Abstract
Multicarrier code-division multiple access (MC-CDMA) combines multicarrier transmission with direct sequence spread spectrum. Recently, different approaches have been adopted without assuming a perfectly known channel. In this paper, we consider the more realistic case that the velocity of mobile station is time-varying. Thus, we present a channel estimation algorithm called Adaptive Unscented Filter (AUF) that can be robust to the variational fading rate. First, we model the mobile radio channel as an AutoRegressive (AR) random process. Then we jointly estimate the parameters of the AR process and the channel gain using the proposed AUF to achieve the robust estimation under variational fading rate. Following channel estimation, the parameters produced in the computation of AUF are used to enhance the performance of the MMSE equalizer. In tracking mode, we adopt decision-directed scheme based on AUF to track both the dynamics and gains of channel and then to detect the signal using the enhanced MMSE equalizer. Simulation results indicate that the proposed AUF-based decision-directed channel tracking algorithm can track the channel more precisely and robustly than the conventional channel estimator. And the enhanced MMSE method can achieve more robust equalization of MC-CDMA communication systems over the rapid multipath Rayleigh fading channel.