The RAKE receiver exploits multipath channel characteristics and scrambling codes with good cross-correlation properties to realize a maximum ratio diversity combiner. Multipath propagation and the resulting channel impulse response)
Fig. 2 shows a typical baseband multipath channel transmission model for DS-CDMA on the uplink. The binary user and control data at the rate of R bits/s taking on values ±1 are multiplied by orthogonal channelization (OVSF) codes at the rate of SF×R chips/s where SF is the spreading factor. The spread user and control signals are I/Q-code multiplexed and then multiplied by a complex scrambling code which enables separation of separate mobile users at Node B. The scrambled signal goes through the multipath channel. The output of the multipath channel is distorted by additive white Gaussian noise (AWGN) and multiuser interference.