Abstract: In the data call handover method, the mobile communication terminal registers a Mobile Internet Protocol (MIP address) through an asynchronous mobile communication network and receives data call service when a data call connection event is initiated by the mobile communication terminal. It is determined whether the mobile communication terminal has entered an area in which the asynchronous mobile communication network and a synchronous mobile communication network overlap. If the mobile communication terminal has entered the overlap area, it is determined whether to perform handover to the synchronous mobile communication network based on the intensity of a signal of the asynchronous mobile communication network. If handover is to be performed, a data call between the mobile communication terminal and the synchronous mobile communication network is established and the MIP address is registered.

Abstract: The present invention relates to a mode switching method for a multi-mode multiband mobile communication terminal in a multi-access communication network, which is capable of effectively providing handoff to the user mobile communication terminal in heterogeneous communication networks. The method includes the first step of calculating the link quality of a Wireless Local Area Network (WLAN); the second step of comparing the link quality with a first reference value; the third step of measuring a signal from the portable Internet having coverage wider than that of the current communication network if it is determined that the link quality of the WLAN is lower than the first reference value; the fourth step of calculating the link quality of the portable Internet; and the fifth step of switching the mode of the mobile communication terminal to perform handoff to the portable Internet if it is determined that the link quality of the portable Internet is higher than a second reference value.

Abstract: The present invention discloses an apparatus and method for deciding an access system based on WLAN signal strength in a WLAN/mobile phone network interworking system, and a mobile terminal therefor. The method for deciding the access system based on the WLAN signal strength in the WLAN/mobile phone network interworking system includes an initialization step for performing an initialization process on a WLAN driver module and a mobile phone network driver module, and measuring and displaying WLAN signal strength, a service decision step for selecting a WLAN service or mobile phone network service according to the measured WLAN signal strength, and a service access step for enabling the corresponding driver module to access the service decided in the service decision step.

Abstract: In an orthogonal frequency division multiplexing (OFDM) system, a receiver includes a received signal transformer, a frequency offset estimator and a frequency compensator. The received signal transformer removes from a training symbol a guardtone and a sub-carrier deviated from a mean value of effective sub-carrier signals by over a predetermined value. The frequency offset estimator estimates the frequency offset of the OFDM digital signal and the frequency compensator compensates the frequency offset of received signals by using the estimated frequency offset. Thus, data transmission efficiency can be greatly improved and influence from a frequency-selective noise channel can be minimized. Further, by removing data unnecessary for the frequency offset estimation, the calculation amount can be reduced.

Abstract: The present invention relates to a roaming method between a WLAN and a cellular network which can interwork the WLAN and the cellular network on the basis of a mobile IP system for smooth roaming.

Abstract: The present invention discloses an authentication system and method having mobility in a public wireless LAN. The authentication system includes an access point for requesting authentication of a wireless terminal to an access point manager, enabling data transmission and reception of the authenticated wireless terminal, and requesting the access point manager to charge the wireless terminal, and the access point manager for authenticating the wireless terminal which has already been authenticated on the basis of previously-registered registration information upon the request of the access point, authenticating the wireless terminal which has not been registered through an authentication server of a wireless network operator, and transmitting the authentication information to the access point.

Abstract: The present invention discloses a method for selecting a system and transmitting data for a WLAN/mobile phone network interworking service in a WLAN and mobile phone network interworking system, which includes: a signal measuring step for setting up a service set ID list of a WLAN in an access point in order for a terminal to allow access, and measuring signal strength for the WLAN access; an access deciding step for selecting an access system based on the signal strength measured in the signal measuring step; a WLAN performing step for periodically measuring signal strength of a WLAN channel satisfying the access allowable service set ID list, and accessing the corresponding WLAN channel or a mobile phone network according to the existence or absence of the WLAN channel guaranteeing signal quality for the WLAN access, when the WLAN access is confirmed in the access deciding step; and a mobile phone network performing step for periodically measuring signal strength of the WLAN channel satisfying the access al

Abstract: The present invention discloses an apparatus and method for deciding an access system based on WLAN signal strength in a WLAN/mobile phone network interworking system, and a mobile terminal therefor. The method for deciding the access system based on the WLAN signal strength in the WLAN/mobile phone network interworking system includes an initialization step for performing an initialization process on a WLAN driver module and a mobile phone network driver module, and measuring and displaying WLAN signal strength, a service decision step for selecting a WLAN service or mobile phone network service according to the measured WLAN signal strength, and a service access step for enabling the corresponding driver module to access the service decided in the service decision step.

Abstract: The present invention relates to a point-to-multipoint traffic routing method that routes a multicast traffic through a determined tree on an MPLS network. A node on an MPLS network conducting a point-to-multipoint traffic routing method receives a message with an object including topology information on a determined tree, determines whether itself is a copy node or not based on the topology information, and copies, if determined to a copy node, the received message to transmit to at least two nodes specified as next by the topology information. The present routing method ensures smooth operations of a copy and a merge node as well as an overall network.

Abstract: In an orthogonal frequency division multiplexing (OFDM) system, a receiver includes a received signal transformer, a frequency offset estimator and a frequency compensator. The received signal transformer removes from a training symbol a guardtone and a sub-carrier deviated from a mean value of effective sub-carrier signals by over a predetermined value. The frequency offset estimator estimates the frequency offset of the OFDM digital signal and the frequency compensator compensates the frequency offset of received signals by using the estimated frequency offset. Thus, data transmission efficiency can be greatly improved and influence from a frequency-selective noise channel can be minimized. Further, by removing data unnecessary for the frequency offset estimation, the calculation amount can be reduced.

Abstract: The present invention relates to a method of determining at least one traffic route in an MPLS (Multi-Protocol Label Switching) network.