Phase rotated ICI self-cancellation scheme with frequency diversity for OFDM systems

Carrier frequency offset (CFO) destroys the orthogonality of the subcarriers and causes intercarrier interference (ICI). ICI self-cancellation scheme proposed by Zhao et al. is the simplest scheme to mitigate the effect of ICI. It repeats the same data symbol on two adjacent subcarriers with phase inversion and therefore does not provide any frequency diversity. To achieve frequency diversity Tang et al. proposed a symmetric data conjugate transmission scheme to mitigate the effect of ICI but its BER performance degrades at higher values of CFO. In order to improve its BER performance, a phase rotated symmetric data conjugate transmission scheme to mitigate the effect of ICI has been proposed in this paper. Like symmetric data conjugate scheme, proposed scheme also repeats the same data symbol with phase rotation on two symmetrically located subcarriers to achieve frequency diversity. The analytical expression for optimal phase rotation factor to optimize the carrier-to-interference ratio (CIR) performance of the proposed scheme is also derived. It has been shown that proposed scheme provides better performance than that of the conventional symmetric data conjugate scheme especially at high CFO.