The effect of carrier frequency offset for MC-CDMA systems over Rayleigh multi-path fading channels

In this paper, we consider the MC-CDMA system, which is a combination of the multi-carrier modulation technique and the CDMA, multiple access technique. The performance of the system is investigated over AWGN channels as well as over Rayleigh multi-path fading channels. We show that for a given spreading factor, the performance of the system degrades as the number of the sub-carriers increases. Furthermore, the performance of the system is evaluated when a RAKE receiver is used. Finally, the problem of carrier frequency offset is studied. We show that, the performance of the system degrades rapidly as the ratio between the carrier frequency offset and the carrier spacing exceeds a certain ratio, and the system becomes more sensitive to carrier frequency offset as the number of the sub-carriers increases. Results are given in terms of SER obtained by means of computer simulations.