An Improved ICI Cancellation Method to Reduce the Impact of Frequency Offset in OFDM Systems

Abstract

The problem of frequency offset is very serious in case of orthogonal frequency division multiplexing communication systems (OFDM). The reason is that the frequency offset disturbs the relation of orthogonality among the sub carriers and lead to an interference known as inter-carrier interference (ICI). This paper studies the existing inter-carrier interference self cancellation methods and proposes a new and effective method to suppress the effect of frequency offset on OFDM systems. The method comprises of two simple steps. The first step is carried out at the transmitter end where a data symbol and its conjugate are mapped onto four sub carriers. The second step is carried out at the receiver end where the received signals are linearly combined. The result is that the ICI existing among the sub carriers is sufficiently reduced. The proposed method is supported with mathematical work and the simulation is done on MATLAB which proves that our proposed method reduces the bit error rate (BER) to a greater extent and also carrier-to-interference ratio (CIR) is increased than the existing self cancellation schemes.