A conjugate operation for mitigating intercarrier interference of OFDM systems

In order to mitigate intercarrier interference (ICI), a two-path algorithm is developed for orthogonal frequency division multiplexing (OFDM) systems. The first path is a regular OFDM system for transmitting and receiving. The second path requires a conjugate operation of the 1st block of data to form the 2nd block of data for transmission. The received 2nd block of data is conjugated at the receiver and then demodulated. The demodulated results of the 1st path are combined with that of the 2nd path with equal weights to form the final detected data symbols. This conjugate cancellation (CC) scheme provides (1) a high signal-to-ICI power ratio in the presence of small frequency offsets - 33 dB higher than that of linear self-cancellation algorithms (Zhao, Y. and Haggman, S.-G., 2001; Armstrong, J., 1999) at ΔfT = 0.1% of subcarrier frequency spacing; (2) backward compatibility with the existing OFDM system; (3) significantly better BER performance in both additive white Gaussian noise (AWGN) and frequency selective fading channels.