Abstract: Techniques are described for implementing multiband digital predistortion in a broadband transmitter in a manner that provides effective compensation of non-linear distortion arising from integration of a high-power amplifier (HPA). Embodiments segment the signal spectrum of a transmit signal into multiple sub-band signals and apply non-linear distortion compensation separately and concurrently for each sub-band signal. The resulting multi-band digital predistortion (mDPD) compensates both for in-band distortion and for distortions from non-linear interactions between the frequency sub-bands. The disclosed mDPD can provide enhanced performance features, such as handling of memory effects, reduced sampling rate requirements for DPD components, and minimizing detrimental spectral regrowth at the HPA output.

Abstract: Techniques are described for implementing multiband digital predistortion in a broadband transmitter in a manner that provides effective compensation of non-linear distortion arising from integration of a high-power amplifier (HPA). Embodiments segment the signal spectrum of a transmit signal into multiple sub-band signals and apply non-linear distortion compensation separately and concurrently for each sub-band signal. The resulting multi-band digital predistortion (mDPD) compensates both for in-band distortion and for distortions from non-linear interactions between the frequency sub-bands. The disclosed mDPD can provide enhanced performance features, such as handling of memory effects, reduced sampling rate requirements for DPD components, and minimizing detrimental spectral regrowth at the HPA output.

Abstract: Techniques are described for implementing multiband digital predistortion in a broadband transmitter in a manner that provides effective compensation of non-linear distortion arising from integration of a high-power amplifier (HPA). Embodiments segment the signal spectrum of a transmit signal into multiple sub-band signals and apply non-linear distortion compensation separately and concurrently for each sub-band signal. The resulting multi-band digital predistortion (mDPD) compensates both for in-band distortion and for distortions from non-linear interactions between the frequency sub-bands. The disclosed mDPD can provide enhanced performance features, such as handling of memory effects, reduced sampling rate requirements for DPD components, and minimizing detrimental spectral regrowth at the HPA output.

Abstract: A system and method for providing multi-input multi-output (MIMO) feeder links for a multibeam satellite system. The method includes configuring a X×Y MIMO antenna system using X-antennae having dominant line-of-sight (LoS) of Y-antennae; transmitting, simultaneously, a Tx signal as X Tx signals on a MIMO channel with the X-antennae; receiving the X Tx signals on the MIMO channel with the Y-antennae as Y Rx signals, wherein each of the Y-antennae generate one of the Y Rx signals; and ground-interference processing the X Tx signals or the Y Rx signals to recover the Tx signal; satellite-interference processing the X Tx signals or the Y Rx signals to recover the Tx signal. In the method, the ground interference processing includes countermeasures as either pre-interference processing when the X-antennae are disposed on a ground or post-interference processing when the X-antennae are disposed in a Geosynchronous orbit satellite.

Abstract: Systems and methods are described for generating and implementing pulse-shaping filters for efficient utilization of limited spectral resources in wireless communication systems. Wireless communication systems operating at high spectral efficiency conventionally use pulse shaping filters that rely on Nyquist waveforms for good main lobe performance with low inter-symbol interference (ISI) power. Conventional uses of non-Nyquist waveforms typically involve an orthogonalization process to convert those non-Nyquist waveforms to Nyquist waveforms for ISI free performance. Embodiments of pulse shaping filters described herein generate a non-Nyquist partial response (NNPR) transmit filter and/or matched receive filter based on applying a tunable second-weighted orthogonalization to a tunable first-weighted non-Nyquist waveform to obtain a pulse-shaping waveform with parametric control over throughput and power penalty.

Abstract: The present teachings disclose a multibeam satellite system and methods that can achieve orthogonality between spatially multiplexed signals in a multi-input multi-output (MIMO) configuration when operating in line-of-sight (LOS) uplink and downlink channels on the feeder link side, using essentially a common spot beam. The teachings maximize a MIMO capacity across multiple frequency bands by disclosing an antenna array geometry for disposition on-board a single satellite and for a ground segment.

Abstract: A system and method for providing multi-input multi-output (MIMO) feeder links for a multibeam satellite system. The method includes configuring a X×Y MIMO antenna system using X-antennae having dominant line-of-sight (LoS) of Y-antennae; transmitting, simultaneously, a Tx signal as X Tx signals on a MIMO channel with the X-antennae; receiving the X Tx signals on the MIMO channel with the Y-antennae as Y Rx signals, wherein each of the Y-antennae generate one of the Y Rx signals; and ground-interference processing the X Tx signals or the Y Rx signals to recover the Tx signal; satellite-interference processing the X Tx signals or the Y Rx signals to recover the Tx signal. In the method, the ground interference processing includes countermeasures as either pre-interference processing when the X-antennae are disposed on a ground or post-interference processing when the X-antennae are disposed in a Geosynchronous orbit satellite.

Abstract: Some implementations describe a method including: receiving, by multiple receivers of multiple gateways of a ground receiver system, from multiple transmitters of a satellite over a downlink of a LoS MIMO feeder link, multiple RF signals; obtaining, at the ground receiver system, from the RF signals, preamble signals and pilot signals including first sequences of pilot symbols associated with second sequences of pilot symbols transmitted by the transmitters; estimating, based on the first sequences of pilot symbols and second sequences of pilot symbols, first channel state information (CSI) of the pilot signals; estimating, using the first CSI, frequency offsets and phase offsets of links between the receivers and the transmitters; adjusting, based at least on the frequency offsets and the phase offsets, the preamble signals to obtain adjusted preamble signals; and estimating, at the ground receiver system, using the adjusted preamble signals, second CSI of the downlink.

Abstract: The present teachings disclose a multibeam satellite system and methods that can achieve orthogonality between spatially multiplexed signals in a multi-input multi-output (MIMO) configuration when operating in line-of-sight (LOS) uplink and downlink channels on the feeder link side, using essentially a common spot beam. The teachings maximize a MIMO capacity across multiple frequency bands by disclosing an antenna array geometry for disposition on-board a single satellite and for a ground segment.

Abstract: A Radio Frequency Impairments (RFI) compensator and a process to remove RFI is disclosed. The RFI compensator including: a conjugator to conjugate a signal {tilde over (x)}[n] to provide a signal {tilde over (x)}*[n]; and a filter to apply coefficients that equalize a linear distortion of the signal {tilde over (x)}[n] and reject an interfering image of the signal {tilde over (x)}*[n]. The signal {tilde over (x)}[n] maybe a single wideband carrier or may include multiple carriers at different carrier frequencies.

Abstract: A transmitter, including a signal processor programmed to generate, based on input serial data, for each of an integer number of subcarriers mutually orthogonal to each other, a respective first parallel data stream. The signal processor is further programmed to modulate each of the integer number of subcarriers respectively with the respective parallel stream to generate the integer number of data-modulated subcarriers. The signal processor is further programmed to modulate a single carrier occupying a same bandwidth as the integer number of subcarriers with a unique word and one or more pilot symbols to generate a second signal. The signal processor combines the first signal and second signal to generate a third signal. The signal processor generates an output signal by applying a transmit filter to the third signal.

Abstract: A communications apparatus to receive a composite signal including a desired signal and interferer signals, where the desired signal may include desired symbols and the interferer signals may include interferer symbols. The system may include N frameworks, each framework may include a detector to partition the desired symbols and the interferer symbols based on an interference severity into a dominant group and a non-dominant group, and to generate A Posteriori Probabilities (APP) of the desired symbols and the interferer symbols. The detector of each of the N frameworks generates the APP based on a feedback of a priori probabilities from each of the N frameworks.

Abstract: Implementations described herein are directed to satellite transmitters and receivers for applying OFDM-like signaling in broadband satellite transmissions. In such systems, one or more data signals may be shaped and composited into a composite data signal at an OFDM-like transmitter for transmission over a satellite channel. The data signals that are carried over the satellite channel by the composited signal may have their own carrier, and each signal may carry multiple OFDM subcarriers. Further implementations are directed to correcting for distortion in satellite communications systems that utilize OFDM-like signaling.

Abstract: Some implementations of the disclosure are directed to symbol-timing tracking systems and methods. A symbol-timing tracking system may include: an ADC to generate a digital signal by sampling an analog signal received at a receiver; an interpolator to adjust a sampling rate of the digital signal; a receive filter to apply a receive filtering function to the digital signal to generate a filtered signal; a timing error detector configured to generate a timing error signal from the filtered signal; a high-order loop filter to filter the timing error signal to generate a filtered timing error signal; and a numerically controlled oscillator to control timing data based on the filtered timing error signal and provide the timing data to the interpolator, wherein the interpolator is to correct for timing of the digital signal and adjust the sampling rate of the digital signal based on the timing data.

Abstract: A Radio Frequency Impairments (RFI) compensator and a process to remove RFI is disclosed. The RFI compensator including: a conjugator to conjugate a signal {tilde over (x)}[n] to provide a signal {tilde over (x)}*[n]; and a filter to apply coefficients that equalize a linear distortion of the signal {tilde over (x)}[n] and reject an interfering image of the signal {tilde over (x)}*[n]. The signal {tilde over (x)}[n] may be a single wideband carrier or may include multiple carriers at different carrier frequencies.

Abstract: Implementations described herein are directed to satellite transmitters and receivers for applying OFDM-like signaling in broadband satellite transmissions. In such systems, one or more data signals may be shaped and composited into a composite data signal at an OFDM-like transmitter for transmission over a satellite channel. The data signals that are carried over the satellite channel by the composited signal may have their own carrier, and each signal may carry multiple OFDM subcarriers. Further implementations are directed to correcting for distortion in satellite communications systems that utilize OFDM-like signaling.

Abstract: Implementations described herein are directed to satellite transmitters and receivers for applying OFDM-like signaling in broadband satellite transmissions. In such systems, one or more data signals may be shaped and composited into a composite data signal at an OFDM-like transmitter for transmission over a satellite channel. The data signals that are carried over the satellite channel by the composited signal may have their own carrier, and each signal may carry multiple OFDM subcarriers. Further implementations are directed to correcting for distortion in satellite communications systems that utilize OFDM-like signaling.

Abstract: A receiver, transmitter and system are programmed to communicate based on a signal including a plurality of signal components associated respectively with a plurality of subcarriers over a communications channel. The receiver is programmed to determine, from the plurality of subcarriers, a subcarrier subject to interference and erase the signal component associated with the subcarrier subject to interference. The receiver is further programmed to reconstruct the signal based on the plurality of first signal components excluding the erased first signal component.

Abstract: A transmitter, including a signal processor programmed to generate, based on input serial data, for each of an integer number of subcarriers mutually orthogonal to each other, a respective first parallel data stream. The signal processor is further programmed to modulate each of the integer number of subcarriers respectively with the respective parallel stream to generate the integer number of data-modulated subcarriers. The signal processor is further programmed to modulate a single carrier occupying a same bandwidth as the integer number of subcarriers with a unique word and one or more pilot symbols to generate a second signal. The signal processor combines the first signal and second signal to generate a third signal. The signal processor generates an output signal by applying a transmit filter to the third signal.

Abstract: A receiver, transmitter and system are programmed to communicate based on a signal including a plurality of signal components associated respectively with a plurality of subcarriers over a communications channel. The receiver is programmed to determine, from the plurality of subcarriers, a subcarrier subject to interference and erase the signal component associated with the subcarrier subject to interference. The receiver is further programmed to reconstruct the signal based on the plurality of first signal components excluding the erased first signal component.