Patent ID: 8483177

Claim:
A method of performing handover of a mobile terminal, comprising: in a state where a mobile terminal is connected to a first radio network, when a second radio network having a different connection procedure from a connection procedure of the first radio network and connected to an evolved packet core (EPC) of the first radio network is sensed, selecting the second radio network and starting handover to the second radio network using a second radio network interface ID for the second radio network; generating an IP packet in accordance with the second radio network interface ID and performing an IP mobility procedure; being connected to the second radio network to perform an association procedure through subscriber authentication, to request the second radio network to update IP addresses, and to register the updated IP addresses; and receiving packet data through the second radio network using the updated IP addresses, in a state where the mobile terminal is connected to the second radio network, starting handover to the first radio network through a first radio network interface ID for the first radio network, after starting handover to the first radio network, generating and transmitting an IP packet for performing a mobility procedure in accordance with the first radio network interface ID and requesting the first radio network to reset a radio access bearer (RAB); transiting a connection state to the first radio network from an idle state to an active state; and requesting the first radio network to update IP addresses to register updated IP addresses and to receive packet data through the first radio network.