Frequency-Domain Digital Predistortion for OFDM

In this letter, a novel frequency-domain (FD) digital predistortion (DPD) solution for orthogonal frequency division multiplexing (OFDM) transmitters (TXs) is proposed. The proposed approach allows to flexibly control the linearization performance, in FD, such that different degrees of linearization can be provided at different parts of the spectrum. Such a feature can be of special interest in the millimeter-wave (mmWave) bands, where the inband signal quality requirements can limit the feasible TX power, while also varying across the active subcarriers due to frequency multiplexing of different users with different modulation and coding schemes. The performance of the proposed FD DPD is demonstrated and validated through over-the-air (OTA) measurements on a 64-element phased-array operating at 28-GHz carrier frequency.