Under a sectorized cell architecture in a mobile communication system, a scrambling code applied to multiplication of a transmission signal is selected and switched among different types of downlink physical channels in a unified manner. One of multiple transmission signals to be transmitted on a corresponding one of the different types of downlink physical channels is generated. A first code is selected according to the type of the physical channel to enable multiplying the transmission signal by the first code. The transmission signal is multiplied by an intracell common scrambling code used in common among sectors in a same cell in addition to or in place of the multiplication of the first code. The transmission signal multiplied by at least one of the first code and the intracell common scrambling code is transmitted on the corresponding physical channel.