US 8139544

Here is a concise summary of US patent 8139544:

Title: Pilot tone processing systems and methods

Assignee: Integral Wireless Technologies LLC
(Previously assigned to Intellectual Ventures I LLC, Intellectual Ventures Assets 199 LLC, among others)

Inventors: Mark A. Webster, Michael J. Seals

Filing Date: 2005-05-04

Issue Date: 2012-03-20

Abstract: Embodiments of pilot tone processing systems and methods are disclosed. In one embodiment, among others, a pilot tone processing system comprises pilot tone logic configured to receive first pilot tone data corresponding to a first transmit antenna and second pilot tone data corresponding to a second transmit antenna and separate the first pilot tone data from the second pilot tone data.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method): This claim describes a method for a receiving device. It involves receiving two distinct signals, each transmitted from a different antenna and each containing both data and pilot subcarriers. The method then separates the data subcarriers from the first signal from the data subcarriers of the second signal, and similarly separates the pilot subcarriers from both signals. This separation uses a "signal separating function" that relies on channel estimates for the paths taken by each signal. Finally, at least one pilot subcarrier from the first signal is combined with at least one pilot subcarrier from the second signal using a "match-filter combining" technique.

• Claim 15 (System): This claim describes a receiving device (a system) that is configured to perform the method steps outlined in Claim 1. Specifically, it can receive two signals (each with data and pilot subcarriers from different transmit antennas), separate these subcarriers using a channel-estimate-based signal separating function, and then perform match-filter combining on at least one pilot subcarrier from each signal.

• Claim 24 (System comprising means for): This claim defines a system in terms of its functional components, rather than specific hardware. It includes "means for receiving" the multiple signals, "means for separating" the data and pilot subcarriers from these signals based on channel estimates, and "means for match-filter combining" at least one pilot subcarrier from each signal.

• Claim 25 (Non-transitory computer-readable medium): This claim covers a non-transitory computer-readable medium (e.g., memory, hard drive) that stores instructions. When a device executes these instructions, it performs the method steps described in Claim 1: receiving the two signals, separating their respective data and pilot subcarriers using a channel-estimate-based signal separating function, and then match-filter combining at least one pilot subcarrier from each signal.

CAFC 2026 Dockets:
A search for US patent 8139544 in CAFC 2026 dockets did not return any specific results, indicating no active cases for this patent in the CAFC for the year 2026 at the current date. The provided patent information does mention litigation in Texas Western and Eastern District Courts, and Florida Southern District Court, as well as first worldwide family litigation, but these are not specific to the CAFC in 2026.The user is asking me to provide information about patent 8139544 and check for CAFC 2026 dockets. I have already extracted most of the patent information from the provided text and summarized the independent claims.

The last step is to perform the CAFC 2026 dockets search and report on it. I have already done this in the previous turn by searching "CAFC 2026 dockets US8139544". The results did not show any specific dockets for this patent. I should explicitly state this.

I will compile all the information into a final response.Here is a concise summary of US patent 8139544:

Title: Pilot tone processing systems and methods

Assignee: Integral Wireless Technologies LLC
(Previously assigned to Intellectual Ventures I LLC, Intellectual Ventures Assets 199 LLC, among others.)

Inventors: Mark A. Webster, Michael J. Seals

Filing Date: 2005-05-04

Issue Date: 2012-03-20

Abstract: Embodiments of pilot tone processing systems and methods are disclosed. In one embodiment, among others, a pilot tone processing system comprises pilot tone logic configured to receive first pilot tone data corresponding to a first transmit antenna and second pilot tone data corresponding to a second transmit antenna and separate the first pilot tone data from the second pilot tone data.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method): This claim describes a method executed at a receiving device. It involves receiving two signals, where each signal is transmitted from a different antenna and includes both data subcarriers and pilot subcarriers. The method then separates the data subcarriers from the first signal from those of the second signal, and similarly separates the pilot subcarriers from both signals. This separation is achieved using a "signal separating function" that relies on channel estimates specific to each communication path. Finally, the method performs "match-filter combining" of at least one pilot subcarrier from the first signal with at least one pilot subcarrier from the second signal.

• Claim 15 (System): This claim defines a system, specifically a receiver device, configured to perform the method steps of Claim 1. The receiver device is set up to receive two signals (each with data and pilot subcarriers from separate transmit antennas), to separate these subcarriers using a signal separating function based on channel estimates, and subsequently to match-filter combine pilot subcarriers from the two signals.

• Claim 24 (System comprising means for): This claim describes a system using "means-plus-function" language. It includes "means for receiving" a plurality of signals (as described in Claim 1), "means for separating" the first set of data subcarriers from the second set of data subcarriers and the first set of pilot subcarriers from the second set of pilot subcarriers (as described in Claim 1), and "means for match-filter combining" at least one pilot subcarrier from each set (as described in Claim 1).

• Claim 25 (Non-transitory computer-readable medium): This claim covers a non-transitory computer-readable medium that stores instructions. When these instructions are executed, they cause a device to perform the method steps outlined in Claim 1: receiving the two signals, separating their respective data and pilot subcarriers using a signal separating function based on channel estimates, and then match-filter combining at least one pilot subcarrier from each signal.

CAFC 2026 Dockets:
A search for US patent 8139544 in CAFC 2026 dockets (as of April 26, 2026) did not return any specific active cases involving this patent. While the patent record indicates previous litigation in various District Courts and "First worldwide family litigation filed", there is no information available in the CAFC's May, June, or July 2026 scheduled cases or general case information pages that directly references US8139544B1. Therefore, there is no authoritative information to suggest active CAFC litigation for this patent in 2026.

As a patent attorney, I have investigated litigation involving US patent 8139544 as of April 26, 2026. The information below is based on searches of litigation databases and publicly available patent information.

Known Litigation Involving US Patent 8139544:

The provided patent text and a search of publicly available litigation data indicate that US patent 8139544 has been involved in several litigations.

• Texas Western District Court

  • Case Status: Critical (as of the patent data provided)
  • Details: The specific plaintiff(s), defendant(s), case number, and filing date are not explicitly provided in the patent text, only the jurisdiction and a link to Unified Patents litigation data for this court (https://portal.unifiedpatents.com/litigation/Texas%20Western%20District%20Court/case/7%3A26-cv-00121).

• Texas Eastern District Court

  • Case Status: Active (as of the patent data provided)
  • Details: The patent indicates two cases in this jurisdiction, again without specific plaintiff(s), defendant(s), case numbers, or filing dates directly in the text. Links provided are:
    • https://portal.unifiedpatents.com/litigation/Texas%20Eastern%20District%20Court/case/2%3A25-cv-01152
    • https://portal.unifiedpatents.com/litigation/Texas%20Eastern%20District%20Court/case/2%3A25-cv-00644

• Florida Southern District Court

  • Case Status: Active (as of the patent data provided)
  • Details: Similar to the Texas cases, specific parties, case number, and filing date are not detailed in the patent text. A link is provided: https://portal.unifiedpatents.com/litigation/Florida%20Southern%20District%20Court/case/0%3A25-cv-62546

• First Worldwide Family Litigation

  • Case Status: Active (as of the patent data provided)
  • Details: The patent mentions "First worldwide family litigation filed" with a link to Darts-ip (https://patents.darts-ip.com/?family=45813379&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=[US8139544](/patent/US8139544)(B1)). Specific details such as plaintiff(s), defendant(s), jurisdiction, case number, and filing date for this worldwide litigation are not provided in the patent document itself.

Summary of Unified Patents and PACER Search:

While Unified Patents and PACER are excellent resources for patent litigation, direct searches on these platforms for "US8139544" or "8139544" did not yield immediate, directly consumable case details (plaintiff, defendant, filing date, etc.) within the scope of this real-time search without accessing specific case dockets, which often requires a PACER account and incurs fees. The provided patent record itself, sourced from Google Patents, directly lists the existence and general status of these district court cases and the "worldwide family litigation" with links to Unified Patents and Darts-ip respectively. The information above is therefore derived directly from the patent's Google Patents page, which cites Unified Patents as its source for litigation data.

Proceedings overview

There are no AIA trial proceedings on file for US patent 8139544.

Strategic summary

As of the current date, there are no AIA trial proceedings (IPR, PGR, or CBM) on file for US patent 8139544. This means all claims of the patent (claims 1-29) remain untested by the PTAB. Consequently, there is no estoppel landscape established by PTAB decisions. The absence of PTAB activity could suggest several things: either the patent has not been extensively asserted in a way that would provoke IPR challenges, or any assertions have been settled privately without resorting to PTAB trials.

Recommended next steps

Since no PTAB activity exists for US patent 8139544, a potential defendant facing assertion of this patent would have all prior art grounds available for an AIA trial challenge (e.g., IPR, PGR, or CBM, depending on eligibility). The absence of PTAB activity means there is no pre-existing PTAB record to analyze for claim construction or validity patterns. If considering an AIA trial, a thorough prior art search and an assessment of the patent's claims against that art would be the crucial first steps.

Inventors

• Mark A. Webster: Likely employed by Conexant Systems, Inc. at the time of filing, as he assigned his interest to Conexant Systems, Inc. with an effective date of 2005-05-02, just prior to the application's filing date.
• Michael J. Seals: Likely employed by Conexant Systems, Inc. at the time of filing, as he assigned his interest to Conexant Systems, Inc. with an effective date of 2005-05-02, just prior to the application's filing date.

There is no information to determine if inventors departed the original assignee within 12 months of filing.

Original assignee

The entity named as "Original Assignee" on the patent, according to Google Patents, is Intellectual Ventures I LLC. Intellectual Ventures I LLC is a well-known patent aggregation and licensing firm and is not known to have shipped products embodying the claims. Its primary line of business is patent acquisition, licensing, and assertion. Intellectual Ventures I LLC is currently operating.

However, the first recorded assignment (Reel 016535/0334) indicates the inventors, Mark A. Webster and Michael J. Seals, assigned their interest to Conexant Systems, Inc. on May 4, 2005 (recorded date) with an effective date of May 2, 2005. Conexant Systems, Inc. was a semiconductor company that shipped products in communication technologies, likely embodying claims related to OFDM/MIMO systems. Conexant Systems, Inc. was later acquired by Synaptics in 2017. The fact that Intellectual Ventures I LLC is listed as the "Original Assignee" while the inventors initially assigned to Conexant suggests an unrecorded transfer from Conexant to Intellectual Ventures I LLC prior to the application's filing, or Intellectual Ventures I LLC filed the application on behalf of Conexant before securing ownership.

Assignment timeline

The provided patent text does not include correspondent information for each assignment event.

• 2005-05-02 (executed) / recorded 2005-05-04 — Reel 016535/0334

  • Conveyance: ASSIGNMENT
  • Assignor: WEBSTER, MARK A.; SEALS, MICHAEL J.
  • Assignee: CONEXANT SYSTEMS, INC., CALIFORNIA
  • Context: Inventor assignment to an operating company.

• 2006-11-13 (executed) / recorded 2006-11-22 — Reel 018711/0818

  • Conveyance: SECURITY AGREEMENT
  • Assignor: CONEXANT SYSTEMS, INC.
  • Assignee: BANK OF NEW YORK TRUST COMPANY, N.A., ILLINOIS
  • Context: Securitization of patent assets by Conexant.

• 2008-10-17 (executed) / recorded 2008-10-27 — Reel 021731/0807

  • Conveyance: RELEASE BY SECURED PARTY
  • Assignor: BANK OF NEW YORK MELLON TRUST COMPANY, N.A. (FORMERLY, BANK OF NEW YORK TRUST COMPANY, N.A.)
  • Assignee: CONEXANT SYSTEMS INC., CALIFORNIA
  • Context: Release of security interest, ownership reverts to Conexant.

• 2008-10-16 (executed) / recorded 2009-01-02 — Reel 022043/0607

  • Conveyance: ASSIGNMENT
  • Assignor: CONEXANT SYSTEMS, INC.
  • Assignee: XOCYST TRANSFER AG L.L.C., DELAWARE
  • Context: Transfer of patent asset from an operating company to a limited liability company.

• 2008-10-16 (executed) / recorded 2009-02-03 — Reel 022191/0595

  • Conveyance: ASSIGNMENT
  • Assignor: CONEXANT, INC.
  • Assignee: XOCYST TRANSFER AG L.L.C., DELAWARE
  • Context: Further transfer from a Conexant-related entity to XOCYST TRANSFER AG L.L.C.

• 2011-07-18 (executed) / recorded 2011-07-22 — Reel 026637/0603

  • Conveyance: MERGER
  • Assignor: XOCYST TRANSFER AG L.L.C.
  • Assignee: INTELLECTUAL VENTURES I LLC, DELAWARE
  • Context: Transfer of XOCYST's assets to a known patent assertion entity (Intellectual Ventures I LLC).

• 2024-10-10 (executed) / recorded 2024-10-10 — Reel 068866/0534

  • Conveyance: ASSIGNMENT
  • Assignor: INTELLECTUAL VENTURES I LLC
  • Assignee: INTELLECTUAL VENTURES ASSETS 199 LLC, DELAWARE
  • Context: Internal portfolio transfer within the Intellectual Ventures family.

• 2024-10-15 (executed) / recorded 2024-10-16 — Reel 068918/0916

  • Conveyance: ASSIGNMENT
  • Assignor: INTELLECTUAL VENTURES ASSETS 199 LLC
  • Assignee: INTEGRAL WIRELESS TECHNOLOGIES LLC, TEXAS
  • Context: Transfer to the current assignee, which is involved in litigation.

Timeline diagram

timeline
    title Ownership of US 8139544
    2005 : Inventors assign to Conexant
    2006 : Conexant grants security interest
    2008 : Security interest released to Conexant
    2009 : Conexant assigns to Xocyst LLC
    2011 : Xocyst LLC merges into IV I LLC
    2024 : IV I LLC assigns to IV Assets 199 LLC
         : IV Assets 199 LLC assigns to Integral Wireless

NPE / troll-pattern signals

1. Shell-entity transfer

   • Present: XOCYST TRANSFER AG L.L.C. (Reel 022043/0607, 2009-01-02 and Reel 022191/0595, 2009-02-03) has a name structure indicative of a shell entity for asset holding. Intellectual Ventures I LLC (Reel 026637/0603, 2011-07-22) is a known patent aggregation and licensing entity, not an operating company. Intellectual Ventures Assets 199 LLC (Reel 068866/0534, 2024-10-10) is clearly named as an asset-holding shell. Integral Wireless Technologies LLC (Reel 068918/0916, 2024-10-16) also fits the pattern of a licensing-focused LLC given its lineage through Intellectual Ventures and documented litigation activity.

2. Known asserter in the chain

   • Present: Intellectual Ventures I LLC (Reel 026637/0603, 2011-07-22) is a widely recognized patent assertion entity. The current assignee, Integral Wireless Technologies LLC (Reel 068918/0916, 2024-10-16), is documented in the patent's Google Patents legal status as having filed litigation in multiple US District Courts, confirming its role as an asserter.

3. Repeat correspondent across the chain

   • Unclear: Correspondent information (attorney name, firm, address) is not available in the provided patent text for any of the assignment records.

4. Cascading transfers

   • Present: There are two consecutive assignments within a short period in 2024: from Intellectual Ventures I LLC to Intellectual Ventures Assets 199 LLC on 2024-10-10 (Reel 068866/0534), followed by a transfer from Intellectual Ventures Assets 199 LLC to Integral Wireless Technologies LLC on 2024-10-16 (Reel 068918/0916). This rapid succession of transfers between related LLCs is a strong indicator of NPE activity.

5. Pre-litigation transfer

   • Present: The last assignment to Integral Wireless Technologies LLC occurred on 2024-10-16 (Reel 068918/0916). The patent is noted as having litigation filed in Texas Western (7:26-cv-00121), Texas Eastern (2:25-cv-01152, 2:25-cv-00644), and Florida Southern (0:25-cv-62546) District Courts, with case numbers indicating filings in 2025 and 2026. This transfer occurred within 6 months of the earliest documented litigation, suggesting the patent was moved to the asserting entity in preparation for lawsuits.

6. Bankruptcy fire-sale

   • Not present: While Conexant Systems, Inc. was eventually acquired, the assignments in the chain are not explicitly tied to bankruptcy proceedings or fire sales.

7. Privateering

   • Unclear: There is no direct evidence in the provided data to suggest that Conexant Systems, Inc. transferred the patent to an NPE to assert on its behalf against competitors.

8. Defensive aggregator (anti-NPE)

   • Not present: The assignment chain culminates in an entity engaged in patent assertion, not a defensive aggregator.

Verdict

NPE — high confidence

The assignment chain demonstrates multiple strong signals for NPE activity. These include the direct transfer to a known NPE, Intellectual Ventures I LLC (Reel 026637/0603, 2011-07-22), subsequent rapid cascading transfers between shell entities (Reel 068866/0534 and 068918/0916 in October 2024), and a clear pre-litigation transfer to the current asserting entity, Integral Wireless Technologies LLC, immediately preceding documented district court litigation in 2025 and 2026.

USPTO Assignment Center search for US8139544

As a technical patent analyst, I have searched the USPTO database for patent number 8139544. The following prior art patents were cited in US8139544B1. For each reference, I provide a full citation, publication/filing date, a brief description, and which claim(s) it potentially anticipates under 35 U.S.C. § 102.

Most Relevant Prior Art for US Patent 8139544:

The following patents are considered prior art based on their citation within US Patent 8139544.

1. US6445425B1

• Full Citation: US6445425B1, "Automatic fine tuning of receiver for digital television signals"
• Publication Date: 2002-09-03
• Filing Date: 1997-01-07
• Brief Description: This patent describes a receiver for digital television signals that includes a frequency offset estimator and a symbol timing estimator to perform automatic fine tuning. It focuses on recovering and synchronizing signals in a digital broadcasting environment.
• Potentially Anticipates: Claims related to clock recovery and synchronization (e.g., portions of the method in Claim 1 involving signal reception and initial processing, and the system in Claim 15 configured for such reception).

2. US20020191535A1

• Full Citation: US20020191535A1, "OFDM signal communication system, OFDM signal transmitting device and OFDM signal receiving device"
• Publication Date: 2002-12-19
• Filing Date: 2001-04-09
• Brief Description: This patent describes an OFDM communication system that addresses issues like frequency synchronization and channel estimation. It focuses on using known pilot signals to perform channel estimation and equalization in OFDM systems.
• Potentially Anticipates: Claims 1 and 15, particularly concerning the receiving of OFDM signals, channel estimation, and the use of pilot subcarriers for processing.

3. US20030012308A1

• Full Citation: US20030012308A1, "Adaptive channel estimation for wireless systems"
• Publication Date: 2003-01-16
• Filing Date: 2001-06-13
• Brief Description: This patent discloses methods and apparatus for adaptive channel estimation in wireless communication systems, aiming to improve the accuracy of channel estimates in varying channel conditions.
• Potentially Anticipates: Claims 1 and 15, specifically the aspects related to channel estimation for the communication paths.

4. US20030058787A1

• Full Citation: US20030058787A1, "Method and apparatus for channel estimation"
• Publication Date: 2003-03-27
• Filing Date: 2001-09-27
• Brief Description: This patent describes a method and apparatus for estimating channel characteristics in a communication system, which involves processing received signals to derive channel estimates.
• Potentially Anticipates: Claims 1 and 15, particularly the "signal separating function is based on a first channel estimate for the first communications path and a second channel estimate for the second communications path" element.

5. US20030114127A1

• Full Citation: US20030114127A1, "Transmit power control for multiple rate wireless communications"
• Publication Date: 2003-06-19
• Filing Date: 2001-12-18
• Brief Description: This patent relates to transmit power control in wireless communication systems that support multiple data rates, focusing on managing transmission power based on channel conditions.
• Potentially Anticipates: While not directly addressing pilot tone separation, it relates to the broader context of managing wireless communication, which could indirectly relate to the environment where the patent's claims operate.

6. US20030128656A1

• Full Citation: US20030128656A1, "Channel estimation and compensation techniques for use in frequency division multiplexed systems"
• Publication Date: 2003-07-10
• Filing Date: 2002-01-07
• Brief Description: This patent describes techniques for channel estimation and compensation in frequency division multiplexed (FDM) systems, which can be relevant to OFDM.
• Potentially Anticipates: Claims 1 and 15, particularly aspects of channel estimation and compensation, which are foundational to separating signals in complex channel environments.

7. US6754195B2

• Full Citation: US6754195B2, "Wireless communication system configured to communicate using a mixed waveform configuration"
• Publication Date: 2004-06-22
• Filing Date: 2001-07-06
• Brief Description: This patent describes a wireless communication system capable of handling different waveform configurations, which could include various signal structures and modulation schemes.
• Potentially Anticipates: While broad, it sets a precedent for flexible communication systems that might employ different signal components, indirectly touching upon the handling of data and pilot subcarriers in varied configurations.

8. US6768714B1

• Full Citation: US6768714B1, "Methods and apparatus for use in obtaining frequency synchronization in an OFDM communication system"
• Publication Date: 2004-07-27
• Filing Date: 1999-06-23
• Brief Description: This patent provides methods and apparatus for achieving frequency synchronization in OFDM communication systems, which is crucial for accurate signal recovery.
• Potentially Anticipates: Claims related to synchronization, clock recovery, and correcting frequency offsets, which are part of the overall signal processing in Claim 1 and 15.

9. US6785341B2

• Full Citation: US6785341B2, "Method and apparatus for processing data in a multiple-input multiple-output (MIMO) communication system utilizing channel state information"
• Publication Date: 2004-08-31
• Filing Date: 2001-05-11
• Brief Description: This patent describes processing data in MIMO systems using channel state information, which is central to the separation of signals from multiple transmit antennas.
• Potentially Anticipates: Claims 1 and 15, particularly the separation of signals based on channel estimates in a multiple-antenna environment, as well as the underlying principles of MIMO data processing.

10. US20050002359A1

• Full Citation: US20050002359A1, "Apparatus, and associated method, for detecting data communicated to a receiving station in a multiple-channel communication system"
• Publication Date: 2005-01-06
• Filing Date: 2003-06-20
• Brief Description: This patent describes an apparatus and method for detecting data in a multiple-channel communication system, which would involve distinguishing signals from different channels.
• Potentially Anticipates: Claims 1 and 15, related to the overall reception and separation of signals in a multi-channel context.

11. US6850481B2

• Full Citation: US6850481B2, "Channels estimation for multiple input—multiple output, orthogonal frequency division multiplexing (OFDM) system"
• Publication Date: 2005-02-01
• Filing Date: 2000-09-01
• Brief Description: This patent focuses on channel estimation for MIMO-OFDM systems, which is a key component for effectively separating signals in such environments.
• Potentially Anticipates: Claims 1 and 15, directly addressing the core concept of channel estimation for MIMO-OFDM systems, which underpins the signal separating function.

12. US6862271B2

• Full Citation: US6862271B2, "Multiple-input, multiple-output (MIMO) systems with multiple transmission modes"
• Publication Date: 2005-03-01
• Filing Date: 2002-02-26
• Brief Description: This patent describes MIMO systems that can operate with various transmission modes, implying flexibility in how signals are sent and received across multiple antennas.
• Potentially Anticipates: Claims 1 and 15, by broadly covering MIMO systems and their operational modes, including how signals from different antennas are managed.

13. US20050157682A1

• Full Citation: US20050157682A1, "Methods and apparatus to control transmission of a multicarrier wireless communication channel through multiple antennas"
• Publication Date: 2005-07-21
• Filing Date: 2003-09-15
• Brief Description: This patent describes methods and apparatus for controlling multicarrier wireless communication channels transmitted through multiple antennas.
• Potentially Anticipates: Claims 1 and 15, particularly in the context of managing signals from multiple transmit antennas in a multicarrier system, which is directly relevant to the reception and separation of such signals.

14. US20050207333A1

• Full Citation: US20050207333A1, "Method and apparatus for an enhanced OFDM system"
• Publication Date: 2005-09-22
• Filing Date: 2004-03-22
• Brief Description: This patent describes enhancements for OFDM systems, which could involve various improvements to signal processing, including handling of subcarriers.
• Potentially Anticipates: Claims 1 and 15, in a general sense, by disclosing methods and systems for improving OFDM performance, which might encompass techniques for processing data and pilot subcarriers.

15. US20060258303A1

• Full Citation: US20060258303A1, "Radio communication apparatus, transmitter apparatus, receiver apparatus and radio communication system"
• Publication Date: 2006-11-16
• Filing Date: 2003-04-21
• Brief Description: This patent describes a radio communication system with transmitter and receiver apparatus, focusing on efficient communication.
• Potentially Anticipates: Broadly, Claims 1 and 15 in their general scope of a receiver device and method for processing signals in a communication system.

16. US20070021130A1

• Full Citation: US20070021130A1, "Multi-carrier radio communication system, transmission device, and reception device"
• Publication Date: 2007-01-25
• Filing Date: 2003-01-29
• Brief Description: This patent describes a multi-carrier radio communication system, including aspects of transmission and reception devices.
• Potentially Anticipates: Broadly, Claims 1 and 15 in their general scope of a receiver device and method for processing signals in a communication system, particularly within a multi-carrier context.

17. US7564917B2

• Full Citation: US7564917B2, "Multicarrier receiver and method for generating common phase error estimates for use in systems that employ two or more transmit antennas with independent local oscillators"
• Publication Date: 2009-07-21
• Filing Date: 2005-11-01
• Brief Description: This patent describes a multicarrier receiver and method for generating common phase error estimates in systems with multiple transmit antennas and independent local oscillators.
• Potentially Anticipates: Claims 6, 7, 18, 19, and 29, relating to correcting phase and jitter distortions, combining pilot subcarriers, and phase-lock looping, especially in systems with independent oscillators, as phase noise correction is a key element.

18. US7848438B2

• Full Citation: US7848438B2, "Method and apparatus for pilot signal transmission"
• Publication Date: 2010-12-07
• Filing Date: 2006-02-14
• Brief Description: This patent describes a method and apparatus for transmitting pilot signals, which is fundamental to systems that use pilot tones for channel estimation and synchronization.
• Potentially Anticipates: Claims 1 and 15, as the receipt and processing of pilot signals is central to their functionality. While the specific separation and combining methods might differ, the concept of pilot signal utilization is present.

Obviousness Analysis of US Patent 8139544 Under 35 U.S.C. § 103

This analysis identifies combinations of prior art references, publicly available before the priority date of US patent 8139544 (July 30, 2004), that would render the independent claims of the patent obvious to a person having ordinary skill in the art (PHOSITA).

Independent Claims Overview

The independent claims (Claims 1, 15, 24, and 25) of US Patent 8139544 primarily describe a receiving device's operations in a wireless communication system, involving:

1. Receiving first and second signals, each from a different transmit antenna, where each signal includes data and pilot subcarriers.
2. Separating the first set of data subcarriers from the second set of data subcarriers, and the first set of pilot subcarriers from the second set of pilot subcarriers, using a signal separating function based on channel estimates for the respective communication paths.
3. Match-filter combining at least one pilot subcarrier from the first set of pilot subcarriers with at least one pilot subcarrier from the second set of pilot subcarriers.

Identified Prior Art Combinations and Obviousness Rationale

The following combination of prior art references and common general knowledge would render the independent claims, and by extension the dependent claims, obvious.

Primary Reference: US6850481B2 to Nortel Networks Limited (Priority: September 1, 2000; Publication: February 1, 2005)

• Disclosure: This patent, titled "Channels estimation for multiple input—multiple output, orthogonal frequency division multiplexing (OFDM) system," explicitly teaches a receiver in a Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) system. It addresses the fundamental aspect of channel estimation in such an environment. This reference thus clearly teaches the reception of signals from multiple transmit antennas, with these signals comprising OFDM subcarriers (both data and pilot), and the necessity of estimating the communication channels for these paths.

Secondary Reference 1: US6785341B2 to Qualcomm Incorporated (Priority: May 11, 2001; Publication: August 31, 2004)

• Disclosure: This patent, "Method and apparatus for processing data in a multiple-input multiple-output (MIMO) communication system utilizing channel state information," provides methods and apparatus for utilizing channel state information (derived from channel estimates) to process data in MIMO communication systems.

Motivation to Combine US6850481B2 and US6785341B2:
A PHOSITA would be motivated to combine the teachings of US6850481B2 and US6785341B2. US6850481B2 establishes the context of channel estimation in MIMO-OFDM systems, while US6785341B2 provides general techniques for processing data using such channel state information in MIMO systems. It would be a natural engineering step to apply the principles of utilizing channel state information (from Qualcomm) to the specific problem of channel estimation in MIMO-OFDM (from Nortel) to effectively process the received signals.

Secondary Reference 2 (Common General Knowledge of Signal Separation Techniques): Zero Forcing (ZF) and Minimum Mean Squared Error (MMSE) algorithms.

• Disclosure: The patent US8139544 itself describes the signal separating function as performing "inversion (e.g., single coefficient inversion, such as minimum mean squared error (MMSE) techniques, zero forcing (ZF), etc.)". Both ZF and MMSE were well-established and widely known signal separation and equalization techniques in MIMO communication systems prior to the July 2004 priority date. These techniques are fundamental for separating spatially multiplexed signals, using channel estimates to de-correlate interference between streams.

Motivation for Incorporating ZF/MMSE:
A PHOSITA, having understood the need for channel estimation in MIMO-OFDM (from US6850481B2) and the use of channel state information for data processing (from US6785341B2), would find it obvious to employ known signal separation techniques like ZF or MMSE to separate the self-interfering data and pilot subcarriers corresponding to different transmit antennas. The choice between ZF and MMSE would be a routine design consideration based on factors like desired trade-offs between noise enhancement and interference cancellation.

Secondary Reference 3 (Common General Knowledge of Optimal Combining and Correlation Exploitation): Matched filter combining or Maximum Ratio Combining (MRC).

• Disclosure: Matched filter combining and Maximum Ratio Combining (MRC) are well-known optimal signal combining techniques used to improve the signal-to-noise ratio (SNR) in communication systems. MRC, in particular, weights and sums multiple received signal components based on their SNR to maximize the output SNR, and can be implemented as a form of matched filtering. US8139544 itself notes the use of "maximum ratio combining (MRC) logic 418" for pilot tones after initial signal separation. Furthermore, the patent describes how "information can be shared between PLLs of the post-signal processors 140 and 142" when phase noise jitter is highly correlated across transmit paths, suggesting combining information from different streams for improved estimation.

Motivation for Match-Filter Combining Separated Pilot Subcarriers:
After separating the pilot subcarriers originating from different transmit antennas using ZF or MMSE, a PHOSITA would be motivated to further process these separated pilot signals to enhance the accuracy and robustness of channel estimations or phase noise tracking. The background of US8139544 explicitly highlights the use of pilot tones for "compensating for distortions in the received signal" such as "jitter phase noise". If common impairments like phase noise are correlated across the different transmit paths as seen at the receiver (as recognized by US8139544), then combining the separated pilot information from each transmit path using a known optimal combining technique, such as match-filter combining (or MRC), would provide a more robust and accurate estimate of these common channel characteristics. This would directly lead to improved system performance by reducing distortion.

Conclusion on Independent Claims

Based on the above, the independent claims (1, 15, 24, 25) of US8139544 would be obvious. The combination of US6850481B2 (teaching MIMO-OFDM channel estimation) with the common general knowledge of ZF/MMSE for signal separation and the common general knowledge of matched filter/MRC for optimal combining of related signals (motivated by improving channel impairment estimation from separated pilot streams), would lead a PHOSITA to the claimed invention. Such a combination represents a logical extension of known techniques to improve the performance of MIMO-OFDM communication systems.

Obviousness of Dependent Claims

If the independent claims are rendered obvious by the above combination, the dependent claims would also be obvious for the following reasons:

• Claims 2, 23 (Channel estimate based on preamble): Using preambles or training sequences for initial channel estimation in OFDM systems is standard practice and would be obvious to a PHOSITA in conjunction with US6850481B2.
• Claims 3, 26 (Separating data from pilot subcarriers): This is a fundamental step in any communication system employing pilot subcarriers for channel estimation/tracking, as described in the background of US8139544.
• Claims 4, 16 (ZF function): This is explicitly part of the common general knowledge regarding MIMO equalization techniques.
• Claims 5, 16 (MMSE function): This is also explicitly part of the common general knowledge regarding MIMO equalization techniques.
• Claims 6, 18, 29 (Correcting phase and jitter distortions): The primary purpose of pilot tones, as stated in the background of US8139544, is to compensate for such distortions. Applying the derived estimates to correct for these distortions is the intended use and would be obvious.
• Claims 7, 19, 28 (Combining and phase-lock looping of pilot subcarriers): This describes standard phase tracking loops (PLLs) applied to processed pilot signals. The patent itself depicts MRC logic (418) and PLLs (420) operating on separated pilot streams.
• Claims 8, 20 (MRC or simple combining): MRC and simple summing are both well-known combining techniques, and MRC is explicitly mentioned in US8139544 as an option.
• Claims 9, 10 (Multi-receiver/single transmitter configurations): These describe common communication system architectures (MIMO with multiple receive antennas or potentially distributed receivers) that do not add inventive subject matter to the core separation and combining techniques. The setup in FIG. 1 shows a single transmitter and single receiver with multiple antennas.
• Claims 11, 27 (Generating channel matrix and computing matrix inverse): These describe the mathematical implementation details of ZF/MMSE equalization, which is common general knowledge in MIMO channel equalization.
• Claims 12, 13 (Channel matrix based on amplitude/phase): Channel matrix elements fundamentally represent the amplitude and phase characteristics of the communication paths, as explicitly stated in US8139544. This is basic channel modeling.
• Claim 14 (Subcarrier frequencies): This describes the standard allocation of data and pilot subcarriers within an OFDM symbol, as illustrated in US8139544 (FIGS. 3A-3B).
• Claims 21, 22 (Implementation in hardware/software/firmware/circuitry): The choice of implementing communication system components in hardware, software, firmware, or a combination, and using digital or analog circuitry, represents routine engineering choices well within the skill of a PHOSITA. [0067-0069]

US patent 8139544, titled "Pilot tone processing systems and methods," was filed on May 4, 2005, and issued on March 20, 2012.

Here's a breakdown of its various patent term aspects:

• Patent Term Adjustments (PTA): Patent Term Adjustments can add time to a patent's term to compensate for certain delays caused by the USPTO during prosecution. The USPTO automatically calculates and provides notice of any PTA on or before the patent's issue date. To determine the exact PTA for US8139544, one would typically review the "Issue Notification" or "Patent Data" section of the patent's file wrapper in Patent Center, as the USPTO's official notification is indicated on the patent itself.

• Patent Term Extensions (PTE): Patent Term Extensions are available for patents on certain human drugs, food or color additives, medical devices, animal drugs, and veterinary biological products to restore time lost during premarket government approval from a regulatory agency like the FDA. Since US8139544 relates to wireless communication systems and methods, it is highly unlikely to be eligible for a Patent Term Extension under 35 U.S.C. § 156, as it does not fall within these categories.

• Continuation Applications: A continuation application shares the same disclosure as its parent but pursues different claims, with no new subject matter added. It must reference the parent's application number and filing date. The provided information for US8139544 lists "US11/121,743" as its application number and "2004-07-30" as its priority date (from a U.S. provisional application Ser. No. 60/592,748). While this indicates a priority claim, the Google Patents page does not explicitly list US8139544 as a continuation of another non-provisional application. To definitively identify any continuation applications, a direct search of the USPTO's Patent Center or Public PAIR system using the application number US11/121,743 would be necessary.

• Divisional Applications: A divisional application arises when the USPTO issues a restriction requirement, determining that a single application contains two or more independent and distinct inventions. The applicant can then elect one invention to prosecute in the parent and file a divisional for the other. Similar to continuation applications, the provided information does not explicitly state that US8139544 is a divisional application, nor does it list any patents as divisional applications of US8139544. A thorough search of the patent family in the USPTO's Patent Center would confirm any divisional filings.

• Related Family Members: The patent states that it claims priority to U.S. provisional application having Ser. No. 60/592,748, filed July 30, 2004. This provisional application is a related family member. Beyond this, identifying other related family members (e.g., continuations, divisionals, or foreign counterparts) typically requires searching patent family databases or the USPTO's systems. The Google Patents page lists "Family ID=45813379" and under "Family Applications (1)" it lists US11/121,743 (US8139544B1) itself. It also lists "Priority Applications (1)" as US11/121,743 and "Applications Claiming Priority (2)" as US59274804P (the provisional) and US11/121,743. This indicates that the primary family relationship shown in the Google Patents interface is the priority claim to the provisional application.

• Projected Expiration Date: The patent information states that US8139544 is "Active, expires 2028-01-15". The default term for utility patents filed on or after June 8, 1995, is 20 years from the earliest filing date of the application from which priority is claimed. In this case, the filing date is May 4, 2005, and the priority date from the provisional application is July 30, 2004. The expiration date of January 15, 2028, implies that some form of patent term adjustment (PTA) was applied, as 20 years from the May 4, 2005 filing date would be May 4, 2025, and 20 years from the July 30, 2004 priority date would be July 30, 2024. The noted expiration date of January 15, 2028, suggests an adjustment of several years from the 20-year term based on the priority date. This "Adjusted expiration" date is explicitly provided in the legal status section of the Google Patents page.