Wisconsin Alumni Research Foundation

Akbar Muhammad Sayeed

John H Brady

Eko Nugroho Onggosanusi

Nader Behdad

Barry Van Veen

Robert David Nowak

Vasanthan Raghavan

Thiagarajan Sivanadyan

Waheed Uz Zaman Bajwa

Ke Liu

Jarvis Haupt

A receiver detects a plurality of information symbols. A first signal and a second signal are received from a first transmitted signal and a second transmitted signal, respectively, transmitted by a first plurality of antennas and received by a second plurality of antennas connected to the receiver. The second signal is received after the first signal. The receiver spatially filters the first signal using a spatial filter matrix. The receiver computes a conjugate of the first filtered signal to define a conjugate first signal, and spatially filters a second signal using the spatial filter matrix. The receiver computes a Hadamard product of the first filtered signal and the conjugate first signal to define a differential measurement signal. The receiver detects the plurality of information symbols from the differential measurement signal.

Differential MIMO transceiver

A method of estimating a spatial filter matrix is provided. A conjugate of a received first signal defines a conjugate first signal. A Kronecker product of the defined first signal and a received second signal define a differential measurement signal. The computations are repeated for a plurality of first and second signals sufficient to compute an estimate of a channel matrix from the differential measurement signals. A spatial filter matrix is computed from the computed estimate of the channel matrix. The computed spatial filter matrix is used in a data communication phase between the first plurality of antennas and the second plurality of antennas.

A method of locating a radiator is provided. A channel measurement vector is defined that includes a signal value measured at each of a plurality of antennas in response to a signal transmitted from a radiator. (a) A cell covariance matrix of a first cell from a plurality of cells defined for a region in which the radiator is located is selected. (b) A likelihood value that the radiator is located in the first cell is calculated using the selected cell covariance matrix and the defined channel measurement vector. (a) and (b) are repeated with each cell of the plurality of cells as the first cell. A cell location of the radiator is selected based on the calculated likelihood value for each cell of the plurality of cells.

Radiator localization

Beam measurement values are computed by transforming a signal to a beamspace representation using a beamforming matrix that includes a plurality of columns that define a plurality of beams. A second plurality of beams is selected from the plurality of beams based on a power captured by each beam derived from the computed beam measurement values. For each beam of the second plurality of beams as a first beam, a spatial phase shift component and a temporal delay component is computed based on the fixed spatial angle associated with the first beam and a carrier frequency, a filter is defined using the spatial phase shift component and the temporal delay component, a beam measurement value associated with the first beam from the computed beam measurement values is selected, and the defined filter is applied to the selected beam measurement value to define a filtered value.

Wideband transceiver for antenna array

A transmitter supporting multiple-input, multiple-output communications is provided. The transmitter includes a signal processor, a plurality of feed elements, and an aperture. The signal processor is configured to simultaneously receive a plurality of digital data streams and to transform the received plurality of digital data streams into a plurality of analog signals. The number of the plurality of digital data streams is selected for transmission to a single receive antenna based on a determined transmission environment. The plurality of feed elements are configured to receive the plurality of analog signals, and in response, to radiate a plurality of radio waves toward the aperture. The aperture is configured to receive the radiated plurality of radio waves, and in response, to radiate a second plurality of radio waves toward the single receive antenna.

Hybrid analog-digital phased MIMO transceiver system

A device, method, and computer-readable medium are provided. The device includes, but is not limited to, an antenna configured to receive a multipath signal and a processor operably coupled to the antenna to receive the multipath signal. The processor is configured to determine a training signal transmitted from a second device to create the received multipath signal; sample the received multipath signal; and determine channel coefficients based on the sampled multipath signal and the determined training signal using a mixed-norm convex optimization process, wherein the channel coefficients characterize a channel associated with the multipath signal.

Determining channel coefficients in a multipath channel

A wireless communication system supporting improved performance in a sparse multi-path environment is provided that uses spatially reconfigurable arrays. The system includes a first device and a second device. The first device includes a plurality of antennas and a processor operably coupled to the plurality of antennas. The plurality of antennas are adapted to transmit a first signal toward a the second device and to receive a second signal from the second device. The processor is configured to determine an antenna spacing between the plurality of antennas based on an estimated number of spatial degrees of freedom and an estimated operating signal-to-noise ratio. The second device includes a receiver adapted to receive the first signal from the first device, a transmitter adapted to transmit the second signal toward the first device, and a processor. The processor estimates the number of spatial degrees of freedom and the operating signal-to-noise ratio from the received first signal.

Method and system for improving performance in a sparse multi-path environment using reconfigurable arrays

A system supporting data retrieval from a plurality of wireless sensor nodes is defined. The system includes the plurality of wireless sensor nodes and a data retrieval device. The plurality of wireless sensor nodes include a transceiver receiving a first signal and transmitting a second signal. The second signal includes a sensed datum or an encoded statistic based on the sensed datum identified at the plurality of wireless sensor nodes. The data retrieval device includes a plurality of antennas transmitting the first signal toward the plurality of wireless sensor nodes and receiving the second signal from the plurality of wireless sensor nodes, and a processor coupled to receive the received second signal from the plurality of antennas, the processor defining a virtual receive signal from the received second signal for the plurality of antennas and processing the defined virtual receive signal to determine the identified sensed datum.

Method and system for retrieving information from wireless sensor nodes

A system and method for performing extended space-time processing. An improved symbol decision is generated of a desired sub-channel of the signal vector by first generating a baseline decision for the sub-channel. A contribution of a strongest sub-channel is subtracted from the signal vector to generate a modified signal vector. The modified signal vector is multiplied by a unitary matrix generated from a QR decomposition of another channel matrix. Channel interference of the remaining sub-channels of the modified signal vector is cancelled from a remaining sub-channel.

Layered space time processing in a multiple antenna system

A method and system is described for more optimally managing the usage of a wideband space-time multipath channel. The wideband space-time multipath channel is decomposed into a plurality of orthogonal sub-channels, where the orthogonal sub-channels having the best signaling characteristics are used for transmitting one or more signal streams. For purposes of decomposing the wideband space-time multipath channel into a plurality of orthogonal sub-channels, channel estimates are determined for each signal propagation path. A closed-form singular value decomposition of the channel corresponding to each receive antenna before coherent combining is utilized to obtain an orthogonal decomposition of the overall effective space-time channel after coherent combining. By using the overall effective space-time channel after coherent combining rather than before coherent combining, the complexity and correspondingly the resources required for obtaining the orthogonal sub-channels is significantly reduced. The method and system further provide for transmit power to be allocated between the selected sub-channels in order to minimize the effective bit-error rate for a fixed average throughput or to maximize average throughput for a fixed minimum effective bit-error rate.

Growing community of inventors

Madison, WI, United States of America

Akbar Muhammad Sayeed