An adaptive ICI self cancellation scheme to compensate the frequency offset for OFDM system

For orthogonal frequency-division multiplexing (OFDM) systems, the frequency offsets in mobile radio channels distort the orthogonality between subcarriers resulting intercarrier interference (ICI). Intercarrier interference (ICI) self cancellation is a very simple way for suppressing ICI in OFDM system. In this paper, an adaptive ICI self cancellation scheme is proposed. The basic concept and the structure of the adaptive scheme are introduced. The frequency offset and the signal power and noise power ratio (SNR) are given as the metrics for adaptive switching among the candidates of the digital modulation and ICI self cancellation scheme. Under the constraint of a fixed target bit error rate (BER) of 10/sup -5/, the switching intervals of the frequency offset and SNR are determined and an adaptive strategy based on 2-dimensional metrics is presented. The analysis results show that compared with the fixed modulation coding schemes, the proposed scheme has a wider dynamical range, a stronger capability to combat the frequency offset and more bandwidth efficiency at the required bit error rate performance.