Abstract: Transmission data is spread by spreaders through two orthogonal codes generated by orthogonal code generators, the spread signals are subjected to binary phase modulation with a given carrier wave by BPSK modulators, and are then transmitted from separate antennas positioned in differing spatial locations. Thus, it is possible to provide a radio communication system capable of realizing transmission diversity even in the case of initial transmission where there is yet no information regarding the location, direction, etc., of a partner station, or where a base station is to transmit data directed to all of a plurality of mobile stations, such as in mobile communication systems.

Abstract: A delay detection is performed to baseband signals subjected to an orthogonal demodulation to obtain a delay detection output and a frequency error is found from the delay detection output. The frequency error is converted into a control frequency which is accumulated to generate a phase rotation .phi. which is used to rotate the input baseband signals before being subjected to the delay detection, thereby to perform frequency correction. By providing filters downstream of a phase rotation circuit and upstream of a delay detection circuit, automatic frequency control can be realized without performance deterioration.