Motorola Corporation

General Dynamics C4 Systems, Inc.

General Dynamics Decision Systems, Inc.

John Eric Kleider

Chad Scott Bergstrom

William Michael Campbell

Jeffery Scott Chuprun

Bruce Alan Fette

Carl Steven Gifford

Robert Baxley

Jeffrey Scott Chuprun

Glen Patrick Abousleman

Khaled Assaleh

Cynthia Ann Jaskie

Byron Tarver

Steve Henry Arneson

Anthony Smith

Benjamin Russell Hamilton

Clifford A Wood

Kelly Anderson

Richard James Pattison

Charles Conway Broun

Keith Matthew Nolan

Derrick Duane Hughes

Michael Eugene Humphrey

Amy Michelle Guzek

J Scott Chuprun

A communication system is provided that includes a transmitter device and a receiver device. The transmitter device transmits input data as a transmitted signal having the known non-linear distortion (NLD) characteristic. The receiver receives a received signal that represents a channel affected version of the transmitted signal and that has the known NLD characteristic. The received signal includes power amplifier distortion (PAD) induced by the transmitter device's power amplifier. The receiver is designed to iteratively estimate, based on the known NLD characteristic, remaining PAD caused by the power amplifier, and to iteratively cancel estimated PAD to reduce PAD in the received signal.

Reducing transmitter-to-receiver non-linear distortion at a transmitter prior to estimating and cancelling known non-linear distortion at a receiver

Embodiments include methods for determining synchronization/pilot sequences (SPS) to be utilized in conjunction with transmissions by antennas of a multiple-antenna transmitter. The SPS include pilot signals that are positioned at subcarriers that are orthogonal in frequency with subcarriers at which pilot signals of other antennas are positioned. The pilot signals may be unevenly spaced across the in-band subcarriers. The multiple-antenna transmit system generates a plurality of wireless signals, each of which may include an SPS having synchronization information in a first plurality of in-band subcarriers and the pilot signals in a second plurality of in-band subcarriers. The wireless signals are simultaneously radiated over a wireless communication channel using a different antenna. A receiver receives channel-affected versions of the wireless signals, and produces a corrected signal by applying corrections to the received signal based on estimated channel perturbations within the received signal.

Methods and apparatus for multiple-antenna communication of wireless signals with embedded synchronization/pilot sequences

An embodiment includes a method for generating a set of synchronization/pilot sequences (SPS) by generating a plurality of candidate SPS using different initial conditions. Correlations are performed among the candidate SPS to generate a plurality of correlation values, and a plurality of permutations of the candidate SPS are determined, where each permutation includes a different set of candidate SPS, and wherein each permutation includes a number, D, of candidate SPS. In addition a selected permutation is identified from the plurality of permutations, where the selected permutation corresponds to the set of SPS being generated. A system includes a transmitter adapted to generate a wireless signal in which an SPS is embedded by combining each SPS of the set with phase shifted input data, determining peak-to-average power ratios (PARs) for at least some of the combined signals, and identifying a selected combined signal based on the PARs.

Methods and apparatus for generating synchronization/pilot sequences for embedding in wireless signals

A method and system are provided for reducing power amplifier induced distortion. Power amplifier induced distortion is iteratively estimated and cancelled. When the difference between the current estimated power amplifier distortion and the previous estimated power amplifier distortion is less than a convergence threshold, particular M-QAM constellation points that are still in error are determined A M-QAM constellation point correction routine is provided that can move the incorrectly estimated M-QAM constellation points that are in error towards their expected quadrants by generating updated M-QAM constellation points. The remaining estimated non-linear power amplifier induced distortion in the received signal can then be estimated and canceled.

Cancelling non-linear power amplifier induced distortion from a received signal by moving incorrectly estimated constellation points

Embodiments of methods and apparatus for wirelessly communicating signals include one or more transmitters configured to generate a plurality of wireless signal for transmission. Each of the wireless signals includes a plurality of pilot signals represented in a plurality of unevenly spaced, in-band subcarriers. Pilot signals of each wireless signal are positioned at subcarriers that are orthogonal in frequency with subcarriers at which pilot signals of all other wireless signals are positioned. According to an embodiment, subcarrier indices each the plurality of pilot signals are determined using a third order or higher order polynomial parameterization of pilot subcarriers in conjunction with a convex optimization algorithm to produce pilot signals having near-optimal channel estimate mean square error (MSE) performance. The wireless signals are simultaneously radiated over a wireless communication channel using a plurality of co-located or distributed antennas.

Methods and apparatus for multiple-antenna communication of wireless signals with embedded pilot signals

An embodiment for wirelessly communicating a signal includes a transmitter combining a plurality of phase shifted input data signals with a plurality of synchronization/pilot sequences to produce a plurality of combined signals, performing frequency domain-to-time domain transformations of the combined signals to produce a plurality of candidate signals, determining peak-to-average ratios for at least some of the plurality of candidate signals, identifying a selected signal from the plurality of candidate signals based on the peak-to-average ratios, and transmitting the selected signal over a wireless communication channel. An embodiment further includes a receiver receiving a channel-affected version of the transmitted, selected signal, determining an estimate of a selective mapping index, which identifies the synchronization/pilot sequence from the plurality of synchronization/pilot sequences, applying corrections to the received signal based on estimated channel perturbations to produce an equalized combined signal, and producing an output data symbol from the equalized combined signal.

Methods and apparatus for wirelessly communicating signals that include embedded synchronization/pilot sequences

In an embodiment, a receiver includes an antenna configured to receive a communication frame. The communication frame may include an acquisition code symbol sequence, which in turn may include a plurality of acquisition code symbols. In an embodiment, an acquisition code symbol includes a subcode sequence having a plurality of subcodes. A receiver also may include a correlation calculator coupled to the antenna. The correlation calculator may be configured to determine a correlation between the subcodes of the received communication frame and a stored version of the subcodes. The correlation may be used in determining a timing offset for further processing of the communication frame.

Signal acquisition methods and apparatus in wireless communication systems

An embodiment for wirelessly communicating a signal includes a transmitter generating and transmitting a wireless signal over a wireless communication channel. The wireless signal includes a guard band, data represented within a plurality of data-bearing subcarriers, and a plurality of pilot signals represented within a plurality of pilot subcarriers. In an embodiment, the plurality of pilot signals have variable pilot signal parameters selected from a group of parameters that includes pilot power and pilot spacing with respect to adjacent pilots. An embodiment further includes a receiver receiving a channel-affected version of the wireless signal, and producing a corrected signal by applying corrections to the received signal based on estimated channel perturbations within the received signal, where the estimated channel perturbations are determined based on the plurality of pilot signals. The receiver also produces an output data symbol from the corrected signal.

Methods and apparatus for generating and communicating wireless signals having pilot signals with variable pilot signal parameters

Embodiments include methods and apparatus for verifying the detection of a correlation peak, which may represent an acquisition of a received acquisition code symbol sequence. The method includes determining a series of coherently-aligned peaks from a series of correlation peaks. Determining the plurality of coherently-aligned peaks includes correcting a frequency offset and a phase offset for each of the plurality of correlation peaks. A coherent match filter process is performed on the plurality of coherently-aligned peaks. A detection of the correlation peak may be verified when the match filter result exceeds a threshold.

Methods and systems for acquiring signals using coherent match filtering

A method () of orthogonal frequency-division multiplex (OFDM) communication via a plurality of subchannels () within a noncontiguous wideband channel () is provided. The method () determines an SNR for each of the subchannels (). The method () then designates a subchannel () as clear () when its SNR is greater than a least-SNR threshold (), as impeded () when its SNR is less than the least-SNR threshold and greater than an SNR-evaluation threshold, and as obstructed () when its SNR is less than both the least-SNR and the SNR-evaluation thresholds. The method () then transmits OFDM data () so that each of the clear subchannels receives the OFDM data () at a maximum subchannel signal level (), each of the impeded subchannels receives the OFDM data () at an intermediate subchannel signal level (), and each of the obstructed subchannels receives the OFDM data () at zero subchannel signal level ().

Method of multiple-carrier communication within a noncontiguous wideband spectrum and apparatus therefor

Apparatus are provided for a communication signal processing apparatus having a channel estimator configured to generate a first channel estimation at a first time point, a linear predictor coupled to the channel estimator, and an adaptive filter coupled with the linear predictor. The linear predictor is configured to predict a second channel estimation based on a second time point and a channel frequency. The second time point is concurrent or subsequent to the first time point. The second channel estimation includes a first coefficient. The linear predictor includes a first predictor having a sample time point. The first predictor is configured to generate the first coefficient of the second channel estimation based on the sample time point and the second time point. The sample time point is prior to the second time point. The adaptive filter is configured to recursively determine the second channel estimation.

Communication channel tracking apparatus

A symbol synchronizer () is provided for a software-defined communications system (). The symbol synchronizer (), when integrated into either a pre- or post-detection diversity signal combiner (), enables highly accurate signal synchronization with minimal added system complexity. The symbol synchronizer () includes a single complex sliding window-matched filter () for filtering an input digital signal with a match filtering function based on predetermined signal transfer function characteristics to average out receiver noise from the signal. A signal delay bank () includes a plurality of delay blocks each for delaying the digital signal filtered by the single matched filter for a predetermined number of samples. A complex correlator () correlates the digital signal filtered by the single complex sliding window matched filter () and delayed by the complex correlator () with a correlator reference signal, and selects an index of a path having a peak correlator value. As a result of such a configuration, the symbol synchronizer () is capable of determining symbol boundaries of channel signals in a multi-channel communications system to enable system signal measurement statistics and demodulated to be more accurately generated.

Symbol synchronizer for software defined communications system signal combiner

A multi-carrier communication system () groups subchannels () into different quality-of-signal (QoS) regions (). An unconstrained optimization process () is performed independently for the subchannels () of the different QoS regions () to allocate bit rates and power to the individual subchannels () so that the indicated QoS will result. Coders () partition and error-correction encode source information using encoding schemes matched to the different QoS regions (). A set () of only a few directed QoS partition vectors () direct the unconstrained optimization process () to attempt bit-rate and power allocations on only a few promising groupings of subchannels () and QoS regions (). An iterative process may take place between bit-rate and power allocation on one side and source information coding on the other for different directed QoS partition vectors () to identify the best solution. A coder () may use a dual allocation process () to iteratively combine a rate-allocation process () with a QoS-region-allocation process () to specify codebooks () for use by a codebook quantizer ().

Method and apparatus for encoding compressible data for transmission over variable quality communication channel

A multi-carrier communication system () groups subchannels () into different quality-of-signal (QoS) regions (). An unconstrained optimization process () is performed independently for the subchannels () of the different QoS regions () to allocate bit rates and power to the individual subchannels () so that the indicated QoS will result. Coders () partition and error-correction encode source information using encoding schemes matched to the different QoS regions (). A set () of only a few directed QoS partition vectors () direct the unconstrained optimization process () to attempt bit-rate and power allocations on only a few promising groupings of subchannels () and QoS regions (). An iterative process may take place between bit-rate and power allocation on one side and source information coding on the other for different directed QoS partition vectors () to identify the best solution.

Growing community of inventors

Atlanta, GA, United States of America

John Eric Kleider