Practical predistortion architectures for multiband radios

A method of operation of a digital predistortion actuator system for a radio node for a wireless network, the method comprising:

• receiving a plurality of input signals (x1, . . . , XB) for a plurality of frequency bands (b1, . . . , bB), respectively;
• for each frequency band (b1) of the plurality of frequency bands (b1, . . . bB);
• generating a plurality of predistorted signals for the frequency band (bi) based on the plurality of input signals (X1, . . . , XB) and a plurality of Look-Up Tables, LUTs, each having less than B dimensions;
• and
• combining the plurality of predistorted signals for the frequency band (b1) to provide a combined predistorted signal for the frequency band (b1),
• wherein, for each frequency band (bi) of the plurality of frequency bands (b1, . . . , bB), generating the plurality of predistorted signals for the frequency band (b1) comprises:
• for each value of r from at least a subset of a set of values {q, q+1, . . . , B−2} where 1≤q≤B−2:
• generating a predistorted input signal for the frequency band (b1) for the value of r, based on:
• a sum of magnitudes of input signals for a set of frequency band combinations that consists of at least one combination of B-r frequency bands from among the plurality of frequency bands (b1, . . . , bB);
• and
• a set of LUTs that comprises a single-dimension LUT for each frequency band combination in the set of frequency band combinations.

A digital predistortion actuator system for a radio node for a wireless network, the digital predistortion actuator system comprising:

• a plurality of Separate Digital Predistortion, S-DPD, actuators for a plurality of frequency bands (b1, . . . , bB), respectively;
• wherein each S-DPD actuator of the plurality of S-DPD actuators is configured to:
• receive a plurality of input signals (x1, . . . , xB) for the plurality of frequency bands (b1, . . . , bB), respectively;
• generate a plurality of predistorted signals for a frequency band (bl) of the plurality of frequency bands (b1, . . . , bB) based on the plurality of input signals (x1, . . . , xB) and a plurality of Look-Up Tables, LUTs, each having less than B dimensions;
• and
• combine the plurality of predistorted signals for the frequency band (b1) to provide a combined predistorted signal for the frequency band (bl),
• wherein each S-DPD actuator of the plurality of S-DPD comprises:
• for each value of r from at least a subset of a set of values {q, q+1, . . . . B−2} where 1≤q≤B−2:
• a sub-DPD actuator configured to generate a predistorted input signal for the frequency band (b1) for the value of r, based on:
• input signals for a set of frequency band combinations that consists of at least one combination of B-r frequency bands from among the plurality of frequency bands (b1, . . . bB);
• and a set of LUTs that comprises a B-r dimension LUT for each frequency band combination in the set of frequency band combinations;
• or
• a sum of magnitudes of input signals for a set of frequency band combinations that consists of at least one combination of B-r frequency bands from among the plurality of frequency bands (b1, . . . bB);
• and a set of LUTs that comprises a single-dimension LUT for each frequency band combination in the set of frequency band combinations.