On the Impact of Non-Linear High Power Amplifiers on Coded OFDM

The high peak-to-average power ratio (PAPR) is one of the main disadvantages of OFDM systems, which reduces the transmission efficiency with non-linear power amplifiers and causes unwanted distortions and out-of-band radiation. There are many schemes proposed in the literature to mitigate this problem. However, the majority of these contributions only analyse the PAPR reduction and do not consider the system BER performance in the presence of an amplifier. When BER analysis for non-linear amplifiers is found in the literature, it is usually done not considering channel coding, even though OFDM in most real systems is coded. In this contribution we investigate the performance of an OFDM system in terms of total degradation, also considering channel coding, and show that with strong coding the effect of a nonlinear amplifier is far less negative than in an uncoded system. We also see that some schemes that effectively reduce PAPR, may in fact bring about very little performance gain when coding is taken into account.