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 MIP 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 MIP packets are passed through. After the MIP 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: A method and system for processing a call change request in an IMS are provided, in which a network entity receives a call request message requesting a first call from a calling UE, stores call information and caller information of the call request message, forwards the call request message to a called UE, acquires, upon receipt of a call change request message requesting change of the first call to a second call from the called UE during the first call, the caller information of the calling UE using an old call information included in the call change request message and the stored call information, inserts the caller information in receiver information of the call change request message, delivers the call change request message to the calling UE, and establishes the second call between the calling UE and the called UE by replacing the first call with the second call.

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 seamless handoff system and method reduces delay and packet loss during handoff of user equipment (UE) from a Wireless Local Area Network (WLAN) network to a Universal Mobile Telecommunication System (UMTS) network. The handoff system and method performs pre-registration and pre-authentication processes before the occurrence of a handoff, buffers packets being delivered to a UE during a handoff period, and forwards the buffered packets to the UE after completion of the handoff, thereby reducing packet loss that can occur during handoff.

Abstract: Disclosed is an apparatus and a method for allocating persistent resources in order to support a packet service in a mobile communication system. The method includes acquiring scheduling information including an allocation period of a persistent resource corresponding to a predetermined packet state in a process of call setup between the communication apparatus and the Node B; receiving an allocation period and a size of a persistent resource to be allocated based on the packet state; and receiving a packet through the allocated persistent resource.

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: A method for supporting a communication service of an idle mode terminal located in a common routing area in a mobile communication system that includes a Node B, an Access Gateway (AGW), and a Home Subscriber Server (HSS), and has a Long Term Evolution (LTE) network and a 3rd Generation (3G) network connected to each other to perform transmission/reception. The AGW receives tracking area information of the LTE network, including routing area information of the 3G network, from the idle mode terminal via the Node B. The AGW sends common routing area indication information and identification information of the terminal to the HSS if the routing area information is coincident with the tracking area information. The HSS stores the common routing area indication information and the identification information of the terminal, and sends a response message according to the indication information.

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 apparatus for transmitting and receiving CQI in a wireless communication system are provided, in which when a UE transitions from a continuous reception state to a DRX state, CQI report resources are reallocated to the UE according to a CQI report resource reallocation rule agreed between the UE and an E-RAN, which obviates the need for signaling information about allocated new CQI report resources.

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: An efficient uplink timing synchronization procedure performed with a target cell upon handover of a User Equipment (UE) in active mode in a mobile communication system is provided, in which a cell transmitter signals to the UE that the uplink timing synchronization procedure is not required in the target cell, and the UE carries out uplink transmission to the target cell at an uplink timing used in a source cell without the uplink timing synchronization procedure.

Abstract: Disclosed is a method and system for mutually exchanging capability information of UEs for communication between a Circuit-Switched (CS) and IMS services (CSI) UE, which can use a CS call for voice communication while using an IMS session for PS service, and an IMS UE which uses an IMS session for both voice communication and PS service. A MGCF performs interworking of capability information between a CS message and an IMS message so that the IMS UE can process UE capability information through an IMS session request/response. When a call request message containing no capability information is created from a UE not supporting capability exchange, a CSI AS transfers the call request message to a peer UE after inserting estimable capability information of the UE into the call request message, and stores capability information of the counterpart UE for the UE.

Abstract: Disclosed is a method and system of deriving new keys for accessing a new system. The method enables an optimized authentication procedure during handover form an existing system to a new system by using the existing system access keys. The user equipment that is accessing the new system receives a temporary ID during handover preparation which enables the user equipment to perform a fast re-authentication. The method uses existing system access keys to derive system access keys for the new network.

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 call setup method and apparatus for minimizing call setup delay by a UE in a mobile telecommunications system are provided. The method includes the steps of: if call setup for a packet call service is requested, determining by the UE if the requested service is a predetermined service sensitive to call setup delay; if the requested packet call service is the predetermined service sensitive to the call setup delay, establishing control information representing that the packet call service is sensitive to the call setup delay; and transmitting a request message requesting the call setup to a network, the request message including the control information. In the method, a network causes a UE using a packet call service sensitive to call setup delay to maintain a connected state, so that restart delay of the packet call service can be minimized.

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: Preference of a home public land mobile network (HPLMN) is applied when a roaming user equipment (UE) selects a visited public land mobile network (VPLMN). The roaming UE sends an available VPLMN list to the HPLMN. A control message of a non-access stratum (NAS) or an application can be used to receive a preferred VPLMN list from the HPLMN or to send the preferred VPLMN list after the HPLMN requests that the UE should send the available VPLMN list or without a request. The HPLMN manages a VPLMN to be used by the roaming UE and enables a user to receive a better service.

Abstract: A method and apparatus for communications of a UE using an IP address in a mobile communication system are provided. When the UE moves from an old subnet managed by an old gateway to a new subnet managed by a new gateway, the UE determines whether there are allocated radio resources. In the absence of the allocated radio resources, the UE determines whether an IP-based application service is in progress. If the IP-based application service is in progress, the UE determines to reuse an old IP address in the new subnet. If the IP-based application service is not in progress, the UE determines to use a new IP address in the new subnet. Then the UE sends to the new gateway an RAU request message including an indication indicating whether the old IP address or the new IP address will be used in the new subnet.

Abstract: A method and an apparatus for adaptively transmitting and receiving channel quality information of each AMC sub-band in application of an AMC technology in a broadband OFDM-based system are provided. A speed status of the UE is determined, a determination is made based on a determined speed status whether to receive the channel quality information of the UE, a channel quality information transmission mode is reported to indicate a type of the channel quality information, to the UE when it is determined to receive the channel quality information of the UE. The channel quality information is received from the UE according to the channel quality information transmission mode and radio resources are allocated to the UE in consideration of the received channel quality information.

Abstract: A method and terminal apparatus for transmitting a status report comprising a received status of packet data in a mobile communication system are provided, in which whether transmission of an implicit Negative Acknowledge (NACK) signal is required for requesting retransmission of at least one non-received data packet whose sequence number is unidentified is determined, if transmission of the implicit NACK signal is required, the implicit NACK signal including a sequence number of the last packet is generated among successfully received data packets, and a status report including the implicit NACK signal is transmitted to the transmitter, and if transmission of the implicit NACK signal is not required, a status report is transmitted to the transmitter including at least one of an ACK signal comprising a sequence number of a successfully received data packet and an explicit NACK signal comprising a sequence number of a non-received data packet whose sequence number is identified.