US 7822141

Here is a concise summary of US patent 7822141:

Patent Number: US7822141B2

Title: Multiple input, multiple output communications systems

Current Assignee: Integral Wireless Technologies LLC

Inventors: James Wight

Filing Date: 2006-08-31

Issue Date: 2010-10-26

Abstract: Embodiments of the present invention provide systems and methods for optimizing transmitter and receiver weights in a Multiple-Input, Multiple-Output (MIMO) system. One embodiment focuses on optimizing weights to create and steer "beam nulls" to substantially decouple each transmitted signal from others between the MIMO transmitter and receiver. Another embodiment selects weights so that the signal strength of each weighted signal, transmitted through a communications channel along its path, is substantially equivalent, even if the weighting vectors are not necessarily orthogonal. A further embodiment ensures each transmitted signal is coupled only between its own transmitter and receiver antennas with a gain (eigenvalue) that results from the weights and is bounded to a desired range, while the weighting vectors remain orthogonal. The patent also describes embodiments utilizing various decomposition techniques.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method): This claim describes an iterative method for optimizing weights in a MIMO system. It involves generating and transmitting forward weighted signals using initial transmitter weights, receiving reverse weighted signals with receiver weights, determining these receiver weights, and then choosing updated transmitter weights for the forward channels based on the determined receiver weights to achieve a target gain. This process of transmitting, receiving, and determining is repeatedly performed until the transmitter and/or receiver weights reach target optimal values.

• Claim 7 (MIMO Signal Transmitter): This claim defines a MIMO signal transmitter apparatus. It includes multiple signal inputs, multiple vector multipliers (each weighting an input signal with a vector V), multiple combiners to combine these weighted signals, and multiple antennas to transmit the combined weighted signals.

• Claim 10 (MIMO Signal Transmission System): This claim describes a complete MIMO signal transmission system. It comprises a transmitter section (signal inputs, transmit vector multipliers using vector V, transmit combiners, transmit antennas) and a receiver section (receive antennas, receive vector multipliers using a vector of the form V⁻¹L⁻¹, receive combiners, and signal outputs).

• Claim 14 (Method of Assigning Weighting Factors): This claim outlines a method for assigning antenna array weighting factors in a multiple antenna transmitter. It involves calculating a transmission matrix H, then using a first decomposition technique to break H down into a lower triangular matrix L and a unitary matrix Q (H=LQ). Subsequently, Q is orthogonalized using a second decomposition technique into a matrix V (transmitter weighting coefficients), a diagonal matrix A (eigenvalues), and an inverse matrix V⁻¹ (Q=VAV⁻¹). Finally, the results are combined such that H=LVAV⁻¹.

• Claim 17 (MIMO Signal Transmitter with Orthonormal V): This claim is similar to Claim 7, defining a MIMO signal transmitter. Key additions are that the weighting matrix V is orthonormal, and each vector V is selected to ensure that the signal strength of each weighted signal received at a receive array along its path is substantially equivalent.

• Claim 20 (MIMO Signal Transmission System with Orthonormal V): Similar to Claim 10, this describes a MIMO signal transmission system. The distinguishing feature is that the weighting matrix V, used by the transmit vector multipliers, is orthonormal.

• Claim 23 (Method of Assigning Weighting Factors with Unit Magnitude Eigenvalues): This claim builds upon Claim 14, specifying the method for assigning weighting factors. The crucial addition is that all eigenvalues in the diagonal matrix A have a unit magnitude, which results in equal Signal-to-Noise Ratios (SNRs) for the output signals.

• Claim 26 (MIMO Signal Transmitter with H=LQ and V as Q's Eigenvectors): This claim describes a MIMO signal transmitter. It specifies that the channel matrix H is formed as the product of a lower triangular matrix L and a unitary matrix Q (H=LQ), and the transmitter weighting matrix V is explicitly defined as a matrix of eigenvectors for the unitary matrix Q.

• Claim 29 (MIMO Signal Transmission System with H=LQ and V as Q's Eigenvectors): This claim details a MIMO signal transmission system. Similar to Claim 26, it states that the channel matrix H is formed from the product of a lower triangular matrix L and a unitary matrix Q (H=LQ), and the transmitter weighting matrix V comprises eigenvectors for the unitary matrix Q. The receive vector multipliers utilize a vector of the form V⁻¹L⁻¹.

Litigation Information (CAFC and other dockets):
The patent US7822141B2 has been involved in litigation. As of the provided data, cases have been filed in:

• Texas Eastern District Court (case 2:26-cv-00263)
• Texas Eastern District Court (case 2:25-cv-00644)
• Florida Southern District Court (case 0:25-cv-62546)
  Additionally, there is a record of the first worldwide family litigation filed.

Known litigation involving US patent 7822141 is listed below. The information is derived from the "Litigation Information" section of the patent summary, which is based on the Google Patents record for US7822141B2.

Patent Number: US7822141B2

Current Assignee: Integral Wireless Technologies LLC (Likely Plaintiff, but not explicitly stated for each case in the source.)

Known Litigation Cases:

• Case 1

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:26-cv-00263
  • Plaintiff(s): Not explicitly stated in the provided patent text. (Likely Integral Wireless Technologies LLC, the current assignee.)
  • Defendant(s): Not explicitly stated in the provided patent text.
  • Filing Date: The case number indicates a filing in 2026. The specific date is not explicitly stated in the provided patent text.
  • Outcome/Current Status: Not explicitly stated in the provided patent text.

• Case 2

  • Jurisdiction: Texas Eastern District Court
  • Case Number: 2:25-cv-00644
  • Plaintiff(s): Not explicitly stated in the provided patent text. (Likely Integral Wireless Technologies LLC, the current assignee.)
  • Defendant(s): Not explicitly stated in the provided patent text.
  • Filing Date: The case number indicates a filing in 2025. The specific date is not explicitly stated in the provided patent text.
  • Outcome/Current Status: Not explicitly stated in the provided patent text.

• Case 3

  • Jurisdiction: Florida Southern District Court
  • Case Number: 0:25-cv-62546
  • Plaintiff(s): Not explicitly stated in the provided patent text. (Likely Integral Wireless Technologies LLC, the current assignee.)
  • Defendant(s): Not explicitly stated in the provided patent text.
  • Filing Date: The case number indicates a filing in 2025. The specific date is not explicitly stated in the provided patent text.
  • Outcome/Current Status: Not explicitly stated in the provided patent text.

Additionally, the patent record notes the "First worldwide family litigation filed," with a link to darts-ip.com, but no specific case details are provided within the patent text itself for this broader family litigation.

No further specific details regarding plaintiffs, defendants, precise filing dates, or outcomes for these particular case numbers were explicitly found in the provided patent text or the conducted search results.

Proceedings overview

There are no AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method) on file for US7822141B2 as of the most recent ingest from the USPTO Open Data Portal, and web searches did not surface any additional proceedings. This means the patent has not been subjected to PTAB challenges, offering a different defensive posture than a patent that has survived multiple IPRs.

Strategic summary

As there are no PTAB proceedings on file for US7822141B2, all claims (1-30) remain untested by the PTAB. There are no claims that have been canceled or sustained through an AIA trial, and no estoppel has been created under § 315(e)(2). This implies that a potential defendant facing assertion of this patent would have a full range of prior art grounds available for a new IPR or PGR petition, should they choose to challenge the patent's validity at the PTAB. The absence of PTAB activity could indicate that the patent has not been extensively asserted in the past, or that prior challenges (if any) did not proceed to an AIA trial.

Recommended next steps

If you are a defendant currently facing an assertion of US7822141B2, the absence of PTAB activity means that all claims are currently presumed valid without the benefit or detriment of prior PTAB scrutiny. You could consider initiating a new AIA trial (such as an Inter Partes Review or Post-Grant Review, depending on the claims and relevant prior art) if a robust invalidity argument can be built against the asserted claims based on prior art. This would allow you to proactively challenge the patent's validity at the USPTO, potentially narrowing the claims or invalidating the patent entirely. Without any prior PTAB decisions, there is no estoppel to consider regarding the grounds that can be raised.

Inventors

• James Wight: Likely employed by or associated with IceFyre Semiconductor, Inc. at the time of filing. IceFyre Semiconductor Inc. was a WiFi chip startup that was winding down operations in May 2005.

Original assignee

The patent lists "Individual" as the original assignee, referring to the inventor, James Wight. The first corporate entity in the chain, IceFyre Semiconductor, Inc., was a WiFi chip startup focused on single-chip modem solutions for 5-GHz wireless local area networks. IceFyre Semiconductor Inc. was reportedly winding down its operations in May 2005, which was prior to the patent's filing date of August 31, 2006. Thus, IceFyre Semiconductor Inc. did not ship a product embodying the claims under this patent's ownership. The company's current status is presumed dissolved or defunct given its reported winding down in 2005.

Assignment timeline

• 2007-10-23 (executed) / recorded 2007-11-02 — Reel 020478/0746
  • Conveyance: ASSIGNMENT
  • Assignor: ICEFYRE SEMICONDUCTOR, INC.
  • Assignee: ZARBANA DIGITAL FUND LLC
  • Correspondent: DANIEL E. HOULE, ESQ., WEIDE & MILLER, LTD., 11815 S. EASTERN AVENUE, SUITE 220, HENDERSON, NEVADA, 89074.
  • Context: Transfer from an apparently defunct operating company (IceFyre Semiconductor, Inc.) to an investment fund.
• 2024-10-10 (executed) / recorded 2024-10-16 — Reel 065586/0328
  • Conveyance: ASSIGNMENT
  • Assignor: ZARBANA DIGITAL FUND LLC
  • Assignee: INTELLECTUAL VENTURES ASSETS 199 LLC
  • Correspondent: Intellectual Ventures Management, LLC, 2711 Centreville Road, Suite 400, Wilmington, DE, 19808. This correspondent also appears on the subsequent assignment for this patent.
  • Context: Transfer from a fund to an entity associated with Intellectual Ventures, a known patent monetization firm.
• 2024-10-10 (executed) / recorded 2024-10-16 — Reel 065586/0329
  • Conveyance: ASSIGNMENT
  • Assignor: INTELLECTUAL VENTURES ASSETS 199 LLC
  • Assignee: INTEGRAL WIRELESS TECHNOLOGIES LLC
  • Correspondent: Intellectual Ventures Management, LLC, 2711 Centreville Road, Suite 400, Wilmington, DE, 19808. This correspondent also appears on the preceding assignment for this patent.
  • Context: Divestment from an Intellectual Ventures entity to Integral Wireless Technologies LLC, a Texas-based patent monetization firm.

Timeline diagram

timeline
    title Ownership of US 7822141
    2006 : Filed by inventor James Wight
    2007 : Assigned to Zarbana Digital Fund LLC
    2010 : Issued
    2024 : Assigned to Intellectual Ventures Assets 199
         : Assigned to Integral Wireless Technologies LLC
    2025 : First infringement suit filed

NPE / troll-pattern signals

1. Shell-entity transfer — Present

   • IceFyre Semiconductor, Inc. to Zarbana Digital Fund LLC: IceFyre was winding down operations in 2005, indicating it was no longer an operating entity at the time of the 2007 assignment (Reel 020478/0746). Zarbana Digital Fund LLC's name suggests an investment or fund-based business, rather than product development.
   • Zarbana Digital Fund LLC to Intellectual Ventures Assets 199 LLC: Intellectual Ventures (and its asset-holding LLCs) is widely described as a patent monetization firm and "patent troll" (Reel 065586/0328).
   • Intellectual Ventures Assets 199 LLC to Integral Wireless Technologies LLC: Integral Wireless Technologies LLC was created in Texas on September 30, 2024, and has been identified as a "Texas monetization firm" that has received patents from Intellectual Ventures and commenced litigation (Reel 065586/0329).

2. Known asserter in the chain — Present

   • Intellectual Ventures Assets 199 LLC is an entity associated with Intellectual Ventures, which is a widely recognized patent monetization firm and is often characterized as a "patent troll." (Reel 065586/0328).
   • Integral Wireless Technologies LLC is the current assignee and has filed multiple patent infringement lawsuits involving this patent. RPX identifies Integral Wireless as a "Texas monetization firm." (Reel 065586/0329).

3. Repeat correspondent across the chain — Present

   • Intellectual Ventures Management, LLC, of Wilmington, DE, is listed as the correspondent for two consecutive assignments in 2024 (Reel 065586/0328 and Reel 065586/0329).

4. Cascading transfers — Present

   • Two consecutive assignments were executed on the same day (2024-10-10) and recorded on the same day (2024-10-16): from Zarbana Digital Fund LLC to Intellectual Ventures Assets 199 LLC, and then from Intellectual Ventures Assets 199 LLC to Integral Wireless Technologies LLC (Reel 065586/0328 and Reel 065586/0329).

5. Pre-litigation transfer — Present

   • The patent was assigned to Integral Wireless Technologies LLC on October 10, 2024 (execution date) (Reel 065586/0329). Litigation involving this patent, such as the case filed in the Florida Southern District Court (0:25-cv-62546), was initiated on March 12, 2025, which is within six months of the assignment. Another case (Integral Wireless Technologies LLC v. Social Mobile) was filed on June 18, 2025.

6. Bankruptcy fire-sale — Not present

7. Privateering — Unclear

   • While RPX reports that Intellectual Ventures appears to retain an interest in the monetization of portfolios divested to firms like Integral Wireless Technologies LLC, direct evidence of an operating company's involvement on whose behalf the patent is being asserted is not explicitly stated in the provided records.

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

Verdict

NPE — high confidence

The patent exhibits multiple strong signals consistent with NPE activity. It was transferred to Intellectual Ventures, a well-known patent monetization firm, and then to Integral Wireless Technologies LLC, identified as a "Texas monetization firm." The transfers included cascading assignments and a pre-litigation transfer, with lawsuits commencing shortly after the final assignment. The consistent use of Intellectual Ventures Management, LLC as correspondent further supports this conclusion.

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

Most Relevant Prior Art for US Patent 7822141

To identify the most relevant prior art for US patent 7822141, I will examine the patent citations listed on the face of the patent. The patent document itself is the authoritative source for these citations.

Note: The provided patent text for US7822141B2 does not explicitly list "Prior Art References" in a structured section with full citations and descriptions. Instead, it mentions "Prior art keywords" and "Priority claimed from US10/884,633" which indicates a parent application. To fulfill the request, I will treat the "Priority claimed from US10/884,633" as the most directly relevant prior art reference, as it represents a continuation or divisional relationship. If other prior art references were explicitly listed within the patent text, I would include them.

Priority Application: US10/884,633

• Full Citation: U.S. patent application Ser. No. 10/884,633
• Publication/Filing Date: July 2, 2004
• Brief Description: US7822141B2 claims the benefit of and priority to U.S. patent application Ser. No. 10/884,633. This indicates that US10/884,633 is a foundational application for the subject matter of US7822141B2. The disclosure of US10/884,633 is incorporated by reference in its entirety into US7822141B2, meaning its content is considered part of the current patent's disclosure.
• Potentially Anticipates Claim(s) under 35 U.S.C. § 102: Given that US7822141B2 claims priority to US10/884,633 and incorporates its disclosure by reference, it is highly probable that US10/884,633 would anticipate all claims (Claims 1-30) of US7822141B2 under 35 U.S.C. § 102. This is because the earlier filed application likely describes the same invention. If the claims of US7822141B2 are not patentably distinct from the disclosure of US10/884,633, then the priority application would directly anticipate them. The purpose of claiming priority is typically to leverage the earlier filing date for common subject matter.

Since the provided text only explicitly mentions the priority application US10/884,633 as a direct reference, and does not list other "Prior Art References" with full details, this is the most relevant prior art directly cited within the provided patent information. For a more exhaustive prior art analysis, a comprehensive search of the USPTO database for examiner-cited art and applicant-cited art would typically be performed.

The following analysis of obviousness for US patent 7822141 under 35 U.S.C. § 103 relies solely on the known techniques, concepts, and mathematical procedures described within the patent's "BACKGROUND OF THE INVENTION" and "Mathematical Description" sections, as no specific prior art documents (e.g., patent numbers, publications) were explicitly provided in the designated "Prior Art section" of the initial Google Patents data or in previously generated sections. This limits the analysis to combinations of recognized general knowledge in the field as described by the patent itself.

A Person Having Ordinary Skill in the Art (PHOSITA) in 2004 would have been knowledgeable in linear algebra, matrix decompositions, and the principles of MIMO wireless communication systems.

General Considerations for Obviousness

The patent primarily introduces two key approaches for optimizing MIMO weights: an iterative method (Claim 1) and methods based on specific matrix decompositions, particularly Alternative Unit Magnitude Decomposition (AUMD) (Claims 10, 14, 17, 20, 23, 26, 29).

Obviousness Analysis of Independent Claims

Claim 1 (Method: Iterative Optimization for TDD)

Combination of Prior Art Elements:
Claim 1 describes an iterative method for optimizing transmitter and receiver weights in a MIMO system, specifically leveraging the reciprocal nature of channels in a Time Division Duplex (TDD) link.

• Known Elements:
  • MIMO Systems and Weighting: The general concept of MIMO systems utilizing multiple antennas at both transmitter and receiver, and applying weighting vectors to signals, was well-known to improve signal quality and capacity.
  • TDD Channel Reciprocity: The patent explicitly states that in TDD systems, "the wireless LAN channel is reciprocal," meaning the forward and reverse channels are identical. This reciprocity allows weights determined for one link (e.g., receive weights on the reverse link) to be used or adapted for the other (e.g., transmit weights on the forward link).
  • Iterative Optimization: Iterative processes for refining parameters to achieve an optimal state are a fundamental concept in signal processing and control systems. The patent itself mentions "an elegant and rapid iterative optimization can be used to obtain the transmission and receive weighting values."
  • Maximizing Gain / Target Values: Goals like maximizing channel gain or achieving specific target signal properties (e.g., equal signal strengths) are common objectives in communication system design.

Motivation for Combination:
A PHOSITA would be motivated to improve the performance of MIMO systems by efficiently determining optimal transmit and receive weights. Given the known reciprocity of TDD channels, it would be a straightforward and obvious approach to leverage information from one link (e.g., receiver weights determined on the reverse link) to update weights for the other (e.g., transmitter weights for the forward link). The iterative nature of the process is a natural way to converge towards optimal values when direct, single-step solutions are complex or depend on dynamically changing channel conditions. The patent itself articulates this motivation, stating that "processing at both the transmitter and receiver, as specified herein, is particularly advantageous when the forward and reverse channels are identical, as in Time Division Duplexing links. Not only do the transmitters at both ends of the link have knowledge of the same channel, their individual weights can be used for both transmission and reception." Therefore, combining these known elements into an iterative method for TDD systems would have been obvious to a PHOSITA seeking to optimize MIMO performance.

Claim 7 (MIMO Signal Transmitter)

Combination of Prior Art Elements:
Claim 7 describes a MIMO signal transmitter comprising signal inputs, vector multipliers, combiners, and antennas.

• Known Elements:
  • MIMO Transmitter Architecture: The fundamental components of a MIMO transmitter, including multiple antennas, were explicitly known. The patent's background describes antenna arrays being used at both transmission and reception locations.
  • Weighting Signals: The concept of weighting signals prior to transmission with "appropriate weighting vectors" to maintain specific gain and phase relationships among antennas in an array was a known practice. This implies the use of vector multipliers.
  • Combining Signals: Summation elements or combiners for combining weighted signal components before transmission are depicted in prior art diagrams (e.g., FIG. 3, which is described as illustrating "preferred elements within the transmitter...").

Motivation for Combination:
The architecture described in Claim 7 is a conventional representation of a MIMO transmitter. A PHOSITA would routinely design a transmitter with these basic functional blocks (inputs, weighting, combining, transmitting antennas) based on the well-established principles of MIMO and smart antenna systems. The innovation of the patent primarily lies in how the weighting vectors are determined, not in the fundamental components themselves. The combination of these generic components to form a MIMO transmitter would have been obvious to a PHOSITA.

Claim 10 (MIMO Signal Transmission System) & Claim 14 (Method of Assigning Weighting Factors - AUMD)

These claims, and subsequent dependent claims (17, 20, 23, 26, 29) that build upon them, center around the Alternative Unit Magnitude Decomposition (AUMD) technique. We will analyze the obviousness of the AUMD concept and its implementation.

Combination of Prior Art Elements (for AUMD):

• Goal of Diagonalization in MIMO: A primary goal in MIMO systems is to diagonalize the effective channel matrix (UᵀHV = Λ) to enable the transmission of multiple, independent data streams with minimized interference.
• Known Matrix Decompositions:
  • LQ Decomposition: The patent states that "an arbitrary channel matrix H can be written as the product of a lower triangular matrix L and a unitary matrix Q (H=LQ)." This phrasing suggests that LQ decomposition (analogous to the well-known QR decomposition) is a standard mathematical procedure in linear algebra.
  • Eigenvalue Decomposition (EVD) of Unitary Matrices: The patent explicitly describes that "the unitary matrix Q can then be orthogonalized using eigenvalue decomposition" and that a "unitary matrix Q can be expressed in terms of its eigenvectors and eigenvalues as: Q=VΛV⁻¹." It also states that eigenvalues of a unitary matrix "all lay on the unit circle of the complex plane."
• Desired Performance Characteristics: A PHOSITA would be motivated to achieve:
  • Equal Signal-to-Noise Ratios (SNRs) at the receiver: The patent notes that "equal signal-to-noise ratios for each of the signals s_o will be equal, thereby minimizing packet error rate degradation due to unequal signal-to-noise ratios." It explicitly links this to eigenvalues lying on the unit circle for unitary matrices.
  • Orthogonal Weighting Vectors (minimizing crosstalk): The patent highlights that orthogonal eigenvectors "can result in significant suppression of cross-talk between the multiple signals on the link."
  • Equal Composite Signal Strengths to Power Amplifiers: The patent points out the benefit of "equal composite power levels to the multiple power amplifiers of the MIMO transmitter" to avoid "different power back-off and lower power-added efficiency" associated with other methods like SVD with water-filling.

Motivation for Combination (Claims 10, 14, and related claims):
A PHOSITA, aiming to design an optimal MIMO system with the desired properties (diagonalized channel, equal SNRs, orthogonal vectors, efficient power amplifier use), would systematically explore known mathematical tools and their combinations.

1. Addressing known limitations: The patent describes limitations of existing EVD and UMD techniques, specifically mentioning unequal power amplifier loading (EVD) and potential lack of orthogonal eigenvectors or full rank (UMD). The AUMD method is presented as a solution to these issues, promising "equal signal-to-noise ratios at the receiver outputs" and "equal signal levels at the transmitter power amplifiers, since the transmitter weighting coefficient matrix V is now orthonormal." This clear problem-solution context establishes a strong motivation.
2. Straightforward Mathematical Derivation: Given the goal of diagonalizing the channel H, and the knowledge of LQ decomposition (H=LQ) and eigenvalue decomposition of a unitary matrix (Q=VΛV⁻¹), a PHOSITA would find the combined expression H=LVΛV⁻¹ to be a straightforward mathematical manipulation. Furthermore, to achieve S_o = Λ S_i, it would be an obvious mathematical step to select the transmitter weights as V and the receiver weights as V⁻¹L⁻¹.
3. Achieving Known Benefits: By combining these known mathematical decompositions, the PHOSITA would recognize that the resulting properties (eigenvalues of Q having unit magnitude leading to equal SNRs, and V being orthonormal leading to equal power to amplifiers) directly achieve the long-sought desirable performance characteristics for MIMO. The AUMD approach inherently yields these benefits as a consequence of the chosen decomposition strategy, making the features of claims 17, 20, 23, 26, and 29 obvious once AUMD itself is considered obvious.

In summary, the general architecture of a MIMO system (Claim 7) and the iterative TDD method (Claim 1) would likely be considered obvious combinations of known techniques. The AUMD method (Claim 14) and systems/transmitters implementing it (Claims 10, 17, 20, 26, 29) are also likely obvious given that the component mathematical decompositions (LQ and EVD of unitary matrices) are described as known in the art, and a PHOSITA would be motivated to combine these techniques to achieve recognized and desirable performance benefits in MIMO communication.