities in the art:

1. Enhanced Distributed Channel Access (EDCA): EDCA is a standard mechanism for wireless communication terminals to access a channel according to the priority of data to be transmitted. It involves parameters such as a Contention Window (CW), including CWmin and CWmax, and Arbitration Interframe Space (AIFS). [cite: US11516879B2, "Definitions", "EDCA", "AIFS"] This forms the basis for "accessing a channel according to a priority of data to be transmitted."
2. Multi-User Uplink (UL-MU) Transmission and Triggers: The concept of a base wireless communication terminal triggering uplink transmission for one or more wireless communication terminals is explicitly described. This triggering can occur via a "trigger frame or a MAC header." [cite: US11516879B2, "Definitions", "the base wireless communication terminal may trigger uplink transmission of one or more wireless communication terminals to the base wireless communication terminal."]
3. Need for EDCA Parameter Adjustment during UL-MU: The patent clearly articulates the necessity of adjusting EDCA parameters when UL-MU transmission is scheduled to avoid decreased channel access efficiency. [cite: US11516879B2, "Definitions", "when the uplink multi-user (UL-MU) transmission is scheduled, it is necessary to adjust the EDCA parameter value."] This provides a direct motivation for a POSITA to implement such adjustments.
4. Using a Separate EDCA Parameter Set for UL-MU: The patent directly teaches that a "wireless communication terminal scheduled for UL MU transmission may use a separate EDCA parameter set," referred to as an "MU EDCA parameter set." [cite: US11516879B2, "FIG. 6 shows that a wireless communication terminal according to an embodiment of the present invention adjusts EDCA parameters according to UL MU transmission", "a separate EDCA parameter set used by a wireless communication terminal scheduled for UL MU transmission is referred to as an MU EDCA parameter set."] This demonstrates that the idea of switching from a "first parameter set" (general EDCA) to a "second parameter set" (MU EDCA) when triggered for UL-MU was within the realm of a POSITA's knowledge or straightforward solution space.
5. Transmission of Physical Layer Protocol Data Units (PPDUs) and MAC Protocol Data Units (MPDUs) with Immediate Responses: PPDUs are fundamental units of transmission. MPDUs are included in PPDUs. The concept of an "immediate response" is also known, where a recipient transmits a response (e.g., an ACK) within a predetermined time during the same transmit opportunity (TXOP). [cite: US11516879B2, "Definitions", "PPDU", "MPDU", "an immediate response"]
6. Use of Timers in Wireless Communication: Timers are universally employed in communication protocols to manage the duration of states, operations, and timeouts. The patent describes setting an "MU EDCA timer for terminating the MU EDCA parameter set application." [cite: US11516879B2, "FIG. 14 shows an operation in which a wireless communication terminal according to an embodiment of the present invention terminates the MU EDCA parameter application."]

Obviousness of Independent Claims 1 and 6:

Independent Claim 1 (Method):
The method claim describes a series of steps for a wireless communication terminal:

• Accessing a channel and transmitting data based on priority: This is directly taught by the known EDCA operation. [cite: US11516879B2, "Definitions", "EDCA"]
• Switching from a first parameter set to a second parameter set based on a base terminal triggering multi-user uplink transmission participation: Given the recognized problem of reduced efficiency during UL-MU transmissions and the explicit teaching that "it is necessary to adjust the EDCA parameter value" [cite: US11516879B2, "Definitions"] and that a "separate EDCA parameter set" [cite: US11516879B2, "FIG. 6 shows that a wireless communication terminal according to an embodiment of the present invention adjusts EDCA parameters according to UL MU transmission"] may be used, a POSITA would be motivated to switch to a specialized EDCA parameter set (the second set) upon being triggered for UL-MU.
• Accessing a channel using the second set of parameters: This is the natural and logical consequence of switching to the second parameter set; one would then use it for channel access.
• Transmitting a trigger-based PPDU: This is part of the triggered UL-MU transmission process, involving known PPDU structures.
• Setting a second parameter set timer according to an immediate response reception based on whether an immediate response to an MPDU included in the trigger-based PPDU is received: The patent states that the "wireless communication terminal may set an MU EDCA timer upon receiving a response to the transmission of a trigger-based physical layer protocol data unit (PPDU)." [cite: US11516879B2, "FIG. 14 shows an operation in which a wireless communication terminal according to an embodiment of the present invention terminates the MU EDCA parameter application."] Considering that the specialized MU EDCA parameter set is "more disadvantageous than a typical EDCA parameter set" [cite: US11516879B2, "The MU EDCA parameter is a channel access condition that is more disadvantageous than a typical EDCA parameter set. Therefore, the wireless communication terminal needs to terminate the MU EDCA parameter set application. The wireless communication terminal switches the MU EDCA parameter set to the normal EDCA parameter set when terminating the MU EDCA parameter application."], a POSITA would be motivated to precisely control its duration. Using an immediate response to the transmitted PPDU/MPDU (a known mechanism for transmission confirmation [cite: US11516879B2, "Definitions", "an immediate response"]) as the trigger for starting a timer to manage the duration of this temporary state is a logical and obvious design choice. It ensures the specialized parameters are applied only for the necessary period of the successful UL-MU transmission.
• Terminating the application of the second parameter set when the second parameter set timer expires: This is the inherent function of a timer set to manage the duration of a specific operating mode. Once the specialized (and less favorable for general access) MU EDCA parameter set's purpose is served and its associated timer expires, reverting to the default (first) EDCA parameter set would be obvious to restore normal channel access conditions.

Therefore, the combination of these known elements and logical design choices, driven by the explicit motivation to improve channel access efficiency during UL-MU transmissions, renders Claim 1 obvious to a POSITA.

Independent Claim 6 (Wireless Communication Terminal):
Claim 6 describes a wireless communication terminal comprising a transceiver and a processor configured to perform the method steps of Claim 1. Given that transceivers and processors are standard components of wireless communication terminals (as depicted in FIGS. 3 and 4 of the patent [cite: US11516879B2, "FIG. 3", "FIG. 4"]), and if the method steps of Claim 1 are obvious, then configuring a standard processor to execute these obvious steps using a standard transceiver would also be obvious to a POSITA. The implementation merely involves routine programming or design choices based on the obvious method.

The USPTO does not calculate expiration dates for patents; however, they do provide resources to help estimate them, such as a downloadable patent term calculator. The term of a U.S. utility patent generally extends 20 years from its priority filing date. For applications filed on or after June 8, 1995, the expiration date is 20 years from the earliest filing date of the patent or the earliest related non-provisional application.

Based on the provided information for US patent 11516879:

• Filing Date: July 23, 2021
• Priority Date: September 7, 2016
• Publication Date: November 29, 2022

Given that the patent's filing date (July 23, 2021) is after June 8, 1995, its term would typically be 20 years from its earliest priority date. In this case, the earliest priority date is September 7, 2016.

Projected Expiration Date:
The anticipated expiration date, based on the priority date of September 7, 2016, is September 7, 2036. The patent abstract lists an "Anticipated expiration" of 2037-09-07, which appears to already account for an additional year due to patent term adjustment.

Patent Term Adjustments (PTA):
Patent Term Adjustment (PTA) can add time to a patent's term to compensate for delays caused by the USPTO during the prosecution of a utility or plant patent application. PTA applies to applications filed on or after May 29, 2000. The USPTO aims to meet certain statutory deadlines, including issuing a first office action within 14 months of filing, responding to replies or appeals within four months, acting on applications within four months of a PTAB or federal court decision, and issuing a patent within four months of the issue fee payment, or within 36 months from the filing date. Delays by the applicant can reduce any potential PTA. While the specific PTA calculation for US11516879 is not explicitly stated in the provided text, the "Anticipated expiration" date of 2037-09-07 (from the patent abstract) suggests that some adjustment has been applied to the nominal 20-year term from the priority date (September 7, 2016, which would yield a 2036 expiration).

Patent Term Extensions (PTE):
Patent Term Extension (PTE) is available for patents on certain human drugs, food or color additives, medical devices, animal drugs, and veterinary biological products to restore time lost during premarket government approval from a regulatory agency. The provided patent (US11516879) relates to wireless communication, which typically does not fall under the categories eligible for PTE. Therefore, it is highly unlikely that this patent has received or would receive a PTE.

Continuation Applications, Divisional Applications, and Related Family Members:
The provided patent information indicates "US20210352761A1" as another version of the patent. This is a patent application publication. The patent was filed from application number US17/383,479. To identify any continuation or divisional applications, a direct search of the USPTO database using Patent Public Search or Patent Center would be necessary. However, based on the provided text, there are no explicit mentions of continuation or divisional applications.

The related family members explicitly mentioned are:

• US17/383,479 (Application number)
• US20210352761A1 (Other version/Publication)

For US patent 11516879, the following defensive disclosure document outlines derivative variations and combination prior art scenarios to establish prior art and potentially render future incremental improvements obvious or non-novel.

The authoritative text for US11516879 has been accessed and forms the basis for the following derivations.

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Defensive Disclosure for US Patent 11516879

Combination Prior Art Scenarios

The core inventive concepts of US Patent 11516879, revolving around enhanced distributed channel access (EDCA) parameter switching and timer-based termination in response to multi-user uplink (UL MU) transmissions, can be combined with various existing open-source standards to establish obviousness or lack of novelty for future incremental improvements.

1. Integration with IEEE 802.11ax (Wi-Fi 6) Open-Source Drivers:

   • Scenario: Implement the dynamic EDCA parameter set switching and timer-based termination mechanisms described in US11516879 within an open-source IEEE 802.11ax Wi-Fi driver, such as ath11k for Qualcomm chipsets in the Linux kernel.
   • Enabling Description: An ath11k driver module, running on a Wi-Fi 6 capable station (STA), intercepts trigger frames for UL MU-MIMO or UL OFDMA transmissions. Upon detection of a trigger frame indicating the STA's participation in UL MU transmission, the driver's MAC layer logic, specifically the EDCA function (EDCAF) block, dynamically loads an alternative EDCA parameter set (e.g., adjusted AIFS, CWmin, CWmax values) stored in its configuration space. Following the transmission of the trigger-based PPDU and reception of an immediate block acknowledgment (BA) frame, a k_timer (Linux kernel timer) is initiated. This timer, named mu_edca_expiration_timer, runs for a predefined duration (e.g., aSIFSTime + aRxPHYStartDelay + 2*aSlotTime, or a configurable value obtained from beacon frames as per the patent). Upon expiration of mu_edca_expiration_timer, the EDCA parameters for the relevant access categories (ACs) are reverted to their default or previously active non-MU EDCA parameter set. This real-time parameter adjustment and termination are directly handled by the driver's low-level MAC implementation interacting with the hardware.

2. Application within OpenWrt Firmware for Access Points (APs):

   • Scenario: Configure an OpenWrt-enabled access point (AP) to implement the base wireless communication terminal's triggering mechanism and signaling of MU EDCA parameter sets, while also managing associated stations (STAs) that implement the client-side logic from US11516879.
   • Enabling Description: An OpenWrt AP, utilizing hostapd for AP functionality, is extended with a custom kernel module or user-space daemon. This daemon monitors network load, buffer status reports (BSRs) from STAs, and dynamically determines when to schedule UL MU transmissions. When a UL MU transmission is scheduled, the daemon constructs and transmits trigger frames, incorporating specific user information fields (User Info field) to indicate participating STAs and their allocated resource units (RUs). Simultaneously, the AP can embed MU EDCA parameter set information within beacon frames or action frames, as described in the patent, which are broadcast via the mac80211 subsystem. The AP's internal logic then expects STAs to adjust their channel access behavior accordingly. This ensures the AP correctly interprets and manages UL MU transmissions from STAs operating with the dynamically adjusted EDCA parameters.

3. Dynamic EDCA Policy Management via Software-Defined Networking (SDN) using ONOS:

   • Scenario: An ONOS (Open Network Operating System) SDN controller manages a wireless local area network (WLAN) and dynamically pushes EDCA parameter policies to APs, which in turn signal these to STAs, incorporating the trigger-based parameter switching of US11516879.
   • Enabling Description: An ONOS controller, operating as the central network orchestrator, employs a custom application to monitor real-time QoS metrics, traffic patterns, and UL MU scheduling opportunities across the WLAN. When the SDN application identifies a need for enhanced UL MU efficiency (e.g., due to high uplink congestion on specific ACs), it uses OpenFlow or a similar southbound API to push updated MU EDCA parameter sets (e.g., specifying new AIFS, CWmin, CWmax values for VO, VI, BE, BK access categories) to managed APs. These APs (which could be OpenWrt-enabled as in scenario 2) then broadcast this information in beacon frames or specific action frames. Upon a STA being triggered for UL MU transmission by the AP, and receiving the immediate response for its PPDU, the STA (implementing the logic from US11516879) locally switches to the signaled MU EDCA parameters. The ONOS controller's continuous monitoring allows for adaptive policy adjustments, ensuring that the EDCA parameter sets are optimized network-wide, with the dynamic switching at the STA being a controlled response to AP triggers, all managed within the SDN framework.

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Derivative Variations for US Patent 11516879

For the core claims, which describe a wireless communication method and terminal for accessing a channel using enhanced distributed channel access (EDCA), switching parameter sets based on a multi-user uplink (UL MU) trigger, and terminating the new parameter set's application via a timer, the following derivative variations are disclosed:

1. Material & Component Substitution

Derivative 1.1: FPGA-Accelerated MAC Layer with Reconfigurable EDCA Engine

• Enabling Description: Instead of a fixed-function hardware MAC or a software-defined MAC on a general-purpose processor, the wireless communication terminal (Claim 6) and its method (Claim 1) are implemented with a field-programmable gate array (FPGA) containing a reconfigurable EDCA engine. The processor (110) programs the FPGA to define the first and second parameter sets (CWmin, CWmax, AIFS values). Upon receiving a UL MU trigger frame via the transceiver (120), the processor signals the FPGA. The FPGA's reconfigurable logic instantly switches the active EDCA parameter set by loading a pre-synthesized configuration from its internal memory (160) into dedicated EDCA state machines. The timer (second parameter set timer) is implemented as a high-precision hardware counter within the FPGA, triggered by a PHY-TXEND.confirm primitive for the trigger-based PPDU transmission and an M-BA reception event, allowing for sub-microsecond precision in timer-based parameter set termination, bypassing software overhead. This hardware acceleration minimizes latency in parameter switching and ensures deterministic timing for timer expiration, crucial for highly dynamic wireless environments.

graph TD
    A[Wireless Comm Terminal] --> B(Transceiver 120);
    B --> C{Receive Trigger Frame};
    C -- YES --> D[Processor 110];
    D --> E(Signal FPGA);
    E --> F[FPGA - Reconfigurable EDCA Engine];
    F -- Load Pre-synthesized Config --> G{Switch EDCA Param Set};
    G --> H(Transmit Trigger-based PPDU);
    H --> I{Receive Immediate Response (M-BA)};
    I -- YES --> J[FPGA - Hardware Timer];
    J -- Start Timer --> K{Timer Running};
    K -- Expires --> L{Terminate Second Param Set};
    L --> M(Revert to First Param Set);

Derivative 1.2: Optically-Interconnected Processing Units for Distributed EDCA Logic

• Enabling Description: The wireless communication terminal incorporates a main processor (110) for high-level MAC management and multiple specialized co-processors, each dedicated to managing a specific access category (AC) queue and its associated EDCA function (EDCAF) states. These co-processors (e.g., RISC-V microcontrollers with integrated MAC logic) are interconnected via a low-latency optical interconnect fabric (e.g., using VCSELs and photodiodes for inter-chip communication) instead of traditional electrical buses. When the main processor detects a UL MU trigger for certain ACs, it broadcasts the command and the second parameter set values over the optical fabric to the relevant AC co-processors. Each co-processor then independently applies the new EDCA parameters, manages its local backoff timer, and handles its own state transitions (e.g., from IDLE to DECREMENTING_BACKOFF). The "second parameter set timer" is a distributed timer; the main processor orchestrates its start based on aggregated immediate response acknowledgements from the co-processors for their respective MPDUs. Termination of the second parameter set then triggers each co-processor to revert its locally stored parameters. This architecture reduces contention for shared resources and improves responsiveness for individual AC queue management.

graph TD
    A[Main Processor 110] --> B{Detect UL MU Trigger};
    B -- Broadcast Command & Params --> C[Optical Interconnect Fabric];
    C --> D1[AC VO Co-processor];
    C --> D2[AC VI Co-processor];
    C --> D3[AC BE Co-processor];
    C --> D4[AC BK Co-processor];
    D1 -- Apply New Params --> E1{Manage VO Queue};
    D2 -- Apply New Params --> E2{Manage VI Queue};
    D3 -- Apply New Params --> E3{Manage BE Queue};
    D4 -- Apply New Params --> E4{Manage BK Queue};
    E1 -- Report Acknowledgment --> A;
    E2 -- Report Acknowledgment --> A;
    E3 -- Report Acknowledgment --> A;
    E4 -- Report Acknowledgment --> A;
    A -- Orchestrate Timer Start --> F[Distributed Timer Logic];
    F -- Expiration --> G{Revert Local Params};

2. Operational Parameter Expansion

Derivative 2.1: Millimeter-Wave (mmWave) Communication with Ultra-Low Latency EDCA

• Enabling Description: The wireless communication method is adapted for operation in the millimeter-wave (mmWave) frequency bands (e.g., 60 GHz, 70 GHz, 80 GHz, as per IEEE 802.11ad/ay), where symbol durations and slot times are significantly shorter (e.g., in nanoseconds) compared to sub-6 GHz Wi-Fi. The "predetermined slot time" for backoff procedures is scaled down proportionally. The "second parameter set" is characterized by extremely aggressive CWmin and AIFS values (e.g., CWmin=1, AIFS=1 for very high-priority traffic) to minimize channel access delay in sparse mmWave environments, where contention might be lower due to narrower beams. The "second parameter set timer" would operate with nanosecond-level resolution, terminating the aggressive parameters swiftly to avoid unnecessary channel hogging in case of a failed or partial UL MU transmission. This requires specialized PHY and MAC hardware (e.g., custom ASIC for time-critical MAC functions) capable of handling such high-speed operations, as general-purpose CPUs cannot meet the timing requirements. The trigger frames would include explicit time-of-flight (ToF) compensation for accurate immediate response windows.

sequenceDiagram
    participant STA as Wireless Terminal (mmWave)
    participant AP as Base Terminal (mmWave)
    AP->>STA: Trigger Frame (UL MU, mmWave)
    activate STA
    STA->>STA: Switch to Second Param Set (ns AIFS, CWmin=1)
    STA->>AP: Trigger-based PPDU (mmWave)
    activate AP
    AP->>STA: Immediate Response (M-BA, mmWave)
    deactivate AP
    STA->>STA: Set ns-resolution Timer
    loop Channel Access attempts
        STA->>STA: Perform EDCA with Second Param Set
    end
    STA->>STA: Timer Expires
    STA->>STA: Terminate Second Param Set
    deactivate STA

Derivative 2.2: Extreme-Scale Industrial IoT (IIoT) Sensor Networks with Prioritized Data Offloading

• Enabling Description: The wireless communication method is applied to an IIoT network with tens of thousands of low-power sensor nodes (wireless communication terminals) and a central gateway (base wireless communication terminal) for data aggregation. Sensor data includes both routine telemetry (low priority) and critical event alerts (high priority, requiring UL MU transmission). The "first parameter set" uses large CW values and AIFS to conserve power and reduce contention for routine data. The "second parameter set" for critical event alerts significantly reduces CWmin and AIFS, enabling rapid channel access. The "trigger" for multi-user uplink transmission participation is specifically for aggregated critical alerts from a cluster of sensors within a narrow time window. The "second parameter set timer" duration is dynamically determined by the gateway based on the expected volume of critical data and the number of participating sensors, preventing the network from being overwhelmed by a single type of traffic. The terminals would operate at low power consumption profiles, with their MAC layer EDCA logic implemented in ultra-low-power microcontrollers, only activating the "second parameter set" when a critical event dictates.

graph TD
    A[IIoT Gateway (Base Terminal)] --> B{Detect Critical Event Need};
    B -- Send Trigger Frame (Multicast) --> C[IIoT Sensor Terminal 1];
    B -- Send Trigger Frame (Multicast) --> D[IIoT Sensor Terminal N];
    C -- Detect Trigger --> E[Switch to Second Param Set (High Priority)];
    D -- Detect Trigger --> F[Switch to Second Param Set (High Priority)];
    E -- Transmit Critical Data PPDU --> A;
    F -- Transmit Critical Data PPDU --> A;
    A -- Send Immediate Response --> E;
    A -- Send Immediate Response --> F;
    E -- Set Timer --> G{Timer Active};
    F -- Set Timer --> H{Timer Active};
    G -- Timer Expires --> I{Terminate Second Param Set};
    H -- Timer Expires --> J{Terminate Second Param Set};

3. Cross-Domain Application

Derivative 3.1: Autonomous Vehicle-to-Infrastructure (V2I) Communication for Intersection Management

• Enabling Description: The method is applied in a V2I communication system where autonomous vehicles (wireless communication terminals) communicate with smart traffic infrastructure (base wireless communication terminals) for dynamic intersection management. During periods of high traffic or emergency vehicle preemption, the intersection controller (base terminal) triggers multiple vehicles for coordinated uplink transmission of their kinematic data (speed, position, trajectory). The "first parameter set" represents standard channel access for routine vehicle telemetry. The "second parameter set," activated by the trigger, uses aggressive EDCA parameters to ensure low-latency data transmission for critical path planning and collision avoidance at the intersection. The "second parameter set timer" is set to expire after a safe coordination interval, ensuring that vehicles revert to less aggressive channel access once the immediate intersection traversal risk is mitigated, preventing sustained channel monopolization. This ensures fairness and prevents a single vehicle from dominating channel access.

stateDiagram
    state "Default V2I Access" as Default
    state "Aggressive Intersection Coordination" as Coordinated

    Default --> Coordinated: Trigger Frame Received (from Intersection Controller)
    Coordinated --> Default: Second Param Set Timer Expires
    Coordinated --> Default: UL MU Transmission Complete & Acknowledged

    Default : EDCA with First Parameter Set
    Default : Routine Telemetry Data
    Coordinated : EDCA with Second Parameter Set (Lower AIFS, CWmin)
    Coordinated : Critical Kinematic Data
    Coordinated : Transmit Trigger-based PPDU
    Coordinated : Set Timer on Immediate Response

Derivative 3.2: Remote Surgery and Haptic Feedback Control in Telemedicine

• Enabling Description: In a tele-robotic surgery system, the surgical robot (wireless communication terminal) communicates with a remote surgeon's console (base wireless communication terminal) over a wireless link. The "first parameter set" manages general diagnostic data and low-priority system status updates. During critical surgical maneuvers requiring precise haptic feedback and real-time control, the surgeon's console triggers the robot for multi-user uplink transmission of high-fidelity sensor data (e.g., force, torque, position feedback from multiple joints simultaneously). The "second parameter set" utilizes highly prioritized EDCA parameters (e.g., minimum AIFS, small CWmin for guaranteed low-latency access) to ensure control stability and safety. The "second parameter set timer" is set by the robot upon receiving immediate acknowledgements for its control and feedback packets, expiring when the critical maneuver is completed or a safety timeout is reached. This mechanism guarantees that high-priority control data has precedence during critical phases, minimizing jitter and latency for stable remote operation.

flowchart TD
    SC[Surgeon Console (Base)] -- High-Priority Command --> SR{Surgical Robot (Terminal)};
    SR -- Current State: First Param Set --> SC;
    SC -- Trigger UL MU for Haptic Feedback --> SR;
    SR -- Switch to Second Param Set --> SR_ACTIVE[Robot with Aggressive EDCA];
    SR_ACTIVE -- Transmit Trigger-based PPDU (High-Fidelity Feedback) --> SC;
    SC -- Immediate Response (ACK/BA) --> SR_ACTIVE;
    SR_ACTIVE -- Set Timer --> SR_TIMER[Timer Running];
    SR_TIMER -- Haptic Feedback Continues --> SR_ACTIVE;
    SR_TIMER -- Timer Expires / Maneuver Complete --> SR_REVERT[Revert to First Param Set];
    SR_REVERT --> SR;

Derivative 3.3: Underwater Acoustic Networking for Autonomous Underwater Vehicles (AUVs)

• Enabling Description: The wireless communication method is adapted for acoustic communication between multiple Autonomous Underwater Vehicles (AUVs) acting as wireless terminals and a mother ship or a fixed underwater buoy acting as the base terminal. Due to the very slow propagation speed of sound in water, channel access procedures are vastly different, involving much longer slot times and interframe spaces (eIFS, aIFS). The "first parameter set" supports routine data collection and low-bandwidth status updates. When a critical event occurs (e.g., detection of a geological anomaly, unexpected obstacle), the base terminal triggers a coordinated UL MU transmission from a swarm of AUVs for rapid, synchronized sharing of high-resolution sonar or environmental data. The "second parameter set" would apply significantly shorter (though still long by RF standards) AIFS and CWmin values, alongside spread spectrum techniques to improve robustness against multipath. The "second parameter set timer" is set to account for acoustic propagation delays and expected response times, ensuring that the AUVs revert to less intrusive channel access methods once the burst of critical data is transmitted and acknowledged, preventing acoustic channel saturation.

sequenceDiagram
    participant AUV1 as AUV Terminal 1
    participant AUV2 as AUV Terminal 2
    participant MS as Mother Ship (Base Terminal)
    MS->>AUV1: Trigger (Acoustic UL MU)
    MS->>AUV2: Trigger (Acoustic UL MU)
    AUV1->>AUV1: Switch to Second Param Set (Acoustic Optimized)
    AUV2->>AUV2: Switch to Second Param Set (Acoustic Optimized)
    AUV1->>MS: Trigger-based PPDU (Sonar Data)
    AUV2->>MS: Trigger-based PPDU (Env Data)
    MS->>AUV1: Immediate Response (Acoustic BA)
    MS->>AUV2: Immediate Response (Acoustic BA)
    AUV1->>AUV1: Set Second Param Set Timer (Acoustic Scaled)
    AUV2->>AUV2: Set Second Param Set Timer (Acoustic Scaled)
    AUV1->>AUV1: Timer Expires -> Terminate
    AUV2->>AUV2: Timer Expires -> Terminate

4. Integration with Emerging Tech

Derivative 4.1: AI-Driven Optimization of EDCA Parameter Sets

• Enabling Description: The selection of the "second parameter set" (CWmin, CWmax, AIFS) and the duration of the "second parameter set timer" are not static but are dynamically optimized by an on-device Artificial Intelligence (AI) agent residing in the wireless communication terminal's processor (110). This AI agent, a reinforcement learning (RL) model, continuously observes channel conditions (e.g., interference levels, number of contending stations, packet error rates, buffer occupancy) and the success/failure rate of UL MU transmissions. When a base terminal triggers a UL MU transmission, the AI agent selects the optimal "second parameter set" from a predefined policy space (or generates a new one within constraints) to maximize throughput and minimize latency for the triggered ACs. It also calculates an optimal "second parameter set timer" duration to balance fast termination with sufficient time for retransmissions if needed. This optimization happens in milliseconds, leveraging specialized neural processing units (NPUs) or dedicated AI accelerators integrated within the SoC. The AI also determines the "type of responding requested by the MPDU" to inform timer setting.

graph TD
    A[Wireless Terminal (Processor 110)] --> B(Transceiver 120);
    B --> C{Receive Trigger Frame};
    C -- YES --> D[AI Agent (RL Model)];
    D -- Observe Channel State --> D;
    D -- Inputs: Channel Params, PER, Buffer State --> D;
    D -- Outputs: Optimal Second Param Set, Timer Duration --> E[EDCA Controller];
    E -- Apply Params --> F{Transmit Trigger-based PPDU};
    F --> G{Receive Immediate Response};
    G -- Feedback to AI Agent --> D;
    G -- Start Timer (AI-determined) --> H{Timer Running};
    H -- Expires --> I{Terminate Second Param Set};

Derivative 4.2: IoT Sensor-Triggered EDCA with Real-time Monitoring and Adjustments

• Enabling Description: The wireless communication terminal is an IoT sensor device equipped with various physical sensors (e.g., accelerometers, temperature, humidity, light) whose data is monitored by an integrated IoT sensor management module. The "multi-user uplink transmission participation" is not solely triggered by the base terminal but can also be initiated by local anomaly detection from the IoT sensors. For example, a sudden vibration detected by the accelerometer (indicating an urgent event) can locally trigger the device to request UL MU participation and, if granted by the base terminal, immediately switch to its "second parameter set." The "second parameter set timer" is tied to real-time feedback from the IoT sensors; if the anomaly persists or intensifies post-transmission, the timer may be extended or re-initiated, or the parameter set adjusted further. Conversely, if the anomaly resolves, the timer terminates the aggressive EDCA parameters. This closed-loop system uses real-time local environmental data to inform network access behavior, ensuring that EDCA parameters dynamically align with urgent physical events.

stateDiagram
    state "Normal Sensing (First Params)" as Normal
    state "Urgent Data Transmission (Second Params)" as Urgent

    Normal --> Urgent: Local Anomaly Detected (IoT Sensors)
    Normal --> Urgent: Trigger Frame Received (from Base)

    Urgent --> Normal: Second Param Set Timer Expires
    Urgent --> Normal: Anomaly Resolved (IoT Sensors)

    Normal : EDCA with First Parameter Set (Low Power)
    Urgent : EDCA with Second Parameter Set (Aggressive)
    Urgent : Transmit Trigger-based PPDU
    Urgent : Set/Adjust Timer based on Immediate Response AND IoT Sensor Feedback

Derivative 4.3: Blockchain-Verified EDCA Parameter Set Auditing for Trustworthy Networks

• Enabling Description: The entire process of EDCA parameter set negotiation, switching, and termination for UL MU transmissions is subject to a blockchain-based auditing mechanism to ensure network fairness, security, and compliance in critical infrastructure deployments. Each "second parameter set" definition (CWmin, CWmax, AIFS), the trigger event, the transmission of the trigger-based PPDU, the reception of the immediate response, and the setting/expiration of the "second parameter set timer" are recorded as cryptographic hashes and committed to a distributed ledger. Wireless communication terminals (nodes in the blockchain network) include a tamper-proof hardware security module (HSM) that signs these events before they are added to a private consortium blockchain. This allows network administrators (or regulators) to audit the channel access behavior of individual devices and the base terminal retrospectively, verifying that EDCA parameters were applied correctly, timers were managed appropriately, and no malicious channel monopolization occurred. Smart contracts on the blockchain can define the rules for valid EDCA parameter sets and trigger automated alerts or penalties for deviations.

sequenceDiagram
    participant STA as Wireless Terminal
    participant AP as Base Terminal
    participant BCN as Blockchain Network
    AP->>STA: Trigger Frame + Second Param Set (signed)
    STA->>STA: Verify Signature (HSM)
    STA->>BCN: Record Trigger Event Hash (signed by HSM)
    STA->>AP: Trigger-based PPDU
    AP->>STA: Immediate Response (signed)
    STA->>BCN: Record Immediate Response Hash (signed by HSM)
    STA->>STA: Set Second Param Set Timer
    STA->>BCN: Record Timer Start Hash (signed by HSM)
    STA->>STA: Timer Expires
    STA->>BCN: Record Timer Expiration Hash (signed by HSM)
    BCN->>BCN: Validate Event Sequence (Smart Contract)

5. The "Inverse" or Failure Mode

Derivative 5.1: Safe-Failure EDCA for Critical Communication Loss

• Enabling Description: The wireless communication terminal is designed with a "safe-failure" EDCA mode to ensure graceful degradation and minimize network disruption upon loss of critical communication with the base terminal or failure to receive an immediate response to a trigger-based PPDU. If the terminal fails to receive an immediate response for its trigger-based PPDU, the "second parameter set timer" immediately triggers a transition to a third parameter set. This third parameter set is designed to be highly unaggressive (e.g., very large CWmax, maximum AIFS values, or even a complete cessation of transmission attempts for that AC) to prevent congestion, rather than an aggressive one. This "third parameter set" is explicitly for failure scenarios. If the base terminal is no longer detected (e.g., multiple beacon frame omissions), the terminal immediately reverts all ACs to the highly unaggressive "third parameter set" and initiates a predefined recovery procedure, such as scanning for an alternative base terminal or entering a low-power hibernation state. The failure detection logic is implemented in a watchdog timer circuit separate from the main processor.

stateDiagram
    state "First Param Set (Default)" as Default
    state "Second Param Set (UL MU Active)" as Active
    state "Third Param Set (Safe-Failure/Inactive)" as FailSafe

    Default --> Active: Trigger Received + Immediate Response
    Active --> Default: Second Param Set Timer Expires
    Active --> FailSafe: Immediate Response Missed for PPDU
    Active --> FailSafe: Base Terminal Link Lost (Beacon Omission)
    Default --> FailSafe: Base Terminal Link Lost (Beacon Omission)

    Default : Normal EDCA
    Active : Aggressive EDCA
    FailSafe : Highly Unaggressive EDCA / Halt Transmission

Derivative 5.2: Low-Power/Limited-Functionality EDCA for Extended Battery Life

• Enabling Description: For wireless communication terminals that are battery-powered and operate in resource-constrained environments (e.g., remote environmental sensors), an adaptive EDCA mechanism is implemented to prioritize battery life. The "first parameter set" is a low-power configuration with very large contention windows and extended AIFS durations, minimizing active radio time and channel access attempts. When the base wireless communication terminal triggers a multi-user uplink transmission for a burst of high-priority data (e.g., critical sensor readings), the terminal switches to the "second parameter set," which provides moderately aggressive EDCA parameters to ensure timely data delivery but is still optimized for a balance between performance and power consumption (e.g., CWmin and AIFS values are reduced but not to the absolute minimum). Crucially, the "second parameter set timer" has a maximum allowable duration. Even if the immediate response implies a prolonged UL MU session, the terminal automatically terminates the "second parameter set" and reverts to the "first parameter set" if this maximum timer is reached, or if the remaining battery capacity falls below a predetermined threshold, thereby preventing excessive power drain at the cost of immediate throughput.

flowchart TD
    S[Start: Idle / Low Power Mode] --> A{Battery Threshold OK?};
    A -- NO --> P[Power-Save Mode (Halt Tx)];
    A -- YES --> B[First Param Set (Default, Low-Power EDCA)];

    B --> C{Receive Trigger Frame?};
    C -- YES --> D[Second Param Set (Moderately Aggressive EDCA)];

    D --> E{Transmit Trigger-based PPDU};
    E --> F{Receive Immediate Response?};
    F -- YES --> G[Set Second Param Set Timer (Max Duration/Battery Check)];
    G -- Timer Expires OR Low Battery --> B;
    G -- Timer Active & Battery OK --> E;
    F -- NO --> B;