Probability of error of space-time coded OFDM systems with frequency offset in frequency-selective Rayleigh fading channels

In this paper, we analyze the performance of space-time coded (ST-coded) orthogonal frequency division multiplexing (OFDM) systems with carrier frequency offset (CFO) in a frequency-selective Rayleigh fading channel. Closed-form analytical expressions are derived for the symbol error probability (SEP) for M-PSK and M-QAM modulation schemes. The SEP expressions derived are valid and exact for OFDM systems with highly frequency-selective wireless channels where the subcarrier channel responses are i.i.d. with Rayleigh fading. Also, for the case where imperfect channel knowledge is used for space-time decoding, we derive expressions for constellation phase-rotation and post-equalized SINR (signal-to-interference-and-noise ratio) degradation due to CFO. The numerical results demonstrate the sensitivity of the receiver error performance to CFO in ST-coded OFDM systems.