Method and system for minimizing delay that is owing to hard hand-off in wireless communication system

PURPOSE: A delay minimization method and a system thereof in a hard handoff in a wireless communications system are provided to minimize data transmission delay in hard handoff in a boundary area. CONSTITUTION: An AT(Access Terminal)(110) moves from first sub network to a second sub network in a wireless communication system. The first sub-network and the second sub network have versions different from each other. A GAN(150) buffers the packet data over the expected level. The GAN checks a packet sequence in the AT. If the hard handoff is completed by using the buffered data, the GAN transmits the packet transmitted in AT.