BEP Analysis of OFDM Relay Links with Nonlinear Power Amplifiers

This paper studies the performance of a two-hop infrastructure-based relay link. The relay operates in a half-duplex mode using an amplify-and-forward protocol. Considering transmission of OFDM signals with nonlinear power amplifiers (PAs), we determine exact closed-form expressions for end-to-end bit error probabilities (BEPs). The expressions allow us to analyze the effect of nonlinear distortion as well as the special case of linear PAs. Furthermore, we derive asymptotic BEP floor values which illustrate how the end-to-end performance is limited by both the nonlinear PA distortion and the weakest hop. Our discussion indicates that the influence of the nonlinear distortion can be mitigated by properly adjusting the PA back-offs.