Outage analysis of AF OFDM relaying systems with power amplifier nonlinearity

The high peak-to-average power ratio (PAPR) is one of the main problems of orthogonal frequency division multiplexing (OFDM), which may cause the introduction of intercarrier interference (ICI) due to the presence of nonlinear power amplifiers (PAs). On the other hand, cooperative diversity is a very promising technology for the future wireless network. In this paper, a performance analysis of an amplify-and-forward (AF) cooperative OFDM systems accounting for nonlinear distortions introduced by a nonlinear power amplifier (PA) is developed. In particular, a close-form expression for a tight lower-bound of the outage probability is presented and validated through computer simulations. Our analysis is based on the sum of the mutual information of all the subcarriers, contrarily to previous works that have analyzed the performance of the nonlinear cooperative OFDM systems based on a single subcarrier. Our analysis shows in what situations the PA nonlinearity affects significantly the outage probability.