Northrop Grumman Systems Corporation

University of California

Stmicroelectronics S.r.l.

Trellisware Technologies, Inc.

Silvus Technologies, Inc.

Michael Paul Fitz

Daniel N Liu

Massimiliano Siti

Scott Warren Enserink

Keith Michael Chugg

Cenk Köse

Mark Johnson

Thomas R Halford

Andreas Polydoros

Scott W Enserink

Moein Sadeghi

Xiaofen Chen

Isaak John Woldeit

Systems and methods to accomplish a power control system in a MANET are described herein. To reduce detectability of the MANET, the controllercan reduce transmit power at individual links while operating the link's modulation and coding data rate and data queue backlog at levels that are sufficient to meet the user's offered load.

Adaptive power control for mobile ad-hoc networks

Throughput for rate-adaptive wireless communication is maximized by accounting for the rate loss associated with selecting a transmission rate as a function of the actual rate supported by the channel. An optimal rate is selected by minimizing a set of average cost functions; each of the average cost functions is based on the delayed LQMs and rate-loss cost functions associated with selecting a candidate transmission rate as a function of a maximum rate supported by the channel.

Methods and systems for maximizing throughput for rate-adaptive wireless communication

A blind equalizer apparatus includes a decision-directed (DD) least mean squares (LMS) blind equalizer. A blind equalizer apparatus includes: a DD LMS blind equalizer, wherein: the blind equalizer uses a finite impulse response filter with tap weights that are adaptively updated using a filter tap update algorithm, wherein blind equalization of one of an in-phase (I) channel and a quadrature (Q) channel is carried out by maximizing the Euclidean distance of binary modulated waveforms, wherein the blind equalizer averages a block to compute an independent phase estimate for a block, wherein the blind equalizer computes an error variable for a block from the phase estimate for the block, wherein the blind equalizer uses the phase estimate and alternating I/Q one dimensional/binary slicing to make a hard decision, and wherein the blind equalizer uses the hard decision to derive an error variable that is used to update the filter tap weights.

Blind equalization in a single carrier wideband channel

An apparatus for joint analog and digital interference cancellation includes a receiver configured to receive an analog reference interfering signal on a reference path, and a sum of an analog interference signal and an analog signal of interest on an antenna path. An analog interference canceller may be configured to produce an analog partially interference-cancelled signal using the analog reference interfering signal and the sum of the analog interference signal and the analog signal of interest. A first analog-to-digital converter may be configured to digitize the analog reference interfering signal to produce a digital reference interfering signal. A second analog-to-digital converter may be configured to digitize the analog partially interference-cancelled signal to produce a digital partially interference-cancelled signal. A digital interference canceller may be configured to produce an interference-cancelled signal using the digital reference interfering signal and the digital partially interference-cancelled signal.

Joint analog and digital interference cancellation in wireless systems

A method and system for providing adaptive coded modulation in LEO satellite communication system is provided. The received power signal at the receiver is predicted by the LEO satellite transmitter without using channel feedback from the receiver. The receiver rapidly detects changes in transmission rate and changes its demodulation rate in tandem with the LEO satellite. Certain conditions that vary slowly, such as local weather and ground moisture level, are provided to the transmitter from the receiver at a much slower rate than that used in normal data communications.

Adaptive coded modulation in low earth orbit satellite communication system

A method, apparatus, and computer program for detecting sequences of digitally modulated symbols transmitted by multiple sources are provided. A real-domain representation that separately treats in-phase and quadrature components of a received vector, channel gains, and a transmitted vector transmitted by the multiple sources is determined. The real-domain representation is processed to obtain a triangular matrix. In addition, at least one of the following is performed: (i) hard decision detection of a transmitted sequence and demapping of corresponding bits based on a reduced complexity search of a number of transmit sequences, and (ii) generation of bit soft-output values based on the reduced complexity search of the number of transmit sequences. The reduced complexity search is based on the triangular matrix.

Apparatus and method for detecting communications from multiple sources

A method for removing distortions in a transmitted signal transmitted by a high power amplifier in a satellite communications system. The method characterizes the high power amplifier to define a series of Volterra coefficients and uses those coefficients in an equalizer in a receiver in the communications system to remove the distortions. The equalizer is a non-linear soft interference cancellation and minimum mean square error equalizer that employs three processing operations including parallel soft interference cancellation, minimum mean square error filtering and a priori log-likelihood ratio calculations.

Iterative equalization with non-linear soft interference cancellation in non-linear satellite channels

A method for providing timing recovery from a received digital data stream where the digital data stream is a series of consecutive data samples. The method separates the data stream into a series of consecutive observation periods where each observation period includes the same number of consecutive data samples. The method also includes identifying a series of consecutive timing recovery data samples in each observation period where the timing recovery data samples are used for timing recovery and other data samples in the observation period are not used for timing recovery, and where the number of data samples used for timing recovery in each observation period is less than the number of data samples that are not used for timing recovery in the observation period. The method then uses the timing recovery data samples for timing recovery in each observation period.

Snapshot processing of timing data

A timing recovery system that provides a timing estimate between a transmitter clock and a receiver clock. The system includes a down-converter that converts a received intermediate frequency signal in the receiver and down-converts, using Fs/4 down-conversion, the received signal into baseband in-phase and quadrature phase signals. The baseband in-phase and quadrature phase signals are sent to a direct down-converter that frequency shifts the in-phase and quadrature phase. The frequency-shifted in-phase and quadrature phase baseband signals are then low-pass filtered in order to isolate the frequency components of interest, reduce noise, and remove zeros that are artifacts of the Fs/4 down-conversion. The signals are sent to a square-law non-linearity circuit that provides squaring non-linearity to generate non-linear in-phase and quadrature phase signals. The non-linear in-phase and quadrature phase signals are sent to a single-pole, low-pass post-filter circuit that generates the timing estimate.

Universal timing recovery circuit

A system for receiving signals is set forth. The system includes an open loop frequency offset updating system adapted to receive an input signal. The open loop frequency offset updating system updates a frequency offset recursively, using a real time update value for value &#x393;(f,N). The system samples the signal and calculates an alternate quantity based on &#x393;(f,N) to determine a maximum value of the alternate quantity.

Recursive frequency estimation

A method (-), apparatus (), and computer program for detecting sequences of digitally modulated symbols transmitted by multiple sources (-) are provided. A real-domain representation that separately treats in-phase and quadrature components of a received vector, channel gains, and a transmitted vector transmitted by the multiple sources (-) is determined. The real-domain representation is processed to obtain a triangular matrix. In addition, at least one of the following is performed: (i) hard decision detection of a transmitted sequence and demapping of corresponding bits based on a reduced complexity search of a number of transmit sequences, and (ii) generation of bit soft-output values based on the reduced complexity search of the number of transmit sequences. The reduced complexity search is based on the triangular matrix.

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Michael Paul Fitz