PAPR reduction of space-frequency coded OFDM systems using Active Constellation Extension

摘要

Active Constellation Extension (ACE) is one of the techniques introduced for Peak to Average Power Ratio (PAPR) reduction of OFDM systems. In this technique, the constellation points are extended such that the PAPR is minimized but the minimum distance of the constellation points does not decrease. In this paper, an iterative ACE method is proposed for the PAPR reduction of OFDM systems with spatial diversity of Space Frequency Block Coding (SFBC). The proposed method is such that the PAPR is reduced simultaneously at all antennas, while the spatial encoding relationship still holds. In this method, at each iteration, the antenna with maximum PAPR is selected and the ACE algorithm is applied; then the signal of the other antennas are constructed from the resultant signal using SFBC relationship. Simulation results show that the algorithm converges and its performance is very close to the performance of the ACE in single antenna systems and it outperforms the alternative methods for PAPR reduction of SFBC-OFDM systems when the number of subcarriers increases.