User equipment for communicating with a base station via a radio frame includes a receiver to receive, from the base station, information indicating a downlink region or an uplink region, and information on a RACH configuration table indicating allocation of RACH resources associated with a time domain; a control unit to identify an available RACH resource, based on the information indicating a downlink region or an uplink region, and the information on the RACH configuration table; and a transmitter to transmit a preamble to the base station using the identified available RACH resource. The information indicating the downlink region or the uplink region includes an unknown region used for one of downlink and uplink, and availability of the RACH resource in the unknown region is explicitly or implicitly identified in case where the information on the RACH configuration table indicates that the RACH resource is allocated to the unknown region.