Subcarrier pairing for self-heterodyne OFDM

In this paper, we present a subcarrier pairing scheme to improve the overall error performance of self-heterodyne (self-het) OFDM communications. The proposed pairing scheme exploits the average signal-to-interference-to noise ratios (SINRs) imbalance experienced among self-het OFDM subcarriers. At the transmitter, two simple operations, symbol constellation rotation and component interleaving, are performed before pairing the good and the bad OFDM subcarriers, and maximum likelihood detection is used at the receiver to decode the information. The simulation results show that the proposed pairing scheme improves the system performance by 2.5 dB and 0.6 dB for Rayleigh fading and AWGN channels at bit error rate (BER) of 10^-3, respectively, without any coding overhead. In addition, we show that, in the presence of phase noise, self-het OFDM using the proposed pairing scheme outperforms the conventional OFDM schemes with superheterodyne receiver structures.