Interference Cancellation Based Iterative Detection for OFDM Systems over Time-Varying Multipath Channels

For orthogonal frequency-division multiplexing (OFDM) communication systems, the frequency offset caused by time-varying channels induces the loss of orthogonality among subcarriers, and results in Intercarrier Interference (ICI), which seriously degrades the performance of OFDM systems. A novel iterative detection based on parallel interference cancellation is proposed in this paper. The received signal is first processed with MMSE detector, and the decision estimated vector is obtained, then the ICI item can be reconstructed. With the principle of maximize the minimum signal-to-interference and noise power ratio, the strongest interference item will be replaced. The more iterations is carried out, the more the time diversity over time-varying multipath channels will be exploited. Simulation results show that this iterative detector improves the BER performance significantly. When the normalized Doppler frequency offset is comparably large, the BER of the proposed detection can be more improved. Compared with existing ICI mitigation scheme, the proposed scheme has lower computational complexity and better convergence stability.