Multi-cell processing architectures for modeling and impairment compensation in multi-input multi-output systems

Abstract

The present invention relates to a method for multiple-input multiple-output impairment pre-compensation comprising: receiving a multiple-input signal; generating a pre-distorted multiple-input signal from the received multiple-input signal; generating a multiple-output signal by feeding the pre-distorted multiple-input signal into a multiple-input and multiple-output transmitter; estimating impairments generated by the multiple-input and multiple-output transmitter; and adjusting the pre-distorted multiple-input signal to compensate for the estimated impairments. The present invention also relates to a pre-compensator for use with a multiple-input and multiple-output transmitter, comprising: a multiple-input for receiving a multiple-input signal; a matrix of pre-processing cells for generating a pre-distorted multiple-input signal from the received multiple-input signal; and a multiple-output for feeding the pre-distorted multiple-input signal to the multiple-input and multiple-output transmitter. The pre-processing cells are configured so as to estimate impairments generated by the multiple-input and multiple-output transmitter and adjust the pre-distorted multiple-input signal to compensate for the estimated impairments.

1 . A method for a multiband transmitter comprising:
 inputing a multiband signal for transmission by a multi-band transmitter;   predistorting the input multiband signal to provide a predistorted signal to compensate for inter-band distortions and intra-band distortions of the multiband transmitter;   generating a output multi-band signal by feeding the pre-distorted signal to the multi-band transmitter.   
     
     
         2 . The method of  claim 1 , wherein the predistorting includes estimating the inter-band and intra-band distortions and multi-band impairments. 
     
     
         3 . The method of  claim 2 , including using the estimated distortions and estimated impairments for adjusting the multiband input signal. 
     
     
         4 . The method of  claim 3 , wherein the adjusting includes introducing linear and nonlinear distortions in each signal path of each frequency band. 
     
     
         5 . The method of  claim 3 , wherein the adjusting further includes introducing interference between each signal path of the plurality of frequency bands. 
     
     
         6 . The method of  claim 1 , wherein each of the inter-band distortions and intra-band distortions is a function of distinct ones of a plurality of frequency bands of the multiband signal. 
     
     
         7 . The method of  claim 1 , wherein the predistorting includes:
 feeding the input multiband signal to a matrix of pre-processing cells to generate the predistorted signal, each of the pre-processing cells of the matrix including:
 nonlinear processing blocks to compensate for multi-band impairments and nonlinear distortions in the multi-band transmitter; and 
 linear processing blocks to compensate for linear distortions in the multi-band transmitter. 
   
     
     
         8 . The method of  claim 7 , including estimating a nonlinear function for each nonlinear processing block. 
     
     
         9 . The method of  claim 8 , the nonlinear processing block including processing the input multiband signal and the output multi-band signal to determine the nonlinear function. 
     
     
         10 . The method of  claim 7 , including estimating a linear function for each linear processing block. 
     
     
         11 . The method of  claim 8 , the linear processing block including processing the input multiband signal and the output multi-band signal to determine the linear function. 
     
     
         12 . A pre-compensator for multiband predistortion, comprising:
 an input for receiving an input multiband signal for transmission by a multi-band transmitter;   precompensator circuit configured to predistort the input multiband signal to compensate for non-linearity of the multi-band transmitter so as to provide a predistorted signal; and   an output for feeding the pre-distorted signal to the multi-band transmitter.   
     
     
         13 . The pre-compensator of  claim 12 , wherein the nonlinearities include distortions are functions of interactions between the multiple bands. 
     
     
         14 . The pre-compensator of  claim 12 , including a matrix of pre-processing cells, each of the pre-processing cells including:
 nonlinear processing blocks to compensate for multi-band impairments and nonlinear distortions in the multi-band transmitter; and   linear processing blocks to compensate for linear distortions in the multi-band transmitter.   
     
     
         15 . A system for multi-band predistortion comprising:
 a predistortion circuit, wherein   the predistortion circuit applies a first adjustable distortion to a first band input based on the first band input and at least one further band input to provide a first band output,   the predistortion circuit applies an at least one further adjustable distortion to the at least one further band based on the at least one further band input and the first band input to provide an at least one further band output, and   the predistortion circuit is configured to drive an output port configured to be coupled to an amplifier;   an output processor coupled to an evaluation input, the evaluation input couplable to an output of the amplifier; and   a coefficient calculation block coupled to an output of the output processor, the first band input, and the at least one further band input, the coefficient calculation block calculating coefficients for the first adjustable distortion and the at least one further adjustable distortion based on the first band input, the at least one further band input and the output of the output processor.   
     
     
         16 . A system providing digital predistortion for a dual-band transmitter comprising:
 first tuning circuitry adapted to tune a first baseband signal to a first intermediate frequency to provide a first intermediate frequency signal;   second tuning circuitry adapted to tune a second baseband signal to a second intermediate frequency to provide a second intermediate frequency signal;   combiner circuitry adapted to combine the first intermediate frequency signal and the second intermediate frequency signal to provide a combined intermediate frequency signal; and   predistortion circuitry adapted to predistort the combined intermediate frequency signal to compensate for a non-linearity of a power amplifier in a transmit chain of the dual-band transmitter, thereby providing a predistorted signal;   wherein a separation between the first intermediate frequency and the second intermediate frequency is at or near a minimum separation value below which one or more frequency bands in the predistorted signal for up to a target intermodulation order overlap frequency bands in the predistorted signal centered at the first and second intermediate frequencies.   
     
     
         17 . A method of providing digital predistortion for dual-band transmitter comprising:
 tuning a first baseband signal to a first intermediate frequency to provide a first intermediate frequency signal;   tuning a second baseband signal to a second intermediate frequency to provide a second intermediate frequency signal; combining the first intermediate frequency signal and the second intermediate frequency signal to provide a combined intermediate frequency signal; and   predistorting the combined intermediate frequency signal to compensate for a non-linearity of a power amplifier in a transmit chain of the dual-band transmitter, thereby providing a predistorted signal; wherein a separation between the first intermediate frequency and the second intermediate frequency is at or near a minimum separation value below which frequency bands in the predistorted signal for up to a target intermodulation order overlap frequency bands in the predistorted signal centered at the first and second intermediate frequencies.