There is provided mechanisms for beamformed transmission using a precoder. A method is performed by a radio transceiver device. The radio transceiver device comprises hardware. The hardware impacts transmission of signals from the radio transceiver device. The method comprises acquiring channel conditions of a radio propagation channel between the radio transceiver device and at least one other radio transceiver device. The method comprises determining a precoder, in form of a linear precoding matrix, for beamformed transmission towards the at least one other radio transceiver device. The precoder is determined according to the channel conditions and a model of how the hardware impacts the transmission of signals from the radio transceiver device. The method comprises transmitting, using the precoder, a signal towards the at least one other radio transceiver device.

A method of operating a communications system includes receiving a signal at a digital predistorter (DPD), introducing predistortion to the signal using the DPD, and converting the predistorted signal to an analog signal using a digital-to-analog converter having a first bandwidth. The method also includes amplifying the analog signal, sampling the amplified signal using an analog-to-digital converter having a second bandwidth less than the first bandwidth, and extracting coefficients of the DPD from the sampled signal.

An OFDM modulator including a predistortion module configured to receive the N consecutive data carriers and configured to compensate for distortion subsequently introduced by a polyphase filter bank connectable to the output of the OFDM modulator, a transformation module configured to apply a discrete inverse Fourier transform of constant size N.sub.IDFT independently of the numbering and transmission band used by the OFDM transmitter including the OFDM modulator, a filling module, the input of which is connected to the output of the predistortion module, and the output of which is connected to the input of the transformation module, and configured to insert (N.sub.IDFT−N.sub.c) null carriers in succession to the N.sub.c consecutive data carriers independently of the parity of the index i associated with the OFDM modulator.

An Analog-to-Digital Converter, ADC, system is provided. The ADC system comprises a plurality of ADC circuits and a first input for receiving a transmit signal of a transceiver. One ADC circuit of the plurality of ADC circuits is coupled to the first input and configured to provide first digital data based on the transmit signal. The ADC system further comprises a second input for receiving a receive signal of the transceiver. The other ADC circuits of the plurality of ADC circuits are coupled to the second input, wherein the other ADC circuits of the plurality of ADC circuits are time-interleaved and configured to provide second digital data based on the receive signal. Additionally, the ADC system comprises a first output configured to output digital feedback data based on the first digital data, and a second output configured to output digital receive data based on the second digital data.

An apparatus for transmitting output signals includes a pre-distortion circuit configured to perform digital pre-distortion (DPD) on input signal samples using a plurality of DPD coefficients to generate a plurality of pre-distorted samples. The apparatus further includes an estimation window search circuit configured to determine a signal power characteristic for each pre-distorted sample of the plurality of pre-distorted samples, and select a subset of the plurality of pre-distorted samples based on the determined signal power characteristics. The subset of the plurality of pre-distorted samples is selected to fit within a predetermined estimation window size. The plurality of DPD coefficients is updated based on the subset of the plurality of pre-distorted samples.

Described examples provide for digital communication circuits and systems that implement digital pre-distortion (DPD). In an example, a system includes a DPD circuit configured to compensate an input signal for distortions resulting from an amplifier. The DPD circuit includes an infinite impulse response (IIR) filter configured to implement a transfer function. The IIR filter includes a selection circuit configured to selectively output a selected parameter. The transfer function is based on the selected parameter.

A method for distortion compensation in a transmission link comprising obtaining information of an amplitude distribution of a signal prior to being transmitted by a transmitter, receiving the transmitted signal at a receiver and determining a received signal amplitude distribution, comparing the received signal amplitude distribution to the amplitude distribution of the signal prior to transmission and using results of the comparison to estimate the AM/AM non-linearity in the transmitter.

Systems and methods are disclosed herein for providing efficient Digital Predistortion (DPD). In some embodiments, a system comprises a DPD system comprising a DPD actuator. The DPD actuator comprises a Look-Up Table (LUT), selection circuitry, and an approximate multiplication function. Each LUT entry comprises information that represents a first set of values {p.sub.1, p.sub.2, . . . , p.sub.k} and a second set of values {s.sub.1, s.sub.2, . . . , s.sub.k} that represent a LUT value of s.sub.1.Math.2.sup.p.sup.1+s.sub.2.Math.2.sup.p.sup.2+ . . . +s.sub.k.Math.2.sup.p.sup.k where each value s.sub.i ∈{+1 , −1} where k≥2. The selection circuitry is operable to, for each input sample of an input signal, select a LUT entry based on a value derived from the input sample that is indicative of a power of the input signal. The approximate multiplication function comprises shifting and combining circuitry that operates to, for each input sample, shift and combine bits that form a binary representation of the input sample in accordance with {p.sub.1, p.sub.2, . . . , p.sub.k} and {s.sub.1, s.sub.2, . . . , s.sub.k} to provide an output sample.

The invention relates to a device for linearising a power amplifier by employing digital predistortion, comprising: a digital predistortion module, configured to infer a polar domain predistortion to be applied to a signal, and comprising a first neural network and a second neural network respectively configured to correct amplitude and phase distortion produced by the amplifier; an optimisation module of each of said neural networks configured to implement meta-learning, using: a meta-initialisation providing a prior initialisation of the initial weights of each of said neural networks; a meta-matching of the initial weights into optimal weights of each of said neural networks.

According to one configuration, a system includes a first wireless station in communication with a second wireless station. Signal processor hardware receives, from a first phase noise predictor (model), a first common phase error signal to compensate for: i) first phase noise associated with a first wireless station, and ii) second phase noise associated with a second wireless station. The signal processor hardware implements a predictive feedback compensation loop (such as including a second phase noise predictor) to produce a second (i.e., corrected) common phase error signal from the received common phase error signal. The signal processor hardware outputs the corrected common phase error signal to adjust phases of sub-carrier frequencies used to communicate data from the first wireless station to the second wireless station.