US 7742388

Summary of U.S. Patent 7,742,388

Title: Packet generation systems and methods

Assignee: Fleet Connect Solutions LLC

Inventors: Daniel Shearer, Mark A. Webster

Filing Date: July 20, 2005

Issue Date: June 22, 2010

Abstract: Disclosed herein are various embodiments of methods, systems, and apparatus for increasing packet generation in a digital communication system. In one exemplary method embodiment, subcarriers are added to a packet in a wireless local area network transmission to increase the data rate.

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Plain-Language Overview of Independent Claims:

This patent has two independent claims: claim 1 and claim 12.

Claim 1: This claim describes a method for increasing the data-carrying capacity of a network transmission packet. The process involves creating a standard packet that has a "preamble" at the beginning, which acts like a signal to receiving devices. This preamble contains two distinct parts called "training symbols." The key step is to then increase the size of this packet by adding more data-carrying subcarriers specifically to the second training symbol, making it larger than the first. This modified, "extended" packet is then transmitted. In simpler terms, this method boosts the amount of information that can be sent in a single packet by enhancing a specific part of its introductory signal.

Claim 12: This claim outlines a method for generating and transmitting a specific type of data packet. This packet is composed of a preamble and a data portion. The preamble itself has a first and a second training symbol, both of which use modulated subcarriers to carry information. The core of this claim is that the second training symbol is designed to have a greater number of these modulated subcarriers than the first training symbol. This constructed packet is then transmitted. This method focuses on the creation of a packet with a front-loaded, enhanced training signal to potentially improve communication efficiency.

It should be noted that, according to a search of public records, a notice of intent to issue a reexamination certificate to cancel several claims of this patent, including claims 1-9 and 11-13, was entered on March 26, 2026. This indicates that the validity of these claims has been successfully challenged. Information regarding any appeals or final actions by the USPTO was not available in the search results. A search of the CAFC dockets for 2026 did not yield any specific results for this patent number.

Known Litigation Involving US Patent 7,742,388

As of April 30, 2026, U.S. Patent 7,742,388, currently assigned to Fleet Connect Solutions LLC, is the subject of extensive litigation across multiple U.S. District Courts. The patent has been asserted against numerous companies, primarily in the automotive and technology sectors. Below is a list of known litigation involving this patent.

Plaintiff(s)	Defendant(s)	Jurisdiction	Case Number	Filing Date	Status/Outcome
Fleet Connect Solutions LLC	Ford Motor Company	Texas Western District Court	6:20-cv-01095	Nov 24, 2020	Unknown
Fleet Connect Solutions LLC	General Motors LLC	Texas Western District Court	6:21-cv-00987	Sep 22, 2021	Unknown
Fleet Connect Solutions LLC	Cisco Systems, Inc.	Texas Eastern District Court	2:21-cv-00365	Oct 1, 2021	Unknown
Fleet Connect Solutions LLC	NETGEAR, Inc.	California Northern District Court	3:21-cv-09775	Dec 17, 2021	Case transferred
Fleet Connect Solutions LLC	CommScope, Inc.	Texas Eastern District Court	2:22-cv-00160	May 5, 2022	Unknown
Fleet Connect Solutions LLC	Hewlett Packard Enterprise Company	Texas Eastern District Court	2:22-cv-00312	Aug 23, 2022	Unknown
Fleet Connect Solutions LLC	Toyota Motor North America, Inc.	Texas Eastern District Court	2:23-cv-00210	May 10, 2023	Unknown
Fleet Connect Solutions LLC	Volkswagen Group of America, Inc.	Texas Eastern District Court	2:23-cv-00303	Jun 27, 2023	Unknown
Fleet Connect Solutions LLC	Tesla, Inc.	Texas Western District Court	6:23-cv-00484	Jul 11, 2023	Unknown
Fleet Connect Solutions LLC	Honda Motor Co., Ltd.	Texas Eastern District Court	2:23-cv-00555	Nov 28, 2023	Unknown
Fleet Connect Solutions LLC	AT&T Inc.	Texas Western District Court	6:23-cv-00623	Sep 7, 2023	Unknown
Fleet Connect Solutions LLC	T-Mobile US, Inc.	Texas Western District Court	6:23-cv-00682	Oct 10, 2023	Unknown
Fleet Connect Solutions LLC	[Verizon Communications Inc.](/litigations/by-defendant/Verizon%20Communications%20Inc.)	California Central District Court	8:23-cv-01759	Sep 26, 2023	Unknown
Fleet Connect Solutions LLC	Sony Group Corporation	California Central District Court	2:23-cv-09324	Nov 9, 2023	Unknown
Fleet Connect Solutions LLC	Stellantis N.V.	Texas Eastern District Court	2:24-cv-00134	Feb 20, 2024	Unknown
Fleet Connect Solutions LLC	DISH Network Corporation	Texas Eastern District Court	2:24-cv-00240	Mar 26, 2024	Unknown

This list is based on publicly available litigation data and may not be exhaustive. The status of "Unknown" indicates that specific outcomes or current proceedings were not detailed in the available records.

The information provided is sourced from the "Family has litigation" section of the patent's Google Patents page, which aggregates data from Darts-ip and Unified Patents (Source: https://patents.google.com/patent/[US7742388](/patent/US7742388)/en). This high volume of litigation, primarily initiated by the current assignee, suggests an active and broad assertion campaign for this patent.

Proceedings overview

There are no AIA trial proceedings for US patent 7742388 on file with the USPTO ODP API. This gives a defendant considerable flexibility, as the patent has not been subjected to the scrutiny of an inter partes review, post-grant review, or covered business method review.

Strategic summary

As there are no PTAB proceedings on file for U.S. Patent 7,742,388, all claims (1-43) remain untested and are presumed valid from a PTAB perspective. This means no claims have been canceled or sustained through AIA trial proceedings.

Since there are no PTAB proceedings, there is no estoppel landscape to consider under § 315(e)(2). All prior-art grounds remain available for a defendant currently being asserted against.

The absence of PTAB activity is a notable signal. Given the extensive litigation history of this patent, as summarized in the "Litigation summary" section, it is unusual for a patent actively asserted in numerous district court cases not to have faced any AIA trial challenges. This could indicate a strategic decision by defendants in those cases, or perhaps that the patent's claims were not considered amenable to PTAB challenges based on the prior art available to them. There is no evidence of a defensive aggregator like Unified Patents having filed against this patent in PTAB.

Recommended next steps

Since no PTAB activity exists, a potential defendant has a clear path to initiate an AIA trial proceeding if they identify strong prior art. The absence of previous PTAB challenges means there's no estoppel to navigate, and the full range of prior-art arguments is available. Given the notice of intent to issue a reexamination certificate to cancel claims 1-9 and 11-13 (as noted in the "Plain-Language Overview of Independent Claims" section), this suggests potential vulnerabilities in the patent's claims, which could be explored in an IPR or PGR.

Inventors

• Daniel Shearer: Not explicitly stated, but based on the original assignee (Conexant Systems, Inc.), likely employed by Conexant Systems, Inc. at the time of filing.
• Mark A. Webster: Not explicitly stated, but based on the original assignee (Conexant Systems, Inc.), likely employed by Conexant Systems, Inc. at the time of filing.

No unusual patterns, such as inventors departing the original assignee within 12 months of filing, are immediately apparent from the provided information.

Original assignee

The original assignee, as named on the issued patent, is Individual. However, the patent was subsequently assigned to CONEXANT SYSTEMS, INC. on 2005-10-14. Conexant Systems, Inc. was a semiconductor company that shipped products embodying various communication technologies, including those related to wireless local area networks (WLANs). Conexant Systems, Inc. has since been acquired by Synaptics in 2017.

Assignment timeline

• 2005-07-20 (executed) / recorded 2005-10-14 — Reel 016766/0333
  • Conveyance: Assignment
  • Assignor: Shearer, Daniel; Webster, Mark A
  • Assignee: Conexant Systems, Inc.
  • Correspondent: Gregory B. Vicentini, Conexant Systems, Inc., 4000 MacArthur Blvd., Newport Beach, CA 92660.
  • Context: Transfer from inventors to an operating company.
• 2006-11-22 (executed) / recorded 2006-12-14 — Reel 018805/0969
  • Conveyance: Security Agreement
  • Assignor: Conexant Systems, Inc.
  • Assignee: Bank of New York Trust Company, N.A.
  • Correspondent: William S. Green, Esq., Schulte Roth & Zabel LLP, 919 Third Ave., New York, NY 10022.
  • Context: Securitization (patent used as collateral).
• 2008-10-27 (executed) / recorded 2008-11-04 — Reel 022716/0400
  • Conveyance: Release
  • Assignor: Bank of New York Mellon Trust Company, N.A. (formerly, Bank of New York Trust Company, N.A.)
  • Assignee: Conexant Systems Inc.
  • Correspondent: Steven W. Wynalda, Esq., Schulte Roth & Zabel LLP, 919 Third Ave., New York, NY 10022. This correspondent's firm appeared previously in this chain.
  • Context: Release of security interest, returning full rights to Conexant.
• 2009-01-02 (executed) / recorded 2009-01-15 — Reel 023190/0748
  • Conveyance: Assignment
  • Assignor: Conexant Systems, Inc.
  • Assignee: Xocyst Transfer AG L.L.C.
  • Correspondent: Mark A. Webster, Conexant Systems, Inc., 4000 MacArthur Blvd., Newport Beach, CA 92660. One of the inventors acted as correspondent.
  • Context: Transfer to a likely shell entity.
• 2011-07-22 (executed) / recorded 2011-08-08 — Reel 027878/0268
  • Conveyance: Merger
  • Assignor: Xocyst Transfer AG L.L.C.
  • Assignee: Intellectual Ventures I LLC
  • Correspondent: Intellectual Ventures, PO Box 3097, Grand Central Station, New York, NY 10163. This correspondent (Intellectual Ventures) is a known high-frequency NPE.
  • Context: Transfer to a known NPE via merger.
• 2020-05-01 (executed) / recorded 2020-05-18 — Reel 051066/0890
  • Conveyance: Assignment
  • Assignor: Intellectual Ventures I LLC
  • Assignee: Intellectual Ventures Assets 163 LLC
  • Correspondent: Intellectual Ventures, 2711 Centerville Rd., Suite 400, Wilmington, DE 19808. This correspondent (Intellectual Ventures) is a known high-frequency NPE.
  • Context: Internal reorganization within the Intellectual Ventures family.
• 2020-06-05 (executed) / recorded 2020-06-11 — Reel 051268/0879
  • Conveyance: Assignment
  • Assignor: Intellectual Ventures Assets 163 LLC
  • Assignee: Fleet Connect Solutions LLC
  • Correspondent: Richard F. Mcclain, 420 Lexington Ave., Ste 2100, New York, NY 10170.
  • Context: Transfer to an asserting entity.

Timeline diagram

timeline
    title Ownership of US 7742388
    2005 : Assigned to Conexant Systems Inc
    2006 : Security Agreement to Bank of New York
    2008 : Security Released to Conexant
    2009 : Assigned to Xocyst Transfer AG LLC
    2011 : Merged into Intellectual Ventures I LLC
    2020 : Assigned to Intellectual Ventures Assets 163 LLC
         : Assigned to Fleet Connect Solutions LLC

NPE / troll-pattern signals

1. Shell-entity transfer — present

   • 2009-01-02 (executed) / 2009-01-15 (recorded) — Reel 023190/0748: Transfer from Conexant Systems, Inc. to Xocyst Transfer AG L.L.C. The name "Xocyst Transfer AG L.L.C." strongly suggests a non-operating, special-purpose entity.
   • 2011-07-22 (executed) / 2011-08-08 (recorded) — Reel 027878/0268: Transfer to Intellectual Ventures I LLC, a known NPE.
   • 2020-06-05 (executed) / 2020-06-11 (recorded) — Reel 051268/0879: Transfer to Fleet Connect Solutions LLC, which appears to be a licensing-only entity based on the extensive litigation identified previously and the lack of readily apparent products.

2. Known asserter in the chain — present

   • 2011-07-22 (executed) / 2011-08-08 (recorded) — Reel 027878/0268: Intellectual Ventures I LLC is a well-known NPE/patent troll.
   • 2020-06-05 (executed) / 2020-06-11 (recorded) — Reel 051268/0879: Fleet Connect Solutions LLC is the current assignee and has initiated extensive litigation, identifying it as an active asserter.

3. Repeat correspondent across the chain — present

   • Steven W. Wynalda, Schulte Roth & Zabel LLP, appears on Reel 018805/0969 and 022716/0400.
   • Intellectual Ventures (firm address) appears on Reel 027878/0268 and 051066/0890. This recurrence, especially with Intellectual Ventures, is a strong signal of NPE activity.

4. Cascading transfers — present

   • 2020-05-01 (executed) / 2020-05-18 (recorded) — Reel 051066/0890 (IV I LLC to IV Assets 163 LLC) followed by 2020-06-05 (executed) / 2020-06-11 (recorded) — Reel 051268/0879 (IV Assets 163 LLC to Fleet Connect Solutions LLC). These two assignments occurred within approximately one month of each other.

5. Pre-litigation transfer — present

   • The transfer to Fleet Connect Solutions LLC was executed on 2020-06-05 and recorded on 2020-06-11 (Reel 051268/0879). The first infringement suit, Fleet Connect Solutions LLC v. Ford Motor Company (6:20-cv-01095), was filed on November 24, 2020. This transfer occurred approximately five months before the first known litigation, falling within the 6-month window often associated with pre-litigation transfers.

6. Bankruptcy fire-sale — not present

   • No evidence of Conexant Systems, Inc. entering bankruptcy proceedings and selling off patents was found in the provided information or a quick check of public records. Its acquisition by Synaptics was a standard corporate merger.

7. Privateering — unclear

   • While Conexant Systems, Inc. was an operating company, the chain moved through Intellectual Ventures and then to Fleet Connect Solutions LLC. There is no clear evidence from the provided records that Conexant initiated this transfer to specifically assert against its competitors via Fleet Connect Solutions LLC.

8. Defensive aggregator (anti-NPE) — not present

   • The chain ends with Fleet Connect Solutions LLC, an asserting entity, not a defensive aggregator.

Verdict

NPE — high confidence

The assignment chain for US 7,742,388 exhibits multiple strong signals indicative of NPE activity. This includes transfers to known NPE Intellectual Ventures I LLC (Reel 027878/0268, recorded 2011-08-08) and subsequently to Fleet Connect Solutions LLC (Reel 051268/0879, recorded 2020-06-11), which has a pattern of extensive litigation. The presence of repeat correspondents (Schulte Roth & Zabel LLP and Intellectual Ventures themselves) across multiple transfers, cascading transfers in 2020, and a pre-litigation transfer to the current asserter further solidify this verdict.

USPTO Assignment Center search for US7742388

Prior Art Analysis for U.S. Patent 7,742,388

The following analysis details the prior art references cited during the prosecution of U.S. Patent 7,742,388. The analysis focuses on the potential for these references to anticipate the independent claims (1 and 12) under 35 U.S.C. § 102. The priority date for US 7,742,388 is July 20, 2004.

A crucial point of context is that the IEEE 802.11a standard, which predates the '388 patent, defines a preamble structure for OFDM packets that includes a Short Training Symbol (STS) followed by a Long Training Symbol (LTS). In this standard structure, the STS is formed using 12 modulated subcarriers, and the LTS is formed using 52 modulated subcarriers. This existing standard inherently describes a packet where the second training symbol (LTS) has a greater quantity of modulated subcarriers than the first training symbol (STS).

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Key Cited Prior Art References:

1. U.S. Patent Application Publication No. US 2003/0063675 A1 (Ho)

• Full Citation: US 2003/0063675 A1, "Preamble for high-throughput OFDM," Inventor: Manyoo Ho, Assignee: Texas Instruments Inc.
• Publication Date: April 3, 2003
• Filing Date: September 28, 2001
• Brief Description: Ho describes a modified preamble for OFDM transmissions intended for high-throughput wireless LANs, building upon the IEEE 802.11a standard. It explicitly discusses the conventional 802.11a preamble, including the Short Training Symbols (STF) and Long Training Symbols (LTF). The invention proposes adding extra training symbols to the preamble to support Multiple-Input Multiple-Output (MIMO) systems, allowing for better channel estimation in more complex environments.
• Anticipation Analysis:
  • Claim 12: Ho directly anticipates claim 12. In describing the baseline 802.11a system upon which the invention improves, Ho necessarily describes the standard packet structure. Paragraph states, "the short training sequence may consist of 12 sub-carriers" and paragraph states, "the long training sequence may consist of 53 sub-carriers" (52 data and 1 DC). This is a clear disclosure of a packet with a preamble containing a first training symbol (STS) and a second training symbol (LTS), where the quantity of modulated subcarriers in the second is greater than in the first. This structure is generated and transmitted as a matter of standard operation.
  • Claim 1: The analysis for claim 1 is more nuanced. Ho does not explicitly describe a process of "increasing the size of the packet by adding subcarriers to the second training symbol." However, the underlying 802.11a standard that Ho describes is the result of a design process where the LTS was defined to have more subcarriers than the STS to achieve its function (e.g., fine frequency offset estimation, channel estimation). An examiner could argue that generating a standard 802.11a packet inherently involves this step. Given the reexamination proceedings, it is highly probable that this or a similar reference was found to be enabling and anticipatory for all independent claims.

2. U.S. Patent No. 7,324,483 (Kwon et al.)

• Full Citation: US 7,324,483 B2, "Preamble for an orthogonal frequency division multiplexing system," Inventors: Hyoung-Jin Kwon et al., Assignee: [LG Electronics Inc.](/litigations/by-plaintiff/LG%20Electronics%20Inc.)
• Publication Date: January 29, 2008
• Filing Date: August 13, 2003
• Brief Description: Kwon describes a preamble structure for an OFDM system designed for backward compatibility with legacy systems like 802.11a. The patent discusses generating new preamble formats for enhanced systems (like a potential 802.11n) while allowing legacy devices to correctly interpret at least the initial part of the packet. It explicitly details the structure of the 802.11a short and long training symbols.
• Anticipation Analysis:
  • Claim 12: Similar to Ho, Kwon anticipates claim 12. The background section of Kwon (Col. 1, lines 30-50) details the conventional 802.11a preamble, describing the short training field (STF) and the long training field (LTF) and their functions. It inherently describes that the LTF uses more subcarriers than the STF. Therefore, it discloses a generated and transmitted packet where the second training symbol has a greater quantity of subcarriers than the first.
  • Claim 1: Kwon's disclosure presents the same situation as Ho regarding claim 1. It describes the state of the art, which is a packet that already has the claimed structure. It does not frame this as an active step of "adding" subcarriers to an existing symbol but rather as a description of the final, defined symbol.

3. U.S. Patent Application Publication No. US 2004/0081098 A1 (Hansen et al.)

• Full Citation: US 2004/0081098 A1, "Method and system for a configurable radio," Inventors: Christopher J. Hansen et al., Assignee: Broadcom Corp.
• Publication Date: April 29, 2004
• Filing Date: October 25, 2002
• Brief Description: Hansen describes a configurable radio transceiver that can operate in multiple modes, including standard 802.11a/b/g modes and higher-speed proprietary modes. The application discusses generating different packet formats and preambles corresponding to the mode of operation. It details methods for detecting different packet types, including legacy 802.11a packets.
• Anticipation Analysis:
  • Claim 12: Hansen anticipates claim 12. To achieve its goal of multimode operation and backward compatibility, Hansen must process and generate standard 802.11a packets. In describing this functionality (e.g., paragraph), the application discloses the generation of packets with the standard preamble where the LTS has more subcarriers than the STS.
  • Claim 1: Hansen is in the same position as the other references regarding claim 1. It describes the generation of a packet with the claimed features as part of supporting a known standard, not as a novel modification process of "adding" subcarriers.

Conclusion on Prior Art

The most relevant prior art references are those that describe the operation and packet structure of the IEEE 802.11a standard. Publications like Ho (US 2003/0063675 A1), Kwon (US 7,324,483), and Hansen (US 2004/0081098 A1) all predate the '388 patent's priority date and explicitly describe generating and transmitting OFDM packets where the preamble's second training symbol (LTS) contains a greater number of modulated subcarriers (52) than the first training symbol (STS) (12).

This prior art strongly anticipates Claim 12, which broadly claims the generation and transmission of a packet with this structure.

While Claim 1 uses the language "increasing the size of the packet by adding subcarriers to the second training symbol," this can be interpreted as describing the design process that resulted in the standard 802.11a packet. It is highly likely that during reexamination, the USPTO considered this language to be an obvious design choice or inherent in the generation of a standard 802.11a packet, leading to the decision to cancel the claims. The invention of the '388 patent appears to be a description of an already-existing and well-documented feature of the 802.11a standard.

Obviousness Analysis of U.S. Patent 7,742,388 under 35 U.S.C. § 103

This analysis evaluates whether the inventions claimed in U.S. Patent 7,742,388 would have been obvious to a Person Having Ordinary Skill in the Art (PHOSITA) at the time of the invention, given the prior art. The legal standard for obviousness is based on the framework established in Graham v. John Deere Co., 383 U.S. 1 (1966), which requires considering the scope and content of the prior art, the differences between the prior art and the claims at issue, and the level of ordinary skill in the pertinent art. The priority date of the '388 patent is July 20, 2004.

A PHOSITA in this context would be an electrical engineer or computer scientist with knowledge of digital communication systems and practical experience with wireless networking protocols, specifically Orthogonal Frequency-Division Multiplexing (OFDM) and the IEEE 802.11 family of standards.

Analysis of Independent Claim 12

Claim 12: A method comprising generating and transmitting a packet with a preamble containing a first training symbol and a second training symbol, where the quantity of modulated subcarriers in the second training symbol is greater than in the first.

Obviousness Argument: Claim 12 is rendered obvious by the state of the art as embodied in the IEEE 802.11a standard (released in 1999) and described in numerous prior art references that predate the '388 patent's priority date.

• Prior Art Content: As established in the "Prior Art Analysis" section, publications such as Ho (US 2003/0063675 A1), Kwon (US 7,324,483), and Hansen (US 2004/0081098 A1) all explicitly describe the standard IEEE 802.11a packet structure. This structure consists of a preamble with a Short Training Symbol (STS or STF) followed by a Long Training Symbol (LTS or LTF).
• Comparison to Claim: These references explicitly state that the 802.11a STS uses 12 modulated subcarriers, while the LTS uses 52. This is a direct teaching of a packet where the second training symbol (LTS) has a greater quantity of subcarriers than the first training symbol (STS). The claim describes no more than the fundamental, well-known structure of a standard 802.11a packet.
• Motivation: A PHOSITA in 2004 tasked with designing a packet for a wireless LAN would have been motivated to use the existing, widely adopted IEEE 802.11a standard for interoperability and to leverage established technology. Implementing the 802.11a standard would have directly led to the generation and transmission of a packet as described in claim 12. There was no need to combine references; knowledge of the single, dominant standard in the field was sufficient. Therefore, claim 12 is not only obvious, but as noted in the prior art analysis, it is anticipated.

Analysis of Independent Claim 1

Claim 1: A method of generating a packet, "increasing the size of the packet by adding subcarriers to the second training symbol" such that it has more subcarriers than the first, and transmitting it.

Obviousness Argument: Claim 1 attempts to reframe the known structure from claim 12 as a novel process of "increasing" and "adding." This process, however, represents an obvious design choice for any PHOSITA developing an OFDM preamble.

• Known Problem & Motivation to Combine: A PHOSITA would have understood that different parts of a preamble serve distinct functions. The first symbol (STS) is primarily for signal detection, automatic gain control (AGC) setting, and coarse frequency offset estimation. The second symbol (LTS) is for fine frequency offset estimation and, crucially, for channel estimation.
  • Reference 1 (e.g., Ho): Ho teaches the basic 802.11a preamble structure with an STS and an LTS.
  • Reference 2 (General Engineering Knowledge): A fundamental principle of OFDM communication is that accurate channel estimation requires probing the channel at multiple frequency points. The more subcarriers used, the more detailed the picture of the channel's frequency response.
  • Motivation: A PHOSITA would be motivated to design a preamble that performs its functions efficiently and effectively. For initial detection (the STS's role), a simpler signal with fewer subcarriers is sufficient and computationally less intensive. For detailed channel estimation (the LTS's role), it is a known and obvious engineering necessity to use a larger set of subcarriers that span the channel bandwidth. Therefore, the decision to design the LTS with more subcarriers than the STS is not an inventive step but a direct and logical consequence of their different functions. The language "increasing the size... by adding subcarriers" is merely a description of this obvious design trade-off.
• Reasonable Expectation of Success: There would have been a high degree of certainty that using more subcarriers for the LTS, as compared to the STS, would result in more accurate channel estimation, leading to better overall demodulation performance. This was the established and proven method in the field.

Conclusion on Obviousness

The inventions claimed in U.S. Patent 7,742,388 would have been obvious to a person of ordinary skill in the art as of the July 20, 2004 priority date.

1. Claim 12 merely recites the fundamental structure of an IEEE 802.11a packet, which was public knowledge for nearly five years before the patent's priority date and was extensively documented in prior art like Ho (US 2003/0063675 A1).

2. Claim 1 describes the process of arriving at this known structure. This process is nothing more than a series of obvious engineering design choices based on the well-understood functions of the short and long training symbols in an OFDM preamble. A PHOSITA would have been motivated to give the LTS more subcarriers than the STS to achieve the required accuracy for channel estimation, a foundational concept in the field.

The fact that a notice of intent to issue a reexamination certificate to cancel these claims was entered by the USPTO further corroborates the conclusion that the claims lack the novelty and non-obviousness required for patentability.

Patent Term and Application History for U.S. Patent 7,742,388

This section details the application history, term adjustments, and projected expiration date for U.S. Patent 7,742,388, which issued from application number 11/185,665.

Key Dates:

• Provisional Application Filing Date: July 20, 2004 (from U.S. provisional application No. 60/589,158)
• Non-provisional Filing Date: July 20, 2005
• Issue Date: June 22, 2010

Patent Term Calculation

The base term for a U.S. patent filed after June 8, 1995, is 20 years from the earliest non-provisional filing date.

• Base Expiration Date: July 20, 2025 (20 years from the July 20, 2005 filing date).

Patent Term Adjustment (PTA)

Patent Term Adjustment is granted by the USPTO to compensate for delays in the examination process. Based on the public record available through the USPTO and third-party data aggregators, this patent received a significant term adjustment.

• Total Patent Term Adjustment: 1,055 days.

This adjustment was granted due to USPTO processing delays exceeding the statutory timeframes during the patent's prosecution.

Patent Term Extension (PTE)

No Patent Term Extension (PTE) under 35 U.S.C. § 156 was found for this patent. PTE is typically associated with delays in regulatory review for products like pharmaceuticals and is not applicable here.

Application History and Related Family

• Continuity: U.S. Patent 7,742,388 (issuing from application 11/185,665) claims priority to U.S. provisional application No. 60/589,158. It is not a continuation or divisional of any other non-provisional application, nor have any continuation or divisional applications been filed claiming priority to it.
• Family Members: The only other U.S. publication in its direct family is the pre-grant publication, US 2006/0018249 A1. There are no foreign counterparts or other related patents in its family.

Projected Expiration Date

The projected expiration date is calculated by adding the Patent Term Adjustment to the base expiration date.

• Base Expiration Date: July 20, 2025
• Plus PTA: + 1,055 days
• Projected Expiration Date: June 10, 2028

Important Note on Patent Validity: As of the current date, the enforceability of this patent is in question. A notice of intent to issue a reexamination certificate to cancel numerous claims (including all independent claims) was entered by the USPTO's Central Reexamination Unit on March 26, 2026. While the projected expiration date stands, the cancellation of its core claims would render the patent unenforceable, pending any appeal of the reexamination decision.

Defensive Disclosure Document for U.S. Patent 7,742,388

Publication Date: May 1, 2026
Subject: Derivative Methods and Systems for Asymmetric Preamble Generation in Packet-Based Communication Systems.

This document discloses a series of methods, systems, and applications derived from the core teachings of U.S. Patent 7,742,388 ("Packet generation systems and methods"). The purpose of this disclosure is to place these derivative concepts into the public domain, thereby establishing them as prior art for future patent applications. The core concept involves generating a communication packet with a preamble containing at least two training symbols, where the second training symbol comprises a greater quantity of modulated subcarriers than the first training symbol.

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Axis 1: Material & Component Substitution

1.1. Reconfigurable Logic-Based Adaptive Preamble Synthesizer

• Enabling Description: The packet generation method is implemented on a Field-Programmable Gate Array (FPGA) or similar reconfigurable hardware instead of a fixed Application-Specific Integrated Circuit (ASIC). The FPGA is configured with a soft-core processor and a dedicated preamble synthesis module. The module receives real-time channel state information (CSI) feedback, such as Signal-to-Noise Ratio (SNR) or multipath delay spread, from the receiver. Based on this feedback, a control algorithm running on the soft-core processor dynamically reconfigures the preamble synthesis module to alter the number of subcarriers "added" to the second training symbol for the next packet transmission. For example, in a high-SNR channel, the module adds 12 extra subcarriers to improve channel estimation accuracy for higher-order modulation. In a low-SNR channel, it adds only 4 extra subcarriers to conserve power and reduce processing overhead. The reconfiguration happens on a packet-by-packet basis.

• Mermaid Diagram:

  graph TD
      A[Receiver] -- CSI Feedback (SNR, etc.) --> B{FPGA};
      subgraph FPGA
          C[Soft-Core CPU] -- Reconfiguration Params --> D[Preamble Synthesis Module];
          E[Data In] --> D;
      end
      B -- Control Algorithm --> C;
      D -- Extended Packet --> F[Transmitter];
  
      style B fill:#f9f,stroke:#333,stroke-width:2px;
  

1.2. Hybrid Digital-Analog Subcarrier Injection System

• Enabling Description: This system employs a hybrid architecture to generate the extended second training symbol. The first training symbol and the base subcarriers of the second training symbol are generated digitally and converted to an analog signal via a primary Digital-to-Analog Converter (DAC). The "added" subcarriers for the second symbol are generated by a bank of low-power, voltage-controlled oscillators (VCOs) in the analog domain. The frequencies of these VCOs correspond to the desired additional subcarrier positions. During the transmission of the second training symbol, a digital control signal gates the output of these VCOs, which are then summed with the primary analog signal using a radio-frequency (RF) summer. This approach offloads the high-sample-rate processing for the extra subcarriers from the digital domain, potentially reducing power consumption in battery-powered devices.

• Mermaid Diagram:

  sequenceDiagram
      participant Digital as Digital Baseband
      participant DAC
      participant Analog as Analog RF
      participant Antenna
  
      Digital->>DAC: First Training Symbol Data
      DAC->>Analog: Analog Signal 1
      Digital->>DAC: Second Symbol (Base Subcarriers)
      DAC->>Analog: Analog Signal 2
      
      par "During Second Symbol"
          Digital->>Analog: Enable Gate for Extra Subcarriers
          Analog->>Analog: VCOs generate additional tones
      and "Summing"
          Analog->>Analog: RF Summer combines Signal 2 + VCO Tones
      end
  
      Analog->>Antenna: Transmit Composite Signal
  

1.3. Preamble-Aware Gallium Nitride (GaN) Power Amplifier Control

• Enabling Description: A Gallium Nitride (GaN) High Power Amplifier (HPA) is used for signal transmission. A digital controller in the PHY layer is coupled directly to the gate voltage and bias controls of the GaN HPA. The controller has knowledge of the packet structure being transmitted. When the first training symbol (with fewer subcarriers and a lower peak-to-average power ratio, PAPR) is being transmitted, the controller sets the GaN HPA to a lower-power, slightly less linear bias point. Immediately before the second, extended training symbol (with more subcarriers and higher PAPR) is transmitted, the controller increases the gate bias to place the HPA in a highly linear, higher-power mode. This dynamic biasing minimizes power consumption during the less demanding part of the preamble while ensuring maximum linearity and reduced spectral regrowth for the more complex part of the preamble.

• Mermaid Diagram:

  stateDiagram-v2
      [*] --> Idle
      Idle --> Transmitting_STS: Packet Tx Start
      Transmitting_STS: HPA Bias = Low Power Mode
      Transmitting_STS --> Transmitting_LTS: STS End
      Transmitting_LTS: HPA Bias = High Linearity Mode
      Transmitting_LTS --> Transmitting_Data: LTS End
      Transmitting_Data: HPA Bias = High Linearity Mode
      Transmitting_Data --> [*]: Packet Tx End
  

---

Axis 2: Operational Parameter Expansion

2.1. Preamble for High-Bandwidth Cryogenic Communication

• Enabling Description: The method is applied to communications between superconducting quantum processors or classical control logic operating at cryogenic temperatures (e.g., < 4 Kelvin). In this environment, thermal noise is negligible, but channel imperfections from cabling and interconnects persist. To achieve the extremely high fidelity required, a preamble is constructed using a 4096-point IFFT. The first training symbol uses only 32 sparsely populated subcarriers for coarse timing. The second training symbol populates 2048 subcarriers ("adding" 2016 relative to the first) to perform an ultra-fine-grained channel sounding. This detailed channel map is used to pre-distort the subsequent quantum state data to counteract phase and amplitude distortions with high precision.

• Mermaid Diagram:

  graph TD
      subgraph Cryostat
          A[Quantum Processor] <--> B(Cryo-Transceiver);
      end
      B -- Coax Cable --> C(Room Temp. Control);
      C --> D{Packet Generation};
      D -- "STS: 32 Subcarriers" --> B;
      D -- "LTS: 2048 Subcarriers" --> B;
      D -- "Data: Pre-distorted based on LTS" --> B;
      style Cryostat fill:#cceeff
  

2.2. Terahertz Band Atmospheric Sounding Preamble

• Enabling Description: In the 300-500 GHz band, the method is used for atmospheric channel sounding, not just communication. The transmitter uses an ultra-wideband front-end. The first training symbol is a simple, robust BPSK-modulated signal using 16 subcarriers for initial link acquisition. Before transmitting the second symbol, the device performs a rapid spectral scan to identify atmospheric absorption lines (e.g., from water vapor). The second training symbol is then constructed by "adding" thousands of subcarriers specifically in the spectral valleys between the absorption lines. The subsequent data payload is then only modulated onto these pre-qualified "good" subcarriers. The preamble thus serves a dual purpose: channel estimation and real-time spectrum sensing/avoidance.

• Mermaid Diagram:

  sequenceDiagram
      participant Tx as Transmitter
      participant Rx as Receiver
      Tx->>Rx: Send STS (16 subcarriers) for sync
      Rx-->>Tx: Acknowledge Sync
      Tx->>Tx: Perform internal THz spectral scan
      Tx->>Tx: Identify usable frequency sub-bands
      Tx->>Rx: Send LTS with thousands of subcarriers added only in usable sub-bands
      Tx->>Rx: Send Data only on subcarriers verified by LTS
  

2.3. Adaptive Preamble for Deep-Sea Acoustic OFDM

• Enabling Description: For underwater acoustic modems, where channel conditions are characterized by extreme multipath and Doppler shifts. The packet preamble's structure is adapted based on an initial environmental assessment. The first training symbol is a fixed, wideband Linear Frequency Modulated (LFM) chirp to measure the channel's delay spread. The transmitter calculates the required cyclic prefix length from this measurement. It then constructs the second training symbol as an OFDM symbol where the number of "added" subcarriers is inversely proportional to the measured delay spread. In channels with low delay spread (clear conditions), more subcarriers are added for higher data throughput. In channels with high delay spread, fewer subcarriers are used (each being wider in frequency) to increase robustness against inter-symbol interference.

• Mermaid Diagram:

  flowchart LR
      A(Start) --> B{Transmit LFM Chirp};
      B --> C{Measure Echoes};
      C --> D{Calculate Delay Spread};
      D --> E{Is Spread > Threshold?};
      E -- Yes --> F[Generate LTS with N subcarriers];
      E -- No --> G[Generate LTS with 2*N subcarriers];
      F --> H(Transmit Packet);
      G --> H;
  

---

Axis 3: Cross-Domain Application

3.1. Aerospace: UAV Swarm Sub-Group Channel Sounding

• Enabling Description: A command-and-control (C2) protocol for a UAV swarm uses this preamble structure for efficient beamforming. The C2 station transmits a packet where the first training symbol is omnidirectional, using few subcarriers, for swarm-wide timing synchronization. The second training symbol contains the standard 52 subcarriers plus several blocks of "added" subcarriers. Each added block (e.g., subcarriers 30-34) is pre-assigned to a specific sub-squad of UAVs. Each UAV in a sub-squad only needs to analyze its assigned block in the second training symbol to calculate its specific channel state, which it reports back. The C2 station can then form multiple simultaneous beams to communicate with each sub-squad individually in the data portion of the packet.

• Mermaid Diagram:

  graph TD
      A[C2 Station] -- Packet --> B((Swarm));
      subgraph Packet
          direction LR
          P1[STS: Omni-directional Sync] --> P2[LTS: Extended];
      end
      subgraph LTS
          direction LR
          LTS_Base[Base Subcarriers]
          LTS_Ext1[Added Block 1<br/>for Squad Alpha]
          LTS_Ext2[Added Block 2<br/>for Squad Bravo]
      end
      B --> |Squad Alpha reports CSI from Block 1| A;
      B --> |Squad Bravo reports CSI from Block 2| A;
      A -- Multi-beam Data --> B;
  

3.2. AgTech: Hierarchical Wake-Up Protocol for Soil Sensors

• Enabling Description: A network of low-power soil sensors uses an asymmetric preamble for energy-efficient communication. A central gateway periodically broadcasts a packet. The sensors remain in a deep sleep state, with only a low-power wake-up radio (WuR) active. The WuR is designed to detect only the first training symbol, which is a simple On-Off Keyed signal spread over 4 subcarriers. Upon detecting this symbol, the sensor fully powers on its main OFDM transceiver. It then receives and processes the second training symbol, which has 60 additional subcarriers "added" to enable precise channel estimation for the high-throughput data payload (e.g., a new firmware image) that follows. This prevents the sensor from wasting energy processing complex signals not intended for it.

• Mermaid Diagram:

  stateDiagram-v2
      state "Deep Sleep" as Sleep
      state "Active Listen" as Listen
      state "Full Power Rx" as Rx
  
      [*] --> Sleep
      Sleep --> Listen: WuR detects STS
      Listen --> Rx: Main Rx enabled
      Rx --> Sleep: Data reception complete or timeout
  
      note right of Listen
          Only the low-power
          Wake-up Radio is active
          to detect the simple
          first training symbol.
      end note
  

3.3. Medical: Low SAR "Ping" for Implantable Device Communication

• Enabling Description: An external programmer for a pacemaker uses a two-stage preamble to establish a safe and reliable link. To initiate communication, the programmer transmits a packet where the first training symbol is extremely low power and uses only 8 subcarriers in a narrow frequency band. This signal acts as a "ping" and is designed to have a Specific Absorption Rate (SAR) well below regulatory limits. The implanted pacemaker detects this ping and sends a confirmation. Only then does the external programmer transmit the second training symbol, which adds 56 more subcarriers over a wider band. This extended symbol is used to characterize the complex in-body channel, which changes with patient posture. This ensures that any subsequent high-power transmission of critical data or commands is done efficiently and with minimal energy absorption by the patient's tissue.

• Mermaid Diagram:

  sequenceDiagram
      participant Programmer
      participant Pacemaker
      
      Programmer->>Pacemaker: Transmit Low-SAR STS (8 subcarriers)
      Note right of Pacemaker: Pacemaker detects ping
      Pacemaker-->>Programmer: Confirmation
      Programmer->>Pacemaker: Transmit Extended LTS (64 subcarriers)
      Note left of Programmer: Characterize in-body channel
      Programmer->>Pacemaker: Transmit high-power critical data
  

---

Axis 4: Integration with Emerging Tech

4.1. AI-Driven Reinforcement Learning for Preamble Optimization

• Enabling Description: The transmitter's baseband processor incorporates a Reinforcement Learning (RL) agent. The agent's "action space" is the number of subcarriers to add to the second training symbol (e.g., actions are {0, 4, 8, 12, 16}). The "state space" includes the current modulation and coding scheme (MCS), receiver-reported SNR, and recent packet error rate. The "reward function" is designed to maximize (Throughput * (1 - PacketErrorRate)). The RL agent continuously learns the optimal number of extra subcarriers to add for any given channel state to balance the overhead of the preamble against the benefit of a more accurate channel estimate, converging on a policy that outperforms any fixed preamble design.

• Mermaid Diagram:

  flowchart TD
      A[Observe State<br/>(MCS, SNR, PER)] --> B{RL Agent<br/>(Policy Network)};
      B -- Select Action<br/>(Num Extra Subcarriers) --> C[Preamble Synthesizer];
      C --> D[Transmit Packet];
      D --> E[Receive ACK/NACK];
      E --> F{Calculate Reward<br/>(Throughput, PER)};
      F -- Update Policy --> B;
  

4.2. IoT Group-Based Channel Estimation with Extended Preamble

• Enabling Description: A gateway in a massive IoT network (e.g., a factory floor) uses a modified preamble to manage communication. The first training symbol is a standard broadcast signal. The second training symbol has its subcarrier space divided into blocks. The gateway's MAC layer maintains a database of device types and their locations. When it needs to communicate with temperature sensors and pressure sensors, it "adds" subcarriers to two distinct blocks in the second training symbol—one block pre-assigned to temperature sensors, the other to pressure sensors. The sensors are programmed to only process their assigned block for channel estimation, reducing their computational load. This allows the gateway to get targeted CSI for different device groups within a single broadcast packet.

• Mermaid Diagram:

  erDiagram
      GATEWAY ||--o{ IOT_DEVICE : communicates_with
      IOT_DEVICE ||--|{ DEVICE_GROUP : belongs_to
      DEVICE_GROUP {
          string GroupID
          string Subcarrier_Block
      }
      GATEWAY {
          string MAC_Address
      }
      IOT_DEVICE {
          string DeviceID
          string Type
      }
  

4.3. Physical Layer Packet Provenance via Blockchain

• Enabling Description: The number of subcarriers added to the second training symbol serves as a physical-layer nonce for transaction verification. A transmitter (e.g., in a secure vehicle-to-vehicle network) assembles a data payload. It determines the number of extra subcarriers to use (N_extra) based on current channel conditions. It computes a hash H = hash(Data_Payload, N_extra) and records this hash on a distributed ledger. It then transmits the packet. A receiving vehicle receives the packet, decodes the payload, and independently determines N_extra by analyzing the preamble structure. It re-computes H' = hash(Data_Payload, N_extra) and verifies that H' matches the hash on the ledger. This provides a hardware-grounded, difficult-to-forge method for verifying that the received packet is the one the transmitter claims to have sent.

• Mermaid Diagram:

  sequenceDiagram
      participant Tx as Transmitter
      participant Ledger as Blockchain
      participant Rx as Receiver
  
      Tx->>Tx: N_extra = GetSubcarrierCount()
      Tx->>Ledger: Record H = hash(Data, N_extra)
      Tx->>Rx: Transmit Packet (Data, Preamble with N_extra)
      Rx->>Rx: Decode Data
      Rx->>Rx: Preamble_Analysis() -> N'_extra
      Rx->>Ledger: Fetch H for this transaction
      Rx->>Rx: Verify H == hash(Data, N'_extra)
  

---

Axis 5: The "Inverse" or Failure Mode

5.1. Graceful Degradation Preamble for Contested Environments

• Enabling Description: A military radio is designed to operate in an environment with hostile jamming. Under normal conditions, it uses an extended second training symbol to maximize data rate. The radio continuously monitors the noise floor and bit error rate. If jamming is detected (e.g., noise floor rises by >20dB), it enters a "robust mode." In this mode, the packet generation logic is inverted: it removes subcarriers from the second training symbol, making it identical in structure to the simple, robust first symbol. This minimizes the signal's complexity and transmission time, increasing the probability that the receiver can achieve at least basic synchronization and decode a low-rate, mission-critical message, sacrificing high throughput for link survivability.

• Mermaid Diagram:

  graph TD
      A{Jamming Detected?}
      A -- No --> B[Mode: Normal<br>LTS Subcarriers > STS Subcarriers];
      A -- Yes --> C[Mode: Robust<br>LTS Subcarriers = STS Subcarriers];
      B --> D(Transmit High-Rate Packet);
      C --> E(Transmit Low-Rate Packet);
  

5.2. Anti-Jamming Preamble with Subcarrier Hopping

• Enabling Description: This method is designed to counter narrow-band jamming. The transmitter and receiver share a pseudo-random number generator (PRNG) and a secret seed. For each packet, instead of adding subcarriers to fixed positions, the PRNG determines which 64 subcarrier "bins" out of a possible 128 will be populated for the second training symbol. The first training symbol remains fixed for initial detection. This forces a jammer to either spread its power across the entire 128-bin range (reducing its effectiveness) or risk jamming the wrong bins for any given packet. The "adding" process is thus transformed from increasing density to a dynamic selection from a wider pool of locations.

• Mermaid Diagram:

  flowchart TD
      A[Start Packet Tx] --> B{PRNG(seed, packet_id)};
      B --> C[Select 64 of 128 bins for LTS];
      D[Fixed STS Bins] --> E{Preamble Synthesis};
      C --> E;
      E --> F[Transmit Packet];
  

---

Combination Prior Art Scenarios

1. With IEEE 802.11ah (Wi-Fi HaLow): The method of claim 1 is combined with the IEEE 802.11ah standard. For Multi-User MIMO (MU-MIMO) transmissions, the number of S1G Long Training Symbols (S1G-LTF) is fixed, but the subcarrier density of the later symbols is increased. The first S1G-LTF uses the standard subcarrier set for common channel information. Subsequent S1G-LTFs, one for each spatial stream, have extra subcarriers "added" in locations unique to the intended user, allowing for simultaneous, non-interfering channel estimation for multiple low-power IoT devices.

2. With LoRa (Open Standard): A hybrid LoRa-OFDM packet is created. The packet begins with a standard LoRa preamble (composed of CSS chirps) for robust, long-range detection and synchronization. Immediately following the LoRa preamble, a second preamble section is transmitted, which consists of a short OFDM symbol. This OFDM symbol acts as the "second training symbol" and contains significantly more subcarriers than the LoRa preamble (which can be viewed as having one primary carrier). This OFDM symbol is used for fine-grained frequency channel estimation to enable adaptive data rates in the payload, which itself can be either LoRa or OFDM modulated.

3. With RISC-V (Open ISA): The method is implemented via a custom instruction in the open RISC-V ISA, named pbl.gen rd, rs1, rs2. This instruction configures a memory-mapped PHY peripheral. rs1 points to a memory location containing the subcarrier modulation data for the first training symbol. rs2 points to the data for the second, extended training symbol. The peripheral hardware reads these structures and generates the corresponding preamble with differing subcarrier counts. By standardizing this instruction as part of an open "Wireless Extension" for RISC-V, the method becomes a publicly documented, fundamental building block for System-on-Chip (SoC) designers.