Impact of clipping on EVM of the predistorted non-linear amplified multicarrier signals

Abstract

In this paper, we analyse the impact of clipping used as a peak-to-average power ratio reduction technique for multicarrier signals, assuming that a linearization stage is implemented before the power amplifier. Therefore, the expression of the Error Vector Magnitude (EVM) of the output signal is analytically derived. We mainly focus on the effect of clipping in both cases with and without the use of the predistortion stage. We provide analytical expressions of the EVM in the form of a series expansion that depends on the clipping threshold, the transition factors of the power amplifier, the predistortion characteristics and the PAPR of the input signal. We show through simulations that the proposed expressions present very good accuracy, even when limiting the series expansion to an order of 4. Finally, a simple scenario is proposed to demonstrate the benefit of our EVM expressions in controlling the average transmitted power with the aim to guarantee a high quality of service.