CDMA mobile communication method and system for realizing an autonomous distributed control of radio channel allocation, a synchronization control for a smooth establishment/switching, and a VOX control for a capacity increase. At either one station of each base station and the mobile station, one of a plurality of prescribed short spread codes is selected, and data sequence to be transmitted is spread by using the selected short spread code and a prescribed long spread code and then transmitted, while at another one station, the data sequence before spreading is reproduced and received by despreading the data sequence from that either one station by using the selected short spread code and the prescribed long spread code. At a time of the handover, each one of data to be communicated between a handover source base station and the mobile station and data to be communicated between a handover target base station and the mobile station is spread by using both a long spread code and a short spread code, and the received data are composed by adjusting timings at each of the mobile station and the base station. Also, a VOX control is carried out for transmission frames to be transmitted through a radio channel in at least one of each base station and the mobile station, and transmitted by randomly allocating an offset with respect to a transmission timing for each channel from a plurality of prescribed offset amounts.