Digital Nonlinearity Cancellation Architecture Based on An Auxiliary Transmit Antenna Array

In multiple antenna arrays, the existence of many radio frequency (RF) links increases the number of power amplifiers (PAs), which brings strong nonlinear distortion to the wireless communication system. This problem brings challenges to the existing nonlinear distortion suppression technology. We propose a nonlinear cancellation architecture digitally based on auxiliary antenna arrays. In this architecture, we add an auxiliary transmitter to the conventional transceiver architecture with a low-cost and low-complexity approach. The transmitter is used to transmit the estimated nonlinear signal to cancel with main signal at the receiving end. For the reconstruction of nonlinear signals, we separate the linear part and the nonlinear part of the PA output and model them in two steps. Moreover, we propose a coefficient update method to estimate and track the channel. We test the effectiveness of the method and compare the architecture with the performance of conventional digital predistortion (DPD) by simulation experiments. The results prove that the proposed methods can show good performance in improving adjacent channel power leakage ratio (ACLR) and in-band distortion. Moreover, under strong distortion, our architecture performs better than conventional DPD.