MOBILE COMMUNICATION TERMINAL APPARATUS, CONTROL METHOD THEREOF, COMMUNICATION SYSTEM, AND LOAMING METHOD THEREOF

摘要

A mobile communication terminal apparatus and a control method thereof wherein a smooth handoff can be quickly achieved in a seamless manner during a roaming between data communication networks of different packet exchange systems. A mobile communication terminal apparatus (100) comprising a network access unit (NAU) (101) having a network access mechanism that has been uniquely established by adjusting the specifications of hardware, software and protocols; and a MADU (Multiple Access Decision Unit) (103) that uses a set of interfaces to exchange information with the NAU (101), thereby deciding a channel to be used in a communication session, and that controls the NAU (101) corresponding to the decided channel; wherein the mobile communication terminal apparatus performs a roaming between data communication networks of different packet exchange systems.