US 6958986

US Patent 6958986, titled "Wireless communication system with enhanced time slot allocation and interference avoidance/mitigation features and related methods," provides a comprehensive framework for optimizing wireless communication in mobile ad-hoc networks (MANETs) using directional antennas.

Summary of US Patent 6958986:

• Title: Wireless communication system with enhanced time slot allocation and interference avoidance/mitigation features and related methods
• Assignee: The original assignee was Harris Corp. The current assignee is Stingray IP Solutions LLC.
• Inventor: Joseph Bibb Cain
• Filing Date: March 27, 2003
• Issue Date: October 25, 2005
• Abstract: A wireless communication system is disclosed, comprising multiple mobile nodes each with a wireless transceiver and a controller. The controller schedules semi-permanent time slots for communication links with neighboring nodes to transmit data of different priority levels. It determines link utilization metrics for each data priority level, scheduling additional "demand assigned" time slots based on these metrics and priorities. The controller can also re-allocate demand assigned time slots based on changing link utilization metrics, even estimating reduced or increased capacity. Each link utilization metric can be based on data sent during prior time slots or data in a transmission queue. An aggregate link metric, a weighted sum of priority-level metrics, can also be determined. The system preferably uses directional communication links via phased array antennas. Another aspect involves scheduling directional links by considering relative positions of neighboring and potentially interfering nodes, only scheduling a link if potential interference is below a threshold. The system can also dynamically re-allocate time slots based on link utilization and signal-to-interference (SIR) values, with different re-allocation time periods depending on link quality.

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a wireless communication network with multiple mobile nodes. Each node has a transceiver and a controller. The controller is configured to:

  • Schedule a "semi-permanent" time slot for each communication link with a neighboring mobile node to transmit data, where this data can have different priority levels.
  • Determine how much each communication link is being utilized for each data priority level (these are "link utilization metrics").
  • Schedule "demand assigned" time slots for additional communication links with neighboring nodes. This scheduling is based on the previously determined link utilization metrics and the data priority levels.

• Independent Claim 13: This claim outlines a method for communication in such a wireless network. The method involves:

  • Scheduling a semi-permanent time slot for communication links between pairs of mobile nodes for transmitting data with different priority levels.
  • Determining link utilization metrics for each data priority level for each communication link.
  • Scheduling demand assigned time slots for additional communication links between these pairs of mobile nodes, using the link utilization metrics and data priority levels as a basis.

• Independent Claim 14: This claim focuses on a wireless communication network with mobile nodes and their controllers, particularly concerning directional communication links. The controller is configured to:

  • Schedule a directional communication link from a first mobile node to a second neighboring mobile node during a specific time slot. This is done by first determining the relative positions of the second mobile node and any other mobile nodes that might cause interference during that time slot.
  • Based on these relative positions, the controller determines the potential interference to the directional communication link.
  • The directional communication link is only scheduled during that time slot if the determined potential interference is below a certain threshold.

• Independent Claim 22: This claim describes a communication method involving scheduling a directional communication link. The method includes:

  • Scheduling a directional communication link from a first mobile node to a second neighboring mobile node during a time slot.
  • Determining the relative positions of the second neighboring mobile node and other potentially interfering mobile nodes that are transmitting during the same time slot.
  • Determining the potential interference to the directional communication link based on these relative positions.
  • Scheduling the directional communication link during the time slot only if the potential interference is below a threshold.

• Independent Claim 23: This claim describes a wireless communication network where mobile nodes establish communication links during assigned time slots and re-allocate these slots based on usage. It outlines a process where:

  • An "initiating mobile node" identifies available time slots shared with its neighbors.
  • It ranks these available time slots based on how much they are used by itself and its neighbors.
  • It then sends a "time slot re-allocation request" to a "receiving mobile node," including the available time slots and their ranking.
  • The receiving mobile node receives this request.
  • The receiving mobile node also ranks the available time slots based on its own usage and that of its neighbors.
  • It generates a combined ranking using both its own ranking and the initiating node's ranking.
  • Finally, the receiving mobile node re-allocates at least one of the available time slots for a communication link between itself and the initiating mobile node, based on this combined ranking.

• Independent Claim 30: This claim describes a communication method for a wireless network focused on re-allocating time slots. The method involves:

  • Identifying available time slots shared between an initiating mobile node and neighboring mobile nodes.
  • Ranking these available time slots based on how much they are utilized by the initiating mobile node and its neighbors.
  • Transmitting a time slot re-allocation request from the initiating mobile node to a receiving mobile node, which includes the available time slots and their ranking.
  • Receiving this request at the receiving mobile node.
  • Ranking the available time slots based on utilization by the receiving mobile node and its neighbors.
  • Generating a combined ranking of the available time slots using the rankings from both the initiating and receiving mobile nodes.
  • Re-allocating at least one of the available time slots for a communication link between the initiating mobile node and the receiving mobile node, based on this combined ranking.

• Independent Claim 31: This claim describes a wireless communication network where pairs of mobile nodes establish communication links to transmit packets during time slots. The system includes:

  • At least one mobile node from a pair determining a "link quality value" for the communication link during a time slot, and then determining if the link is of a "first quality" or a "second quality."
  • The pair of mobile nodes cooperate to re-allocate the communication link to a new time slot within a "first time period" if the link is of the first quality.
  • If the communication link is of the second quality, they cooperate to re-allocate it to a new time slot within a "second time period" that is shorter than the first time period. This implies a faster response for lower quality links.

• Independent Claim 38: This claim details a communication method involving link quality. The method includes:

  • Establishing a communication link between a pair of mobile nodes for transmitting packets during at least one time slot.
  • Determining a link quality value associated with the communication link during that time slot and determining if the communication link is of a first or second quality.
  • Re-allocating the communication link to a new time slot within a first time period if the communication link is of the first quality.
  • If the communication link is of the second quality, re-allocating it to a new time slot within a second time period that is shorter than the first time period.

CAFC 2026 Dockets:

A search for "CAFC 2026 dockets US patent 6958986" does not yield specific docket entries for the year 2026. The provided Google Patents information notes "Family has litigation" with links to Unified Patents and Darts-ip, indicating past and ongoing litigation related to the patent family, but no explicit CAFC 2026 dockets for this specific patent were found in the search results.

Uncertainty Note:

The Google Patents information states the legal status as "Expired - Lifetime, expires 2023-01-25". This indicates the patent has already expired as of the current date (April 26, 2026). This contradicts the idea of ongoing litigation that would appear in 2026 CAFC dockets for the patent itself. However, patent family litigation or disputes over past infringement could still exist. Given the clear expiration status, any 2026 CAFC dockets, if they existed, would likely pertain to appeals of district court cases related to past infringement rather than current validity or infringement.

The patent US6958986B2, titled "Wireless communication system with enhanced time slot allocation and interference avoidance/mitigation features and related methods," has been involved in multiple litigation cases. The patent expired on January 25, 2023.

Based on the provided patent information and search results, the following litigation involving US patent 6958986 is known:

• Case 1:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): Bticino SPA, Legrand France SA, Legrand SA, Legrand SNC
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:21-cv-00201
  • Filing Date: 2021-06-04
  • Outcome or Current Status: Closed

• Case 2:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): [TP-Link Corporation Ltd.](/litigations/by-defendant/TP-Link%20Corporation%20Ltd.), TP-Link USA Corp., TP Link Technologies Co Ltd.
  • Jurisdiction: California Central District Court (transferred from Texas Eastern District Court)
  • Case Number: 2:22-cv-07541 (originally 2:21-cv-00045-JRG in E.D. Tex.)
  • Filing Date: 2021-02-08 (for the original E.D. Tex. case)
  • Outcome or Current Status: Closed. The Federal Circuit granted a mandamus petition on January 9, 2023, vacating the district court's transfer order and instructing the court to recall the cases to the Eastern District of Texas.

• Case 3:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): Somfy Activits SA, Somfy SA
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:21-cv-00195
  • Filing Date: 2021-06-01
  • Outcome or Current Status: Closed

• Case 4:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): Amazon Com Inc., Immedia Semiconductor LLC, Ring LLC, Eero LLC, Amazon Com Services LLC
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:21-cv-00193
  • Filing Date: 2021-06-01
  • Outcome or Current Status: Closed

• Case 5:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): Signify Netherlands BV, Signify China Investment Co Ltd, Signify Hong Kong Ltd, Signify Poland Sp. Z.o.o., Signify Holding BV
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:21-cv-00043
  • Filing Date: 2021-02-08
  • Outcome or Current Status: Closed

• Case 6:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): Assa Abloy IP AB
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:21-cv-00025
  • Filing Date: Not explicitly stated in the provided snippets for this specific case, but other 2:21-cv-000XX cases from Stingray were filed in Feb 2021.
  • Outcome or Current Status: Closed

• Case 7:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): TP-Link Corporation Ltd., TP-Link USA Corp., TP Link Technologies Co Ltd. (This appears to be related to or the same as the 2:21-cv-00045 case that was transferred and recalled by CAFC). The patent record lists 2:21-cv-00045 separately from 2:22-cv-07541 which implies they are distinct filings or that 2:21-cv-00045 was the initial filing that later led to the CAFC mandamus for transfer. Given the search results, 2:21-cv-00045 is directly tied to the CAFC mandamus.
  • Jurisdiction: Texas Eastern District Court (and Federal Circuit for mandamus)
  • Case Number: 2:21-cv-00045
  • Filing Date: 2021-02-08
  • Outcome or Current Status: Closed. The Federal Circuit vacated district court orders transferring two patent cases (including 2:21-cv-00045) to the Central District of California and instructed the court to recall the cases.

• Case 8:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): Not specifically listed in the snippet, but the pattern suggests other entities from the "Texas Eastern District Court" cases.
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:18-cv-00439
  • Filing Date: Not provided in snippets.
  • Outcome or Current Status: The patent text lists this case, but Unified Patents' search result snippets do not provide specific details for this case number directly, and it's not explicitly marked as "Closed" in the available snippets like others. The initial patent listing indicates "litigation" generally.

• Case 9:

  • Plaintiff(s): Stingray IP Solutions LLC
  • Defendant(s): Not specifically listed in the snippet.
  • Jurisdiction: New Jersey District Court
  • Case Number: 3:21-cv-11989
  • Filing Date: Not provided in snippets.
  • Outcome or Current Status: The patent text lists this case, but Unified Patents' search result snippets do not provide specific details for this case number directly.

The "First worldwide family litigation filed" link to Darts-ip (https://patents.darts-ip.com/?family=33309445&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=[US6958986](/patent/US6958986)(B2)) provides a general overview for the patent family, but detailed case-by-case information (like plaintiff, defendant, filing date, and status for each specific case globally) requires direct interaction with the Darts-ip platform, which is beyond the scope of a direct search result snippet. However, the Unified Patents portal has provided sufficient information for the US cases listed in the patent.

It is important to note that all the identified US district court cases initiated by Stingray IP Solutions LLC related to US6958986 are marked as "Closed" in the Unified Patents database. The patent itself expired on January 25, 2023.

Proceedings overview

There are no AIA trial proceedings on file for US patent 6958986 as of the most recent ingest from the USPTO ODP API. Web search did not surface any additional or recently filed proceedings. This means the patent has not been subjected to IPR, PGR, or CBM challenges at the PTAB, and all claims remain untested by these AIA trial mechanisms.

Strategic summary

All claims of US patent 6958986 remain untested by AIA trial proceedings. This means no claims have been canceled or sustained by the PTAB, nor have any prior art grounds been formally adjudicated in this forum. The absence of PTAB activity suggests that any potential petitioner (or defendant in litigation) would have a full range of prior art grounds available under § 315(e)(2), as no estoppel would have been triggered by previous proceedings. There is no pattern of PTAB challenges or appeals to analyze, and no defensive aggregators have filed against this patent at the PTAB.

Recommended next steps

As there is no PTAB activity on file for US patent 6958986, all claims are presumed valid and have not been challenged in an AIA trial. If facing assertion of this patent, a defendant would have the opportunity to initiate an AIA trial proceeding (e.g., an IPR) if appropriate prior art or other grounds can be identified.

Inventors

• Joseph Bibb Cain: At the time of filing, Joseph Bibb Cain was an inventor for Harris Corp. Typically, an inventor's rights to an invention are retained by the inventor unless a specific contract stipulates that the employer will own the invention, which is common in employment agreements for those hired to invent or if the invention is created within the scope of their job using company resources.

Original assignee

The original assignee listed on the patent is Harris Corp.

Harris Corp was an American technology company and defense contractor that produced wireless equipment, tactical radios, electronic systems, and antennas for government, defense, emergency service, and commercial sectors. They specialized in surveillance solutions, microwave weaponry, and electronic warfare. Harris Corp merged with L3 Technologies in 2019 to form L3Harris Technologies. L3Harris Technologies is headquartered in Melbourne, Florida.

Assignment timeline

• 2003-03-27 (executed) / recorded 2003-03-27 — Reel 013898/0609
  • Conveyance: Assignment
  • Assignor: CAIN, JOSEPH BIBB
  • Assignee: HARRIS CORPORATION
  • Correspondent: BLANKENSHIP, TIMOTHY R., HARRIS CORPORATION, 1025 W NASA BLVD, MS A-11I, MELBOURNE, FLORIDA, 32919
  • Context: Transfer of inventor's interest to the employer at the time of patent application filing.
• 2020-06-05 (executed) / recorded 2020-06-12 — Reel 052853/0153
  • Conveyance: Security Agreement
  • Assignor: ACACIA RESEARCH GROUP LLC, AMERICAN VEHICULAR SCIENCES LLC, BONUTTI SKELETAL INNOVATIONS LLC, CELLULAR COMMUNICATIONS EQUIPMENT LLC, INNOVATIVE DISPLAY TECHNOLOGIES LLC, LIFEPORT SCIENCES LLC, LIMESTONE MEMORY SYSTEMS LLC, MERTON ACQUISITION HOLDCO LLC, MOBILE ENHANCEMENT SOLUTIONS LLC, MONARCH NETWORKING SOLUTIONS LLC, NEXUS DISPLAY TECHNOLOGIES LLC, PARTHENON UNIFIED MEMORY ARCHITECTURE LLC, R2 SOLUTIONS LLC, SAINT LAWRENCE COMMUNICATIONS LLC, STINGRAY IP SOLUTIONS LLC, SUPER INTERCONNECT TECHNOLOGIES LLC, TELECONFERENCE SYSTEMS LLC, UNIFICATION TECHNOLOGIES LLC
  • Assignee: STARBOARD VALUE INTERMEDIATE FUND LP, AS COLLATERAL AGENT
  • Correspondent: NATHAN A. MUGGE, KIRKLAND & ELLIS LLP, 601 LEXINGTON AVENUE, NEW YORK, NEW YORK, 10022
  • Context: Securitization of assets by multiple LLCs, including Stingray IP Solutions LLC, to Starboard Value Intermediate Fund LP.
• 2020-06-23 (executed) / recorded 2020-06-25 — Reel 053654/0254
  • Conveyance: Assignment of Assignors Interest
  • Assignor: ACACIA RESEARCH GROUP LLC
  • Assignee: STINGRAY IP SOLUTIONS LLC
  • Correspondent: KEVIN H. FORTIN, KEVIN H. FORTIN, 1209 ORANGE ST, WILMINGTON, DELAWARE, 19801
  • Context: Transfer of interest from Acacia Research Group LLC to Stingray IP Solutions LLC.
• 2020-06-23 (executed) / recorded 2020-06-25 — Reel 053654/0254
  • Conveyance: Assignment of Assignors Interest
  • Assignor: EAGLE TECHNOLOGIES, INC., HARRIS GLOBAL COMMUNICATIONS, INC., L3HARRIS TECHNOLOGIES, INC.
  • Assignee: ACACIA RESEARCH GROUP LLC
  • Correspondent: KEVIN H. FORTIN, KEVIN H. FORTIN, 1209 ORANGE ST, WILMINGTON, DELAWARE, 19801 (This correspondent recurs on Reel 053654/0254 and Reel 053654/0254)
  • Context: Transfer of interest from L3Harris Technologies, Inc. (successor to Harris Corp) to Acacia Research Group LLC.
• 2020-07-08 (executed) / recorded 2020-07-16 — Reel 053748/0503
  • Conveyance: Release of Security Interest in Patents
  • Assignor: STARBOARD VALUE INTERMEDIATE FUND LP
  • Assignee: LIFEPORT SCIENCES LLC, SAINT LAWRENCE COMMUNICATIONS LLC, LIMESTONE MEMORY SYSTEMS LLC, MONARCH NETWORKING SOLUTIONS LLC, ACACIA RESEARCH GROUP LLC, CELLULAR COMMUNICATIONS EQUIPMENT LLC, UNIFICATION TECHNOLOGIES LLC, STINGRAY IP SOLUTIONS LLC, TELECONFERENCE SYSTEMS LLC, PARTHENON UNIFIED MEMORY ARCHITECTURE LLC, MOBILE ENHANCEMENT SOLUTIONS LLC, INNOVATIVE DISPLAY TECHNOLOGIES LLC, AMERICAN VEHICULAR SCIENCES LLC, NEXUS DISPLAY TECHNOLOGIES LLC, R2 SOLUTIONS LLC, SUPER INTERCONNECT TECHNOLOGIES LLC, BONUTTI SKELETAL INNOVATIONS LLC
  • Correspondent: NATHAN A. MUGGE, KIRKLAND & ELLIS LLP, 601 LEXINGTON AVENUE, NEW YORK, NEW YORK, 10022 (This correspondent recurs on Reel 052853/0153)
  • Context: Release of security interest by Starboard Value Intermediate Fund LP, likely after a debt obligation was satisfied or restructured.
• 2021-11-11 (executed) / recorded 2021-11-23 — Reel 055998/0259
  • Conveyance: Corrective Assignment to Correct the Assignor Name
  • Assignor: STINGRAY IP SOLUTIONS LLC
  • Assignee: STARBOARD VALUE INTERMEDIATE FUND LP, AS COLLATERAL AGENT
  • Correspondent: NATHAN A. MUGGE, KIRKLAND & ELLIS LLP, 601 LEXINGTON AVENUE, NEW YORK, NEW YORK, 10022 (This correspondent recurs on Reel 052853/0153 and Reel 053748/0503)
  • Context: Corrective assignment related to a previous security agreement, confirming the security interest.
• 2021-11-11 (executed) / recorded 2021-11-23 — Reel 055998/0259
  • Conveyance: Corrective Assignment to Correct the Assignee Name
  • Assignor: STARBOARD VALUE INTERMEDIATE FUND LP, AS COLLATERAL AGENT
  • Assignee: STINGRAY IP SOLUTIONS LLC
  • Correspondent: NATHAN A. MUGGE, KIRKLAND & ELLIS LLP, 601 LEXINGTON AVENUE, NEW YORK, NEW YORK, 10022 (This correspondent recurs on Reel 052853/0153, Reel 053748/0503 and Reel 055998/0259)
  • Context: Corrective assignment related to a previous security agreement, confirming the release of security interest.

Timeline diagram

timeline
    title Ownership of US 6958986
    2003 : Assigned to Harris Corp
    2020 : Securitized to Starboard Value
         : Assigned to Stingray IP Solutions LLC
         : Assigned to Acacia Research Group LLC
         : Security interest released by Starboard
    2021 : Corrective assignment

NPE / troll-pattern signals

1. Shell-entity transfer — present. In 2020, the patent was assigned from L3Harris Technologies, Inc. (the successor to the original operating company, Harris Corp) to Acacia Research Group LLC (Reel 053654/0254). Acacia Research Corporation (the parent company of Acacia Research Group LLC) specializes in patent licensing and enforcement, often through its subsidiaries like Stingray IP Solutions LLC. Stingray IP Solutions LLC is described as a non-practicing entity (NPE) focused on monetizing wireless networking intellectual property.
2. Known asserter in the chain — present. Acacia Research Group LLC and Stingray IP Solutions LLC are both in the chain. Acacia Research Corporation (parent of Acacia Research Group LLC) is a well-known patent licensing and enforcement company. Stingray IP Solutions LLC is identified as an NPE that has filed patent infringement suits.
3. Repeat correspondent across the chain — present. Nathan A. Mugge of Kirkland & Ellis LLP appears as the correspondent for the security agreement and subsequent releases/corrective assignments involving Starboard Value Intermediate Fund LP and Acacia/Stingray entities (Reel 052853/0153, Reel 053748/0503, Reel 055998/0259). Kevin H. Fortin is also listed for the two assignments recorded on Reel 053654/0254.
4. Cascading transfers — present. Multiple assignments and security agreements occurred in a short period in 2020 (June 5, June 23, June 23, July 8). Specifically, the patent moved from L3Harris Technologies, Inc. to Acacia Research Group LLC and then to Stingray IP Solutions LLC on the same recorded date (2020-06-25), with a security interest granted to Starboard Value Intermediate Fund LP around the same time.
5. Pre-litigation transfer — unclear. While Stingray IP Solutions LLC is a known asserter, the earliest litigation data found for Stingray IP Solutions LLC and this patent family did not specifically reference US6958986. Further investigation into specific litigation filing dates would be needed to definitively confirm if the 2020 transfers were pre-litigation for this particular patent.
6. Bankruptcy fire-sale — not present. Harris Corp merged with L3 Technologies to form L3Harris Technologies, Inc., which then assigned the patent. There is no indication of bankruptcy in this process.
7. Privateering — unclear. While L3Harris Technologies, Inc. transferred the patent to Acacia, it is not definitively stated that Acacia is asserting on L3Harris's behalf against competitors. Further research into specific litigation would be required to confirm privateering.
8. Defensive aggregator (anti-NPE) — not present. The chain ends with Stingray IP Solutions LLC, an NPE, and does not involve any known defensive aggregators.

Verdict

NPE — high confidence
The presence of multiple strong signals supports a high confidence NPE verdict. The patent was transferred from an operating company (L3Harris Technologies, Inc.) to known patent licensing entities, Acacia Research Group LLC and Stingray IP Solutions LLC, in 2020 (Reel 053654/0254). Stingray IP Solutions LLC is explicitly identified as a non-practicing entity engaged in patent assertions. The rapid succession of assignments and security agreements in 2020, involving a hedge fund (Starboard Value Intermediate Fund LP) and multiple shell-like LLCs under the Acacia umbrella, further indicates a monetization-focused strategy.

USPTO Assignment Center search page: https://assignmentcenter.uspto.gov/patent/index.html

To identify the most relevant prior art for US patent 6958986, I will examine the patent citations listed within the patent document itself. The USPTO provides tools to search for patent information, including citations.

Since I cannot directly access the USPTO database for live search results in this environment, I will rely on the provided patent text to identify the cited prior art. The patent text typically includes a "References Cited" section that lists relevant patents and publications.

After identifying the cited patents, I will then extract the requested information for each reference: full citation, publication/filing date, a brief description (based on the patent's own characterization if available, or a general understanding of the reference's relevance to the patented invention), and which claim(s) of US6958986 it potentially anticipates under 35 U.S.C. § 102.

Based on the provided patent text for US6958986, the following prior art is explicitly mentioned:

Most Relevant Prior Art for US Patent 6958986

1. Pritchett '807 patent

• Full Citation: The provided text refers to "the Pritchett '807 patent" without a full patent number. Assuming this is a US patent, the full citation format would typically be US X,XXX,807. Without the full patent number, a precise publication/filing date or direct link to the patent is not available from the provided text alone.
• Publication/Filing Date: Not explicitly stated in the provided text for "the Pritchett '807 patent."
• Brief Description: This patent "discloses the acquisition, by a fixed initiating wireless communication system from a fixed receiving wireless communication system, of a list of the wireless communication systems operating in the network and a corresponding respective time slot list for each wireless communication system. A table is then created based upon the list for scheduling time slots among the wireless communication systems."
• Potential Anticipation (35 U.S.C. § 102): The Pritchett '807 patent describes a system for scheduling time slots in a network of fixed wireless communication systems. US6958986, in its broadest sense, concerns wireless communication systems with enhanced time slot allocation. The key distinguishing feature highlighted in US6958986 is the application to mobile communication systems and the use of directional antennas, which are described as being complex to schedule (e.g., "Scheduling time slots for wireless communication systems operating with directional antennas, particularly when the wireless communication systems are mobile, is complex."). Therefore, Pritchett '807 would likely anticipate aspects of US6958986 related to general time slot scheduling and network topology discovery in wireless systems, but not those specifically tied to mobility, directional antennas, or dynamic interference avoidance/mitigation inherent in the claims of US6958986. For example, claims related to determining relative positions of mobile nodes and potential interference to directional links (e.g., as generally described in the "Another communication method aspect of the invention" where a controller determines relative positions of a neighboring mobile node and potentially interfering mobile nodes for scheduling a directional link if interference is below a threshold) would likely not be anticipated by Pritchett '807 due to its focus on fixed systems. However, any claim broadly covering the concept of creating a list of wireless communication systems and their time slots for scheduling could potentially be anticipated. Without specific claims of US6958986 to analyze against the full text of Pritchett '807, a definitive determination is difficult.

To conduct a more thorough analysis of potential anticipation, the full text of the Pritchett '807 patent and the specific claims of US6958986 would be required. Given the information, the focus of US6958986 on mobility and directional antennas with associated interference management and dynamic allocation strategies appears to be a key differentiation from the described Pritchett '807 patent.

The following analysis addresses the obviousness of US patent 6958986 under 35 U.S.C. § 103, considering the provided patent text and its references to prior art.

Person Having Ordinary Skill in the Art (PHOSITA)

A PHOSITA in the context of US6958986 would be a telecommunications engineer or computer scientist with expertise in wireless communication systems, particularly in areas such as Time Division Multiple Access (TDMA), mobile ad-hoc networks (MANETs), Quality of Service (QoS) protocols, interference management, and antenna technologies (e.g., directional and phased array antennas). This individual would possess several years of experience in designing, implementing, or optimizing wireless network architectures.

Prior Art References

Based on the provided patent text, the key prior art references and generally acknowledged knowledge include:

1. US6904032B2 (Cain): This patent, sharing the same inventor and original assignee as US6958986 and holding a priority date of 2002-01-10, discloses a "Method and system for providing time division multiple access (TDMA) communications in a wireless communication system and related methods." Specifically, it teaches a wireless communication system with mobile nodes, transceivers, and controllers for scheduling TDMA time frames and slots. It emphasizes the use of directional antennas to establish communication links and notably allows for establishing "communication links between other mobile communication systems within the same scheduled time slot," indicating spatial reuse. It also covers basic time slot assignment protocols.
2. "Pritchett '807 patent": As described in US6958986, this patent "discloses the acquisition, by a fixed initiating wireless communication system from a fixed receiving wireless communication system, of a list of the wireless communication systems operating in the network and a corresponding respective time slot list for each wireless communication system. A table is then created based upon the list for scheduling time slots among the wireless communication systems." While focused on fixed systems, it establishes a foundational concept of time slot scheduling in a network.
3. General Knowledge in Wireless Communications: The patent's background and definitions acknowledge various established concepts as prior art, including:
   • TDMA Principles: Division of time frames into time slots for communication.
   • Antenna Types: Use of omni-directional antennas for broadcast/discovery and directional antennas for focused communication to reduce interference and increase gain.
   • Phased Array Antennas: Known for steerable beams and pattern control.
   • Quality of Service (QoS): Metrics like bandwidth, delay, and probability of data loss, and the need for reporting link quality to routing protocols (e.g., OLSR).
   • Mobile Ad-Hoc Networks (MANETs): Networks where mobile nodes are continuously entering and dropping out.
   • Interference Management: The patent explicitly states that "procedures for interference detection and avoidance are needed" in complex mobile environments with directional antennas.
   • Link Utilization: Measuring traffic requirements based on data sent or queued data.

Motivation to Combine

A PHOSITA would be motivated to combine the teachings of these references to overcome known challenges in wireless communication, particularly in dynamic mobile ad-hoc networks using directional antennas. The primary motivations would include:

• Improving Network Efficiency and Resource Utilization: Optimizing the use of limited time-frequency resources in TDMA systems, especially with spatial reuse enabled by directional antennas.
• Enhancing Quality of Service (QoS): Providing differentiated service for various types of data traffic with different priority levels (e.g., real-time video vs. background data).
• Mitigating Interference: Effectively managing and avoiding interference inherent in systems that employ spatial reuse with directional antennas in mobile environments.
• Adapting to Network Dynamics: Developing robust and flexible mechanisms to handle node mobility, topology changes, and fluctuating traffic demands characteristic of MANETs.

Obviousness Analysis of Independent Claims

1. Independent Claims 1 and 13 (System and Method for Time Slot Allocation with Priority and Demand Assignment)

Claim Elements: These claims describe scheduling "semi-permanent" time slots for data with different priority levels, determining "link utilization metrics for each data priority level," and scheduling "demand assigned" time slots based on these metrics and priority levels.

Prior Art & PHOSITA Knowledge:

• US6904032B2 establishes the core of a mobile TDMA system with directional antennas and semi-permanent time slot allocation for communication links, allowing for spatial reuse.
• General Knowledge of QoS: The concept of data having "different priority levels" (e.g., for real-time traffic versus best-effort data) and the use of "link state information" and "QoS metrics" was well-established in networking prior to the priority date.
• Link Utilization: Measuring "link utilization" based on factors like data sent or queued data was a standard practice for network monitoring and resource management. US6958986 itself describes such metrics.
• Demand Assignment: The principle of "demand assigned" or "on-demand" resource allocation to adapt to varying traffic loads was a known technique in telecommunications.

Obviousness Argument:
A PHOSITA, starting with the mobile TDMA system of US6904032B2, would be motivated to enhance its efficiency and QoS capabilities. Given the widespread knowledge of QoS and data prioritization in networking, it would have been obvious to integrate the concept of "different priority levels" into the time slot allocation scheme. To effectively manage these priorities and optimize resource use in a dynamic network, it would be an obvious design choice to:

1. Quantify the demand for each priority level by determining "link utilization metrics for each data priority level."
2. Use these metrics to dynamically allocate "demand assigned time slots" to supplement the semi-permanent slots, thereby addressing fluctuating traffic needs and ensuring high-priority data is served. This directly addresses the stated problem of "unbalanced traffic loads" and the need for "coordination mechanisms... to allocate a time slot in any Tx/Rx split of traffic."

2. Independent Claims 14 and 22 (System and Method for Directional Link Scheduling with Interference Avoidance)

Claim Elements: These claims focus on scheduling a "directional communication link" by determining "relative positions" of nodes, identifying "other potentially interfering mobile nodes," determining "potential interference" based on relative positions, and scheduling the link only if interference is "below a threshold."

Prior Art & PHOSITA Knowledge:

• US6904032B2 teaches the use of "directional antennas" in a TDMA system, explicitly enabling "additional communication links... within the same scheduled semi-permanent time slot" (spatial reuse). The very nature of spatial reuse necessitates interference management.
• Interference Management: The patent explicitly acknowledges that "procedures for interference detection and avoidance are needed" for mobile communication systems operating with directional antennas.
• Position Determining Devices: Mobile nodes commonly include "position determining devices for measuring a respective position thereof."
• RF Propagation: Calculating "potential interference" based on "relative positions" and considering factors like "plane-earth attenuation algorithm and a free space attenuation algorithm" or "side lobes from signals transmitted by the potentially interfering nodes" are fundamental aspects of RF engineering and wireless network planning.
• Thresholds: Using an "interference threshold" (e.g., minimum Signal-to-Interference Ratio (SIR)) to determine acceptable link quality is a standard practice in wireless communication.

Obviousness Argument:
Starting with a directional antenna-based TDMA system as taught by US6904032B2, where spatial reuse is a feature, a PHOSITA would immediately recognize the challenge of co-channel interference. To address the acknowledged need for "interference detection and avoidance," it would be obvious to:

1. Utilize available "position determining devices" on mobile nodes to ascertain "relative positions" of a target neighbor and "other potentially interfering mobile nodes."
2. Employ known RF propagation models and antenna pattern characteristics to calculate "potential interference" based on these relative positions.
3. Implement a decision rule to "schedule the directional communication link" only if this "potential interference is below a threshold," ensuring that the link quality remains acceptable. This systematic approach to interference avoidance during scheduling is a logical and obvious application of existing RF engineering principles to a directional TDMA network.

3. Independent Claims 23 and 30 (System and Method for Dynamic Time Slot Re-allocation Based on Usage)

Claim Elements: These claims describe a process where an "initiating mobile node" identifies and ranks "available time slots" based on "link utilization," transmits a "re-allocation request" to a "receiving mobile node," which also ranks slots based on its utilization, and then a "combined ranking" is generated for "re-allocating" at least one time slot.

Prior Art & PHOSITA Knowledge:

• US6904032B2 provides the foundation of a system with assigned time slots for communication links between mobile nodes.
• Time Slot Scheduling/Re-allocation: "Pritchett '807" describes a system for scheduling time slots. US6958986 itself states the network includes "plurality of mobile nodes establishing communication links therebetween during assigned time slots and re-allocating the assigned time slots based upon usage requirements."
• Link Utilization Metrics: As discussed, using link utilization (e.g., traffic demand, queue length) as a basis for resource allocation and re-allocation is a common network management technique to optimize bandwidth.
• Distributed Resource Negotiation: In distributed systems like MANETs, negotiation protocols between nodes for shared resources are standard. Ranking options (e.g., available time slots) based on local criteria and then combining preferences for a mutual decision is a conventional algorithmic approach.

Obviousness Argument:
Given a mobile TDMA system with assigned time slots (as in US6904032B2 and Pritchett '807), and the known dynamic nature of MANETs ("continuously entering into and dropping out of the network"), a PHOSITA would be motivated to develop more flexible and adaptive time slot management. It would be obvious to:

1. Implement "re-allocation based upon usage requirements" (i.e., link utilization), which is a standard method to dynamically optimize resource assignment.
2. In a distributed environment, a natural way for two nodes to agree on a re-allocation would involve a negotiation process: the "initiating mobile node" identifies "available time slots" and "ranks" them based on its perceived "link utilization."
3. This ranking is communicated in a "re-allocation request" to the "receiving mobile node."
4. The "receiving mobile node" similarly assesses its own and its neighbors' utilization to "rank" the available slots.
5. Finally, to reach a mutually agreeable decision, a "combined ranking" would be "generated" to select the optimal slot for re-allocation. This distributed, demand-driven, and negotiated re-allocation process would be an obvious method for a PHOSITA to enhance network adaptability and efficiency in a mobile environment.

4. Independent Claims 31 and 38 (System and Method for Link Quality-Based Re-allocation Timing)

Claim Elements: These claims relate to determining a "link quality value" (first or second quality) for a communication link and re-allocating the link to a new time slot within a "first time period" if of "first quality," or within a "second time period" (shorter) if of "second quality."

Prior Art & PHOSITA Knowledge:

• US6904032B2 teaches establishing communication links and transmitting packets during time slots.
• Link Quality Measurement: Measuring "link quality" using metrics like "SIR" or "packet reception error value (PREV)" is fundamental to wireless communication.
• Quality Thresholds: Defining different "quality thresholds" to categorize link performance (e.g., good, marginal, poor) is a common practice in QoS management.
• Adaptive Strategies: Responding to changes in link quality by re-allocating resources is a known adaptive technique in wireless systems.
• Differential Response Timing: The patent itself explains the rationale: a "second quality" (worse) link requires "relatively quickly" re-allocation to "minimize disruption," while a "first quality" (marginal but usable) link allows for "longer" re-allocation delay to "reduce conflicts between competing pairs of nodes." This acknowledges the known engineering trade-off between responsiveness and system stability.

Obviousness Argument:
Building upon a system that establishes communication links in time slots (from US6904032B2), a PHOSITA would routinely monitor "link quality" to ensure reliable communication. It would be obvious to:

1. Measure "link quality values" (e.g., SIR, PREV) and "determine if the communication link is of a first or second quality" by comparing these values against predefined thresholds, categorizing the severity of degradation.
2. Implement an adaptive re-allocation strategy where the timing of the "re-allocation" is differentiated based on the perceived link quality. The concept that more severe degradation ("second quality") warrants a "shorter" re-allocation time period to quickly restore service, while less severe degradation ("first quality") allows for a "longer" period to avoid unnecessary churn and potential conflicts, is a standard and obvious engineering optimization balancing urgency with system overhead. This directly addresses the known problems of maintaining reliable links and minimizing disruption in dynamic wireless environments.

Conclusion

The independent claims of US patent 6958986, while representing valuable advancements in wireless communication systems, would have been obvious to a PHOSITA based on the combination of US6904032B2, the described "Pritchett '807 patent," and general knowledge in the field of wireless networking. The motivations for these combinations would stem from the desire to improve network efficiency, ensure QoS, manage interference, and adapt to the dynamic nature of mobile ad-hoc networks, all of which were known challenges in the art prior to the invention.