Abstract: A method and system for processing a message in an Internet protocol-based mobile communication system supporting a multimedia service. In the system, application servers include a representative application server and multiple backend application servers. A method for defining a control message between application servers to set up a session using the standard Internet protocol is provided. When an application server performs a call processing operation, control message processing load and control message transmission delay is reduced.

Abstract: The present invention relates to the field of mobility in heterogeneous wireless networks. In particular, the invention proposes a system and method of providing User Equipment (UE) initiated and assisted backward handover in the heterogeneous wireless networks. Depending on certain criteria, the UE may decide that if it needs a handover from a serving network to a target network. The UE initiates the backward handover by sending handover request message to the target network through the serving network. The serving network checks for the capabilities of the UE and authorizes the backward handover. The target network prepares for the backward handover and informs the UE when the target network is ready. The UE then starts the handover procedure.

Abstract: A method and apparatus for establishing an RRC connection are provided, in which a UE compares the strength of a signal received from a serving cell with a threshold, upon receipt of a request for RRC connection establishment, transmits an RRC connection request message to a RAN, measures the strengths of signals from neighbor cells during a first time period and monitors a downlink channel of the serving cell to receive a response message for the RRC connection request message during a second time period, if the signal strength of the serving cell is less than the threshold, and receives the response message from the RAN on the downlink channel.

Abstract: Disclosed is an apparatus and a method for radio connection setup in a mobile communication system. In the method, a UE reports mobility information to a network, and the network performs according to the mobility information of the UE. Therefore, it is possible to reduce complexity of the UE and reduce the waste in power consumption thereof, and reduce the signaling overhead of the network, thereby achieving efficient use of resources.

Abstract: A method for connection roaming a Mobile Node (MN) to a Network GateWay (NGW) for providing secure data path using Internet Protocol (IP) security procedure. Also Mobile IP (MIP) is required for providing mobility to the user, when the MN moves from one sub-network to another. However, when the Home Address of the network is not known, a cyclic interdependency is observed between the IP Security (Ipsec) procedures and IP procedures. If the home address of the MN is not known initially during the procedure, IPsec Security Associations (SA's) are formed between the MN and NGW such that only IP packets are passed through. After the IP Registration is completed, the Home Address of the MN is known from the MIP registration Reply. MN now forms a data path tunnel with the NGW by exchanging Create_Child_SA messages.

Abstract: Disclosed is a method for maintaining uplink timing synchronization by a User Equipment (UE) in a mobile communication system, without uplink transmission of a preamble from a UE or without transmission of uplink timing difference information from an Evolved Node B (E-NB) to solve the inefficient use problem of radio resources, occurring due to periodic transmission of uplink signaling and downlink signaling during maintenance of the uplink timing synchronization, and a UE apparatus for the same.

Abstract: A method and system in which upon occurrence of a P-CSCF failure, a network sends an IMS reregistration request message to a UE. An S-CSCF or an AS monitors a P-CSCF to detect occurrence of a failure in the P-CSCF. Upon detecting the occurrence of a P-CSCF failure, the S-CSCF or the AS sends a request message for IMS reregistration to the UEs being served by the failed P-CSCF. In this manner, the UE can continuously receive the service even though a failure occurs in the P-CSCF.

Abstract: A method and apparatus for processing an IMS terminal's call request for real-time service and non-real-time service received over an IMS domain in a CSI terminal. When deciding to use a CS call for real-time service and an IMS session for non-real-time service, the CSI terminal sends an IMS session response for the non-real-time service. In the mean time, the CSI terminal generates a CS call request for the real-time service and sends the CS call request to an AS in an IMS domain. The AS sends the CS call request in association with the IMS session response to the IMS terminal, thereby completing a call setup. For the association, the AS sends its MSISDN to the CSI terminal and identifies from the MSISDN included in the CS call request and the IMS session response that the two messages are related to the IMS terminal's call request.

Abstract: A method and apparatus is provided for reducing a signaling overhead in routing area update performed by a mobile station in a mobile communication system. The method includes grouping cells of the mobile communication system into predetermined cell groups by the network entity, wherein each of the predetermined cell groups is a minimum unit for routing area update; determining cell group identifiers of the cell groups by the network entity; and determining metric information for determining a shape of the routing area by the network entity.

Abstract: A method and apparatus performs handover from an OFDM-based E-UMTS system to a CDMA-based UMTS system. A UE in communication with a PDN via the E-UMTS system, measures signal strength of the UMTS system, and sends a measurement report message indicating the measured signal strength to the E-UMTS system. A radio access network (E-RAN) of the E-UMTS system, determines whether to perform handover from the E-UMTS system to the UMTS system based on the measured signal strength. If the handover is to be performed, a core network (E-CN) of the E-UMTS system generates a PDP context and an MM context for the UE in response to a handover request from the E-RAN. The E-CN sets up a data tunnel for the UE to a GGSN of the UMTS system using the PDP/MM context. After setting up the data tunnel, the E-CN sends to the UE a handover command message including information on a radio bearer (RB) to be used by the UE to access the UMTS system. The UE accesses the UMTS system using the RB information.

Abstract: A method and apparatus for, upon generation of an event triggering a change in the state of a UE participating in a call, sending service information changed due to the state change to the other participating entity and notifying each user of the service information are provided. When a state change event occurs to a UE, the UE checks its available services and sends a message including service information indicating the available services to the other entity connected to the UE. Therefore, the other entity has knowledge of the actual available services of the UE in a changed environment.

Abstract: The present invention provides session continuity when a User Equipment (UE) moves from one network to another network. A method and system for providing access to nodes supporting, for example, both Internet Protocol Version 4 (IPv4) and Internet Protocol Version (IPv6) on a network supporting only one of the IP versions are provided. In addition, both network based mobility and UE based mobility mechanisms are supported to allow a UE supporting dual stack mobility access to a network supporting only one of IPv4 or IPv6. The invention provides for a reduction of header overhead and signaling overhead.

Abstract: A communication method and apparatus using the IP address of a gateway for an MN in a VPN are provided. When the MN is to access the VPN, the gateway acting an FA in the VPN performs a Mobile IP registration on behalf of the MN and is allocated a HoA for the MN from an HA. Therefore, the number of addresses required for the Mobile IP registration of the MN is reduced and overlap between an IP-in-IP tunnel for Mobile Internet and an IPsec tunnel for the VPN is avoided. As a result, packet transmission overhead is reduced.

Abstract: A method for controlling a rate of a voice service in a mobile communication system supporting the voice service via a packet network. The method includes the steps of receiving a control message at a terminal from a radio network controller (RNC); if the control message indicates control of a downlink rate, determining a downlink rate according to the control message; setting a Change Mode Request (CMR) field of an uplink Voice over Internet Protocol (VoIP) packet according to the downlink rate, and transmitting the uplink VoIP packet from the terminal to the RNC; if the received control message indicates control of an uplink rate, determining an uplink rate according to the control message; and generating an uplink VoIP packet including uplink voice data generated according to the determined uplink rate and frame type (FT) information indicating the determined uplink rate, and transmitting the uplink VoIP packet from the terminal to the RNC.

Abstract: A method for controlling a rate of a voice service in a mobile communication system supporting the voice service via a packet network. The method includes the steps of receiving a control message at a terminal from a radio network controller (RNC); if the control message indicates control of a downlink rate, determining a downlink rate according to the control message; setting a Change Mode Request (CMR) field of an uplink Voice over Internet Protocol (VoIP) packet according to the downlink rate, and transmitting the uplink VoIP packet from the terminal to the RNC; if the received control message indicates control of an uplink rate, determining an uplink rate according to the control message; and generating an uplink VoIP packet including uplink voice data generated according to the determined uplink rate and frame type (FT) information indicating the determined uplink rate, and transmitting the uplink VoIP packet from the terminal to the RNC.

Abstract: The present invention relates to the field of mobility in heterogeneous wireless networks. In particular, the invention proposes a system and method of providing User Equipment (UE) initiated and assisted backward handover in the heterogeneous wireless networks. Depending on certain criteria, the UE may decide that if it needs a handover from a serving network to a target network. The UE initiates the backward handover by sending handover request message to the target network through the serving network. The serving network checks for the capabilities of the UE and authorizes the backward handover. The target network prepares for the backward handover and informs the UE when the target network is ready. The UE then starts the handover procedure.

Abstract: A method and apparatus are provided for transmitting a Session Initiation Protocol (SIP) message by a User Equipment (UE) in an idle mode in an Internet Protocol Multimedia Subsystem (IMS) system. The UE transmits one combined message of an AS control message and a NAS control message including information indicating transmission of an SIP message, thereby having an effect on an upper node to reduce a delay due to message processing.

Abstract: A method and system for processing a message in an Internet protocol-based mobile communication system supporting a multimedia service. In the system, application servers include a representative application server and multiple backend application servers. A method for defining a control message between application servers to set up a session using the standard Internet protocol is provided. When an application server performs a call processing operation, control message processing load and control message transmission delay is reduced.

Abstract: The present invention provides session continuity when a User Equipment (UE) moves from one network to another network. A method and system for providing access to nodes supporting, for example, both Internet Protocol Version 4 (IPv4) and Internet Protocol Version (IPv6) on a network supporting only one of the IP versions are provided. In addition, both network based mobility and UE based mobility mechanisms are supported to allow a UE supporting dual stack mobility access to a network supporting only one of IPv4 or IPv6. The invention provides for a reduction of header overhead and signaling overhead.

Abstract: Provided is a handover method, in which a call manager of a network having a Circuit Switching (CS) network, a Long Term Evolution (LTE) network, and an Internet Protocol Multimedia Subsystem (IMS) network, provides handover, from the LTE network to the CS network, to a terminal that uses one radio channel. The handover method includes upon receiving a request for handover from the terminal via a node of the LTE network, establishing a line to a Mobile Switching Center (MSC) of the CS network; sending, to the call manager, a request for a change in a session to another party's terminal in communication with the terminal, to establish an Internet Protocol (IP) bearer between the call manager and the other party's terminal; and sending a handover command to the terminal during the establishment of an IP bearer, to establish a radio channel to the base station of the CS network.