Transmission period of scheduling request SR to be optimal is adaptively controlled for each user terminal, so that useless SR transmission is reduced. For the controlling, a base station modifies a transmission period of a radio resource allocation request in an adaptive manner during communication based on communication quality between with a user terminal; notifies the user terminal of the modified transmission period of the radio resource allocation request; and transmits the radio resource allocation request requesting the radio resource from the user terminal to the base station at the notified transmission period.