A mobile station apparatus 101-1 detects and reports a reception quality value of a known signal transmitted from a base station apparatus 102-1. Base station apparatus 102-1 has a quality deficiency signal generation section 1021 that compares the reception quality value with a predetermined threshold value and generates a quality deficiency signal when it is shown that the reception quality value is less than the predetermined threshold value, and a quality deficiency signal reporting section 1024 that reports an identifier of mobile station apparatus 101-1 corresponding to the quality deficiency signal to a base station control apparatus 103. Base station control apparatus 103 has a control signal transmitting section 1031 that transmits a control signal to switch data transmission by means of HSDPA for mobile station apparatus 101-1 to data transmission by means of DPCH.
