Digital Predistortion for Power Amplifiers in Hybrid MIMO Systems with Antenna Subarrays

• Published in: 2015 IEEE 81st Vehicular Technology Conference (VTC Spring) pp. 1 - 5
• Main Authors: Sangil Lee, Minhyun Kim, Youngwook Sirl, Eui-Rim Jeong, Soonil Hong, Seongjin Kim, Lee, Yong H.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.05.2015
• Subjects: Adaptation models; Antennas; Array signal processing; Least squares approximations; MIMO; Radio frequency; Training
• ISSN: 1550-2252
• DOI: 10.1109/VTCSpring.2015.7145777

We consider digital predistortion (DPD) for linearizing power amplifiers (PAs) of hybrid MIMO systems with subarrays. Designing such a DPD scheme is difficult because one DPD should linearize all PAs of a subarray whose beamforming coefficients are time-varying. We develop an adaptive DPD technique for each subarray based on direct learning method minimizing the sum of squared errors between the input and output signals of PAs. Use of the least mean square (LMS) Newton algorithm is proposed to adaptively control the DPD parameters. It is shown that the proposed DPD can simultaneously linearize multiple PAs in a subarray irrespective of its beamforming coefficients. Computer simulation results demonstrate that the proposed scheme can perform better than an alternative scheme that designs the DPD based on one of the PA outputs and uses the resulting DPD for all PAs of the subarray.