To provide a radio capable of reducing wiring costs without increasing the number of transmission lines of a radio signal in an on-vehicle radio 1 that needs to cope with a number of radio systems and needs an adaptive reception technique, where mobile reception is assumed, and to provide an assignment control method of an optical multiplex transmission line.

An ADC 14a, or the like can adjust sampling rate and/or the number of quantizations from a radio signal control section 30. A control section 36 transmits control information s/q-c for controlling the sampling rate and/or the number of quantizations to the side of the ADC14a, or the like to perform resource assignment control of the optical multiplex transmission line 24 between respective radio systems, based on the reception performance of a signal in each radio system demodulated by a group of demodulators 34a, or the like. The control information s/q-c instructs a reduction in a sampling rate and/or in the number of quantizations for the signal in a radio system having the high reception performance of the signal demodulated by the group of demodulators 34a, or the like, and instructs an increase in the sampling rate and/or in the number of quantizations for the signal in a radio system having low reception performance.