Novel Low-Complexity Post-IFFT PAPR Reduction Technique for OFDM Systems

The near Gaussian-distribution of the time-domain signal samples of multicarrier transmission, such as OFDM or DMT, gives rise to unacceptable peak-to-average power ratio (PAPR) which leads to a significant degradation in the trasnmission power efficiency. As a consequence, several PAPR reduction techniques have been proposed in the literature each offering a different combination of system performance, complexity and bandwidth efficiency. One of the most promising of these is the selective mapping (SLM) technique which has been shown to offer PAPR reductions of several dBs. However, the fact that the SLM technique requires invoking the IFFT process several times per transmitted OFDM-block increases the system complexity and hence results in long latencies and high power consumption. Inspired by the SLM approach, we propose a novel post-IFFT PAPR reduction technique combined with a suitable selection strategy for determining a unique set of time-domain sequences per OFDM block that can minimise the PAPR. It will be shown that PAPR reductions within 0.7 dB of the ordinary SLM performance can be achieved with our proposed technique which requires several order of magnitude less complexity than that of the SLM technique.