Performance analysis of OFDM mobile systems for wireless communication

Abstract

This paper studies an efficient inter-carrier interference (ICI) Cancellation scheme. The scheme works in two very simple steps. At the transmitter side, one data symbol is modulated on to a group of adjacent sub-carriers with a group of weighting coefficients. The weighting coefficients are designed such that the ICI caused by the channel frequency errors can be minimized. At the receiver side, by linearly combining the received signal on these sub-carriers with proposed coefficients, the residual ICI contained in the received signal can then be further reduced. In this paper performance of Orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency offset between the transmitter and the receiver has been simulated in terms of carrier-to-interference (CIR) ratio and bit error rate (BER) performance. In this paper BER curves were used to evaluate the performance of ICI self-cancellation scheme. It is observed from the figure that in presence of small frequency offset and binary alphabet size, self cancellation gives the best results. From figure it has been concluded that BER of standard OFDM with ICI self cancellation using binary phase shift keying (BPSK) is better than BER of standard OFDM with ICI self cancellation using quardrature phase shift keying (QPSK). ICI self cancellation scheme is used for lower frequency offset values and lower modulation schemes like BPSK But as self cancellation scheme does not require very complex hardware and software implementation this scheme gives the best result for lower frequency offset and alphabet size.