Adaptive channel estimation in DS-CDMA downlink systems

We design an adaptive channel estimator (ACE) in the DS-CDMA downlink that has a common pilot channel (CPICH). The proposed ACE first estimates the channel condition, including the maximum Doppler frequency, without requiring exact a priori information on the operating condition. Then, it adjusts the impulse response of the channel estimation filter in response to the estimated channel condition. The performance of the proposed ACE is verified by computer simulation. The performance improvement with the use of the proposed ACE increases as the channel experiences severe frequency selective fading or the mobile is getting closer to the cell boundary.