Abstract: A method and an apparatus for synchronizing the keep-alive packet transmission timings of the direct push applications are provided to improve an electric current consumption characteristic. The method includes detecting a network event, synchronizing transmission timings of keep-alive packets of direct push applications with reference to an occurrence time of the network event, and transmitting the keep-alive packets of the direct push application at a synchronized transmission timing simultaneously.

Abstract: Disclosed is a mobile communication system for handover between heterogeneous mobile communication networks. A dual-mode terminal has first and second modules capable of performing communication in first and second heterogeneous communication technologies, respectively. The dual-mode terminal measures strength of a signal received by the first module to determine whether the dual-mode terminal has moved between the mobile communication networks. If it is determined that the dual-mode terminal moves to a different network, the dual-mode terminal measures the strength of a signal transmitted from the different network, and converts measurement information into a first SMS message. A first mobile communication network device provides a service for performing communication with the first module, restores data from the first SMS message, and transmits the restored data to an interface network.

Abstract: A device for tracking a mobile station's position in a mobile communication system. The device comprises a receiver for receiving single tone signals and positional information transmitted from at least three base stations; a tone phase measurer for measuring phase differences, dependent on propagation delay, of the tone signals on the basis of a base station's system reference time before propagation delay; and a mobile station's position calculator for calculating positional information of the mobile station using the measured phase differences and the positional information of the base stations.