Method, medium, and apparatus controlling handover between different networks

A method for controlling a router in a network system, wherein a mobile terminal performs a handover from a first network to a second network during data transmission and/or reception through an existing data transmission tunnel between a router and an access point within the first network, comprising:

• receiving a vertical handover (VHO) request message from the mobile terminal;
• building a new data transmission tunnel between the router and an access point within the second network based on the received VHO request message;
• and
• transceiving data through the new data transmission tunnel between the router and the access point within the second network when a message acknowledging a changing of the transmission bandwidth of the data transmission and/or reception, based on a message, during employment of the existing data transmission tunnel, from the mobile terminal to the server requesting a transmission bandwidth change of the data transmission and/or reception so as to have a transmission bandwidth supported by the second network, is received from the server.

A network system, wherein a mobile terminal performs a handover from a first network to a second network during data transmission and/or reception through an existing data transmission tunnel between a router and an access point within the first network, comprising:

• the mobile terminal to transmit to a server a message, during employment of the existing data transmission tunnel, requesting a transmission bandwidth change of the data transmission and/or reception to a transmission bandwidth supported in the second network, after performing the handover;
• the server to change the transmission bandwidth of the data transmission and/or reception to the transmission bandwidth supported by the second network based on receipt of the message requesting the transmission bandwidth change, and to transmit a message to the router acknowledging a changing of the transmission bandwidth of the data transmission and/or reception, after the changing of the transmission bandwidth of the data transmission and/or reception;
• and
• the router to transceive data through a new data transmission tunnel between the router and an access point within the second network based on the message acknowledging the changing of the transmission bandwidth of the data transmission and/or reception.