Adaptive Decision Feedback Channel Estimation with Periodically Phase Correction for DS-CDMA Signal Transmission with Coherent Frequency-domain Equalization

DS-CDMA can achieve good bit error rate (BER) performance in a severe frequency-selective fading channel by using frequency-domain equalization (FDE) based on MMSE criterion instead of rake combining. FDE requires accurate channel estimation (CE). Recently, a decision feedback (DF)MMSE-CE using a fixed DF filter coefficient has been proposed. The DF filter coefficient is an important design parameter and the optimum coefficient depends on the received signal-to-noise power ratio (SNR) and the Doppler spread. In this paper, we propose an adaptive DF (ADF)-MMSE-CE, in which the DF filter coefficient is adapted to changing channel conditions based on the recursive least square (RLS) algorithm. Furthermore, the channel estimate is phase corrected upon the reception of the periodically inserted pilot chip block. It is shown by computer simulation that the ADF-MMSE-CE with periodical phase correction is very robust against the Doppler spread. KeywordsDS-CDMA, frequency-domain equalization, adaptive decision feedback, channel estimation.