Enhanced channel estimation for W-CDMA forward link using pilot symbols over Rayleigh-fading multipath channels

A three-stage channel estimation scheme is proposed for the down link of an asynchronous W-CDMA system in a frequency-selective Rayleigh-fading channel. At the first stage, zero-delay channel estimation can be obtained by using a decision-directed prediction filter in SIR measurement, therefore we can achieve fast power control. The second stage performs the data decision to make a virtual pilot channel for the next stage by using the weighted multi-slot averaging (WMSA) channel estimation scheme. Finally, the third stage performs the channel estimation of the "block-wise sliding average" type by using the virtual pilot channel obtained in the second stage. The performance of the proposed channel estimation scheme is compared with that of other schemes for various Doppler frequencies. By using Monte-Carlo computer simulations, we show that the proposed channel estimator is superior to other estimation schemes such as the WMSA (K=1) and DD-RAKE.