SNR enhancement by the noise elimination technique for decomposed OFDM signals

In general, it is difficult to reduce the noise power selectively from the received signals in wireless communication systems. Thus, in order to improve the SNR, there are variety of signal processing techniques to obtain some processing gain; e.g. various kinds of diversity techniques, spectrum spreading/de-spreading technique, and so forth. In this paper, a novel SNR enhancement technique has been proposed and demonstrated. After the multiple of constant-amplitude signals and the residual signal separated from the OFDM signal are transmitted in parallel from antennas of a MIMO scheme, noise added on the on-off-signals can be eliminated taking advantage the knowledge of their constant amplitude at the receiver. It is confirmed that the proposed scheme improves the receiver SNR by 1.1dB for the single-threshold and 2dB for the dual-thresholds at the BER of 10⁻³, respectively. In addition to the SNR enhancement, the proposed scheme also has the large advantage of PAPR reduction for OFDM signals.