Evaluation of oversampling rate limited dual-channel digital predistortion with 3-Box nonlinear model of power amplifier

Abstract

Because of the license-free and wideband properties, 60 GHz band has become one of the candidates for the next generation wireless communication systems. In 60 GHz millimeter wave (mmWave) wireless systems, orthogonal frequency division multiplexing (OFDM) scheme can provide high data rate over than 6 Gbps; however, the high peak-to-average power ratio (PAPR) of OFDM signals will reduce the power efficiency of the power amplifier (PA). Digital predistortion (DPD) methods were proposed to compensate the nonlinearity and to improve the power efficiency of the PA; as well as dual-band concurrent DPD was proposed to simplify the RF circuit of the transmitter. However, the low oversampling rate in the baseband of the mmWave channels lets it become a difficult task. In this paper, we evaluate a dual-channel DPD scheme for 60 GHz band mmWave OFDM systems with a cascade 3-box nonlinear PA model that can represent the memory effects of the PA. In the simulation results, at the back-off of 6 dB, error vector magnitudes (EVM) of the channels are improved more than 9 dB and 11 dB in the passbands of channels with DPD compensation up to the 3rd and 5th order, respectively.