Error Performance Analysis of Clipped Alamouti Space-Time Coded OFDM Systems

In this paper we investigate the performance of clipped Alamouti space-time coded (STC) orthogonal frequency division multiplexing (OFDM) systems. The high peaks in STC-OFDM signals are clipped to limit the peak-to-average power ratio (PAPR). In STC-OFDM and OFDM, clipping can achieve significant PAPR reduction while maintaining a low symbol error rate (SER). Previous studies on OFDM have concluded that the effect of channel fading on clipping noise must be considered for an accurate error performance analysis. We extend this further to incorporate STC-OFDM systems and jointly study the impact of channel fading and receiver combining on clipping noise. At the STC-OFDM receiver, effective clipping noise governing the signal-to-noise ratio has different characteristics compared to the same for OFDM. Simulations indicate that STC-OFDM is more sensitive to clipping effects than OFDM. The theoretical and simulated SER are also compared for clipped STC-OFDM.