An iterative ICI cancellation and decoding scheme for coded OFDM systems in mobile channels
Recently, it has been shown that the received signal in the orthogonal frequency-division multiplexing (OFDM) systems can be viewed as the synchronous code-division multiple access (SCDMA) signal in receiver after some mathematical manipulation, and the ICI term in the OFDM system is equivalent to the multiple access interference (MAI) term in SCDMA system. They proposed a successive interference cancellation multicarrier detector and it performs better than the conventional single-carrier detection schemes. To further improve the performance of OFDM systems in the presence of ICI, we propose to use a soft-in soft-out (SISO) multicarrier detector and a SISO convolutional decoder in an iterative (turbo) way. Note that full-complexity turbo multicarrier detector and turbo decoder are not used to strike a balance between performance and complexity of OFDM systems. And the transmitter structure of OFDM systems is unchanged. The simulation results show that the first iteration of the proposed scheme demonstrates 2-3 dB gain compared to the previous multicarrier detection schemes. The second and third iterations improve the performance further.
ici ofdm cdma turbo principle doppler spread