A radio communication system comprising: base stations that include a first base station (eNB) and a second base station (PhNB), the first base station performing radio communication using a first frequency band and covering a first cell that is identified by a first cell identity, the second base station performing radio communication using a second frequency band and covering a second cell that is identified by a second cell identity; and a user device configured to perform radio communication with each of the base stations, wherein the first base station (eNB) includes: a first transmitting unit configured to transmit, at a first transmission timing, a first synchronization signal that indicates the first cell identity, which identifies the first cell covered by the first base station, wherein the second base station (PhNB) includes: a second transmitting unit configured to transmit an identification signal that indicates the second cell identity, which identifies the second cell covered by the second base station, wherein the user device includes: a cell searcher configured to detect the first transmission timing based on the first synchronization signal received from the first base station and perform timing-search processing that establishes synchronization with the first base station, wherein the first base station (eNB) further includes: an information notifying unit configured to notify the user device of synchronization state information related to a synchronization state between the first base station and the second base station and of frequency information related to an identification signal frequency that the second base station uses to transmit the identification signal, the identification signal frequency being included in the second frequency band, wherein the synchronization state information indicates whether the first base station and the second base station are synchronized or indicates a transmission offset value for the first transmission timing at the first base station, and wherein the cell searcher of the user device, based on the synchronization state information from the first base station, is configured to perform identifying processing on the identification signal frequency indicated by the frequency information to identify the second cell identity indicated by the identification signal. base stations that include a first base station (eNB) and a second base station (PhNB), the first base station performing radio communication using a first frequency band and covering a first cell that is identified by a first cell identity, the second base station performing radio communication using a second frequency band and covering a second cell that is identified by a second cell identity; and a user device configured to perform radio communication with each of the base stations, a first transmitting unit configured to transmit, at a first transmission timing, a first synchronization signal that indicates the first cell identity, which identifies the first cell covered by the first base station, a second transmitting unit configured to transmit an identification signal that indicates the second cell identity, which identifies the second cell covered by the second base station, a cell searcher configured to detect the first transmission timing based on the first synchronization signal received from the first base station and perform timing-search processing that establishes synchronization with the first base station, an information notifying unit configured to notify the user device of synchronization state information related to a synchronization state between the first base station and the second base station and of frequency information related to an identification signal frequency that the second base station uses to transmit the identification signal, the identification signal frequency being included in the second frequency band, wherein the synchronization state information indicates whether the first base station and the second base station are synchronized or indicates a transmission offset value for the first transmission timing at the first base station, and wherein the cell searcher of the user device, based on the synchronization state information from the first base station, is configured to perform identifying processing on the identification signal frequency indicated by the frequency information to identify the second cell identity indicated by the identification signal.