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.