Abstract: A method and system for error scaling for crest factor reduction (CFR) are disclosed. According to one aspect, a method for regulating peak to average power ratio (PAR) of an output signal of the CFR circuit is disclosed. In one embodiment, the method includes receiving an input signal at an input of the CFR circuit. The magnitude of the input signal is determined and clipped to a target level to produce an error signal by comparing the input signal magnitude to a threshold in a comparator. The error signal is filtered to produce a processed error signal. The filter provides a bandpass filter frequency response. The PAR of the output signal is regulated by scaling the processed error signal by an error scaling factor to achieve a target signal to noise ratio (SNR) for the output signal corresponding to a target error vector magnitude (EVM).

Abstract: A first radio node including processing circuitry configured to configure the first radio node to: obtain a first interference subspace, obtain beamforming weights based on the first interference subspace where the beamforming weights configured to modify a radiation pattern in at least one communication direction of at least one interference source, and perform wireless communications based on the beamforming weights.

Abstract: A method and system for detecting PIM signals in a wireless communication base station are disclosed. According to one aspect, a method includes receiving radio frequency, RF, signals over a frequency band spanning a plurality of frequencies of signals transmitted by at least a first transmitter external to the base station and at least a second transmitter. The method includes determining frequencies at which signals are present among the received radio frequency signals. PIM signal frequencies are calculated based on the determined frequencies at which signals are present. The method includes determining whether the calculated PIM signal frequencies interfere with selected uplink channels.

Abstract: A method and system for error scaling for crest factor reduction (CFR) are disclosed. According to one aspect, a method for regulating peak to average power ratio (PAR) of an output signal of the CFR circuit is disclosed. In one embodiment, the method includes receiving an input signal at an input of the CFR circuit. The magnitude of the input signal is determined and clipped to a target level to produce an error signal by comparing the input signal magnitude to a threshold in a comparator. The error signal is filtered to produce a processed error signal. The filter provides a bandpass filter frequency response. The PAR of the output signal is regulated by scaling the processed error signal by an error scaling factor to achieve a target signal to noise ratio (SNR) for the output signal corresponding to a target error vector magnitude (EVM).

Abstract: Systems and methods are disclosed herein that related to Peak-to-Average Power Ratio (PAPR) reduction in a (e.g., massive) Multiple-Input Multiple-Output (MIMO) Orthogonal Division Multiplexing (OFDM) transmitter system. In some embodiments, a method of operation of a MIMO OFDM transmitter system comprises, for each carrier of two or more carriers, performing precoding of a plurality of frequency-domain input signals for the carrier to provide a plurality of frequency-domain precoded signals for the carrier, the plurality of frequency-domain input signals for the carrier being for a plurality of transmit layers for the carrier, respectively. The method further comprises processing the frequency-domain precoded signals for the two or more carriers in accordance with a multi-carrier Convex Reduction of Amplitudes (CRAM) processing scheme to provide a plurality of multi-carrier time-domain transmit signals for a plurality of antenna branches, respectively, of the MIMO OFDM transmitter system.

Abstract: A method, detector and radio unit for non-linear interference detection in a communication system having a victim signal and an offending signal are disclosed. According to one aspect, a method includes determining a magnitude of the victim signal raised to a first power to produce a first signal. The method also includes determining a magnitude of the offending signal raised to a second power to produce a second signal. The first signal and the second signal are correlated to produce an output signal indicative of an extent to which the offending signal interferes with the victim signal.

Abstract: A method, detector and radio unit for non-linear interference detection in a communication system having a victim signal and an offending signal are disclosed. According to one aspect, a method includes determining a magnitude of the victim signal raised to a first power to produce a first signal. The method also includes determining a magnitude of the offending signal raised to a second power to produce a second signal. The first signal and the second signal are correlated to produce an output signal indicative of an extent to which the offending signal interferes with the victim signal.

Abstract: A method and system for identifying passive intermodulation, PIM, at a base station in a wireless communication system are disclosed. In some embodiments, a method includes measuring the noise floor in a radio frequency, RF, channel of an uplink carrier, the uplink carrier comprising a carrier transmitted from a wireless device to the base station. The method includes comparing the measured noise floor to a predetermined noise floor. The method also includes determining whether PIM is present based on a result of the comparison.

Abstract: Embodiments of a transmitter having an architecture that reduces power consumption and complexity are disclosed. In some embodiments, a transmitter comprises a modulator comprising an actuator, modulation circuitry, and an adaptor. The actuator is operable to apply at least one adjustment to at least one modulator input signal to provide at least one adjusted modulator input signal. The modulation circuitry is operable to perform a modulation operation on the at least one adjusted modulator input signal to provide a modulated signal, and the adaptor is operable to adaptively configure the at least one adjustment applied to the at least one modulator input signal such that a Peak-to-Average Ratio (PAR) of the modulated signal is reduced.

Abstract: Embodiments of a system and a method of operation of the system to reduce Peak-to-Average Power Ratio (PAPR) in an input signal for transmission over one or more carriers are disclosed. In some embodiments, the method of operation of the wireless transmission system comprises configuring a frequency-domain mask such that, for each subcarrier of a plurality of subcarriers of a carrier of the input signal, a value in the frequency-domain mask for the subcarrier is a function of a modulation scheme utilized in the input signal for the subcarrier. The method further comprises transforming the frequency-domain mask into a time-domain pulse and utilizing the time-domain pulse according to a pulse injection scheme to reduce a PAPR of the input signal.

Abstract: A method and system for identifying passive intermodulation, PIM, at a base station in a wireless communication system are disclosed. In some embodiments, a method includes measuring the noise floor in a radio frequency, RF, channel of an uplink carrier, the uplink carrier comprising a carrier transmitted from a wireless device to the base station. The method includes comparing the measured noise floor to a predetermined noise floor. The method also includes determining whether PIM is present based on a result of the comparison.

Abstract: A method and system for detecting PIM signals in a wireless communication base station are disclosed. According to one aspect, a method includes receiving radio frequency, RF, signals over a frequency band spanning a plurality of frequencies of signals transmitted by at least a first transmitter external to the base station and at least a second transmitter. The method includes determining frequencies at which signals are present among the received radio frequency signals. PIM signal frequencies are calculated based on the determined frequencies at which signals are present. The method includes determining whether the calculated PIM signal frequencies interfere with selected uplink channels.

Abstract: Embodiments of a transmitter having an architecture that reduces power consumption and complexity are disclosed. In some embodiments, a transmitter comprises a modulator comprising an actuator, modulation circuitry, and an adaptor. The actuator is operable to apply at least one adjustment to at least one modulator input signal to provide at least one adjusted modulator input signal. The modulation circuitry is operable to perform a modulation operation on the at least one adjusted modulator input signal to provide a modulated signal, and the adaptor is operable to adaptively configure the at least one adjustment applied to the at least one modulator input signal such that a Peak-to-Average Ratio (PAR) of the modulated signal is reduced.

Abstract: Systems and methods are disclosed for digital predistortion for a concurrent multi-band transmitter that compensates for both in-band and out-of-band intermodulation products according to a memory polynomial based baseband model. In one embodiment, a concurrent multi-band transmitter includes a digital predistortion subsystem, power amplifier circuitry, and an adaptation subsystem. The digital predistortion subsystem includes multiple digital predistorters configured to process digital input signals for frequency bands of a concurrent multi-band signal to provide predistorted digital input signals each being for a different one of the frequency bands of the concurrent multi-band signal and one or more intermodulation distortion compensation signals each being for a different one of one or more intermodulation distortion frequency bands.

Abstract: Systems and methods are disclosed for digital predistortion for a concurrent multi-band transmitter using a single adaptor and a same set of predistortion coefficients for separate digital predistorters for each band. In one embodiment, the single adaptor is configured to adaptively configure a set of predistortion coefficients based on a memory polynomial digital baseband model of the digital predistorters having a same set of predistortion coefficients for each of the digital predistorters. By using the same set of predistortion coefficients for the separate digital predistorters for each band, a complexity of the digital predistortion is substantially reduced.

Abstract: A method and apparatus for digital down conversion and demodulation of a radio frequency (RF) signal are disclosed. A sampling frequency for sampling the RF signal is chosen, based on a bandwidth and a safety margin, so that a bandwidth of the sampled signal falls substantially within a predetermined frequency zone. The sampled signal may be digitally demodulated at a demodulation frequency selected to be substantially equal to a baseband alias of a carrier frequency of the signal.

Abstract: A method of filtering an input sample stream having a downsampling rate is disclosed to generate an output sample stream having an upsampling rate that is less than the downsampling rate. The input sample stream is input to a rate change filter having multiple filter branches. The input sample stream is filtered at each of the multiple filter branches to output filtered sample substreams. Each of the multiple filter branches have filter coefficients corresponding to a different phase of the filter response. The filtered sample substreams are stored in a memory and the stored filtered sample substreams are combined to generate the output sample stream.

Abstract: A method of filtering an input sample stream having a downsampling rate is disclosed to generate an output sample stream having an upsampling rate that is less than the downsampling rate. The input sample stream is input to a rate change filter having multiple filter branches. The input sample stream is filtered at each of the multiple filter branches to output filtered sample substreams. Each of the multiple filter branches have filter coefficients corresponding to a different phase of the filter response. The filtered sample substreams are stored in a memory and the stored filtered sample substreams are combined to generate the output sample stream.

Abstract: Systems and methods are disclosed for digital predistortion for a concurrent multi-band transmitter that compensates for both in-band and out-of-band intermodulation products according to a memory polynomial based baseband model. In one embodiment, a concurrent multi-band transmitter includes a digital predistortion subsystem, power amplifier circuitry, and an adaptation subsystem. The digital predistortion subsystem includes multiple digital predistorters configured to process digital input signals for frequency bands of a concurrent multi-band signal to provide predistorted digital input signals each being for a different one of the frequency bands of the concurrent multi-band signal and one or more intermodulation distortion compensation signals each being for a different one of one or more intermodulation distortion frequency bands.

Abstract: A method and system for determining adaptation parameters for pre-distorters in a multi-band power amplifier system of a communication system are disclosed. A method includes receiving, at an adaptor, a reference signal comprising a first plurality of signals having substantially overlapping frequency spectra. Each of the first plurality of signals is input to a corresponding one of a plurality of pre-distorters. The adaptor also receives an observation signal comprising a second plurality of signals tuned to substantially a same frequency to have overlapping frequency spectra. Each of the second plurality of signals is derived from an output of the multi-band power amplifier system. The adaptor computes the adaptation parameters based on the reference signal and the observation signal.