Performance of space-frequency codes in MIMO channels with frequency offset

We investigate the pair-wise error probability (PEP) performance of space-frequency (SF) codes over quasistatic, frequency-selective Rayleigh fading channels with frequency offset (FO). The PEP expression shows that the conventional SF code design criteria are remained valid. If the normalized FO (NFO) is less than 1%, the performance loss is negligible. The loss increases with FO and with signal to noise ratio (SNR). We show that diversity can be used to mitigate the effects of FO. However with large FO, the PEP is no longer exponentially decays with SNR. Therefore, we propose a SF coding scheme to combat effectively with even very high NFO (20%). Simulation results confirm our theoretical evaluations.