US006154443A [ii] Patent Number: 6,154,443  Date of Patent: Nov. 28,2000
The present invention provides a CDMA RAKE receiver that computes a data detection using Fast Fourier Transform (FFT) matched filters. Signals received are processed in frequency domain by the RAKE receiver. The RAKE receiver includes a pilot signal spreading code matched filter, a data signal spreading code matched filter and a channel matched filter. The pilot signal spreading code matched filter removes a spreading code of the pilot signal. The data signal spreading code matched filter removes a multiple access spreading code of the data signal. A channel matched filter estimates the channel frequency response and combine the received data signal from different paths before a decision is made. For increasing the CDMA system capacity, the RAKE receiver uses a interference cancellation method. A downlink receiver at a mobile station estimates the interference of a pilot signal and subtracts the pilot interference from the received signal before data detection. The uplink receivers at a base station use a multi-stage parallel interference cancellation process for removing multiple access interference from other users.
32 Claims, 6 Drawing Sheets