PAPR reduction in Precoded OFDM system via carrier interferometry

Recently, precoded orthogonal frequency division multiplexing (Precoded-OFDM) system was proposed to overcome spectral nulls in inter-symbol-interference (ISI) channel and reduce the overhead of cyclic prefix (CP). The Precoded-OFDM inserts (M-K) zeros between each two set of K consecutive information symbols, which can utilize the frequency diversity to remove the spectral nulls' impact at the receiver side. However, due to inserting zeros in the symbols sequence, the average transmitting power is reduced while the peak power remains the same. Hence, the Precoded-OFDM system has bad performance in terms of peak-to-average power ratio (PAPR) value. In this paper, we propose to use the carrier interferometry (CI) techniques in the Precoded-OFDM systems, which will reduce the PAPR values by spreading all information symbols through all subcarriers with CI phase offset. The simulation results are presented and shown the dramatic improvement on the PAPR performance with our proposed method.