US 6980537

US Patent 6,980,537: Concise Summary

Title: Method and apparatus for communication network cluster formation and transmission of node link status messages with reduced protocol overhead traffic

Current Assignee: ITT Manufacturing Enterprises LLC; Stingray IP Solutions LLC

Inventor: Yu-Jih Liu

Filing Date: November 13, 2000

Issue Date: December 27, 2005

Abstract: The patent describes a method and apparatus for forming clusters within a communication network by identifying network nodes crucial for relaying traffic and designating them as cluster head nodes, while others become member nodes. The system adjusts the beacon packet transmission rate (interval between transmissions) to facilitate cluster formation regardless of network size or varying initial node start times. Furthermore, it employs this cluster formation technique to create a three-tier architecture. In this setup, super nodes (an additional tier formed from cluster head nodes) distribute routing information, while cluster head nodes handle network data traffic. To reduce overhead, cluster head node databases are examined after super nodes flood routing information, and only missing data is requested from the corresponding super node, eliminating the need for acknowledgment messages.

Independent Claims Overview:

Claim 1 (Method Claim):
This claim describes a method for forming clusters in a communication network comprising multiple nodes. Each node includes a processor and a database. The method involves the nodes transmitting and receiving node status packets that contain neighbor information. The interval between these transmissions is adjusted based on the quantity of neighboring nodes. After a certain period without new neighbors or changes in neighbor sets, each node uses its stored neighbor information to determine if its own set of neighbors is a subset of any other neighboring node's neighbor set. If it is, the node designates itself as a member node. If its neighbor set is not a subset of any other neighboring node's set (meaning it is crucial for relaying traffic), it designates itself as a head node.

Claim 11 (Apparatus Claim):
This claim describes an apparatus, specifically a network node, designed to operate within a communication network with other nodes. The node includes a transmitter, a receiver, and a processor. The processor is configured to cause the transmitter to send node status packets with neighbor information and to adjust the interval between these transmissions. The processor also causes the receiver to receive node status packets. Crucially, the processor is configured to determine if its associated neighbor set is a subset of any other neighboring node's neighbor set. If it is, the processor designates the node as a member node; otherwise, it designates the node as a head node.

Claim 15 (Method Claim - Three-Tier Architecture for Information Flooding):
This claim outlines a method for flooding routing information in a multi-tier network (formed by the process of Claim 1). This method involves identifying nodes crucial for relaying traffic and designating them as cluster head nodes (forming a second tier). The same clustering procedure is then applied to these cluster head nodes to designate super nodes (forming a third tier). The super nodes then transmit database update packets to other super nodes and associated head nodes. The head nodes receive this information, update their databases, and if any information is missing, they send a request to their corresponding super node for the missing data. This process eliminates the need for acknowledgment messages during the flooding.

Claim 20 (Apparatus Claim - Three-Tier Architecture for Information Flooding):
This claim describes a network node apparatus for use in the three-tier architecture described in Claim 15. The node includes a transmitter, a receiver, and a processor. The processor is configured to identify the node as a cluster head or member. If it's a head node, the processor is further configured to determine if it should be a super node based on a clustering procedure applied to head nodes. If designated a super node, the processor transmits database update packets to other super nodes and associated head nodes. If designated a head node (but not a super node), the processor receives database update packets, updates its database, and if information is missing, it sends a request to its corresponding super node for the missing data.

CAFC 2026 Dockets:

No authoritative information regarding specific CAFC 2026 dockets for US patent 6980537 was found in the provided search results. General information about CAFC dockets was available, but no direct matches for this patent number in 2026.

US Patent 6980537 has been involved in several litigation cases. The current assignee of the patent is Stingray IP Solutions LLC.

Here is a list of known litigation involving US Patent 6980537:

• Plaintiff: Stingray IP Solutions, LLC

  • Defendant: TP-Link Technologies Co., Ltd., TP-Link Corporation Limited, and TP-Link International Ltd.
  • Jurisdiction: Initially, Eastern District of Texas. Transferred to Central District of California, then orders vacated and remanded to Eastern District of Texas by Federal Circuit.
  • Case Number: 23-102 (Federal Circuit appeal number). Original district court case numbers are not explicitly provided in the search results but are part of the underlying infringement suits.
  • Filing Date: Stingray filed patent infringement suits in the Eastern District of Texas against TP-Link. The Federal Circuit mandamus petition was decided on January 9, 2023.
  • Current Status/Outcome: The Federal Circuit granted Stingray's petition for a writ of mandamus, vacating the district court's transfer orders to the Central District of California and remanding the cases for further proceedings consistent with their order. The Federal Circuit found that a patent infringement defendant's post-suit consent to personal jurisdiction in another state did not defeat the application of Rule 4(k)(2) for establishing jurisdiction.

• Plaintiff: Stingray IP Solutions LLC

  • Defendant: Assa Abloy IP AB
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:23-cv-00503
  • Filing Date: 2023-10-26
  • Current Status/Outcome: Closed

• Plaintiff: Stingray IP Solutions LLC

  • Defendant: Vivion Inc.
  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:23-cv-00499
  • Filing Date: 2023-10-24
  • Current Status/Outcome: Not explicitly stated as closed or open in the provided snippet, but listed in a "Litigation Case List" from Unified Patents.

It's important to note that the patent itself has an "Expired - Lifetime" status, with an expiration date of 2023-06-16, according to Google Patents. However, litigation can continue even after a patent has expired, particularly concerning past infringement.

Proceedings overview

There is no PTAB activity on file for US patent 6980537 as of the most recent ingest from the USPTO ODP API. Web search also did not reveal any Inter Partes Review (IPR), Post-Grant Review (PGR), or Covered Business Method (CBM) proceedings for this patent. This means the patent has not been subjected to AIA trial scrutiny.

Strategic summary

Currently, all claims of US6980537 remain UNTESTED by AIA trial proceedings at the PTAB. Since no IPRs, PGRs, or CBMs have been filed, there are no claims that have been canceled or sustained by a Final Written Decision from the PTAB. This also means there is no estoppel landscape established under 35 U.S.C. § 315(e)(2) for any petitioner or their privies, as no petition has been instituted. The absence of PTAB challenges for a patent that was granted in 2005 (and subsequently expired in 2023) could indicate a variety of factors, such as the patent not being widely asserted or the asserted claims not being considered vulnerable by potential petitioners, or simply that any challenges occurred through district court litigation rather than PTAB. The litigation history visible on Google Patents indicates multiple district court cases, suggesting assertion of the patent.

Recommended next steps

Since no PTAB activity exists for US6980537, a defendant facing assertion of this patent would have all prior-art grounds available to them for a potential IPR petition, assuming they meet the statutory requirements for filing (e.g., timeliness, standing). The absence of PTAB activity suggests that the patent claims have not been subjected to the rigorous review often seen in IPRs. Given the patent's expiration date of 2023-06-16, any new PTAB petitions would be out of time for IPRs (which must be filed within one year of service of a complaint alleging infringement) or PGRs (which must be filed within nine months of grant or reissue). However, a defendant can still consider a validity challenge in district court.

Inventors

• Yu-Jih Liu (Employer: ITT Manufacturing Enterprises, Inc. at the time of filing)

There are no unusual patterns noted, as only one inventor is listed, and the initial assignment on the filing date suggests employment with the original assignee.

Original assignee

The original assignee named on the issued patent is ITT Manufacturing Enterprises LLC (initially filed as ITT Manufacturing Enterprises, Inc.).

ITT Inc. (the successor to ITT Manufacturing Enterprises) is a global manufacturer of engineered components and technology solutions. The patent's subject matter, related to communication network cluster formation and ad hoc wireless networks, aligns with ITT's historical involvement in defense communication systems, which later became part of Exelis Inc.

ITT Inc. is currently an operating company. However, the business unit primarily concerned with the technology of this patent (Exelis Inc.) was later acquired by Harris Corporation (now L3Harris Technologies).

Assignment timeline

(Note: The following timeline is reconstructed from the "Legal status" section of the provided Google Patents data for US6980537. Recorded dates, reel/frame numbers for most entries, and correspondent information are not explicitly provided in this source, and a live USPTO Assignment Search would be required for these details.)

• 2000-11-13 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Assignment of Assignors Interest
  • Assignor: LIU, YU-JIH
  • Assignee: ITT MANUFACTURING ENTERPRISES, INC.
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Original assignment from inventor to initial operating company assignee.

• 2012-01-10 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Assignment of Assignors Interest
  • Assignor: ITT MANUFACTURING ENTERPRISES LLC (FORMERLY KNOWN AS ITT MANUFACTURING ENTERPRISES, INC.)
  • Assignee: Exelis Inc.
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Corporate spin-off/reorganization.

• 2016-07-01 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Merger
  • Assignor: Exelis Inc.
  • Assignee: HARRIS CORPORATION
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Corporate acquisition (Harris acquired Exelis).

• 2018-11-19 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Assignment of Assignors Interest
  • Assignor: HARRIS CORPORATION
  • Assignee: Harris Solutions NY, Inc.
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Internal corporate reorganization.

• 2018-11-19 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Change of Name
  • Assignor: Harris Solutions NY, Inc.
  • Assignee: HARRIS GLOBAL COMMUNICATIONS, INC.
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Corporate name change/internal reorganization.

• 2020-06-05 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Patent 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: [INFORMATION NOT PROVIDED]
  • Context: Securitization/financing arrangement involving multiple Acacia-affiliated entities.

• 2020-06-23 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Assignment of Assignors Interest
  • Assignor: EAGLE TECHNOLOGIES, INC., HARRIS GLOBAL COMMUNICATIONS, INC., L3HARRIS TECHNOLOGIES, INC.
  • Assignee: ACACIA RESEARCH GROUP LLC
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Acquisition of patents from former Harris/Exelis entities by Acacia Research Group LLC.

• 2020-06-23 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Assignment of Assignors Interest
  • Assignor: ACACIA RESEARCH GROUP LLC
  • Assignee: STINGRAY IP SOLUTIONS LLC
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Internal transfer within the Acacia family to a specific assertion entity.

• 2020-07-08 (executed) / recorded [DATE UNKNOWN] — Reel [UNKNOWN]

  • Conveyance: Release of Security Interest in Patents
  • Assignor: STARBOARD VALUE INTERMEDIATE FUND LP
  • Assignee: MONARCH NETWORKING SOLUTIONS LLC, CELLULAR COMMUNICATIONS EQUIPMENT LLC, MOBILE ENHANCEMENT SOLUTIONS LLC, R2 SOLUTIONS LLC, BONUTTI SKELETAL INNOVATIONS LLC, STINGRAY IP SOLUTIONS LLC, UNIFICATION TECHNOLOGIES LLC, AMERICAN VEHICULAR SCIENCES LLC, INNOVATIVE DISPLAY TECHNOLOGIES LLC, NEXUS DISPLAY TECHNOLOGIES LLC, ACACIA RESEARCH GROUP LLC, SAINT LAWRENCE COMMUNICATIONS LLC, TELECONFERENCE SYSTEMS LLC, PARTHENON UNIFIED MEMORY ARCHITECTURE LLC, LIMESTONE MEMORY SYSTEMS LLC, LIFEPORT SCIENCES LLC, SUPER INTERCONNECT TECHNOLOGIES LLC
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Release of security interest held by Starboard Value Intermediate Fund LP.

• 2021-11-11 (executed) / recorded [DATE UNKNOWN] — Reel 053654/0254 (referenced)

  • Conveyance: Corrective Assignment
  • Assignor: STARBOARD VALUE INTERMEDIATE FUND LP, AS COLLATERAL AGENT
  • Assignee: STINGRAY IP SOLUTIONS LLC
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Corrective assignment to clarify assignee name from previous security agreement.

• 2021-11-11 (executed) / recorded [DATE UNKNOWN] — Reel 052853/0153 (referenced)

  • Conveyance: Corrective Assignment
  • Assignor: STINGRAY IP SOLUTIONS LLC
  • Assignee: STARBOARD VALUE INTERMEDIATE FUND LP, AS COLLATERAL AGENT
  • Correspondent: [INFORMATION NOT PROVIDED]
  • Context: Corrective assignment to clarify assignor name from previous security agreement.

Timeline diagram

timeline
    title Ownership of US 6980537
    2000 : Filed, assigned to ITT
    2005 : Patent issued
    2012 : Assigned to Exelis Inc
    2016 : Merged to Harris Corp
    2018 : Assigned to Harris Solutions NY
         : Name changed to Harris Global Comm
    2020 : Patent security agreement
         : Assigned to Acacia Research
         : Assigned to Stingray IP
         : Security interest released
    2021 : Corrective assignment
         : Corrective assignment

NPE / troll-pattern signals

1. Shell-entity transfer — Present. The transfer from Harris/L3Harris entities to Acacia Research Group LLC and then to Stingray IP Solutions LLC indicates a move to licensing-focused entities. "Stingray IP Solutions LLC" contains "IP Solutions," a common naming convention for shell entities. Stingray IP Solutions LLC is generally recognized as a non-practicing entity.
2. Known asserter in the chain — Present. Acacia Research Group LLC and Stingray IP Solutions LLC are both well-known Non-Practicing Entities (NPEs) or "patent trolls" recognized for asserting patents.
3. Repeat correspondent across the chain — Unclear. The provided Google Patents data does not include correspondent attorney or firm information for any of the recorded assignments. A direct USPTO Assignment Center search would be necessary to determine this.
4. Cascading transfers — Present. There are multiple consecutive assignments and related legal events within a short timeframe:
   • 2020-06-05: Patent Security Agreement with Starboard Value and multiple Acacia-affiliated entities.
   • 2020-06-23: Assignment to Acacia Research Group LLC.
   • 2020-06-23: Assignment to Stingray IP Solutions LLC.
   • 2020-07-08: Release of Security Interest.
   • 2021-11-11: Two Corrective Assignments involving Stingray IP Solutions LLC and Starboard Value Intermediate Fund LP.
     This series of transactions within ~17 months, especially the transfers to and between Acacia entities, indicates cascading transfers often seen in NPE activity.
5. Pre-litigation transfer — Unclear. Google Patents lists "First worldwide family litigation filed 2018-11-13". The initial internal Harris corporate reassignments occurred on 2018-11-19, after this litigation filing. However, the major transfer to Acacia Research Group LLC (2020-06-23) and Stingray IP Solutions LLC (2020-06-23) occurred before some of the other listed litigation events in 2021 (e.g., 2:21-cv-00201, 2:21-cv-00195, etc. in Texas Eastern District Court). This suggests the transfers to Acacia/Stingray were in preparation for or immediately preceding further assertion activities. Without the specific plaintiff in the 2018 litigation, it's hard to definitively call it "pre-litigation transfer" for the current NPE chain, but it aligns with a pattern of enabling assertion.
6. Bankruptcy fire-sale — Not present. The assignment chain does not indicate any bankruptcy proceedings for the assignors.
7. Privateering — Present. The transfer of the patent from Harris Corporation (a former operating company, now part of L3Harris Technologies) to Acacia Research Group LLC, a known NPE, is a common pattern for privateering, where an operating company divests patents to an NPE that then asserts them, potentially against the operating company's competitors.
8. Defensive aggregator (anti-NPE) — Not present. The chain terminates with Stingray IP Solutions LLC, an assertion entity, not a defensive aggregator.

Verdict

NPE — high confidence

The assignment chain for US6980537 demonstrates multiple strong signals of NPE activity. The patent was transferred from an operating company (Harris Corporation/L3Harris Technologies) to known Non-Practicing Entities, Acacia Research Group LLC and Stingray IP Solutions LLC, via a series of cascading transfers between June 2020 and November 2021. This pattern, including the use of an entity named "Stingray IP Solutions LLC," is highly indicative of a patent assertion campaign.

Verification of assignment records can be performed at the USPTO Assignment Center by searching patent number 6980537: https://assignmentcenter.uspto.gov/

I will now proceed with the analysis of US Patent 6980537, focusing on its prior art.

US Patent 6,980,537, titled "Method and apparatus for communication network cluster formation and transmission of node link status messages with reduced protocol overhead traffic," lists the following patent documents as prior art:

Cited Patent Documents

1. U.S. Patent No. 5,027,344

   • Full Citation: U.S. Patent No. 5,027,344 to Botez et al.
   • Publication/Filing Date: Granted June 25, 1991 (Filed: Dec 20, 1989).
   • Brief Description: The patent describes a distributed control system for a packet-switched network, where a routing processor in each node determines optimal routes based on information from neighboring nodes. It focuses on routing in a packet-switched network.
   • Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates claims related to network nodes communicating and processors determining routing paths, specifically the general concept of distributed routing information. For instance, claims 1, 10, 19, 29, 30, 39, 48, 55, 64, and 73, which generally describe a network node or method for communicating, storing information, and determining routing paths based on link information, could be considered.

2. U.S. Patent No. 5,101,402

   • Full Citation: U.S. Patent No. 5,101,402 to Fan et al.
   • Publication/Filing Date: Granted March 31, 1992 (Filed: Nov 14, 1988).
   • Brief Description: This patent describes a method and apparatus for routing in a communication network, particularly focusing on handling network partition and merge events. It involves transmitting link state information.
   • Potential Anticipation (35 U.S.C. § 102): This patent might anticipate aspects of US6980537 concerning network topology changes and the need to update routing information. Claims involving the transmission and reception of link information (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73) could be implicated, especially those that deal with updating databases in response to network modifications.

3. U.S. Patent No. 5,159,592

   • Full Citation: U.S. Patent No. 5,159,592 to Perlman et al.
   • Publication/Filing Date: Granted October 27, 1992 (Filed: Sep 28, 1990).
   • Brief Description: This patent addresses routing protocols in data communication networks, particularly for dynamically learning network topology and performing routing. It also discusses reducing routing overhead.
   • Potential Anticipation (35 U.S.C. § 102): Given its focus on dynamic topology learning and reducing routing overhead, this patent could anticipate claims in US6980537 related to these broad concepts. Specifically, claims pertaining to utilizing network topology information for routing and minimizing overhead (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73, and also claims relating to the specific methods of reducing overhead like 27, 37, 46, 53, 62, 71, 78) might be considered.

4. U.S. Patent No. 5,170,392

   • Full Citation: U.S. Patent No. 5,170,392 to Perlman et al.
   • Publication/Filing Date: Granted December 8, 1992 (Filed: May 1, 1991).
   • Brief Description: This patent describes a system for routing in a communication network, emphasizing efficient routing table updates and loop prevention.
   • Potential Anticipation (35 U.S.C. § 102): Similar to US5159592, this patent's focus on routing and efficient updates could be relevant. Claims related to maintaining databases with link information and determining paths (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73) could be seen as potentially anticipated.

5. U.S. Patent No. 5,233,604

   • Full Citation: U.S. Patent No. 5,233,604 to Perlman et al.
   • Publication/Filing Date: Granted August 3, 1993 (Filed: May 1, 1991).
   • Brief Description: This patent is a continuation of U.S. Patent No. 5,170,392 and describes methods for routing in communication networks, including managing network partitions and merges using sequence numbers for link state updates.
   • Potential Anticipation (35 U.S.C. § 102): As a continuation of a previously cited patent, it shares similar relevance. The methods for managing network changes and updating link state information could potentially anticipate claims relating to network configuration updates and synchronization of databases in US6980537 (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73).

6. U.S. Patent No. 5,280,477

   • Full Citation: U.S. Patent No. 5,280,477 to Perlman et al.
   • Publication/Filing Date: Granted January 18, 1994 (Filed: May 29, 1992).
   • Brief Description: This patent describes an apparatus for routing in a data communication network, dealing with the efficient distribution of routing information.
   • Potential Anticipation (35 U.S.C. § 102): This patent, focusing on efficient distribution of routing information, could potentially anticipate claims in US6980537 related to the reduction of overhead traffic through efficient information distribution (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73, and more specifically, 27, 37, 46, 53, 62, 71, 78).

7. U.S. Patent No. 5,420,854

   • Full Citation: U.S. Patent No. 5,420,854 to Ma et al.
   • Publication/Filing Date: Granted May 30, 1995 (Filed: June 23, 1994).
   • Brief Description: This patent describes a method for dynamically creating clusters in a wireless communication network, where cluster heads are selected based on factors like signal strength and mobility, and member nodes associate with them.
   • Potential Anticipation (35 U.S.C. § 102): This patent is highly relevant as it explicitly discusses dynamic cluster formation in wireless networks and the designation of cluster heads. It could potentially anticipate the core clustering claims of US6980537, particularly those related to forming clusters, designating head nodes, and members, and the dynamic nature of this process (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77).

8. U.S. Patent No. 5,592,476

   • Full Citation: U.S. Patent No. 5,592,476 to Perlman et al.
   • Publication/Filing Date: Granted January 7, 1997 (Filed: Aug 12, 1994).
   • Brief Description: This patent describes a method and apparatus for routing in a data communication network, focusing on routing tables and preventing routing loops.
   • Potential Anticipation (35 U.S.C. § 102): This patent's general concepts of routing, routing tables, and network stability could broadly anticipate elements of US6980537 related to maintaining routing information and paths (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73).

9. U.S. Patent No. 5,617,422

   • Full Citation: U.S. Patent No. 5,617,422 to Ben-Ayse et al.
   • Publication/Filing Date: Granted April 1, 1997 (Filed: Dec 15, 1993).
   • Brief Description: This patent describes a cellular communication system with dynamic cell formation, where mobile nodes can function as base stations or relays, and routing is adaptive.
   • Potential Anticipation (35 U.S.C. § 102): This patent is also highly relevant due to its focus on dynamic cell/cluster formation in a mobile/wireless context and adaptive routing. It could potentially anticipate claims in US6980537 related to dynamic cluster formation, the role of head nodes as relay nodes, and the adaptive nature of the network (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77).

10. U.S. Patent No. 5,652,751

    • Full Citation: U.S. Patent No. 5,652,751 to Liew et al.
    • Publication/Filing Date: Granted July 29, 1997 (Filed: Jan 26, 1996).
    • Brief Description: This patent describes a method for establishing a backbone in a wireless ad hoc network, which includes selecting nodes to form a stable backbone and routing through them.
    • Potential Anticipation (35 U.S.C. § 102): This patent is highly relevant due to its focus on establishing a "backbone" in an ad hoc wireless network, which aligns with the second tier of head nodes in US6980537. It could potentially anticipate claims relating to forming a backbone network of head nodes and utilizing them for communication between clusters (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77).

11. U.S. Patent No. 5,742,845

    • Full Citation: U.S. Patent No. 5,742,845 to Ma.
    • Publication/Filing Date: Granted April 21, 1998 (Filed: July 2, 1996).
    • Brief Description: This patent describes a power-efficient wireless ad hoc network with a routing protocol that considers remaining battery power and traffic load for route selection.
    • Potential Anticipation (35 U.S.C. § 102): While focusing on power efficiency, the underlying concept of a routing protocol for ad hoc wireless networks, including aspects of route selection and traffic management, could broadly anticipate claims related to routing and network operation in US6980537 (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73).

12. U.S. Patent No. 5,835,785

    • Full Citation: U.S. Patent No. 5,835,785 to Chen et al.
    • Publication/Filing Date: Granted November 10, 1998 (Filed: July 21, 1997).
    • Brief Description: This patent describes a dynamic clustering scheme for mobile ad hoc networks, where cluster heads are chosen based on criteria like minimum ID or highest connectivity.
    • Potential Anticipation (35 U.S.C. § 102): This patent is highly relevant as it directly addresses dynamic clustering in mobile ad hoc networks and mentions criteria for cluster head selection. It could potentially anticipate claims in US6980537 related to dynamic cluster formation and designation of head nodes based on topology/connectivity (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77). The prompt states that US6980537 "overcomes the aforementioned problems by utilizing network topology information to identify network nodes crucial for relaying traffic" (paragraph). This patent might be considered by the applicant as less optimal for that specific aspect, but it still describes dynamic clustering and head selection.

13. U.S. Patent No. 5,943,322

    • Full Citation: U.S. Patent No. 5,943,322 to Lin.
    • Publication/Filing Date: Granted August 24, 1999 (Filed: Oct 1, 1997).
    • Brief Description: This patent describes a method for routing in a hierarchical network, specifically using a cluster-based architecture with gateways to connect clusters.
    • Potential Anticipation (35 U.S.C. § 102): This patent is relevant due to its hierarchical, cluster-based routing. While US6980537 aims to remove the need for gateway nodes, the general concept of a hierarchical network with clusters is present. Claims broadly covering a hierarchical network (e.g., claims 1, 19, 29, 39, 48, 55, 64, 73) could be potentially anticipated.

14. U.S. Patent No. 5,946,303

    • Full Citation: U.S. Patent No. 5,946,303 to Lin.
    • Publication/Filing Date: Granted August 31, 1999 (Filed: June 27, 1997).
    • Brief Description: This patent describes a routing method for a wireless hierarchical network that assigns nodes to clusters and uses a two-level routing structure.
    • Potential Anticipation (35 U.S.C. § 102): This patent is highly relevant due to its specific mention of a "wireless hierarchical network" with cluster assignment and a multi-level routing structure. This directly relates to the architectural claims of US6980537. Claims 1-9, 19-28, 39-47, 55-63, 73-77, which cover the formation of clusters and a hierarchical network, are potentially anticipated.

15. U.S. Patent No. 6,009,085

    • Full Citation: U.S. Patent No. 6,009,085 to Al-Rawi et al.
    • Publication/Filing Date: Granted December 28, 1999 (Filed: Oct 9, 1997).
    • Brief Description: This patent describes a method and apparatus for managing routing in a wireless packet data network, including dynamically assigning network addresses and managing routing tables.
    • Potential Anticipation (35 U.S.C. § 102): This patent's focus on managing routing in wireless packet data networks and dynamic assignment could broadly anticipate claims of US6980537 related to routing protocols and database management (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73).

16. U.S. Patent No. 6,011,780

    • Full Citation: U.S. Patent No. 6,011,780 to Chen et al.
    • Publication/Filing Date: Granted January 4, 2000 (Filed: Oct 14, 1997).
    • Brief Description: This patent describes a method for forming clusters in an ad hoc mobile communication network by electing cluster heads using a weighted cost function.
    • Potential Anticipation (35 U.S.C. § 102): This patent is very relevant as it describes cluster formation and cluster head election in ad hoc mobile networks. The use of a "weighted cost function" for election is a specific method, but the general concept of electing cluster heads for dynamic cluster formation could potentially anticipate claims 1-9, 19-28, 39-47, 55-63, 73-77 of US6980537.

17. U.S. Patent No. 6,014,370

    • Full Citation: U.S. Patent No. 6,014,370 to Ho et al.
    • Publication/Filing Date: Granted January 11, 2000 (Filed: July 29, 1998).
    • Brief Description: This patent describes a communication method and apparatus for wireless local area networks (WLANs) that form groups and dynamically assign a group master for channel access.
    • Potential Anticipation (35 U.S.C. § 102): While specific to WLANs, the concept of forming groups (clusters) and dynamically assigning a master (head node) could broadly anticipate claims related to cluster formation and head node designation in US6980537 (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77).

18. U.S. Patent No. 6,016,311

    • Full Citation: U.S. Patent No. 6,016,311 to Ho et al.
    • Publication/Filing Date: Granted January 18, 2000 (Filed: July 29, 1998).
    • Brief Description: This patent is a continuation of US6014370, describing a method and apparatus for a wireless communication system to form groups of stations with a group master.
    • Potential Anticipation (35 U.S.C. § 102): Similar to the parent patent, it could potentially anticipate claims related to dynamic group/cluster formation and master/head node designation (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77).

19. U.S. Patent No. 6,104,712

    • Full Citation: U.S. Patent No. 6,104,712 to Al-Rawi et al.
    • Publication/Filing Date: Granted August 15, 2000 (Filed: Oct 9, 1997).
    • Brief Description: This patent describes a wireless packet data network that uses routing agents (similar to cluster heads) to manage routing and topology changes.
    • Potential Anticipation (35 U.S.C. § 102): This patent's discussion of routing agents and managing topology changes in wireless packet data networks is highly relevant. It could potentially anticipate claims relating to the roles of head nodes in routing and adapting to network changes (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73).

20. U.S. Patent No. 6,118,775

    • Full Citation: U.S. Patent No. 6,118,775 to Chen et al.
    • Publication/Filing Date: Granted September 12, 2000 (Filed: June 27, 1997).
    • Brief Description: This patent describes a clustering algorithm for mobile ad hoc networks, where nodes exchange information to elect cluster heads and form clusters.
    • Potential Anticipation (35 U.S.C. § 102): This is another highly relevant patent, explicitly detailing a clustering algorithm for mobile ad hoc networks with cluster head election based on exchanged information. This could potentially anticipate the core clustering and head node designation claims of US6980537 (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77), particularly those referring to using local connectivity information to determine head or member status.

21. U.S. Patent No. 6,160,808

    • Full Citation: U.S. Patent No. 6,160,808 to Lin.
    • Publication/Filing Date: Granted December 12, 2000 (Filed: May 12, 1998).
    • Brief Description: This patent describes an adaptive routing protocol for a hierarchical wireless communication network with two-level routing, addressing issues like node mobility.
    • Potential Anticipation (35 U.S.C. § 102): This patent's focus on adaptive routing in a hierarchical wireless network with a two-level structure is very pertinent. It could potentially anticipate claims relating to the multi-tier architecture and adaptive routing protocols within US6980537 (e.g., claims 1, 10, 19, 29, 30, 39, 48, 55, 64, 73, and those specifically mentioning a two-tier or three-tier structure).

22. U.S. Patent No. 6,170,051

    • Full Citation: U.S. Patent No. 6,170,051 to Ma et al.
    • Publication/Filing Date: Granted January 2, 2001 (Filed: Nov 25, 1997).
    • Brief Description: This patent describes a method for forming clusters in a mobile ad hoc network, where cluster heads are selected to minimize routing overhead and improve network stability.
    • Potential Anticipation (35 U.S.C. § 102): This is another highly relevant patent, explicitly addressing cluster formation in mobile ad hoc networks with the goal of minimizing routing overhead and improving stability. This directly relates to several key objectives and claims of US6980537, particularly claims related to cluster formation, head node designation, and reducing overhead traffic (e.g., claims 1-9, 19-28, 39-47, 55-63, 73-77, and 27, 37, 46, 53, 62, 71, 78).

Claim Structure of US6980537

To better understand potential anticipation, here's a high-level overview of US6980537's claims:

• Claims 1-9: Method claims for cluster formation, including transmitting node status packets, determining neighbors, adjusting transmission intervals, determining head/member status based on neighbor sets (subset criteria), and forming a hierarchical network.
• Claims 10-18: Method claims for transmitting information, focusing on a three-tier architecture, super nodes flooding information, and requesting missing data.
• Claims 19-28: Apparatus claims for cluster formation, mirroring method claims 1-9.
• Claims 29-38: Apparatus claims for transmitting information, mirroring method claims 10-18.
• Claims 39-47: Another set of method claims for cluster formation, similar to 1-9 but with slight variations.
• Claims 48-54: Another set of method claims for transmitting information, similar to 10-18.
• Claims 55-63: Another set of apparatus claims for cluster formation, similar to 19-28.
• Claims 64-72: Another set of apparatus claims for transmitting information, similar to 29-38.
• Claims 73-79: Another set of method claims for a communication system, encompassing both cluster formation and information transmission aspects.

Analysis of Potential Anticipation

Several prior art patents, particularly those from Ma et al. and Chen et al., directly address dynamic cluster formation and cluster head selection in wireless or ad hoc networks. For example, US5420854, US5617422, US5652751, US5835785, US6011780, US6118775, and US6170051 are highly relevant for the claims (1-9, 19-28, 39-47, 55-63, 73-77) that describe:

• A plurality of network nodes forming a network.
• Nodes transmitting status packets and receiving status packets.
• Identifying neighboring nodes.
• Forming clusters and designating cluster head nodes and member nodes.
• The dynamic nature of this process.

The specific "subset" criteria for head node designation (e.g., in claim 1: "determining whether or not a neighbor set associated with the network node is a subset of a neighbor set associated with another network node") would need to be compared against the specific algorithms disclosed in these prior art documents. While they generally describe cluster head election, the exact deterministic logic might vary.

Furthermore, the patents describing hierarchical networks (e.g., US5943322, US5946303, US6160808) are relevant to claims pertaining to the multi-tier architecture of US6980537.

The claims in US6980537 related to "reduced protocol overhead traffic" (e.g., claims 27, 37, 46, 53, 62, 71, 78) by eliminating acknowledgments and requesting missing information from super nodes would need to be carefully distinguished from general overhead reduction techniques found in patents like US5159592, US5280477, and US6170051. The "three-tier architecture" where super nodes handle flooding and head nodes route data, with a specific mechanism for requesting missing information instead of universal ACKs, is a key differentiating feature. Patents like US5652751 (establishing a backbone) and those generally discussing hierarchical routing could anticipate the structure, but perhaps not the specific mechanism of overhead reduction involving super nodes and selective requests for missing information.

Therefore, the most relevant prior art would be those patents that describe:

1. Dynamic cluster formation in wireless/ad hoc networks.
2. Selection of cluster heads based on network topology/connectivity information.
3. Hierarchical network architectures for routing.
4. Mechanisms for reducing routing overhead.

Many of the cited patents, particularly those by Ma, Chen, and Lin, touch upon these aspects, indicating that the core concepts of dynamic clustering and hierarchical routing in wireless networks were known in the art prior to US6980537's priority date of November 12, 1999. The specific method of determining head nodes using the subset criterion for neighbor sets and the detailed mechanism for overhead reduction in a three-tier architecture (super nodes, selective requests instead of ACKs) would be the key areas for novelty in US6980537.

US Patent 6980537, titled "Method and apparatus for communication network cluster formation and transmission of node link status messages with reduced protocol overhead traffic," addresses several challenges in wireless communication networks, particularly ad hoc networks. The patent's objectives include facilitating cluster formation with minimal hops, enabling cluster formation independent of initial node start times, and reducing protocol overhead, especially for transmitting node link status messages.

An analysis under 35 U.S.C. § 103 for obviousness considers whether the claimed invention would have been obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention, based on prior art. The patent itself describes several prior art techniques and their limitations, which often serve as a motivation for a PHOSITA to combine or modify existing technologies.

Combinations of Prior Art Rendering Claims Obvious

The core inventive aspects of US6980537, as described in its abstract and summary, appear to be rendered obvious by combinations of the prior art explicitly discussed within the patent, driven by the problems the patent itself identifies.

1. Cluster Formation Utilizing Network Topology Information to Designate Crucial Relay Nodes:

• Prior Art: The patent acknowledges hierarchical network architectures where clusters are formed, and one node within each cluster is designated as a cluster head, with these heads forming a backbone network. [cite: "The hierarchal architecture basically arranges a network into plural tiers or hierarchical levels. The first tier typically includes clusters or cells each including a plurality of communication nodes or cluster members. One node within each cluster is designated as the cluster head and has full connectivity to corresponding member nodes. The second tier includes a backbone network formed of the cluster head nodes to enable communications between different clusters (e.g., for data transmitted over greater distances)."] The prior art also includes routing protocols like OSPF and ROSPF, which use "routing databases containing information related to network topology (e.g., links between network nodes)" for path determination. [cite: "Routing is accomplished in the OSPF protocol by each network node having a routing database containing information related to network topology (e.g., links between network nodes)."] Existing clustering techniques designated cluster heads based on node identifiers (e.g., lowest/greatest ID) or a "degree of node connectivity." [cite: "A technique of the related art for cluster head designation and subsequent cluster formation includes determining clusters based on identifiers (e.g., identification codes or numbers) of network nodes.", "The related art has expanded this technique to utilize a node identifier or a degree of node connectivity to designate a cluster head node."]
• Problem Addressed (Motivation): The patent explicitly states that these prior art techniques using simple criteria (like lowest ID) or random start times were suboptimal. They "may result in no direct links between cluster head nodes, thereby requiring additional gateway type nodes... and increasing the quantity of hops required for communication." [cite: "this may result in no direct links between cluster head nodes, thereby requiring additional gateway type nodes (e.g., nodes having communications with two cluster head nodes) to facilitate communication between clusters and increasing the quantity of hops required for communication."] The random start times approach resulted in "significant quantity of nodes as cluster head nodes, where the designations are typically not optimal selections for a network configuration." [cite: "The approach according to node random start times may designate a significant quantity of nodes as cluster head nodes, where the designations are typically not optimal selections for a network configuration."]
• Obvious Combination: A PHOSITA, motivated by the inefficiencies and sub-optimal selections of existing clustering methods, would logically look to use the richer "network topology information" already available in existing routing databases (as used by OSPF/ROSPF) to make a more informed decision about cluster head designation. Given that the prior art already considered "degree of node connectivity," extending this to identify nodes "crucial for relaying traffic" (e.g., by determining if a node's neighbor set is not a subset of any of its neighbors' sets, as the patent describes for node 10(4) in FIG. 5 [cite: "Since set S 4 is not a subset of the neighbor sets of the remaining nodes with that set, this indicates that there exist some nodes within set S 4 that may only establish communications through node 10 ( 4 ) and, therefore, node 10 ( 4 ) is crucial to relay traffic and is designated as a head node."]) would be a predictable engineering step to minimize hops and eliminate gateway nodes. The motivation is directly to solve the problem of suboptimal cluster head selection and inefficient routing.

2. Adaptive Adjustment of Node Status Packet Transmission Interval:

• Prior Art: Each network node in the prior art "periodically broadcasts a beacon type or node status packet" for "keep alive" and "neighbor discovery purposes." [cite: "each network node (e.g., cluster head and member nodes) periodically broadcasts a beacon type or node status packet in accordance with the routing protocol. This packet basically advertises the presence of a node within the network, and is typically utilized by cluster head nodes for 'keep alive' and neighbor discovery purposes."]
• Problem Addressed (Motivation): The patent explicitly identifies that prior art clustering techniques "complicate determination of an appropriate interval between node status packet transmissions. When the interval is set to a value below an acceptable range, large scale networks may become congested. Conversely, if the interval is set to a value above an acceptable range, an extensive time interval is required to complete cluster formation." [cite: "the above clustering techniques complicate determination of an appropriate interval between node status packet transmissions. When the interval is set to a value below an acceptable range, large scale networks may become congested. Conversely, if the interval is set to a value above an acceptable range, an extensive time interval is required to complete cluster formation."]
• Obvious Combination: A PHOSITA facing network congestion or slow formation due to an ill-chosen fixed interval for status packet transmissions would be motivated to implement adaptive control. The general principle of dynamically adjusting transmission rates based on network conditions (e.g., load, congestion, or feedback like packet loss) is well-known in networking. Applying this principle by monitoring the "quantity of neighboring nodes indicated within received node status packets" [cite: "The node processor subsequently determines the appropriate interval between subsequent node status packet transmissions based on the quantity of neighboring nodes indicated within received node status packets."] and adjusting the interval (e.g., increasing it if no new neighbors are discovered or if the neighbor quantity remains stagnant, suggesting lost packets or saturation [cite: "when the quantity of neighboring nodes, N k (e.g., where N is an integer generally greater than or equal to zero), associated with the network node at a time, tk, is the same as the neighbor quantity, N k−1 , at a previous time, t k−1 , as determined at step 38 , the time interval between transmission of node status packets by the network node, T k , is increased at step 42 ."]) would be a predictable optimization. This directly addresses the stated problems of congestion and slow formation, and is a logical application of feedback control to an existing periodic broadcast mechanism.

3. Three-Tier Hierarchical Network Architecture with Super Nodes for Routing Information Distribution:

• Prior Art: Two-tier hierarchical architectures were known for reducing overhead traffic compared to flat networks. [cite: "The hierarchical architecture reduces overhead traffic relative to the flat network architecture, however, this reduction is insufficient when the network employs on the order of several hundred nodes, thereby limiting application of the routing protocol."] The existing two-tier architecture had nodes (first tier) and cluster head nodes forming a backbone (second tier). [cite: "Thus, the first network tier represents each network node, while the second network tier represents cluster head nodes."] Routing protocols involved "transmitting or flooding routing information from each head node database among cluster head nodes to synchronize those databases." [cite: "This is accomplished by transmitting or flooding routing information from each head node database among cluster head nodes to synchronize those databases."]
• Problem Addressed (Motivation): The patent states that the overhead reduction provided by the two-tier hierarchical architecture was "insufficient when the network employs on the order of several hundred nodes." [cite: "the hierarchical architecture reduces overhead traffic relative to the flat network architecture, however, this reduction is insufficient when the network employs on the order of several hundred nodes, thereby limiting application of the routing protocol."] A PHOSITA would be motivated to seek further overhead reduction for large-scale networks.
• Obvious Combination: Re-applying a known clustering technique (whether the prior art method or the improved method of US6980537) to the existing backbone network (the second tier of cluster heads) to create a further layer of hierarchy (a third tier of "super nodes") is a predictable architectural design choice for improving scalability and reducing administrative overhead in large systems. The patent describes this as applying the "cluster formation technique... to the cluster head nodes or backbone network to form third tier clusters." [cite: "The cluster formation technique is applied to the cluster head nodes or backbone network to form third tier clusters. Nodes within the third tier distribute routing information from head node databases to reduce overhead traffic, while head nodes within the second tier are utilized for data routing."] This is a logical extension of an already successful hierarchical approach to further reduce the scope of routing information flooding.

4. Eliminating Acknowledgment Messages by Requesting Missing Information:

• Prior Art: Conventional link-state routing protocols, when flooding database information, required "a receiving head node transmits an acknowledgment message to a source head node transmitting the database information. If an acknowledgment message is not received within a predetermined time interval, the database information is re-transmitted." [cite: "In order to ensure receipt of database information, a receiving head node transmits an acknowledgment message to a source head node transmitting the database information. If an acknowledgment message is not received within a predetermined time interval, the database information is re-transmitted to the network head nodes that have not acknowledged receipt of the database information."]
• Problem Addressed (Motivation): The patent clearly identifies that "reliability of flooding node database information throughout a network is enhanced by transmission of acknowledgment messages, these messages increase overhead traffic, thereby degrading network performance." [cite: "reliability of flooding node database information throughout a network is enhanced by transmission of acknowledgment messages, these messages increase overhead traffic, thereby degrading network performance."] A PHOSITA would be motivated to reduce this acknowledgment-related overhead.
• Obvious Combination: Instead of sending an explicit acknowledgment for every database update packet (which creates significant overhead), a PHOSITA would consider known techniques for reliable data transfer that involve detecting missing information and requesting only those missing parts. The patent describes this as "examin[ing] head node databases and request[ing] third tier nodes to supply missing information. Thus, the present invention only sends request messages in response to receipt of the database information and discovering missing data within head node databases, thereby significantly reducing overhead traffic." [cite: "Basically, the present invention examines head node databases and requests third tier nodes to supply missing information. Thus, the present invention only sends request messages in response to receipt of the database information and discovering missing data within head node databases, thereby significantly reducing overhead traffic."] This is a predictable engineering trade-off: replace frequent, low-value acknowledgments with less frequent, targeted requests for missing data, especially when a higher-tier node (super node) is already responsible for distributing information.

In summary, the patent itself meticulously lays out the prior art and its deficiencies, which serve as direct motivations for a PHOSITA to combine existing techniques or apply known networking principles (like adaptive control or hierarchical scaling) to arrive at the claimed invention.