Performance Analysis of Adaptive Clipping Technique for Reduction of PAPR in Alamouti Coded MIMO-OFDM Systems

Like single-input single-output orthogonal frequency division multiplexing (SISO-OFDM), multi-input multi-output (MIMO) OFDM systems also suffer from the problem of high peak to average power ratio (PAPR). To account for this issue, amplitude clipping is one of the simplest techniques employed to reduce PAPR. However, it leads to additional distortion. In this paper, adaptive clipping technique is proposed to reduce PAPR of Alamouti coded MIMO-OFDM systems. In this scheme, successive peaks are clipped according to an adaptive algorithm. Simulation results reveal that the proposed clipping technique provides effective reduction in PAPR and better bit error rate (BER) performance. BER performance and PAPR reduction capability of the proposed algorithm in MIMO-OFDM systems are also compared with SISO-OFDM systems. Power spectral density (PSD) for conventionally clipped, adaptively clipped, and normal SISO-OFDM systems is analyzed and plotted. It can be revealed from the PSD plot that the spectral spreading due to the proposed scheme is less than the conventional clipping scheme.