Selective Mapping with Symbol Re-Mapping for OFDM/TDM Using MMSE-FDE
Orthogonal frequency division multiplexing (OFDM) signals have a problem with high peak-to-average power ratio (PAPR). A distortionless selective mapping (SLM) has been proposed to reduce the PAPR, but a high computational complexity prohibits its application to OFDM with a large number of subcarriers. Recently, OFDM combined with time division multiplexing (OFDM/TDM) using minimum mean square error frequency-domain equalization (MMSE-FDE) was proposed to improve the transmission performance of conventional OFDM in terms of the bit error rate (BER) and the PAPR. The PAPR problem, however, cannot be completely eliminated. In this paper, we propose a new SLM to further reduce the PAPR of OFDM/TDM. Unlike the conventional OFDM, where SLM is applied over subcarriers in the frequency domain, we propose the new SLM for OFDM/TDM by exploiting both time and frequency dimensions of OFDM/TDM signal. It is shown, by computer simulation that proposed SLM for OFDM/TDM increases the number of candidate sequences in comparison with the conventional SLM, while reducing the PAPR. Furthermore, OFDM/TDM with proposed SLM achieves a lower PAPR than the conventional OFDM with same or reduced computational complexity.