US 7548592

US Patent 7548592, titled "Multiple input, multiple output communications systems," was invented by James Stuart Wight. The patent was filed on September 30, 2004, and issued on June 16, 2009. The current assignee is Integral Wireless Technologies LLC.

Abstract:
The patent describes systems and methods for optimizing transmitter and receiver weights in a Multiple-Input, Multiple-Output (MIMO) system. One embodiment focuses on creating and steering beam nulls to substantially decouple transmitted signals. Another embodiment selects weights to achieve substantially equivalent signal strength for each weighted signal at the receiver, even if weighting vectors are not orthogonal. A further embodiment ensures each transmitted signal is coupled only between its own transmitter and receiver antennas with a gain (eigenvalue) within a desired range, while maintaining orthogonal weighting vectors. The patent also provides embodiments employing various decomposition techniques.

Independent Claims Overview:

• Claim 1 (Transmitter): This claim describes a MIMO signal transmitter. It includes multiple signal inputs, multipliers to weight each input signal with a vector (V), combiners to combine these weighted signals, and antennas to transmit the combined signals. The key characteristic is that V represents a matrix of transmitter weighting coefficients, and the inverse of V (V⁻¹) along with a lower triangular matrix L (V⁻¹L⁻¹) forms a matrix of receiver weighting coefficients.
• Claim 9 (Transmission System): This claim describes a complete MIMO signal transmission system. It encompasses the components of the transmitter from Claim 1 (signal inputs, multipliers, transmit combiners, transmit antennas) and adds receiver components: receive antennas, receive vector multipliers (which weight received signals with a vector of the form V⁻¹L⁻¹), receive combiners, and signal outputs.
• Claim 16 (Method of Transmitting): This claim outlines a method for transmitting a signal through a transmission channel. It involves calculating a transmission matrix H for the channel. This matrix H is then decomposed using a first technique into a lower triangular matrix L and a unitary matrix Q (H=LQ). Next, the unitary matrix Q is orthogonalized using a second decomposition technique into a product of a transmitter weighting coefficient matrix V, a diagonal matrix Λ (containing eigenvalues), and the inverse of V (V⁻¹), such that Q=VΛV⁻¹. Finally, the results of these decompositions are combined (H=LVΛV⁻¹), and the signal is transmitted using this transmission matrix H.

CAFC 2026 Dockets:
A search for US7548592 in the CAFC 2026 dockets did not return any specific case listings for this patent number. While the patent information page indicates "Family has litigation" with cases filed in Texas District Courts and a "First worldwide family litigation filed" dating back to 2004, no specific 2026 cases at the CAFC were identified.