Analysis of OFDM Signals in Nonlinear High Power Amplifier with Memory

This paper analyzes the effects of nonlinear high power amplifier (HPA) with memory on an orthogonal frequency division multiplexing (OFDM) signal, by modeling the nonlinear HPA as a memory polynomial model with sparse delay taps. In the theoretical framework developed, we show that the in-band distortion due to nonlinear HPA with memory affects each subcarrier differently and the distortion itself can be canonically characterized by a complex attenuation component and nonlinear noise component. Analytical expressions for the complex attenuation and nonlinear noise are derived. From the expressions, a complete analytical approach to evaluate signal to noise ratio and probability of error for each subcarrier in an additive white Gaussian noise (AWGN) channel is obtained and illustrated using a M-QAM OFDM system. A comparison between theoretical and simulated results is also presented to verify the accuracy of our analysis.