A Spectrally Efficient Intercarrier Interference Reduction Scheme for Orthogonal Frequency Division Multiplexing Systems in Low Signal-to-noise Ratio Environment

摘要

The inherent sensitivity of orthogonal frequency division multiplexing (OFDM) systems to any frequency shift in the signal makes their design very challenging. In OFDM systems, the frequency shift may be due to instability of transmitter/ receiver oscillators or because of fading channel. The frequency shift in the signal destroys the orthogonality among subcarriers and results in intercarrier interference (ICI), which affects the system performance severely. A number of solutions are available to mitigate the effect of ICI. The existing ICI mitigation techniques include frequency equalization, time domain windowing, ICI self-cancellation, coding, etc., Among several ICI reduction methods, ICI self-cancellation scheme has received much attention due to its simplicity. The ICI mitigation schemes that depend on carrier frequency offset (CFO) correction at the transmitter are effective under high signal-to-noise ratio (SNR) scenario and those that depend on CFO estimation and correction at the receiver have additional computational complexity and some sort of data symbol redundancy. In this paper, a bandwidth-efficient ICI reduction method for M-ary QAM signals is proposed. The present method is effective in low SNR environment. This method reduces the effect of ICI and improves the performance of the system in terms of bit error rate. It is shown that the proposed ICI cancellation method considerably outperforms the existing ICI self-cancellation schemes in the presence of small CFO while maintaining the throughput level.