Cisco Technology, Inc.

Raytheon Company

Bror Peterson

Hang Jin

Daniel Wee

Matthew Aaron Silverman

Li Guo

Paul Jeffrey Stager

John Grabner

Yanxin Na

William E Coleman, Jr

William H Mosley, Jr

Mark A Gloudemans

Jayanti Patel

Kommanaboyina Subramanyam

Techniques are provided to allow for implicit determination of the full spatial signature of a wireless channel between first and second wireless devices for multiple-input multiple-output (MIMO) wireless communication between the first and second wireless devices. The first wireless device receives uplink signals at a plurality of antennas of the first wireless device that are transmitted via a plurality of antennas of a second wireless device. Values at a plurality of subcarriers of the received signals across the plurality of antennas of the first wireless device are derived. Using a sliding window for groups of adjacent subcarriers, downlink beamforming weights are computed for each group of subcarriers using channel information of one or more proximate groups of subcarriers. The downlink beamforming weights for the respective groups of subcarriers are applied to a number of spatial streams in a downlink transmission to be transmitted to the second wireless device.

Implicit spatial matrix expansion determination for MIMO wireless communication systems

Techniques are provided to pre-distort a signal that is transmitted by a transmitter of a wireless communication device, e.g., a device configured for wireless radio frequency communication. The transmitter of the device inherently introduces distortion to the baseband signal to be transmitted. In at least one frame of a baseband signal to be transmitted, at least one subcarrier in a preamble of the frame is shifted in frequency such that the at least one subcarrier is offset from a normal subcarrier frequency position. The at least one frame of the baseband signal is supplied to the transmitter that is configured to produce a transmit signal for transmission. The transmit signal at an output of the transmitter is sampled or detected and inter-modulation distortion in the transmit signal is determined at one or more frequencies as a result of shifting of the frequency of the at least one subcarrier in the preamble of the at least one frame. The baseband signal is pre-distorted based on the inter-modulation distortion prior to coupling to the transmitter for transmission.

Transmitter characterization for digital pre-distortion using offset preamble subcarriers

A method for determining timing positions in a wireless communications system comprises creating a time-domain timing detection window from a preamble of a receiving signal, generating a first vector of correlations between sampling points in the time-domain timing detection window and sampling points of a known preamble, identifying a pivot position from the largest correlation value of the first vector and generating second vectors based on the pivot position, generating a third vector comprising the largest elements of the second vectors; generating a fourth vector comprising sums of elements in the second vectors, generating fifth and sixth vectors comprising a sum of subsets of the third and fourth vectors, respectively, calculating a seventh vector using the fifth and sixth vectors according to a predetermined equation, and selecting an index of one element from the fifth and seventh vectors to be the timing position according to a predetermined rule.

Method and system for improving timing position estimation in wireless communications networks

A fixed-point IFFT device in an OFDMA digital modulator is disclosed, which comprises a sub-carrier activity detector configured to detect a number of active sub-carriers in an OFDMA symbol set being transmitted in a given OFDMA symbol period, a scale termination calculator configured to generate an output for determining at which stage to terminate the IFFT scaling as a predetermined function of the number of active sub-carriers, a scaling controller configured to generate a plurality of control signals based on the output of the scale termination calculator, and an IFFT unit having a plurality of scaling stages each of which is controlled by one of the generated control signals.

System and method for improving signal to quantization noise ratio of an OFDMA modulator

Reducing the peak-to-average power ratio of a signal comprises receiving the input signal, where the input signal is associated with at least one unacceptable frequency range. The input signal is clipped about an amplitude range to yield a clipped signal and clipped information, where the clipped information represents intermodulation products. The clipped information is filtered to yield an error signal. The error signal represents a subset of the intermodulation products, where an intermodulation product of the subset corresponds to the unacceptable frequency range. The error signal is subtracted from the input signal to yield an output signal.

Reducing the peak-to-average power ratio of a signal

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Murphy, TX, United States of America

Bror Peterson