Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method (200a-200b), apparatus (104), and computer program for detecting sequences of digitally modulated symbols transmitted by multiple sources (102, 102a-102t) 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 (102, 102a-102t) 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.

Abstract: A method (200a-200b), apparatus (104), and computer program for detecting sequences of digitally modulated symbols transmitted by multiple sources (102, 102a-102t) 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 (102, 102a-102t) 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.

Abstract: Equalization techniques are disclosed to reduce intersymbol interference of a received signal. Intersymbol interference is reduced by feedforward filtering and adjusting the input to the feedforward filter with feedback. This approach facilitates the removal of intersymbol interference from sparse signal portions before sparseness is undermined by other equalization procedures. Also, multiplication operations may be reduced and limited multiplier resources more effectively allocated by applying a threshold test to various multiplier coefficients associated with the equalization technique.