Spatial Over-the-Air Post-Distortion Cancellation with an Embedded Distortion-Correcting Transmitter Antenna for Linearizing Phased-Array Transmitters

This paper presents an over-the-air post-distortion method that employs an embedded transmitting antenna to radiate a distortion-correcting waveform toward the intended user direction, enabling spatial-domain linearization of phased-array transmitters. The proposed approach achieves significantly improved linearization performance compared with conventional digital predistortion (DPD) and avoids the additional computational burden imposed on user equipment by receiver-side post-distortion approaches. A proof-of-concept implementation on a four-element 28 GHz beamforming array validates the proposed method. When driven with a 100 MHz OFDM waveform using 256-QAM subcarriers, the proposed method improves the adjacent-channel power ratio (ACPR) and error vector magnitude (EVM) at the receiver from -26.5/-28.3 dBc to -47.5/-47.25 dBc and from 10.7% to 1.5%, respectively. Under identical model complexity (nonlinearity order and memory depth), DPD achieves -40.9/-41.2 dBc ACPR and 2.2% EVM.