Abstract: Disclosed is a method for performing roaming capable of minimizing a ping-pong phenomenon and a dual mode mobile terminal using the same. Functions for the method for performing roaming and the dual mode mobile terminal using the same are realized such that a ping-pong phenomenon occurring in a shadow area of one of the communication networks providing communication services using different mobile communication techniques can be minimized. To this end, it is determined if the dual mode mobile terminal is in a shadow area by counting the number of ping-pong occurrences in the process of performing a mode based on a corresponding communication service and a ping-pong period is adjusted only when the dual mode mobile terminal is in the shadow area, thereby minimizing a ping-pong phenomenon.

Abstract: A method and system for supporting Internet Protocol (IP) mobility of a Mobile Node (MN) in a mobile communication system. In the mobile communication system supporting Mobile IP (MIP) and Session Initiation Protocol (SIP), MIP location registration is performed in a Home Agent (HA) through a first FA (Foreign Agent) of a first foreign network in which the MN is located. When the MN receives a SIP invite message from a Correspondent Node (CN), it sends, to the CN, a SIP response OK message in which a home address of the MN is recorded. The CN sends a packet to the home address of the MN in a state in which a SIP call of the MN is established. The number of signaling messages and a delay time associated with a handover can be reduced, because the CN sends packets only to the home address of the MN regardless of a changed location of the MN.

Abstract: A method classifying service classes of packet data through an algorithm using several parameters is disclosed, in order to control the order of data transmission in a two-way communication network which supports various data transmissions having different kinds of quality of service (QoS).