A hard hand-over method and system without data loss

PURPOSE: A hard handover method and system free from data loss is provided to increase service quality by preventing data loss in a hard hand-over and to efficiently operate a new hard handover method. CONSTITUTION: A base station controller(300) consists of an RRC(Radio Resource Control) layer(310) and an RLC(Radio Link Control) layer(320). The RRC layer(310) comprises a call control part(311). The RLC layer(320) comprises a buffer control part(321) and a handover buffer(322). The call control part(311) controls the buffer control part(321) with call setup and release. If a mobile terminal moves from the coverage of the first base station(100) to the coverage of the second base station(200), it is reported to the base station controller(300) through a measurement report message. Receiving the measurement report message, the base station controller(300) generates a handover. If a handover is generated, the call control part(311) stops the transmission of downlink data to the first base station(100) and directs the buffer control part(321) to store the data incoming from a core network(400) in the handover buffer(322). At the same time, the call control part(311) transmits a handover generation message to inform the first base station(100) that a hand-over has been generated.