A user equipment apparatus for performing user equipment-to-user equipment communication includes a synchronization signal detection unit configured to detect a user equipment-to-user equipment synchronization signal transmitted from a user equipment apparatus in another cell or another carrier; a control unit configured to set reception timing based on the user equipment-to-user equipment synchronization signal; and a reception unit configured to receive scheduling information or a discovery signal transmitted from the user equipment apparatus in the other cell or the other carrier within a time window defined based on the user equipment-to-user equipment synchronization signal.