Alamouti STBC MIMO OFDM System using ZCT Precoded Based SLM Technique for PAPR Reduction

OFDM system is combined with multipleinput multiple-output (MIMO) in order to increase the system capacity and diversity gain. However, one of the major drawback of MIMO-OFDM have high peak-toaverage power ratio (PAPR) in order to the signals transmittted on different antennas. In this paper, we propose Zadoff-Chu matrix Transform (ZCT) precoding based Selected Mapping (SLM) technique to reduce the peak-to-average power ratio (PAPR) in Alamouti STBC MIMO-OFDM systems. The key idea of this paper is that different phase rotation sequences are multiplied by their corresponding input sequence generated by the STBC encoder at the transmitter and precoding the symbols with ZCT precoder and the lowest PAPR is selected for transmission. To reduce the high PAPR, BPSK modulation techniques is used for N=128. Our proposed work shows that ZCT-SLM based MIMOOFDM system using Alamouti STBC has the lowest PAPR performance compared to conventional ZCTSLM based OFDM system. MATLAB simulation shows that the performance of the proposed algorithm significantly improves the PAPR reductions.