Abstract: There is provided mechanisms for PIM removal in an antenna system. A method is performed by a controller of the antenna codebook based beamforming, which transmission radio chains of the antenna system that cause a signal received by receiver radio chains of the antenna system to be impacted by PIM. These transmission radio chains are identified based on which codeword in the codebook is used for the beamforming. The method comprises determining a correction signal by subjecting the signals only as transmitted by the identified transmission radio chains to a model of the PIM. The method comprises removing PIM from the signal received by the receiver radio chains by subtracting the correction signal from the signal received by the receiver radio chains.

Abstract: A method in an adaptive filter system is provided. The method comprises obtaining parameters for a plurality of branches of the adaptive filter system. The method further comprises computing gradient-based information for a selected one of the plurality of branches. The method further comprises updating the parameters for the plurality of branches based on the gradient-based information for the selected branch. An adaptive filter system is also provided.

Abstract: The present disclosure provides a method of linearization for a non-linear system, comprising: a group of steps comprising: inputting an input signal to the non-linear system; obtaining an output signal from the non-linear system in response to the input signal being input to the non-linear system; obtaining a desired signal for the non-linear system; comparing the output signal with the desired signal, to determine whether the input signal is a target signal for the non-linear system to achieve a desired performance; and in response to determining that the input signal is not the target signal for the non-linear system to achieve the desired performance, generating an updated signal in frequency domain by applying a coefficient to eliminate a difference between the output signal and the desired signal, for updating the input signal to the non-linear system. The present disclosure also provides a corresponding device, computer programs, and computer-readable storage.

Abstract: There is provided mechanisms for mitigating passive intermodulation in a first network node, wherein said PIM is caused by radio signals transmitted from at least an adjacent network node. The method is performed by a control device. The method comprises receiving at least an uplink radio signal and down-converting the received UL radio signal to a UL baseband signal. The method applies a cyclic redundancy check, CRC, to detected information bits of the received UL baseband signal, wherein in response to determining by the CRC that the UL baseband signal is detected correctly, directly output the detected information bits. The method comprises in response to determining by the CRC that the UL baseband signal is incorrectly detected, determining a residual signal of the received UL baseband signal applying a blind signal identification scheme on the residual signal of the UL baseband signal to obtain an estimate for a modeled PIM signal.

Abstract: A method in an adaptive filter system is provided. The method comprises obtaining parameters for a plurality of branches of the adaptive filter system. The method further comprises computing gradient-based information for a selected one of the plurality of branches. The method further comprises updating the parameters for the plurality of branches based on the gradient-based information for the selected branch. An adaptive filter system is also provided.

Abstract: There is provided mechanisms for PIM removal in an antenna system. A method is performed by a controller of the antenna system. The method comprises identifying, during transmission using codebook based beamforming, which transmission radio chains of the antenna system that cause a signal received by receiver radio chains of the antenna system to be impacted by PIM. These transmission radio chains are identified based on which codeword in the codebook is used for the beamforming. The method comprises determining a correction signal by subjecting the signals only as transmitted by the identified transmission radio chains to a model of the PIM. The method comprises removing PIM from the signal received by the receiver radio chains by subtracting the correction signal from the signal received by the receiver radio chains.

Abstract: There is provided mechanisms for mitigating passive intermodulation in a first network node, wherein said PIM is caused by radio signals transmitted from at least an adjacent network node. The method is performed by a control device. The method comprises receiving at least an uplink radio signal and down-converting the received UL radio signal to a UL baseband signal. The method applies a cyclic redundancy check, CRC, to detected information bits of the received UL baseband signal, wherein in response to determining by the CRC that the UL baseband signal is detected correctly, directly output the detected information bits. The method comprises in response to determining by the CRC that the UL baseband signal is incorrectly detected, determining a residual signal of the received UL baseband signal applying a blind signal identification scheme on the residual signal of the UL baseband signal to obtain an estimate for a modeled PIM signal.

Abstract: The present disclosure provides a method of linearization for a non-linear system, comprising: a group of steps comprising: inputting an input signal to the non-linear system; obtaining an output signal from the non-linear system in response to the input signal being input to the non-linear system; obtaining a desired signal for the non-linear system; comparing the output signal with the desired signal, to determine whether the input signal is a target signal for the non-linear system to achieve a desired performance; and in response to determining that the input signal is not the target signal for the non-linear system to achieve the desired performance, generating an updated signal in frequency domain by applying a coefficient to eliminate a difference between the output signal and the desired signal, for updating the input signal to the non-linear system. The present disclosure also provides a corresponding device, computer programs, and computer-readable storage.

Abstract: A method in an adaptive filter system is provided. The method comprises obtaining parameters for a plurality of branches of the adaptive filter system. The method further comprises computing gradient-based information for a selected one of the plurality of branches. The method further comprises updating the parameters for the plurality of branches based on the gradient-based information for the selected branch. An adaptive filter system is also provided.

Abstract: A method and a transmitter arrangement for cancelling cross talk and correcting power amplifier (PA) distortion for a transmitter branch of a multiple-input multiple-output (MIMO) configuration having multiple branches. The method comprises combining an original baseband input signal of a first MIMO transmitter branch with a crosstalk output signal generated from two or more signals associated with two or more respective MIMO branches, the two or more signals used as input to, and processed by, a crosstalk model. The method further comprises processing the combined signal to generate an output signal in order to minimize the error of the original baseband input signal caused by the crosstalk and/or PA distortion.

Abstract: A method and a transmitter arrangement for cancelling cross talk and correcting power amplifier (PA) distortion for a transmitter branch of a multiple-input multiple-output (MIMO) configuration having multiple branches. The method comprises combining an original baseband input signal of a first MIMO transmitter branch with a crosstalk output signal generated from two or more signals associated with two or more respective MIMO branches, the two or more signals used as input to, and processed by, a crosstalk model. The method further comprises processing the combined signal to generate an output signal in order to minimize the error of the original baseband input signal caused by the crosstalk and/or PA distortion.

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: 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.