Nokia Technologies Oy

Nuutti Tervo

Marko E Leinonen

Aarno Tapio Pärssinen

Method, apparatus and arrangement for linearizing of a transmitter array having a plurality of non-linear branches for transmitting into a predetermined direction, wherein the non-linear branches may purposively be made different to obtain varying responses of the non-linear branches over the transmitter array. A combined array response is determined via a feedback structure that models an array response to the predetermined direction and predistortion coefficients are determined based on the measured array response. A feedback circuit with a plurality of feedback branches can be used for feeding back individual response signals at the outputs of the non-linear branches through phase shift and attenuation units of the feedback branches, and for combining the response signals at the outputs of the feedback branches, wherein phase shift and attenuation of each feedback branch is controlled to model a transmission channel of the individual response signals to a receiver in a predetermined direction.

Method, apparatus and arrangement for linearizing of a transmitter array

An apparatus comprising means for: applying beam shape coefficients for obtaining a beam shape output for a linear part of the beam formed by an array of transmitters, each transmitter being associated with a respective transmit path comprising a respective power amplifier; varying the output characteristics of at least one transmit path to increase nonlinear characteristics between the transmit paths to provide a beam shape for a non-linear part of the beam; linearizing the output of the array by: determining linearization coefficients for the array for digitally predistorting the input signal to the array; and applying the linearization coefficients to the signal input to the array; and calibrating the transmitter array by: measuring error distributions over at least two transmit paths; modifying the beam shape coefficients to better obtain the beam shapes subsequent to the linearization; and applying the modified beam shape coefficients to the array of transmitters.

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Oulu, Finland

Nuutti Tervo