In an embodiment, an apparatus includes: a modulator to modulate a first signal; a distortion circuit coupled to the modulator to digitally pre-distort the first signal to compensate for a distortion of an amplifier; a distortion characterization circuit coupled to the distortion circuit to determine the distortion of the amplifier and configure the distortion circuit based on the determined distortion; a mixer coupled to the distortion circuit to upconvert the pre-distorted first signal to a pre-distorted radio frequency (RF) signal; and the amplifier coupled to the mixer to amplify the pre-distorted RF signal and output an amplified RF signal.

A wireless communications system includes a pre-distortion actuator configured to receive a carrier-modulated signal and convert the carrier-modulated signal into an output signal, the pre-distortion actuator comprising a behavioral model that models a transmit chain of the system including at least one amplifier and at least one antenna and predict an input-output relationship of the transmit chain of the system between an input to the transmit chain to an output of the transmit chain. The system includes a phased antenna array configured to transmit the output signal. The phased antenna array includes a plurality of antenna elements, each antenna element electrically coupled to a respective power amplifier. The pre-distortion actuator is configured to generate the output signal by applying a correction to the carrier-modulated input signal that cancels out nonlinearities The behavioral model is updated based on feedback from a receiver from a previous output signal transmitted to the receiver.

A linearization device (380) is disclosed, which is configured to determine pre-distortion parameters associated with a plurality of non-linear amplifiers (331, 332, 333, 334). Each of the non-linear amplifiers is associated with one of a plurality of transmit antenna elements and with a non-linear transfer function defining an output of the non-linear amplifier based on an input of the non-linear amplifier and based on a reflection signal for the non-linear amplifier, resulting from mutual couplings among the plurality of transmit antenna elements. The linearization device comprises a first port (381), a second port (382), and determination circuitry (383). The first port is configured to receive a plurality of channel coefficients indicative of channel characteristics of a plurality of communication paths between the plurality of non-linear amplifiers and two or more transmit observation receivers (370, 371, 372). Each transmit observation receiver is configured to receive a sum of transmission signals generated by the plurality of non-linear amplifiers and transferred over the communication paths between the plurality of non-linear amplifiers and the transmit observation receiver. The second port is configured to receive the sums of transmission signals from the transmit observation receivers. The determination circuitry is configured to determine the pre-distortion parameters based on the received plurality of channel coefficients, the received sums of transmission signals, and a model of the non-linear transfer functions of the non-linear amplifiers.

An efficient baseband predistortion linearization method for reducing the spectral regrowth and compensating memory effects in wideband communication systems using effective multiplexing modulation technique such as wideband code division multiple access and orthogonal frequency division multiplexing is disclosed. The present invention is based on the method of piecewise pre-equalized lookup table based predistortion, which is a cascade of a lookup table predistortion and piecewise pre-equalizers.

The present disclosure is a novel utility of a software defined radio (SDR) based Distributed Antenna System (DAS) that is field reconfigurable and support multi-modulation schemes (modulation-independent), multi-carriers, multi-frequency bands and multi-channels. The present disclosure enables a high degree of flexibility to manage, control, enhance, facilitate the usage and performance of a distributed wireless network such as flexible simulcast, automatic traffic load-balancing, network and radio resource optimization, network calibration, autonomous/assisted commissioning, carrier pooling, automatic frequency selection, frequency carrier placement, traffic monitoring, traffic tagging, pilot beacon, etc.

The present disclosure is a novel utility of a software defined radio (SDR) based Distributed Antenna System (DAS) that is field reconfigurable and support multi-modulation schemes (modulation-independent), multi-carriers, multi-frequency bands and multi-channels. The present disclosure enables a high degree of flexibility to manage, control, enhance, facilitate the usage and performance of a distributed wireless network such as flexible simulcast, automatic traffic load-balancing, network and radio resource optimization, network calibration, autonomous/assisted commissioning, carrier pooling, automatic frequency selection, frequency carrier placement, traffic monitoring, traffic tagging, pilot beacon, etc.

A digital predistortion system and method for pre-distorting an input to a non-linear system. The digital predistortion system includes a digital predistortion circuit and a memory. The digital predistortion circuit is configured to receive input data and modify the input data using at least one look-up table. The at least one look-up table is addressed by a signed real value of the input data. The memory is configured to store the at least one look-up table. The at least one look-up table is implemented based on a generalized memory polynomial model.

The present disclosure is a novel utility of a software defined radio (SDR) based Distributed Antenna System (DAS) that is field reconfigurable and support multi-modulation schemes (modulation-independent), multi-carriers, multi-frequency bands and multi-channels. The present disclosure enables a high degree of flexibility to manage, control, enhance, facilitate the usage and performance of a distributed wireless network such as flexible simulcast, automatic traffic load-balancing, network and radio resource optimization, network calibration, autonomous/assisted commissioning, carrier pooling, automatic frequency selection, frequency carrier placement, traffic monitoring, traffic tagging, pilot beacon, etc.

Various examples are directed to systems and methods for operating a plurality of power amplifiers. A predistortion circuit may pre-distort an input signal according to a predistortion configuration to generate a pre-distorted signal for the plurality of power amplifiers. An adaption circuit may receive a first feedback signal from a first power amplifier of the plurality of power amplifiers and generate predistortion correlation data describing a correlation between parameters of a model describing the plurality of power amplifiers. The adaption circuit may receive a first feedback signal from a second power amplifier of the plurality of power amplifiers and update the predistortion correlation data to generate updated predistortion correlation data using the first feedback signal from the second power amplifier. The adaption circuit may also generate the predistortion configuration using the updated predistortion correlation data.

An efficient baseband predistortion linearization method for reducing the spectral regrowth and compensating memory effects in wideband communication systems using effective multiplexing modulation technique such as wideband code division multiple access and orthogonal frequency division multiplexing is disclosed. The present invention is based on the method of piecewise pre-equalized lookup table based predistortion, which is a cascade of a lookup table predistortion and piecewise pre-equalizers.