A theoretical study on demodulation of pre-coded OFDM by pre-coded symbol replacement

In OFDM system, the signal to noise ratio becomes lower on the specific sub-carrier under frequency selective fading channels and the performance is often deteriorated. Under such situation, the performance can be improved by pre-coding data symbols in the frequency domain. Moreover, the demodulation scheme of the pre-coded OFDM signal by replacing the received pre-coded symbols with the pre-coded symbols regenerated from the data symbols after hard decision is effective to achieve better performance with a simple procedure. In this paper, theoretical analysis of the detection scheme of the pre-coded OFDM signal is performed in order to achieve optimal performance.