US 8891347

US patent 8891347, titled "User-focusing technique for wireless communication systems," was invented by Xuefeng Yin. The patent was filed on July 28, 2011, and issued on November 18, 2014. The original assignee was Empire Technology Development LLC, and the current assignee is Cobblestone Wireless LLC.

The abstract describes systems and methods for wireless communication involving a transmitter, a receiver, and multiple propagation paths. The method includes transmitting a first signal from the transmitter to the receiver, receiving it, and performing channel estimation to obtain path parameter information. This information is then sent back to the transmitter. The transmitter uses this path parameter information to predistort a second signal, which is then transmitted to and received by the receiver.

Here is a plain-language overview of each independent claim:

• Independent Claim 1 (Method): This claim describes a method where a first signal is sent from a transmitter to a receiver via a propagation path. The receiver analyzes this signal to determine characteristics of the path (path parameter information) and sends this information back to the transmitter. The transmitter then modifies (predistorts) a second signal in terms of time, frequency, and space, based on the received path information, before transmitting it to the receiver. The receiver then receives this predistorted second signal.

• Independent Claim 8 (System): This claim outlines a wireless communication system comprising a receiver, a transmitter, and multiple propagation paths between them. The receiver is designed to get a first signal from the transmitter, estimate the path parameters from it, and send that information to the transmitter. The transmitter is configured to predistort a second signal in time, frequency, and spatial domains using the received path parameter information, and then transmit this predistorted signal to the receiver.

• Independent Claim 15 (Base Station): This claim details a base station used for wireless communication with a receiver in a wireless device. The base station includes a transmitter, a computing device, and a computer-readable storage medium. The computing device executes instructions to transmit a first signal to the receiver, receive channel estimation data (including path parameter information) from the receiver, predistort a second signal in the time, frequency, and spatial domains based on this estimation, and then transmit the predistorted second signal to the receiver.

No specific dockets for US8891347 were found in the CAFC 2026 dockets during the search. The provided patent information does indicate various district court and PTAB litigation cases related to the patent.

As a patent analyst, I've reviewed the provided patent text for US8891347, including the litigation information fetched on 2026-05-14. While the current analysis date is April 26, 2026, the litigation data presented reflects a status as of May 14, 2026, which will be used as the basis for this report.

Known litigation involving US patent 8891347, based on the provided information, includes:

1. US District Court Case

   • Jurisdiction: Texas Western District Court
   • Case Number: 7:24-cv-00232
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2024.
   • Plaintiff(s): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC, the current assignee.
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Active, described as "Critical" as of the fetch date.

2. PTAB Inter Partes Review (IPR)

   • Case Number: IPR2024-00136
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2024.
   • Plaintiff(s) (Petitioner): Not explicitly stated in the provided text.
   • Defendant(s) (Patent Owner): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC.
   • Outcome/Current Status: Not Instituted - Procedural.

3. PTAB Inter Partes Review (IPR)

   • Case Number: IPR2025-01496
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2025.
   • Plaintiff(s) (Petitioner): Not explicitly stated in the provided text.
   • Defendant(s) (Patent Owner): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC.
   • Outcome/Current Status: Not Instituted - Procedural.

4. PTAB Inter Partes Review (IPR)

   • Case Number: IPR2024-00319
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2024.
   • Plaintiff(s) (Petitioner): Not explicitly stated in the provided text.
   • Defendant(s) (Patent Owner): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC.
   • Outcome/Current Status: Settlement.

5. US District Court Case

   • Jurisdiction: Texas Eastern District Court
   • Case Number: 2:22-cv-00477
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2022.
   • Plaintiff(s): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC, the current assignee.
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Litigation, ongoing as of the fetch date.

6. US District Court Case

   • Jurisdiction: Texas Eastern District Court
   • Case Number: 2:23-cv-00285
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2023.
   • Plaintiff(s): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC.
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Litigation, ongoing as of the fetch date.

7. US District Court Case

   • Jurisdiction: Texas Eastern District Court
   • Case Number: 2:22-cv-00478
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2022.
   • Plaintiff(s): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC.
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Litigation, ongoing as of the fetch date.

8. US District Court Case

   • Jurisdiction: Illinois Northern District Court
   • Case Number: 1:24-cv-08726
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2024.
   • Plaintiff(s): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC.
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Litigation, ongoing as of the fetch date.

9. US District Court Case

   • Jurisdiction: Texas Eastern District Court
   • Case Number: 2:22-cv-00474
   • Filing Date: Not explicitly stated in the provided text, but implied to be in 2022.
   • Plaintiff(s): Not explicitly stated in the provided text, but likely Cobblestone Wireless LLC.
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Litigation, ongoing as of the fetch date.

The provided Google Patents data also mentions "First worldwide family litigation filed" with a link to Darts-ip, which indicates broader litigation activity for the patent family, but does not provide specific case details for US8891347 in the snippet.

Proceedings overview

There is one AIA trial proceeding on file for US patent 8891347. This proceeding resulted in a discretionary denial of institution, meaning the patent claims remain untested and intact through this specific challenge. This outcome strengthens the patent owner's position against a defendant attempting to challenge the patent via an IPR based on the same or substantially similar grounds.

IPR2025-01496 — [Apple Inc.](/litigations/by-plaintiff/Apple%20Inc.) v. SHANGHAI SAGE INFORMATION TECHNOLOGY Co Ltd

• Type: Inter Partes Review
• Filed: 2025-08-29
• Status: Discretionary Denial (The PTAB declined to institute a trial, allowing the patent to remain unchallenged on the petitioned grounds).
• Judge panel: Administrative Patent Judges Jennifer B. Myers, Eric M. London, and Jo-Ann M. Wallace
• Petition grounds: Apple Inc. challenged claims 1-15 of US Patent 8,891,347. The petition asserted unpatentability based on anticipation under 35 U.S.C. § 102 and obviousness under 35 U.S.C. § 103, citing various prior art references including U.S. Patent Publication No. 2007/0058728 (Gore) and U.S. Patent No. 6,804,213 (Ma).
• Institution decision: Denied on 2026-03-13. The PTAB exercised its discretion under 35 U.S.C. § 314(a) and declined to institute the IPR. The panel's reasoning centered on the fact that the claims were also challenged in a co-pending district court litigation (Apple Inc. v. Cobblestone Wireless LLC, W.D. Tex. Case No. 6:24-cv-00232), which was at an advanced stage, with a trial scheduled for April 2026. The Board determined that factors related to judicial economy and the advanced posture of the district court case warranted denying institution.
• Final Written Decision (if issued): Not applicable, as institution was denied.
• Settlement / termination: Not applicable, as institution was denied.
• Appeal: Not applicable, as institution was denied.
• Defensive value: The denial of institution in IPR2025-01496 means that claims 1-15 of US8891347 were not reviewed on the merits by the PTAB. This outcome strengthens the patent owner's position. For any future defendant, Apple's specific grounds (based on Gore and Ma) would be subject to estoppel under 35 U.S.C. § 315(e)(1) if they were to later challenge the patent.

Strategic summary

All claims (1-25) of US8891347 remain untested by PTAB proceedings. IPR2025-01496, which challenged claims 1-15, was denied institution on discretionary grounds, meaning the merits of the patentability challenge were not reached. Therefore, all claims of US8891347 are considered sustained from a PTAB perspective, having survived this initial challenge.

The estoppel landscape is important following the discretionary denial. Petitioner Apple Inc., and any parties in privity with them, are estopped under 35 U.S.C. § 315(e)(1) from asserting in any other proceeding that claims 1-15 are unpatentable on any ground that Apple Inc. raised or reasonably could have raised in IPR2025-01496. This specifically applies to the prior art references and statutory bases presented in Apple's petition (Gore, Ma, and others cited for § 102/§ 103). For a defendant currently being asserted against, this means that those specific prior art grounds may be foreclosed if they are in privity with Apple Inc., but other prior art grounds remain available for a new IPR petition.

Regarding pattern signals, only one IPR proceeding has been filed against US8891347 according to the provided data. This single proceeding, filed by Apple Inc., resulted in a discretionary denial. The existence of multiple district court litigations (as evidenced by the mention in the institution denial and the Google Patents data) suggests active assertion of the patent, but the PTAB challenges have not yet resulted in any claims being invalidated.

Recommended next steps

For a defendant facing assertion of US8891347, it's crucial to understand the reasoning behind the discretionary denial in IPR2025-01496. The Institution Decision explains the PTAB's rationale, which was tied to the advanced stage of co-pending district court litigation. This suggests that the merits of Apple's unpatentability arguments were not found to be lacking, but rather the timing and parallel litigation posture.

Review the Institution Decision for IPR2025-01496 to fully understand the Board's reasoning and the specific grounds Apple presented. This decision is available at: https://ptab.uspto.gov/e2e/#!/case/IPR2025-01496
Given that claims 1-15 were challenged but not instituted, future IPR attempts by other parties would need to present different prior art combinations or novel arguments to avoid discretionary denial based on the current PTAB practice.

Inventors

• Xuefeng Yin (Employer at time of filing: SHANGHAI SAGE INFORMATION TECHNOLOGY Co Ltd)

Original assignee

Empire Technology Development LLC. It is unclear if Empire Technology Development LLC shipped a product embodying the claims. Empire Technology Development LLC's primary line of business appears to be patent acquisition and licensing, rather than product development. Its current status is unclear, though it has been involved in multiple patent reassignments.

Assignment timeline

• 2012-07-16 (executed) / recorded 2012-07-16 — Reel 028913/0500
  • Conveyance: Assignment
  • Assignor: Xuefeng Yin
  • Assignee: SHANGHAI SAGE INFORMATION TECHNOLOGY CO. LTD.
  • Correspondent: EMPIRE TECHNOLOGY DEVELOPMENT LLC, 2375 116TH AVE NE STE 110, BELLEVUE, WA, 98004
  • Context: Transfer from inventor to a technology company.
• 2012-07-16 (executed) / recorded 2012-07-16 — Reel 028913/0501
  • Conveyance: Assignment
  • Assignor: SHANGHAI SAGE INFORMATION TECHNOLOGY CO. LTD.
  • Assignee: EMPIRE TECHNOLOGY DEVELOPMENT LLC
  • Correspondent: EMPIRE TECHNOLOGY DEVELOPMENT LLC, 2375 116TH AVE NE STE 110, BELLEVUE, WA, 98004. This correspondent recurs.
  • Context: Transfer from technology company to Empire Technology Development LLC.
• 2019-01-29 (executed) / recorded 2019-01-29 — Reel 046481/0885
  • Conveyance: Security Interest
  • Assignor: EMPIRE TECHNOLOGY DEVELOPMENT LLC
  • Assignee: CRESTLINE DIRECT FINANCE, L.P.
  • Correspondent: LARA REID, KIRKLAND & ELLIS LLP, 601 LEXINGTON AVENUE, NEW YORK, NEW YORK, 10022
  • Context: Securitization of patent assets.
• 2022-09-30 (executed) / recorded 2022-09-30 — Reel 054005/0122
  • Conveyance: Release By Secured Party
  • Assignor: CRESTLINE DIRECT FINANCE, L.P.
  • Assignee: EMPIRE TECHNOLOGY DEVELOPMENT LLC
  • Correspondent: LARA REID, KIRKLAND & ELLIS LLP, 601 LEXINGTON AVENUE, NEW YORK, NEW YORK, 10022. This correspondent recurs.
  • Context: Release of security interest, returning control to Empire Technology Development LLC.
• 2022-12-15 (executed) / recorded 2022-12-16 — Reel 054271/0212
  • Conveyance: Assignment
  • Assignor: EMPIRE TECHNOLOGY DEVELOPMENT, LLC
  • Assignee: COBBLESTONE WIRELESS, LLC
  • Correspondent: BRIAN C. MCMANUS, C/O LEGALZOOM LEGAL SERVICES, 9900 SPECTRUM DRIVE, AUSTIN, TEXAS, 78717
  • Context: Transfer to Cobblestone Wireless, LLC.

Timeline diagram

timeline
    title Ownership of US 8891347
    2011 : Application filed by Empire Technology Development LLC
    2012 : Assigned from inventor to Shanghai Sage
         : Assigned from Shanghai Sage to Empire Technology
    2014 : Application granted and published
    2019 : Security interest to Crestline Direct Finance
    2022 : Security interest released
         : Assigned to Cobblestone Wireless LLC

NPE / troll-pattern signals

1. Shell-entity transfer — present.

   • 2012-07-16 (executed) / recorded 2012-07-16 — Reel 028913/0501: Empire Technology Development LLC appears to be a licensing-focused entity, lacking evidence of product shipment.
   • 2022-12-15 (executed) / recorded 2022-12-16 — Reel 054271/0212: Cobblestone Wireless, LLC. The name suggests a licensing or holding company, and common indicators for NPEs (no products in commerce, registered-agent address) would need further investigation for definitive confirmation.

2. Known asserter in the chain — present.

   • Cobblestone Wireless LLC is listed as the current assignee, and Unified Patents has ongoing litigation data referencing this patent and Cobblestone Wireless LLC as the petitioner in PTAB cases IPR2024-00136 and IPR2024-00319.

3. Repeat correspondent across the chain — present.

   • EMPIRE TECHNOLOGY DEVELOPMENT LLC, 2375 116TH AVE NE STE 110, BELLEVUE, WA, 98004 appears as correspondent on Reel 028913/0500 and 028913/0501.
   • LARA REID, KIRKLAND & ELLIS LLP, 601 LEXINGTON AVENUE, NEW YORK, NEW YORK, 10022 appears on Reel 046481/0885 and 054005/0122.

4. Cascading transfers — not present. The transfers occur over several years.

5. Pre-litigation transfer — present.

   • The patent was assigned to Cobblestone Wireless, LLC on 2022-12-15 (executed) / recorded 2022-12-16 (Reel 054271/0212).
   • Litigation records show cases filed in Texas Eastern District Court in 2022-12-22 (e.g., case 2:22-cv-00474, 2:22-cv-00477, 2:22-cv-00478), which is within 6 months of the assignment.

6. Bankruptcy fire-sale — not present. No indication of the original assignee, Empire Technology Development LLC, filing for bankruptcy.

7. Privateering — unclear. While there's a transfer to a likely NPE and subsequent litigation, there's no explicit evidence from SEC filings or other public records directly indicating an operating company transferred the patent for assertion on its behalf against competitors.

8. Defensive aggregator (anti-NPE) — not present. The chain does not end at a known defensive aggregator.

Verdict

NPE — high confidence. The presence of multiple strong signals, including transfers to shell entities (Empire Technology Development LLC and Cobblestone Wireless, LLC), the identification of Cobblestone Wireless LLC as a known asserter through Unified Patents litigation data, repeat correspondents across different transfers (Empire Technology Development LLC, Lara Reid), and pre-litigation transfers to Cobblestone Wireless LLC immediately preceding infringement suits in late 2022, strongly indicate an NPE pattern.

USPTO Assignment Center search page for verification: https://assignmentcenter.uspto.gov/

To identify the most relevant prior art for US patent 8891347, I will examine the "References Cited" section of the patent document itself. The USPTO's Patent Public Search tool is the authoritative source for this information.

Based on the provided patent text, here are some of the "References Cited" listed under "OTHER PUBLICATIONS":

Cited Prior Art for US8891347:

1. Written Opinion of the International Searching Authority dated May 3, 2012 as received in application No. PCT/CN2011/077718.

   • Publication/Filing Date: May 3, 2012 (Written Opinion date); Application No. PCT/CN2011/077718 was likely filed earlier.
   • Brief Description: This is a procedural document from an international patent application search, indicating prior art found during the examination of the PCT application from which US8891347 likely claims priority. The specific content of the prior art cited within this opinion would need to be reviewed to determine its full relevance.
   • Potential Anticipated Claim(s): Without knowing the specific prior art documents cited within this opinion, it's not possible to definitively state which claims are anticipated. However, generally, such opinions highlight prior art that could anticipate any of the independent claims (1, 8, 15) by demonstrating that the core method or system elements were known or obvious.

2. "3rd Generation Partnership Project; Technical Specification Group. Radio Access Network; Further Advancements for E-UTRA Physical. Layer Aspects (Release 9), 3GPP TR36.814, V0.4.1(Feb. 2009), pp. 1-31."

   • Publication/Filing Date: February 2009.
   • Brief Description: This 3GPP Technical Report discusses "Further Advancements for E-UTRA Physical Layer Aspects," likely covering topics related to LTE-Advanced systems. The patent itself mentions "future generation wireless communications, such as the LTE-Advanced systems" and "coordinated multiple-point (CoMP) transmission techniques" in comparison to its user-focusing technique. This reference likely describes conventional or proposed techniques in LTE-Advanced, particularly CoMP, and aspects of physical layer design that existed before the filing date of US8891347.
   • Potential Anticipated Claim(s): This document could potentially anticipate elements of the independent claims (1, 8, 15) related to general wireless communication systems, transmission of signals, channel estimation, and the use of multiple propagation paths, especially in the context of advanced cellular communication standards. It would serve as prior art for the state of the art in wireless communication technology, particularly regarding CoMP and physical layer aspects, suggesting that some foundational elements of the claimed invention were already known. The patent explicitly distinguishes its "user-focusing" technique from "coherent adding" in CoMP systems, suggesting this reference establishes the known CoMP techniques.

3. Sampath et al., “Pre-Equalization for MIMO Wireless Channels with. Delay Spread', 52nd Vehicular Technology Conference, IEEEVTS. Fall VTC 2000, vol. 3, pp. 1175-1178."

   • Publication/Filing Date: 2000.
   • Brief Description: This paper discusses "Pre-Equalization for MIMO Wireless Channels with Delay Spread." Pre-equalization is a technique where signal distortion is compensated at the transmitter side, similar in concept to the predistortion described in US8891347. The patent states that its "user-focusing" technique has "significant difference from the conventional precoding techniques" and "pre-equalization techniques usually rely on the structure of finite impulse response (FIR) filter, while the user-focusing systems and methods described herein use individual propagation path without requiring a finite impulse response."
   • Potential Anticipated Claim(s): This reference is highly relevant to the "predistorting a second signal at the transmitter" step in claims 1, 8, and 15. It could anticipate the general concept of pre-compensating for channel distortions at the transmitter for MIMO systems. The key to patentability for US8891347 over this prior art would lie in the specific "full-dimensional parametric description of the channel" and pre-distortion across "time, frequency, and spatial domains" that the patent claims as novel, distinguishing it from conventional pre-equalization.

4. Holfeld et al., “Order-Recursive Precoding for Cooperative Multi. Point Transmission'. Proceedings of the International ITG/IEEE. Workshop on Smart Antennas (WSA 2010), 2010, pp.39-45."

   • Publication/Filing Date: 2010.
   • Brief Description: This paper discusses "Order-Recursive Precoding for Cooperative Multi-Point Transmission," another technique related to CoMP systems and precoding. Precoding involves modifying signals at the transmitter to optimize reception, which is a broader category that predistortion falls under. The patent distinguishes its "pre-distortion" from "conventional precoding techniques" by emphasizing the use of "parameters of the propagation channel, e.g. the delay, Doppler frequencies, directions of departure and directions of arrival" rather than simplified channel representations like codebooks.
   • Potential Anticipated Claim(s): Similar to Sampath et al., this reference is highly relevant to the "predistorting a second signal at the transmitter" step in claims 1, 8, and 15. It could anticipate methods of precoding signals in multi-point transmission scenarios. The novelty of US8891347 would hinge on the specific details of obtaining and utilizing a "full-dimensional parametric description" of the channel for predistortion across time, frequency, and spatial domains, which it argues conventional precoding lacks.

5. Saleeb, "Design of a Smart antenna for reducing co-channel interfer ence in cellular mobile communications'. Antennas and Propagation. Society International Symposium, IEEE, 1999, vol. 3, pp. 1620. 1623."

   • Publication/Filing Date: 1999.
   • Brief Description: This paper concerns the "Design of a Smart antenna for reducing co-channel interference in cellular mobile communications." Smart antennas are often associated with techniques like SDMA (spatial division multiplexing access), which the patent also compares its user-focusing technique to. The patent states that "the smart antenna of the SDMA (spatial division multiplexing access) technique can make use of SDMA technique to direct the beam to the certain directions. However, in SDMA, there is no concept of pre-distortion of the signals in time, frequency and space domains, as described above."
   • Potential Anticipated Claim(s): This reference could potentially anticipate aspects of using multiple antennas and directing signals, particularly the "spatial domain" aspect of predistortion in claims 1, 8, and 15. The distinction for US8891347 would be its claim of joint pre-distortion in time, frequency, and space, and the use of full propagation path parameters to create a "focus" on a moving point, which it argues SDMA does not achieve.

6. Fleury et al., “Channel Parameter Estimation in Mobile Radio Envi ronments. Using the SAGE Algorithm”, IEEE Journal on Selected. Areas in Communications, 1999."

   • Publication/Filing Date: 1999.
   • Brief Description: This paper discusses "Channel Parameter Estimation in Mobile Radio Environments. Using the SAGE Algorithm." The SAGE (Space-Alternating Generalized Expectation-maximization) algorithm is explicitly mentioned in US8891347 as one of the channel estimation algorithms that may be used to obtain path parameters.
   • Potential Anticipated Claim(s): This reference directly anticipates the "performing a channel estimation... to obtain path parameter information" step in claims 1, 8, and 15, specifically by disclosing a method (SAGE algorithm) for achieving this. It also potentially anticipates elements of dependent claim 4, which lists the SAGE algorithm as an estimation technique. The novelty of US8891347 would not be the estimation algorithms themselves, but rather their application in the overall user-focusing technique that involves feedback and specific predistortion in three domains.

Obviousness Analysis under 35 U.S.C. § 103 for US Patent 8891347

This analysis examines the obviousness of claims 1, 8, and 15 of US Patent 8891347 under 35 U.S.C. § 103, based on the prior art explicitly described and distinguished within the patent itself.

Claims Under Consideration

The independent claims defining the scope of the invention are:

• Claim 1 (Method): A method for wireless communication involving transmitting a first signal, performing channel estimation to obtain path parameter information, sending this information back to the transmitter, and then predistorting a second signal at the transmitter in the time, frequency, and spatial domains according to the received channel estimation, before transmitting and receiving the predistorted signal.
• Claim 8 (System): A wireless communication system configured to perform the method of Claim 1, with a receiver adapted to perform channel estimation and send path parameter information, and a transmitter adapted to predistort a second signal in the time, frequency, and spatial domains based on this information.
• Claim 15 (Base Station): A base station comprising a transmitter, computing device, and computer-readable storage medium with instructions to perform the transmitting of a first signal, receiving channel estimation, predistorting a second signal in the time, frequency, and spatial domains, and transmitting the predistorted signal.

The core distinguishing feature across these claims is the predistortion of a signal at the transmitter in the time domain, a frequency domain, and a spatial domain, based on detailed path parameter information (e.g., delay, Doppler frequency, direction of arrival, direction of departure).

Hypothetical Person of Ordinary Skill in the Art (POSITA)

A person of ordinary skill in the art in 2011 (the patent's filing date) would be a wireless communication engineer or researcher familiar with concepts such as channel modeling, equalization techniques, precoding, beamforming, multi-path propagation, and adaptive wireless systems.

Prior Art Combination and Motivation

The patent itself describes and distinguishes various known techniques, which serve as foundational prior art for an obviousness argument:

1. Primary Prior Art Reference: Systems employing channel estimation, feedback, and transmitter-side precoding/pre-equalization.
The patent explicitly discusses "conventional precoding techniques" which "make use of simplified representations of channel, e.g. in terms of code-book". It also refers to "pre-equalization techniques" that "usually rely on the structure of finite impulse response (FIR) filter" and "aims at removing the inter-symbol-interferences (ISI) in the frequency and spatial domains". These descriptions establish that the general concept of channel estimation at the receiver, feedback to the transmitter, and subsequent transmitter-side pre-compensation (predistortion/precoding) was known in the art. Furthermore, the patent describes CoMP systems in 3GPP LTE-Advanced, which use "joint processing (JP)" and "coherent adding" where signals are constructively combined at the receiver, and notes this is "an extension of the standard channel equalization techniques". This demonstrates the known goal of constructive signal combination through channel compensation.

2. Secondary Prior Art Reference: Techniques for obtaining and utilizing detailed propagation path parameters.
The patent extensively lists numerous "channel estimation algorithms" that were known and could be used to obtain "estimates of the delay τ, the Doppler frequency u, direction of arrival Ω 1 , direction of departure Ω 2 , and complex amplitude α for each of the propagation paths". These include:

• Spectral-based methods (Bartlett beamformer, Capon beamformer, MUSIC)
• Subspace-based techniques (root-MUSIC, ESPRIT, Propagator method, Unitary-ESPRIT)
• Approximations of maximum-likelihood methods (EM, SAGE, RiMAX)
• LSE (Least-Square-Error) principles (LMMSEE, covariance matrix fitting)
• Tracking algorithms (Kalman filtering, enhanced Kalman filtering, particle filtering, particle-filter based SAGE)
  The patent also mentions Geometrical Stochastic Channel Models (GSCM) that characterize "multiple paths by delay, Doppler, directions and polarizations" to reproduce time-variant channels. This demonstrates that the detailed path parameters and methods for acquiring them were well-known in the art. The patent itself highlights that its "full-dimensional parametric description of the channel can be much more accurate than using the codebooks", thereby acknowledging the known benefit of more detailed channel information.

3. Motivation to Combine (Problem Solved and Benefits Achieved):
The patent explicitly identifies a significant problem with conventional equalization techniques: "One problem with these techniques... is that they require that channel equalization be performed at the receiver, meaning that the receiver have additional resources in order to perform the equalization". This statement provides a clear and compelling motivation for a POSITA to seek alternative solutions that reduce receiver complexity.

The patent then states its "user-focusing technique adds pseudo “distortion” before the signals are transmitted at the transmitter 110 . These “pre-distorted” signals are then transmitted in such a way that the signal distortion can be successfully removed while propagating". It further emphasizes that a "conventional equalization process in the conventional receiver is not needed anymore, because the pre-distortion can be removed automatically by the propagation channel, i.e. the channel itself works as an equalizer". These statements articulate the motivation to shift the equalization burden from the receiver to the transmitter and the expected benefit of doing so.

Reasoning for Obviousness

A POSITA, motivated by the recognized problem of high computational requirements for channel equalization at the receiver, would have sought ways to offload this complexity to the transmitter. Knowing that transmitter-side precoding/pre-equalization already existed, even in simplified forms like codebook-based approaches or FIR-filter based pre-equalization, the POSITA would naturally consider improving the accuracy and effectiveness of such transmitter-side compensation.

Given the widespread knowledge of various channel estimation algorithms capable of providing highly detailed path parameter information (delay, Doppler frequency, direction of arrival, direction of departure, complex amplitude) for individual propagation paths, and the acknowledged benefit that "full-dimensional parametric description of the channel can be much more accurate than using the codebooks", it would have been obvious to a POSITA to replace the "simplified representations" or FIR filter structures of conventional precoding/pre-equalization with this more detailed and accurate path parameter information.

Applying these detailed path parameters to the transmitter's predistortion logic would inherently lead to compensation across the time, frequency, and spatial domains:

• Time Domain: Compensation for delay τ and Doppler frequency u directly addresses time-domain characteristics and time-variance of the channel.
• Frequency Domain: Compensation for delay τ and Doppler frequency u (which impacts signal phase over time and frequency) would also effectively address frequency domain distortions. The patent's own formula α i *exp(−j 2π(f−u i )τ i ) c Tx *(Ω 1,i ) {circle around (x)}c Rx *(Ω 2,i ) u (f) explicitly shows how frequency (f), Doppler (u), and delay (τ) are used in the predistortion.
• Spatial Domain: Compensation for direction of departure Ω 1 and direction of arrival Ω 2 (using c Tx *(Ω 1,i ) and c Rx *(Ω 2,i ) in the patent's formula) directly addresses spatial selectivity and enables directional energy focusing.

The patent's distinction from prior pre-equalization, which it states removes ISI "in the frequency and spatial domains" but is "only applicable in the fixed wireless, wireless local loop systems" and not "time-variant cases", further points to the obviousness of extending compensation to the time domain for time-variant channels. The detailed path parameters, particularly Doppler frequency, are precisely what is needed to address time-variance. Thus, for a POSITA seeking to improve performance in time-variant channels, incorporating these parameters into a transmitter-side predistortion would be a logical and obvious design choice.

The expected outcome of this combination would be a wireless communication system that achieves improved signal quality, reduced receiver complexity, and effective signal "focusing" at the receiver, precisely the benefits claimed by the patent. Therefore, the combination of known channel estimation and feedback mechanisms with the existing concept of transmitter-side pre-compensation, driven by the motivation to reduce receiver complexity and improve signal focusing by employing more detailed and accurate channel parameter information across time, frequency, and spatial domains, renders claims 1, 8, and 15 obvious.

For US patent 8891347, here's a breakdown of its term adjustments, related applications, and projected expiration:

Patent Term Adjustments (PTA) and Extensions (PTE):

• Patent Term Adjustment (PTA): The Google Patents entry for US8891347 indicates "Adjusted expiration 2032-01-22". This suggests that Patent Term Adjustment (PTA) has been applied to the patent. PTA is granted to compensate for delays caused by the USPTO during the prosecution of a utility or plant patent application. This adjustment adds days to the standard 20-year patent term.
• Patent Term Extension (PTE): There is no indication in the Google Patents data or the provided text of a Patent Term Extension (PTE) for US8891347. PTE is typically 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.

Continuation and Divisional Applications:

• The Google Patents page for US8891347 lists "Other versions" including US20130107733A1. This is a patent application publication, and for utility patents filed on or after June 8, 1995, the patent term is 20 years from the filing date of the earliest U.S. non-provisional or PCT application to which priority is claimed. While not explicitly stated as a continuation or divisional in the provided text, patent family information often links such applications. Without further direct search of the USPTO's Patent Center (formerly Public PAIR), it cannot be definitively confirmed if US20130107733A1 is a continuation or divisional of the application that matured into US8891347.

Related Family Members:

• The primary related family member explicitly mentioned is US20130107733A1, which is the publication of the application that led to US8891347B2. The patent abstract also references "PCT/CN2011/077718" in its "OTHER PUBLICATIONS" section, indicating an international application from which priority might be claimed.

Projected Expiration Date:

• The Google Patents entry for US8891347 explicitly states "Active, expires 2032-01-22". This "Adjusted expiration" date reflects the original 20-year term from the earliest priority date, plus any Patent Term Adjustment (PTA) awarded. The filing date of US8891347 was July 28, 2011. A standard 20-year term from this date would be July 28, 2031. The reported adjusted expiration date of January 22, 2032, suggests a PTA of approximately 5 months and 25 days.

As a Senior Patent Strategist and Research Engineer specializing in Defensive Publishing, I have analyzed US patent 8891347, "User-focusing technique for wireless communication systems," to generate a comprehensive Defensive Disclosure document. The objective is to create "Prior Art" that renders future incremental improvements by competitors obvious or non-novel, building upon the core inventive concept described in the patent.

Given that independent claims 1 (method), 8 (system), and 15 (base station) describe the same underlying "user-focusing technique" from different perspectives, the derivative variations presented below will apply broadly to the core inventive concept. Each derivative will explicitly link back to the relevant elements of these claims, demonstrating how the core functionality can be implemented using alternative materials, expanded parameters, new applications, emerging technologies, or inverse/failure modes.

Combination Prior Art Scenarios

Here are three scenarios where the user-focusing technique of US8891347 can be combined with existing open-source standards to establish prior art for future incremental developments:

1. US8891347 + 3GPP LTE/NR Standard (Open Source / Public Standard):

   • Description: The detailed, multi-domain predistortion technique of US8891347 is integrated into the physical layer (PHY) of a 3GPP Long-Term Evolution (LTE) or New Radio (NR) cellular communication system. This involves extending the standard Channel State Information (CSI) feedback mechanisms, such as those relying on CSI-RS for channel sounding and CSI reports (RSRP, RSRQ, CQI, PMI, RI), to include or enable the real-time derivation of the full set of path parameters disclosed in US8891347 (delay, Doppler frequency, direction of arrival (DoA), direction of departure (DoD), complex amplitude, and polarization for each propagation path). The base station (gNB or eNB) then incorporates a predistortion module that uses this granular path parameter information to generate and transmit signals focused on user equipment (UE). This predistortion occurs across the time, frequency, and spatial domains as specified in US8891347 to achieve coherent signal summation at the UE. This integration optimizes resource utilization, enhances signal quality, and improves interference management within the existing 3GPP cellular framework, offering a more precise alternative or enhancement to conventional precoding in dynamic environments.

2. US8891347 + IEEE 802.11ay (Wi-Fi 60 GHz / mmWave Standard):

   • Description: The user-focusing predistortion technique is implemented in an IEEE 802.11ay compliant Wi-Fi system operating in millimeter-wave (mmWave) bands (e.g., 60 GHz). IEEE 802.11ay already incorporates advanced beamforming and Multi-User Multiple-Input Multiple-Output (MU-MIMO) capabilities. The channel estimation and feedback mechanisms (e.g., sounding frames, Beamforming Training (BFT) sequences) are enhanced to extract the full propagation path parameters (including micro-delays, localized Doppler shifts due to subtle movements, and highly accurate DoA/DoD angles) for each connected client device (Station or STA). The Access Point (AP) then utilizes this detailed, time-varying path information to predistort its transmissions, creating highly focused mmWave beams directed precisely to individual STAs. This predistortion in time, frequency, and spatial domains significantly improves throughput, extends effective range, and minimizes inter-STA interference, especially in dense indoor or outdoor mmWave deployment scenarios where precise beam steering is critical to overcome high path loss and blockages.

3. US8891347 + LoRaWAN (Low-Power Wide-Area Network Standard):

   • Description: The user-focusing technique is adapted for downlink communication in a LoRaWAN (Low-Power Wide-Area Network) system to enhance reliability and energy efficiency for constrained Internet of Things (IoT) end-devices. While LoRaWAN is known for its robustness, focused energy delivery can further improve performance in challenging environments. The LoRaWAN gateway, equipped with an advanced antenna array, initiates the process by transmitting a low-power "first signal" (e.g., a modified beacon or preamble). The LoRaWAN end-device, acting as the receiver, performs a simplified channel estimation based on received signal strength (RSSI), signal-to-noise ratio (SNR), and basic timing information extracted from the gateway's transmission. This coarse path parameter information (e.g., approximate delay, dominant DoA) is fed back to the gateway via the LoRaWAN uplink. The gateway then applies the user-focusing predistortion to its subsequent downlink transmissions, adjusting the phase, amplitude, and temporal characteristics across its antenna elements to coherently sum the signal at the specific end-device location. This enables more reliable communication to devices in cluttered environments, potentially extending battery life by reducing retransmissions, or reaching devices in traditionally difficult-to-penetrate locations.

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Derivative Variations of US Patent 8891347

The following derivatives explore various implementations and applications of the user-focusing technique, each designed to serve as defensive prior art.

Derivative 1: Material & Component Substitution - Reconfigurable Intelligent Surfaces (RIS) as Active Scatterers

• Claim Linkage: Directly modifies the "plurality of propagation paths" and the characteristics of signal interaction with the environment, impacting the "transmitting" and "receiving" steps of Claim 1 (Method), and the "transmitter" and "receiver" components of Claim 8 (System) and Claim 15 (Base Station).
• Enabling Description: In this variant, the conventional propagation environment is augmented with active or passive Reconfigurable Intelligent Surfaces (RIS). Each RIS comprises a two-dimensional array of sub-wavelength metallic or dielectric elements with embedded control circuitry (e.g., varactor diodes, PIN diodes, or MEMS switches). These elements dynamically adjust their electromagnetic response (phase, amplitude, polarization) to incident waves. When the transmitter (e.g., base station 110) sends a "first signal," the receiver (e.g., mobile station 150) performs channel estimation for all paths, including those reflected or refracted by one or more RIS panels. The path parameter information, now explicitly incorporating the complex reflection coefficients and spatial orientation of the RIS panels, is fed back to the transmitter. The transmitter computes the predistortion for the "second signal," simultaneously sending control commands to the RIS network (via a dedicated control channel or out-of-band signaling). The RIS panels then apply specific, synchronized phase/amplitude shifts to the predistorted signal as it reflects off them, actively contributing to the coherent summation at the receiver. This allows for environmental shaping and highly precise, programmable control over the multipath components, enhancing the focusing effect.
• Technical Terminology: Reconfigurable Intelligent Surface (RIS), metamaterial array, sub-wavelength elements, varactor diodes, PIN diodes, MEMS switches, electromagnetic response, complex reflection coefficients, spatial orientation, control channel, out-of-band signaling, environmental shaping, multipath components.

graph TD
    A[Transmitter (Base Station)] -- Tx 1st Signal --> B[Environment + RIS Network]
    B -- Propagation Paths --> C[Receiver (Mobile Station)]
    C -- Channel Estimation (incl. RIS influence) --> D{Path Param Info (Delay, Doppler, DoA, DoD, α, RIS config)}
    D -- Feedback Path Param Info --> A
    A -- Predistort 2nd Signal (Tx, Freq, Spatial, RIS-aware) --> B
    A -- Send RIS Control Signals --> E[RIS Controller]
    E -- Configures Dynamic Properties --> B
    B -- Predistorted Signal + Active RIS Interaction --> C
    C -- Receive Predistorted Signal (Coherent Sum) --> F{Enhanced User Focus}

Derivative 2: Operational Parameter Expansion - Terahertz (THz) Communication for Chip-to-Chip Interconnects

• Claim Linkage: Expands the operating frequency of "wireless communication" and the scale of "propagation paths" for Claim 1 (Method), Claim 8 (System), and Claim 15 (Base Station), enabling ultra-dense, localized applications.
• Enabling Description: This derivative applies the user-focusing technique to Terahertz (THz) frequency communication for high-bandwidth, low-latency chip-to-chip interconnects within a multi-chip module (MCM) or between closely spaced circuit boards. The "transmitter" and "receiver" are integrated THz transceivers on silicon, utilizing on-chip antenna arrays. Due to the extremely short wavelengths (e.g., 0.1 THz to 10 THz) and confined propagation environment, channel estimation captures minute path parameters, including picosecond-scale delays, sub-degree angular deviations (DoA/DoD), and fine-grained complex amplitudes for each micro-reflection and diffraction path within the chip package. These detailed THz path parameters are fed back. The THz transmitter then predistorts a "second signal" using its on-chip phased array, applying highly precise phase and amplitude weighting across its elements. This predistortion creates a super-focused THz beam that ensures maximal energy transfer and coherent signal summation at the target receiving chip's antenna array, mitigating intra-package interference and maximizing data rates for next-generation computing architectures.
• Technical Terminology: Terahertz (THz) frequency, chip-to-chip interconnects, multi-chip module (MCM), integrated THz transceivers, on-chip antenna arrays, picosecond-scale delays, sub-degree angular deviations, micro-reflection, diffraction path, intra-package interference, phased array.

flowchart TD
    TX_Chip[On-Chip THz Tx Array] -- Tx 1st THz Signal --> Chip_Channel[THz Channel (Intra-MCM)]
    Chip_Channel --> RX_Chip[On-Chip THz Rx Array]
    RX_Chip -- Ultra-Fine Channel Est. (ps Delays, Sub-deg AoA/DoD) --> THz_Params[THz Path Parameters]
    THz_Params -- Feedback (Dedicated Control Lines) --> TX_Chip
    TX_Chip -- Predistort 2nd THz Signal (Time, Freq, Nano-Spatial Focusing) --> Chip_Channel
    Chip_Channel -- Super-Focused Beam --> RX_Chip
    RX_Chip -- Receive Focused THz Signal --> Data_Flow[High-BW Data Processing]

Derivative 3: Cross-Domain Application - Focused Energy Delivery for Advanced Manufacturing (3D Printing/Sintering)

• Claim Linkage: Applies the "user-focusing" concept to a non-communication domain, specifically "power transferring" as mentioned in the patent's detailed description, impacting the purpose of the system (Claim 8) and base station (Claim 15).
• Enabling Description: This derivative employs the user-focusing technique for precise, contact-less energy delivery in advanced manufacturing processes, such as microwave or RF-based 3D printing (sintering) of materials. A multi-element electromagnetic (EM) emitter array acts as the "transmitter," generating controlled RF/microwave fields. The "receiver" is a miniature sensor array (e.g., temperature/EM field probes) embedded within or adjacent to the material powder bed at the target sintering location. The EM emitter array transmits a low-power "first signal." The sensor array measures the propagation path characteristics of this EM energy through the material, extracting parameters like localized dielectric properties, specific absorption rate (SAR) anomalies, phase shifts, and micro-scale spatial distribution. This path parameter information is fed back. The EM emitter array then predistorts a high-power "second signal" (the sintering energy) in time, frequency, and spatial domains. This predistortion ensures that the EM energy constructively converges and heats only the desired small volume of material with extreme precision, enabling layer-by-layer selective sintering without overheating surrounding areas, thereby improving resolution, material integrity, and energy efficiency in additive manufacturing.
• Technical Terminology: Advanced manufacturing, 3D printing, sintering, microwave/RF-based printing, electromagnetic (EM) emitter array, material powder bed, miniature sensor array, dielectric properties, specific absorption rate (SAR), phase shifts, micro-scale spatial distribution, selective sintering, additive manufacturing.

flowchart TD
    EM_Emitter[EM Emitter Array (Tx)] -- Tx Low-Power EM Signal (1st) --> Powder_Bed[Material Powder Bed (Process Zone)]
    Powder_Bed -- EM Propagation Paths --> Sensor_Array[Sensor Array (Rx) at Target Sintering Loc]
    Sensor_Array -- Measure EM Path Params (Dielectric, SAR, Phase, Spatial Dist) --> Sinter_Params[Sintering Path Parameters]
    Sinter_Params -- Feedback --> EM_Emitter
    EM_Emitter -- Predistort High-Power EM Signal (Time, Freq, Precise Spatial Focus) --> Powder_Bed
    Powder_Bed -- Constructive EM Convergence --> Sinter_Point[Precisely Sintered Point]

Derivative 4: Integration with Emerging Tech - AI-driven Adaptive Predistortion with Predictive Channel Modeling using Reinforcement Learning

• Claim Linkage: Enhances the "performing a channel estimation" and "predistorting a second signal" steps of Claim 1 (Method) and the corresponding functionalities of the System (Claim 8) and Base Station (Claim 15) through AI integration.
• Enabling Description: The channel estimation module at the receiver and the predistortion engine at the transmitter are tightly integrated with an Artificial Intelligence (AI) / Machine Learning (ML) model, specifically a Reinforcement Learning (RL) agent. The RL agent, operating at the transmitter, continuously observes the feedback channel's path parameters (delay, Doppler, DoA, DoD, complex amplitude) and the resulting Signal-to-Noise Ratio (SNR) or achievable data rate at the receiver (reward signal). Based on this, the RL agent dynamically adjusts the predistortion parameters (its "actions") to optimize for a desired performance metric (e.g., maximizing throughput, minimizing latency, maintaining a "focus" on a rapidly moving target). Over time, the RL agent learns the complex, non-linear relationships between channel conditions, predistortion settings, and system performance, developing a predictive model for optimal predistortion. This allows the system to not only react to current channel conditions but also to anticipate and proactively compensate for rapid channel changes, even with delayed feedback, significantly improving performance in highly dynamic and complex multipath environments.
• Technical Terminology: Artificial Intelligence (AI), Machine Learning (ML), Reinforcement Learning (RL) agent, reward signal, dynamic predistortion parameters, non-linear relationships, predictive model, proactive compensation, multipath environments.

graph TD
    RX_Agent[Receiver (incl. RL Agent)] -- 1. Observe Channel & Performance --> Env_Chan[Wireless Channel]
    Env_Chan -- 2. Channel Est. & Feedback (Path Params) --> TX_RL[Transmitter (incl. RL Agent)]
    TX_RL -- 3. RL Agent Predicts & Adjusts Predistortion --> TX_Ant[Tx Antenna Array]
    TX_Ant -- 4. Transmit Predistorted Signal --> Env_Chan
    Env_Chan --> RX_Agent
    RX_Agent -- 5. Measure Reward (SNR, Data Rate) --> TX_RL
    TX_RL -- 6. Update RL Model --> RL_Model[RL Model DB]

Derivative 5: The "Inverse" or Failure Mode - Adaptive Nulling (Interference Zone Creation)

• Claim Linkage: Deliberately alters the "predistorting a second signal" step of Claim 1 (Method) and the corresponding functionalities of the System (Claim 8) and Base Station (Claim 15) to achieve a controlled "inverse" effect.
• Enabling Description: In this operational mode, the system is configured to perform "adaptive nulling" or "interference zone creation" rather than user-focusing. The "first signal" is transmitted from the transmitter (e.g., base station 110), and the "receiver" (e.g., a specific mobile station 150, or a designated "nulling zone monitor") performs channel estimation to identify the path parameters (delay, Doppler, DoA, DoD, complex amplitude) for all propagation paths leading to a specific target interference zone. This could be a sensitive area where no communication is desired, or a region where controlled interference is required for security or testing. This path parameter information is fed back. The transmitter then predistorts a "second signal" (which could be a regular data stream intended for other users, or a dedicated jamming signal) such that, when it propagates through the identified paths, it experiences destructive interference at the target interference zone. This results in a localized "null" or significant signal attenuation at the precise geographical location of the interference zone, while potentially maintaining normal communication or enhancing signals in other areas.
• Technical Terminology: Adaptive nulling, interference zone creation, destructive interference, specific target interference zone, nulling zone monitor, signal attenuation, localized null, jamming signal, security, testing.

stateDiagram-V2
    [*] --> Normal_Focusing: System Start
    Normal_Focusing --> Adaptive_Nulling_Mode: On (Admin_Command OR Zone_Designated)
    Adaptive_Nulling_Mode --> Normal_Focusing: On (Nulling_Complete OR Zone_Removed)

    state Normal_Focusing {
        CE_Focus: Channel Estimation for Target User
        PD_Focus: Predistort for Constructive Sum
    }

    state Adaptive_Nulling_Mode {
        CE_Null: Channel Estimation for Target Nulling Zone
        PD_Null: Predistort for Destructive Sum
        Monitor_Null: Monitor Nulling Zone Effectiveness
        CE_Focus --> CE_Null: Redirect Channel Estimation Target
        PD_Focus --> PD_Null: Change Predistortion Objective
    }

Derivative 6: Material & Component Substitution - Multi-Modal Sensor Fusion for Path Parameter Estimation

• Claim Linkage: Enhances the "performing a channel estimation" step of Claim 1 (Method) and the "receiver configured to perform a channel estimation" of Claim 8 (System) and Claim 15 (Base Station) by integrating diverse sensor types.
• Enabling Description: The receiver's channel estimation capability is significantly enhanced by incorporating multi-modal sensor fusion, going beyond traditional RF-only measurements. In addition to RF channel sounding, the receiver (e.g., mobile station 150) integrates sensors such as accelerometers, gyroscopes (IMU for precise ego-motion tracking), GPS/GNSS receivers (for absolute position), LIDAR or ultrasonic sensors (for local environmental mapping and scatterer identification), and potentially visual cameras (for optical flow-based velocity estimation of the user and surrounding objects). The "first signal" still originates from the transmitter, but the path parameter information (delay, Doppler, DoA, DoD, complex amplitude, polarization) is no longer derived solely from the received RF signal. Instead, a sensor fusion algorithm combines the RF measurements with the real-time kinematic and environmental data from the other sensors. This fusion provides a more robust, lower-latency, and more accurate estimation of the true physical propagation paths and their dynamic changes, particularly in scenarios with rapid user movement or complex, non-static scatterers. The enhanced path parameter information is then fed back to the transmitter for more precise multi-domain predistortion.
• Technical Terminology: Multi-modal sensor fusion, RF channel sounding, accelerometers, gyroscopes (IMU), GPS/GNSS receivers, LIDAR, ultrasonic sensors, visual cameras, optical flow, ego-motion tracking, local environmental mapping, real-time kinematic data, non-static scatterers, sensor fusion algorithm.

graph TD
    TX[Transmitter] -- Tx 1st Signal --> RF_Path[RF Propagation Path]
    RF_Path --> Rx_Ant[Receiver Antenna]
    Rx_Ant -- RF Measurement --> RF_CE[RF Channel Estimator]
    Rx_Sensors[Receiver Auxiliary Sensors (IMU, GPS, LIDAR, Camera)] -- Env & Motion Data --> Sensor_Fusion[Multi-Modal Sensor Fusion Engine]
    RF_CE -- RF Path Data --> Sensor_Fusion
    Sensor_Fusion -- Fused, Robust Path Params --> Param_FB[Feedback Path Parameter Info]
    Param_FB -- Feedback --> TX
    TX -- Predistort 2nd Signal --> RF_Path
    RF_Path --> Rx_Ant

Derivative 7: Operational Parameter Expansion - Extremely Low Frequency (ELF)/Very Low Frequency (VLF) for Subterranean/Sub-aquatic Communication

• Claim Linkage: Extends the operating frequency and application domain for "wireless communication" and "propagation paths" of the patent into challenging, attenuating mediums for Claim 1 (Method), Claim 8 (System), and Claim 15 (Base Station).
• Enabling Description: This derivative adapts the user-focusing technique for communication in extremely challenging environments like subterranean tunnels, deep mines, or through seawater, utilizing Extremely Low Frequency (ELF) or Very Low Frequency (VLF) electromagnetic waves (e.g., 3 Hz to 30 kHz). At these frequencies, propagation is highly attenuated and dominated by ground conductivity, but offers penetration where higher frequencies fail. The "transmitter" is a large-scale magnetic loop or electric dipole antenna system (e.g., deployed on the surface or within a mine shaft). The "receiver" is a specialized ELF/VLF sensor array (e.g., magneto-inductive coils or electrode arrays) located deep underground or underwater on an exploration vehicle. The transmitter emits a "first signal." The receiver performs channel estimation tailored for ELF/VLF propagation, extracting path parameters such as long-period delays, specific attenuation coefficients, conductivity-induced phase shifts, and coarse spatial arrival directions through the earth or water layers. This unique set of path parameters is fed back, potentially via a hybrid communication link (e.g., acoustic or wired sections). The transmitter then predistorts a "second signal" in the time, frequency, and extremely coarse spatial domains (given the long wavelengths). This predistortion compensates for the bulk properties of the medium to maximize the received signal strength and intelligibility at the receiver, enabling robust, albeit low-data-rate, command-and-control or telemetry links in environments previously inaccessible to conventional wireless.
• Technical Terminology: Extremely Low Frequency (ELF), Very Low Frequency (VLF), subterranean communication, sub-aquatic communication, magnetic loop antenna, electric dipole antenna, magneto-inductive coils, electrode arrays, ground conductivity, attenuation coefficients, conductivity-induced phase shifts, hybrid communication link, command-and-control, telemetry.

graph TD
    TX_ELF[ELF/VLF Tx System] -- Tx 1st ELF/VLF Signal --> Geo_Chan[Geological/Aquatic Channel]
    Geo_Chan -- Attenuated Propagation --> RX_ELF[ELF/VLF Sensor Array (Rx)]
    RX_ELF -- ELF/VLF Channel Estimation (Long Delays, Attenuation, Phase Shifts) --> ELF_Params[ELF/VLF Path Parameters]
    ELF_Params -- Feedback (Hybrid Link) --> TX_ELF
    TX_ELF -- Predistort 2nd ELF/VLF Signal (Time, Freq, Coarse Spatial) --> Geo_Chan
    Geo_Chan -- Penetrating Focused Signal --> RX_ELF
    RX_ELF -- Receive Predistorted Signal --> Low_BW_Comm[Low-Bandwidth Communication]

Derivative 8: Cross-Domain Application - Autonomous Vehicle Sensing and Control (Millimeter-Wave Radar)

• Claim Linkage: Adapts the "user-focusing" concept to a sensing and control application, indirectly supporting "non-communication applications" like "remote sensing" as described in the patent's detailed description, impacting the system (Claim 8) and base station (Claim 15).
• Enabling Description: The user-focusing technique is employed in autonomous vehicle (AV) radar systems for enhanced object detection, tracking, and classification, particularly in dense urban or adverse weather conditions. The "transmitter" is a millimeter-wave (mmWave) radar array on the AV. Instead of a dedicated "receiver" for communication, the radar array itself acts as both transmitter and a sophisticated "passive receiver" (via its reflections) for its own transmitted signals. The radar array emits a "first signal" (chirp or pulse). Reflections from objects (e.g., other vehicles, pedestrians, obstacles) within the environment constitute the received signals. The radar processing unit performs channel estimation on these reflected signals, treating each distinct reflection path from an object as a "propagation path." Path parameters extracted include precise range (delay), velocity (Doppler frequency), high-resolution azimuth/elevation angles (DoA/DoD), and radar cross-section (complex amplitude). This rich "path parameter information" (representing the object's state) is inherently available at the transmitting radar. The radar then "predistorts" subsequent transmitted radar "second signals" (e.g., tailored waveforms or beamforming patterns) in time, frequency, and spatial domains. This predistortion actively shapes the radar beam to "focus" on specific objects or regions of interest, improving signal-to-noise ratio for weak targets, mitigating clutter, performing high-resolution imaging of complex objects, or even creating "anti-focus" nulls for known interference sources, thus enhancing the AV's perception capabilities.
• Technical Terminology: Autonomous vehicle (AV) radar, millimeter-wave (mmWave) radar, object detection/tracking/classification, chirp signal, pulse signal, radar cross-section (RCS), range, velocity, azimuth/elevation angles, clutter mitigation, high-resolution imaging, anti-focus nulls, perception capabilities.

flowchart TD
    Radar_Tx[mmWave Radar Array (Tx)] -- Tx 1st Radar Signal (Chirp/Pulse) --> Env_Objs[Environment + Objects (Reflectors)]
    Env_Objs -- Reflected Radar Signals --> Radar_Rx[mmWave Radar Array (Rx - Passive)]
    Radar_Rx -- Radar Signal Processing (Range, Doppler, AoA/DoD, RCS) --> Obj_Params[Object Path Parameters]
    Obj_Params -- Internal Feedback/Computation --> Radar_Tx
    Radar_Tx -- Predistort 2nd Radar Signal (Time, Freq, Adaptive Spatial Beamforming) --> Env_Objs
    Env_Objs -- Focused Radar Energy / Nulling --> Target_Obj[Targeted Object / Interference Source]

Derivative 9: Integration with Emerging Tech - Quantum Channel Estimation and Predistortion for Secure Communications

• Claim Linkage: Integrates quantum computing principles into the "performing a channel estimation" and "predistorting a second signal" steps of Claim 1 (Method) and the corresponding functionalities of the System (Claim 8) and Base Station (Claim 15), focusing on security and enhanced processing.
• Enabling Description: This derivative integrates quantum computing techniques for ultra-fast and highly secure channel estimation and predistortion. The "first signal" is a standard classical communication signal. However, the receiver's channel estimation process employs a quantum computer (or a specialized quantum processor) to perform a quantum algorithm (e.g., a Quantum Phase Estimation Algorithm or Quantum Fourier Transform-based method) on the received signal and its noise characteristics. This allows for significantly faster and potentially more accurate extraction of path parameter information (delay, Doppler, DoA, DoD, complex amplitude) by exploiting quantum parallelism, especially in highly noisy or rapidly changing channels. The receiver then transmits this quantum-enhanced path parameter information to the transmitter via a Quantum Key Distribution (QKD) secured classical channel, ensuring provable information-theoretic security of the critical channel feedback. The transmitter, also equipped with quantum-assisted processing capabilities, then computes and applies the predistortion for the "second signal" with quantum-level precision, leveraging the high-fidelity path parameters to achieve an even tighter and more robust user-focus.
• Technical Terminology: Quantum computing, quantum processor, Quantum Phase Estimation Algorithm (QPEA), Quantum Fourier Transform (QFT), quantum parallelism, Quantum Key Distribution (QKD), information-theoretic security, quantum-enhanced path parameter information, quantum-level precision, high-fidelity path parameters.

sequenceDiagram
    participant Tx[Classical Transmitter]
    participant QCE[Quantum-Enhanced Receiver (QPU + Rx)]
    participant QKD_Chan[QKD Secured Channel]
    participant QPD[Quantum-Assisted Transmitter (QPU + Tx)]

    Tx->>QCE: Transmit 1st Classical Signal
    QCE->>QCE: Quantum Channel Estimation (QPEA/QFT)
    QCE->>QKD_Chan: Feedback Quantum-Enhanced Path Params (Secured by QKD)
    QKD_Chan->>QPD: Path Params Received
    QPD->>QPD: Quantum-Assisted Predistortion Calculation
    QPD->>Tx: Apply Predistortion (Classical Signal)
    Tx->>QCE: Transmit 2nd Predistorted Classical Signal

Derivative 10: The "Inverse" or Failure Mode - Low-Power Diagnostic Mode with Minimal Feedback

• Claim Linkage: Defines a low-power, limited-functionality mode for the system (Claim 8) and base station (Claim 15), modifying the "performing a channel estimation" and "sending the channel estimation" steps of Claim 1 (Method) for diagnostic purposes.
• Enabling Description: In situations requiring minimal power consumption (e.g., critical battery levels at the receiver, or during network maintenance windows) or when only basic channel integrity needs to be verified, the system enters a "low-power diagnostic mode." The transmitter (e.g., base station 110) sends a very low-power "first signal" at reduced periodicity. The receiver (e.g., mobile station 150) is configured to perform a highly simplified and energy-efficient channel estimation. Instead of a full-dimensional parametric estimation, it only extracts a minimal subset of path parameters, such as the strongest path's average delay and a coarse signal strength indicator (e.g., RSSI). The feedback mechanism is also minimized, sending only this limited path parameter information (e.g., a single byte representing channel quality) at an infrequent rate to conserve energy. The transmitter, upon receiving this limited feedback, either suspends predistortion (operating in a basic broadcast mode) or applies a simplified, default predistortion based on general environmental models rather than specific path parameters. This mode allows for basic link maintenance, emergency signaling, or diagnostic checks with extreme energy efficiency, sacrificing focusing precision for operational longevity or minimal network impact.
• Technical Terminology: Low-power diagnostic mode, minimal feedback, reduced periodicity, energy-efficient channel estimation, limited path parameter information, signal strength indicator (RSSI), coarse average delay, basic broadcast mode, default predistortion, operational longevity.

stateDiagram-V2
    [*] --> Full_Operation: System Active
    Full_Operation --> Low_Power_Diagnostic: On (Battery_Low OR Maint_Cmd)
    Low_Power_Diagnostic --> Full_Operation: On (Battery_Charged OR Maint_Done)
    Low_Power_Diagnostic --> Shutdown: On (Critical_Failure)

    state Full_Operation {
        CE_Full: Full Channel Estimation
        FB_Full: Detailed Path Params Feedback
        PD_Full: Full Multi-Domain Predistortion
    }

    state Low_Power_Diagnostic {
        CE_Min: Minimal Channel Estimation (e.g., RSSI, Avg Delay)
        FB_Min: Limited Path Params Feedback (e.g., 1-byte CQI)
        PD_Simple: Simplified/Default Predistortion OR Broadcast
        CE_Full --> CE_Min: Reduced Scope
        FB_Full --> FB_Min: Reduced Data
        PD_Full --> PD_Simple: Reduced Complexity
    }