ML estimation and correction of frequency offset for MC-CDMA systems over fading channels

Multi-carrier code division multiple access (MC-CDMA) has been proposed as one of the air interface candidates for the third generation wireless communication systems. However, MC-CDMA systems suffer a lot of performance degradation due to carrier frequency offsets. In this paper, we derive the likelihood function for the carrier frequency offset for MC-CDMA systems for the downlink over Rayleigh flat fading channels. We also propose a gradient algorithm to estimate and minimize the carrier frequency offset in a tracking mode. Simulation results show that system performance can be improved significantly even with only a few iterations.