Adaptive filtering for fading channel estimation in WCDMA downlink

In order to perform coherent demodulation in fading channel conditions, channel phase and amplitude estimation is necessary. In a WCDMA downlink, the common pilot code channel is used for channel estimation in order to facilitate multipath diversity combining. The quality of the channel estimates may be improved by averaging or filtering over several pilot symbols. However, the optimal form and bandwidth of the estimation filter depend on the channel fading statistics and signal-to-interference ratio. In this paper, we investigate pilot aided channel estimation through adaptive filtering. Thus, near optimum channel estimates are obtained with different fading channel speeds and frequency offsets.