Signal Shaping for Unique-Word OFDM by Selected Mapping

Selected Mapping (SLM) is known to be a useful method to reduce the peak to average power ratio (PAPR) of OFDM transmit signals. In this paper, the performance of PAPRreduction for Unique Word (UW-) OFDM is investigated where in contrast to usual cyclic prefix (CP-) OFDM correlations between subcarrier data exist due to a complex number Reed-Solomon code along the subcarriers. It is shown that these correlations do not impair the positive properties of SLM for PAPR-reduction. Moreover, SLM is a general method for shaping of transmit signals generated in blocks in order to strengthen some desired signal features and e.g. may be applied to lower efficiently the average power of the redundant subcarriers in UW-OFDM. Furthermore, we show that SLM together with UW-OFDM is well suited for reducing the peak to minimum ratio (PMR) of the transmit signal as well. Analytic results are accompanied by simulation results.