A novel algorithm of inter-subchannel interference cancellation in OFDM systems

Time-varying multipath channels distort the orthogonality between subchannels in orthogonal frequency-division multiplexing (OFDM) transmission. The loss of subchannel orthogonality causes inter-subchannel interference (ICI), which limits the achievable bit-error rate (BER) at high signal-to-noise ratio (SNR). In this paper, we propose a simple but very effective ICI self-cancellation scheme. A pre-filter and a post-filter are inserted in the transmitter and receiver, respectively. The pre-filter modifies the time-domain signal after inverse fast-Fourier-transform (IFFT) operation in the transmitter, while the post-filter makes the ICI self-cancelled in the receiver. By analysis we can show that if the channel variation within one OFDM symbol interval is linear, then the ICI can be completely removed. Simulation results validate the effectiveness of the proposed scheme.