US 7676007

Here's a concise summary of US Patent 7676007:

US Patent 7676007 Summary

• Title: System and method for interpolation based transmit beamforming for MIMO-OFDM with partial feedback
• Current Assignee: Integral Wireless Technologies LLC
• Inventors: Jihoon Choi, Robert W. Heath, Jr.
• Filing Date: 2005-07-21
• Issue Date: 2010-03-09
• Abstract: The patent describes a system and method for transmit beamforming with receive combining in Multiple-Input Multiple-Output (MIMO) systems using Orthogonal Frequency Division Multiplexing (OFDM). To reduce the amount of feedback information from the receiver to the transmitter in non-reciprocal channels, the system employs limited feedback and beamformer interpolation. The receiver sends back a fraction of beamforming vectors and additional "interpolation information" (specifically, phase values) to the transmitter. The transmitter then uses this information to interpolate and compute the beamforming vectors for all OFDM subcarriers. The interpolator may be a spherical interpolator and uses these phase rotation parameters, determined at the receiver to maximize minimum channel gain or capacity, to minimize interpolation distortion. The scheme can also be combined with beamformer quantization.

Plain-Language Overview of Independent Claims:

• Claim 1 (Communication Apparatus - Transmitter Side): This claim describes a communication apparatus (e.g., a base station or user equipment) with antennas and a transmitter. The transmitter sends out signals on multiple subcarriers to a receiver. To do this, it uses limited feedback from the receiver, which includes beamforming vectors for only a subset of the subcarriers, along with interpolation information (specifically, phase values). The transmitter then derives the beamforming vectors for the remaining subcarriers (those not in the subset) by interpolating the received subset beamforming vectors, using the provided phase values to aid this interpolation.
• Claim 19 (Communication Apparatus - Receiver Side): This claim describes a communication apparatus (e.g., user equipment) with antennas and a receiver. The receiver receives signals from a transmitter, decodes them, and then determines and provides beamforming vectors for a subset of the subcarriers and interpolation parameters to the transmitter. These interpolation parameters are specifically designed for the transmitter to use to derive the beamforming vectors for the subcarriers not included in the subset. The receiver achieves this by subsampling the subcarriers, selecting a portion, and generating the interpolation parameters from the evaluated beamforming vectors for that selected subset.
• Claim 25 (Communication Apparatus - Receiver Side, Precoding): This claim describes a receiver apparatus that receives signals via OFDM on multiple subcarriers. It decodes these signals and then provides precoding vectors for some of the subcarriers and interpolation parameters to the transmitter. These parameters enable the transmitter to derive precoding vectors for the other subcarriers through interpolation. Crucially, the interpolation information provided by the receiver includes phase values.
• Claim 28 (Communication Apparatus - Transmitter Side, Precoding): This claim describes a transmitter apparatus with antennas that uses OFDM to send signals on multiple subcarriers. It includes a "precode matrix reconstruct unit" that generates precoding matrices based on channel information from the receiver. This channel information specifically contains precoding vectors for a subset of subcarriers and interpolation parameters. The unit then derives the precoding vectors for the subcarriers not in the subset by interpolating the provided subset precoding vectors, and this interpolation is based on the interpolation parameters. The receiver, in turn, is responsible for subsampling, selecting the subset, evaluating the precoding vectors for that subset, and generating the interpolation parameters.
• Claim 40 (Method - Transmitter Side): This claim describes a method for a transmitter to send signals. The method involves receiving limited feedback from a receiver, which includes beamforming vectors for a subset of subcarriers and interpolation information. The transmitter then derives beamforming vectors for the subcarriers not in the subset by interpolating the received subset beamforming vectors using the interpolation parameters. Finally, it provides output signals based on the input signals and these derived beamforming vectors, with the interpolation specifically using phase values from the feedback.
• Claim 41 (Method - Receiver Side): This claim describes a method for a receiver to receive signals. It involves receiving signals from a transmitter, decoding them, and then generating beamforming vectors for a subset of subcarriers and interpolation parameters. These are then provided to the transmitter, enabling it to derive beamforming vectors for other subcarriers. The key here is that the interpolation parameters include phase values.
• Claim 42 (Method - Transmitter Side, Precoding): This claim describes a method for a transmitter to send signals. It involves receiving limited feedback from a receiver, which includes interpolation information and precoding vectors for a subset of subcarriers. The transmitter then derives precoding vectors for the subcarriers not in the subset by interpolating the provided subset precoding vectors using the interpolation parameters. Finally, it provides output signals based on input signals and these derived precoding vectors. The limited feedback information also includes phase values.
• Claim 43 (Method - Receiver Side, Precoding): This claim describes a method for a receiver to receive signals. It involves receiving signals from a transmitter, decoding them, and then generating precoding vectors for a subset of subcarriers and interpolation parameters. These are then provided to the transmitter, enabling it to derive precoding vectors for other subcarriers. The interpolation parameters include phase values.

USPTO and CAFC 2026 Docket Search:

A search of USPTO and CAFC dockets for patent number US7676007 reveals the following:

USPTO Status:

• The patent US7676007B1 is Active and is set to expire on 2028-08-29. This information is directly from the Google Patents record, which sources its legal status from the USPTO.
• The current assignee is Integral Wireless Technologies LLC.

CAFC 2026 Dockets:

• A review of the CAFC 2026 scheduled cases, specifically for May 2026, did not show any direct listings for patent number 7676007.
• The CAFC website provides general case information and resources, but a direct search for specific patent numbers in their dockets requires navigating their search functionalities. No specific litigation related to 7676007 was found in the provided CAFC search results for 2026.

Therefore, as of April 26, 2026, the patent US7676007B1 is active and assigned to Integral Wireless Technologies LLC, with no specific CAFC 2026 docket entries found in the provided search results directly naming this patent number.