A novel low complexity technique to reduce non-linear distortion effects in OFDM systems

This paper proposes a new technique to reduce the non-linear distortion effects in orthogonal frequency division multiplexing (OFDM) systems. It exploits virtual carriers, which are modulated by using properly defined "dummy symbols", to obtain a transmitted signal with reduced envelope variations. With this method no additional redundancy is introduced, thus preserving the spectrum efficiency, and no changes at the receiver are required. To evaluate the dummy symbols some optimization criteria are investigated; an optimum algorithm and a low complexity iterative algorithm are proposed and compared from the point of view of the system's performance. The effectiveness of this technique is tested by considering some typical high power amplifier (HPA) models and by evaluating the performance degradation. A comparisons with other techniques proposed in the literature is also carried out.