An Adaptive Channel Estimation Algorithm For WCDMA Downlink

RAKE receiver is an effective anti-multi-path technique. Channel estimation is one of the key features of this technique and will lead to the better performance of RAKE receiver. A chip-level channel estimation technique with varing step size is brought forward to improve the performance of RAKE receiver for WCDMA downlink.For the first place, the effects of different channel parameters for WCDMA downlink channel estimation are analyzed. The tapped delay model of the multi-path frequency selective fading channels as well as the diversity receiver technique is introduced, and the principles of RAKE receiver are described. Then various downlink channel estimation techniques, such as simple averaging, WMSA and FBPreLMS are analysed in detail. Considering the disadvantages of these methods in dealing with fast fading channels, a chip-level adaptive channel estimation method is proposed in this thesis and has better performance than other methods. Furthermore, a procedure to derive optimum step length for this technique is given in particular. In the end, the WCDMA downlink channel model simulated with Simulink. The simulation results show that the new method has the better performance over other methods both in the low fading channels and in the high speed mobile environment.