Abstract:
A method and an apparatus for providing, setting, maintaining, and releasing a packet data network (PDN) connection on the basis of a local area in a wireless communication system are provided. The method includes receiving the PDN subscription information on the basis of the local area from a business operator server, inspecting whether the current location information for the terminal exists in the PDN subscription information on the basis of the local area, and starting a procedure for setting the PDN on the basis of the local area when the current location information exists therein.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application is a U.S. National Stage application under 35 U.S.C. §371 of an International application filed on Oct. 31, 2013 and assigned application number PCT/KR2013/009808, which claimed the benefit of a Korean patent application filed on Oct. 31, 2012 in the Korean Intellectual Property Office and assigned Serial number 10-2012-0122706, the entire disclosure of which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to a structure and procedure of a Local Area (LA) Packet Data Network (PDN). More particularly, the present disclosure relates to a method and apparatus for providing, establishing, maintaining, and releasing a PDN connection based on a local area. 
       BACKGROUND 
       [0003]    Wireless communication systems have been developed to provide broadband data service such as multimedia service in addition to traditional voice service. Despite limited communication resources, various types of data services are in demand. Therefore, a more advanced wireless communication system is required. 
         [0004]    To satisfy the demand, wireless communication systems that provide Packet Data Network (PDN)-based enhanced services, such as a Long Term Evolution (LTE) system (or an Evolved Packet System (EPS)) proposed by the  3   rd  Generation Partnership Project 2 (3GPP2) have been deployed and have gained popularity. 
         [0005]    A PDN may be deployed over a local area as well as a wide service area and research on specific procedures for operating a PDN in a local area is needed. 
         [0006]    The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure. 
       SUMMARY 
       [0007]    Aspects of the present disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to provide a method and apparatus for establishing a Local Area (LA) Packet Data Network (PDN) connection in a wireless communication system. 
         [0008]    Another aspect of the present disclosure is to provide a method and apparatus for releasing an LA PDN connection in a wireless communication system. 
         [0009]    Another aspect of the present disclosure is to provide a method and apparatus for maintaining an LA PDN connection in a wireless communication system. 
         [0010]    Another aspect of the present disclosure is to provide a method and apparatus for reestablishing an LA PDN connection in a wireless communication system. 
         [0011]    In accordance with an aspect of the present disclosure, a method for establishing a PDN connection by a User Equipment (UE) in a wireless communication system is provided. The method includes receiving LA PDN subscription information from an operator server, determining whether current location information about the UE is included in the LA PDN subscription information, and in the presence of the current location information about the UE in the LA PDN subscription information, starting an LA PDN establishment procedure. 
         [0012]    In accordance with another aspect of the present disclosure, a UE for establishing a PDN connection in a wireless communication system is provided. The UE includes a receiver configured to receive LA PDN subscription information from an operator server, and a controller configured to determine whether current location information about the UE is included in the LA PDN subscription information, and in the presence of the current location information about the UE in the LA PDN subscription information, to control starting of an LA PDN establishment procedure. 
         [0013]    In accordance with another aspect of the present disclosure, a method for updating subscription information about a UE by a Mobility Management Entity (MME) that manages mobility of the UE in a wireless communication system is provided. The method includes, if LA PDN subscription information about the UE is updated, receiving the updated LA PDN subscription information from an operator server, determining whether current location information about the UE is included in an LA PDN context including a Tracking Area (TA) list of the UE, and in the presence of the current location information about the UE in the LA PDN context, transmitting information indicating the update of the LA PDN subscription information to the UE. 
         [0014]    In accordance with another aspect of the present disclosure, an MME for managing mobility of a UE in a wireless communication system is provided. The MME includes a communication interface configured to transmit and receive messages for updating LA PDN subscription information, and a controller configured, if LA PDN subscription information about the UE is updated, to control reception of the updated LA PDN subscription information from an operator server, to determine whether current location information about the UE is included in an LA PDN context including a TA list of the UE, and in the presence of the current location information about the UE in the LA PDN context, to control transmission of information indicating the update of the LA PDN subscription information to the UE. 
         [0015]    In accordance with another aspect of the present disclosure, a communication method of a Base Station (BS) during handover of a UE using a PDN in a wireless communication system is provided. The communication method includes, if the UE performs handover to a target BS within an LA in a connected state, determining whether current location information about the UE is included in an LA PDN context, and in the presence of the current location information about the UE in the LA PDN context, transmitting a handover request message including an LA PDN context related to the handover to the target BS. 
         [0016]    In accordance with another aspect of the present disclosure, a BS for supporting handover of a UE using a PDN in a wireless communication system is provided. The BS includes a communication interface configured to transmit and receive messages related to the handover of the UE, and a controller configured, if the UE performs handover to a target BS within an LA in a connected state, to determine whether current location information about the UE is included in an LA PDN context, and in the presence of the current location information about the UE in the LA PDN context, to transmit a handover request message including an LA PDN context related to the handover to the target BS. 
         [0017]    In accordance with another aspect of the present disclosure, a method for releasing a PDN connection by an MME that manages mobility of a UE in a wireless communication system is provided. The method includes receiving a Tracking Area Update (TAU) request from the UE, determining whether current location information about the UE is included in an LA PDN TA list, and in the absence of the current location information about the UE in the LA PDN TA list, starting an LA PDN disconnection procedure. 
         [0018]    In accordance with another aspect of the present disclosure, a method for releasing a PDN connection by an MME that manages mobility of a UE in a wireless communication system is provided. The method includes determining whether current location information about the UE is included in an LA PDN TA list, and in the absence of the current location information about the UE in the LA PDN TA list, maintaining an LA PDN context of the UE until expiration of an LA PDN context retain timer. 
         [0019]    In accordance with another aspect of the present disclosure, a method for reestablishing a PDN connection by an MME that manages mobility of a UE in a wireless communication system is provided. The method includes receiving a service request message from the UE that returns to an LA, transmitting an initial context setup request message including an LA PDN context and an LA bearer context of the UE to a BS, and transmitting a bearer modify request for LA PDN reconnection of the UE to a serving gateway. 
         [0020]    In accordance with another aspect of the present disclosure, a method for reestablishing a PDN connection by an MME that manages mobility of a UE in a wireless communication system is provided. The method includes receiving a TAU request from the UE that performs handover in a connected state from a source BS outside an LA to a target BS within the LA, determining whether current location information about the UE is included in an LA PDN context before expiration of an LA PDN context retain timer, and in the presence of the current location information about the UE in the LA PDN context, transmitting to the target BS a bearer setup request including an LA PDN context and a bearer context. 
         [0021]    Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the present disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0023]      FIG. 1A  illustrates a wireless communication system that deploys a Local Area (LA) Packet Data Network (PDN) according to an embodiment of the present disclosure; 
           [0024]      FIG. 1B  illustrates a configuration of LAs according to an embodiment of the present disclosure; 
           [0025]      FIG. 2  is a diagram illustrating a signal flow for a procedure for updating LA PDN subscription information in a wireless communication system according to an embodiment of the present disclosure; 
           [0026]      FIGS. 3A ,  3 B, and  3 C are diagrams illustrating signal flows for a triggering method in an LA PDN establishment procedure in a wireless communication system according to various embodiments of the present disclosure; 
           [0027]      FIG. 4  is a diagram illustrating a signal flow for an LA PDN establishment procedure according to an embodiment of the present disclosure; 
           [0028]      FIG. 5  is a diagram illustrating a signal flow for a procedure for transmitting an LA PDN context during X2 handover according to an embodiment of the present disclosure; 
           [0029]      FIG. 6  is a diagram illustrating a signal flow for a procedure for transmitting an LA PDN context during S1 handover according to an embodiment of the present disclosure; 
           [0030]      FIG. 7  is a diagram illustrating a signal flow for an LA PDN disconnection procedure according to an embodiment of the present disclosure; 
           [0031]      FIG. 8  is a diagram illustrating a signal flow for a deferred LA PDN disconnection procedure according to an embodiment of the present disclosure; 
           [0032]      FIG. 9  is a diagram illustrating a signal flow for an LA PDN reconnection procedure according to an embodiment of the present disclosure; 
           [0033]      FIG. 10  is a diagram illustrating a signal flow for an LA PDN reconnection procedure according to an embodiment of the present disclosure; 
           [0034]      FIG. 11  is a block diagram of a User Equipment (UE) according to an embodiment of the present disclosure; and 
           [0035]      FIG. 12  is a block diagram of an evolved Node B (eNB) according to an embodiment of the present disclosure. 
       
    
    
       [0036]    Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
       DETAILED DESCRIPTION 
       [0037]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
         [0038]    The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents. 
         [0039]    It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
         [0040]    In various embodiments of the present disclosure, a Packet Data Network (PDN) activated in a Local Area (LA) is defined as an LA PDN. The LA includes tracking areas in which a packet data service is available and each tracking area includes adjacent cells. 
         [0041]      FIG. 1A  illustrates a wireless communication system that deploys an LA PDN according to an embodiment of the present disclosure. The wireless communication system illustrated in  FIG. 1  is an LA PDN deployed, for example, in a 3 rd  Generation Partnership Project (3GPP) Evolved Packet System (EPS). However, it is to be understood that the present disclosure may be deployed in any of various communication systems. 
         [0042]    Referring to  FIG. 1A , an operator server  100  is a server of a communication operator or a service operator that provides a packet data service. A Home Subscriber Server (HSS)  200  manages authentication information, subscription information, and service information about a User Equipment (UE)  700 . It is assumed that the UE  700  is any UE accessing a PDN such as the Internet through a PDN GateWay (P-GW) like a Serving GateWay (S-GW)  400  and a Local GateWay (L-GW)  500 . The UE  700  may communicate with other Internet Protocol (IP)-based communication devices (not shown) within a local network (that is, LA)  800   a  by creating a Local IP Area (LIPA) PDN connection through the L-GW  500 . LIPA represents local IP access in an EPS. In an embodiment of the present disclosure, a LIPA PDN is an example of the LA PDN. However, it is to be clearly understood that the LA PDN of the present disclosure is not limited to the LIPA PDN. In other words, the various embodiments of the present disclosure are applicable, for example, to various types of wireless communication systems in which an L-GW may be located near to an evolved Node B (eNB) as well as to Selective IP Traffic Offloading (SIPTO) or LIPA described in3GPP TS 23.401. 
         [0043]    In  FIG. 1A , a Mobility Management Entity (MME)  300  is responsible for mobility and location registration of the UE  700  and management of a Tracking Area (TA) list for location management of the UE  700 . The MME  300  is also responsible for a control plane for exchanging control information between the UE  700  and an Evolved Packet Core (EPC). If subscription information about a UE (i.e., a user) in an LA PDN (referred to as “LA PDN subscription information”) is updated and the current location of the UE  700  is included in an LA PDN context, the MME  300  provides information indicating update of the LA PDN subscription information to the UE  700  in an embodiment of the present disclosure. 
         [0044]    The EPC includes the MME  300 , the S-GW  400 , and the L-GW  500 . The S-GW  400  acts as a reference point that is not changed at a network side during handover. In other words, even though the UE  700  moves between a plurality of eNBs  600  (i.e., eNBs  600 - 1 ,  600 - 2  . . .  600 - n ), the S-GW  400  is not changed. The S-GW  400  provides a data bearer for a packet data service under the control of the MME  300 . The L-GW  500  creates a LIPA PDN connection and assigns an IP address to the UE   500 , upon request of the S-GW  400 . 
         [0045]    The eNBs  600  transmit messages used during procedures for establishing, maintaining, and releasing an LA PDN connection between the network and the UE  700 . If the UE  700  performs handover within an LA, an eNB  600  checks whether current location information about the UE  700  is included in an LA PDN context. In the presence of the current location information about the UE  700 , the eNB  600  provides an LA PDN context related to the handover to a target eNB to which the UE  700  moves. 
         [0046]    In an embodiment of the present disclosure illustrated in  FIG. 1 , it is assumed that other UEs (not shown) that do not use LIPA PDN connections use a general packet data service in a service area  800  b other than an LA. 
         [0047]      FIG. 1B  illustrates a configuration of LAs according to an embodiment of the present disclosure. 
         [0048]    Referring to  FIG. 1B , one LA L 1 , L 2 , or L 3   800   a  may be configured per UE  700 . One eNB eNB 1  or eNB 2  may configure a plurality of LAs. In  FIG. 1B , eNB 1  configures two LAs L 1  and L 2  and eNB 2  configures two LAs L 2  and L 3 . An LA such as L 2  may be configured to be overlapped between different eNBs eNB 1  and eNB 2 . 
         [0049]    After subscription information (that is, LA PDN subscription information) about a UE (i.e., a user) in a PDN (that is, an LA PDN) configured by adding the LAs  800   a  to an existing PDN is initially provided to the UE  700 , the LA PDN subscription information may be updated dynamically. 
         [0050]    Hereinbelow, a description will be given of how an LA PDN is configured initially or dynamically, established, maintained during movement of the UE  700 , and disconnected according to an embodiment of the present disclosure. 
         [0051]    A procedure for initially providing LA PDN subscription information according to an embodiment of the present disclosure will first be described below. 
         [0052]    LA PDN subscription information about a UE is stored in a Universal Subscriber Identity Module (USIM) of the UE. The LA PDN subscription information includes at least one of a TA list, an LA Access Point Name (LA APN), an LA Identifier (LA ID), additional information, and existing PDN configuration data. The additional information may include an LA verbose name and an LA icon. Accordingly, LA PDN subscription information stored in the HSS  200  illustrated in  FIG. 1A  includes at least one of a TA list, an LA APN, an LA ID, and existing PDN configuration data. 
         [0053]    A procedure for dynamically updating LA PDN subscription data or information according to the present disclosure will be described below. 
         [0054]    The operator server  100  illustrated in  FIG. 1A  may update the LA PDN subscription information. If the MME  300  has an LA PDN context and current location information about the UE is included in the LA PDN context, the MME  300  may transmit a message for triggering a procedure for updating the LA PDN subscription information between the UE  700  and the operator server  100 . 
         [0055]    If the LA PDN subscription information stored in the UE  700  has been changed, the operator server  100  may update the LA PDN subscription information to the changed LA PDN subscription information. The UE  700  may request establishment or termination of an LA PDN connection to a network based on the updated LA PDN subscription information. 
         [0056]      FIG. 2  is a diagram illustrating a signal flow for a procedure for updating LA PDN subscription information in a wireless communication system according to an embodiment of the present disclosure. 
         [0057]    Referring to  FIG. 2 , the operator server  100  updates the LA PDN subscription information about the UE  700  using the LA  800   a  , stored in the HSS  200  in operations  201  to  209 . For example, if the LA PDN subscription information about the UE  700  has been changed, the operator server  100  provides the updated LA PDN subscription information to the HSS  200  and the HSS  200  stores the updated LA PDN subscription information in operation  201 . In operation  203 , the HSS  200  transmits the updated LA PDN subscription information to the MME  300 . In operations  201  and  203 , the operator server  100  and the HSS  200  may transmit only the updated LA PDN subscription information or entire subscription information about the UE  700  including the LA PDN subscription information. 
         [0058]    The MME  300  determines whether current location information about the UE  700  (for example, a current TA Indication (TAI) of the UE  700 ) is present in an LA PDN context managed by the MME  300  in operation  205 . The LA PDN context includes an LA APN, a TA list, and existing LA PDN information. 
         [0059]    The LA PDN subscription information about the UE  700  includes existing PDN information and information about an area in which a PDN connection may be created. This LA PDN subscription information includes an APN, an LA ID, a TA list, an LA verbose name, an LA icon, and existing PDN subscription information. After receiving the updated LA PDN subscription information, the UE  700  determines whether the TAI indicating the current location is included in the updated LA PDN subscription information by checking the TAI indicating the current location of the UE  700  and the updated LA PDN subscription information. If the TAI is included in the updated LA PDN subscription information but the UE  700  is not currently connected to any LA PDN, the UE  700  may request creation of an LA PDN. 
         [0060]    In an embodiment of the present disclosure, it is assumed that the LA PDN context includes the current location information about the UE  700 . Subsequently, the MME  300  transmits information indicating that the LA PDN subscription information has been changed to the UE  700  in operation  207  and transmits ACKnowledgement (ACK) information indicating that the MME  300  has received the updated LA PDN subscription information to the HSS  200  in operation  209 . Operation  207  is performed so that the UE  700  may initiate an Over The Air (OTA) connection with the operator server  100  to receive the updated LA PDN subscription information. Operation  207  is optional. Further, even though operation  207  is not performed, the UE  700  may periodically request the updated LA PDN subscription information to the network and receive it from the network. 
         [0061]    In operation  211 , the HSS  200  transmits confirmation information indicating that the LA PDN subscription information about the UE  700  has been updated to the operator server  100 . The operator server  100  transmits the LA PDN subscription information to the UE  700  through a mobile communication network (OTA) in operation  213 . In operation  215 , the UE  700  determines whether the current location information indicating the current location of the UE  700 , for example, the current TAI is included in the updated LA PDN subscription information received in operation  213 . 
         [0062]    In an embodiment of the present disclosure, it is assumed that the current location information (TAI) is present in the updated LA PDN subscription information. In operation  217 , the UE  700  performs an LA PDN establishment procedure, which will be described later. Upon termination of communication in the LA, a later-described UE requested PDN disconnection procedure is performed in operation  219 . 
         [0063]    According to an embodiment of the present disclosure, operation  213  may be performed differently in the following two cases. 
         [0064]    In the case where the current location information (TAI) about the UE  700  is included in the updated LA PDN subscription information but the UE  700  does not have an LA PDN context related to the current location information (TAI), the UE  700  starts an LA entry procedure by a UE requested PDN connectivity procedure. On the other hand, in the case where the current location information (TAI) about the UE  700  is not included in the updated LA PDN subscription information but the UE  700  has an LA PDN context related to the current location information (TAI), the UE  700  starts a UE requested PDN disconnection procedure. 
         [0065]    With reference to  FIGS. 3A to 4 , the LA PDN establishment procedure performed in operation  217  of  FIG. 2  will be described. Before describing the LA PDN establishment procedure, triggering of the LA PDN establishment procedure will first be described below. 
         [0066]      FIG. 3A  illustrates a triggering method in an LA PDN establishment procedure according to an embodiment of the present disclosure. 
         [0067]    Referring to  FIG. 3A , the UE  700  first performs an initial attach procedure defined in section 5.3.2.1 of3GPP TS 23.401 in operation  301 . The MME  300  downloads subscription information about the UE  700  from the HSS  200  in the initial attach procedure. 
         [0068]    In operation  303 , the UE  700  determines whether its current location information (TAI) is included in an LA PDN context. In the presence of the current location information (TAI) in the LA PDN context, the UE  700  starts a UE requested PDN connectivity procedure defined in section 5.10.2 of3GPP TS 23.401. If the UE  700  is allowed to establish an LA PDN, the MME  300  checks the subscription information about the UE  700 . The above-described procedure of  FIG. 3A  may be understood as an attach-triggered PDN establishment procedure. 
         [0069]      FIG. 3B  illustrates a triggering method in an LA PDN establishment procedure according to an embodiment of the present disclosure. 
         [0070]    Referring to  FIG. 3B , when the UE  700  enters an LA in idle state in operation  311 , the UE  700  performs, for example, a Tracking Area Update (TAU) procedure using an active flag as defined in sections 5.5.5.1 &amp; 5.3.3.2 of3GPP 23.401. The MME  300  downloads LA PDN subscription information from an old MME (not shown) used before the UE  700  enters the LA or the HSS  200 . The UE  700  determines whether its current location information (TAI) (the TAI includes a TA Code (TAC) indicating the current location of the UE  700 ) is included in the LA PDN subscription information. In the presence of the current location information (TAI) in the LA PDN subscription information, the UE  700  starts the UE requested PDN connectivity procedure defined in section 5.10.2 of3GPP TS 23.401 in operation  313 . 
         [0071]    If the UE  700  is allowed to establish an LA PDN, the MME  300  checks subscription information about the UE  700 . The above-described procedure of  FIG. 3B  may be understood as a TAU-triggered PDN establishment procedure. 
         [0072]      FIG. 3C  illustrates a triggering method in an LA PDN establishment procedure according to an embodiment of the present disclosure. 
         [0073]    Referring to  FIG. 3C , when the UE  700  enters an LA in connected state, the UE  700  and the network perform, for example, an S1 handover or X2 handover procedure and an accompanying TAU procedure defined in sections 5.3.3.1 &amp; 5.3.3.2 of3GPP 23.401 in operation  321 . The MME  300  downloads LA PDN subscription information from an old MME (not shown) used before the UE  700  enters the LA or the HSS  200 . The UE  700  determines whether its current location information (TAI) is included in the LA PDN subscription information. In the presence of the current location information (TAI) in the LA PDN subscription information, the UE  700  starts the UE requested PDN connectivity procedure defined in section 5.10.2 of3GPP TS 23.401 in operation  323 . If the UE  700  is allowed to establish an LA PDN, the MME  300  checks subscription information about the UE  700 . The above-described procedure of  FIG. 3C  may be understood as a handover &amp; TAU-triggered PDN establishment procedure. 
         [0074]    When the UE  700  enters an LA, the LA PDN establishment procedure may be initiated by one of the above three triggering methods according to an embodiment of the present disclosure. In the LA PDN establishment procedure, the MME  300  checks the LA PDN subscription information received from the HSS  200 . If the LA PDN subscription information is valid, the MME  300  creates an LA PDN session with the L-GW  500  (that is, the P-GW). The MME  300  starts to establish an LA PDN bearer using an LA PDN context. The LA PDN context includes LA PDN information, a TA list, and an LA ID. After the LA PDN bearer is established, the eNB  600  maintains the LA PDN bearer context. 
         [0075]      FIG. 4  is a diagram illustrating a signal flow for an LA PDN establishment procedure according to an embodiment of the present disclosure. 
         [0076]    Referring to  FIG. 4 , the UE  700  determines whether its current location information (TAI) is included in LA PDN subscription information in operation  401 . In an embodiment of the present disclosure, it is assumed that the current location information (TAI) about the UE  700  is included in the LA PDN subscription information. In operation  403 , the UE  700  determines to start an LA PDN connectivity procedure and transmits an LA PDN connectivity request to the MME  300  by a Non Access Stratum (NAS) transport message. 
         [0077]    The MME  300  determines whether the current location information (TAI) about the UE  700  is included in an LA PDN context in operation  405 . In an embodiment of the present disclosure, it is assumed that the current location information (TAI) is included in the LA PDN context. In operation  407 , the MME  300  accepts the LA PDN connectivity request received from the UE  700  in operation  403  and transmits a create session request message along with the LA PDN context to the S-GW  400 . 
         [0078]    The S-GW  400  transmits a create session request message along with the LA PDN context to the L-GW  500  (that is, the P-GW) in operation  409 . In operation  411 , the L-GW  500  (that is, the P-GW) which performs a PCC function creates a session for connection establishment for the UE  700  and transmits a create session response message to the S-GW  400  in operation  413 . The S-GW  400  transmits a create session response message indicating reception of the create session response message in operation  411  to the MME  300  in operation  415 . In operation  417 , the MME  300  allows LA PDN establishment for the UE  700  and transmits a bearer setup request along with the LA PDN context to the eNB  600  according to an embodiment of the present disclosure. 
         [0079]    Subsequently, the eNB  600  transmits a Radio Resource Control (RRC) connection reconfiguration message to the UE  700  in operation  419  and receives an RRC connection reconfiguration complete message from the UE  700  that has completed RRC connection reconfiguration in response to the RRC connection reconfiguration message in operation  421 . In operation  423 , the eNB  600  transmits a bearer setup response message to the MME  300  in response to the bearer setup request message received in operation  417 . 
         [0080]    In operation  425 , the UE  700  transmits a direct transfer message indicating PDN connection completion to the eNB  600 . The eNB  600  transmits a message indicating the PDN connection completion of the UE  700  to the MME  300  in operation  427 . The MME  300  transmits a message requesting bearer establishment for the UE  700  that has completed the PDN connection establishment to the S-GW  400  in operation  429  and the S-GW  400  establishes a bearer and transmits a response message indicating completion of the bearer establishment to the MME  300  in operation  431 . 
         [0081]    In operation  433 , when determining that the bearer establishment is completed, the MME  300  transmits a notify request message to the HSS  200 . The HSS  200  transmits a notify response message to the MME  300  in operation  435 . 
         [0082]    In the above-described LA PDN establishment procedure illustrated in  FIG. 4 , the other operations except operations  401 ,  405 , and  417  may be performed in the same manner as the UE requested PDN connectivity procedure defined in section 5.10.2 of3GPP TS 23.401. 
         [0083]    After the LA PDN connection establishment is completed according to the procedure of  FIG. 4 , the UE  700  may move to another eNB inside or outside the LA in active mode. 
         [0084]    A source eNB to which the LA PDN connection has been established transmits an LA PDN handover context for the UE  700  to a target eNB to which the UE has moved (has performed handover). The LA PDN handover context includes the LA PDN context and an LA PDN bearer context. The LA PDN bearer context is a context including bearer configuration information for transmitting traffic received via an LA PDN connection. The LA PDN context and the LA PDN bearer context may be transmitted by an X2 handover request or S1 handover request message well known to the EPS. The S1 handover request message is transmitted from the source eNB to the target eNB through the MME  300 . 
         [0085]    With reference to  FIGS. 5 and 6 , a procedure for transmitting an LA PDN context during handover according to an embodiment of the present disclosure will be described below. 
         [0086]      FIG. 5  is a diagram illustrating a signal flow for a procedure for transmitting an LA PDN context during X2 handover according to an embodiment of the present disclosure. It is assumed herein that the UE  700  in connected state moves from a source eNB  600   a  to a target eNB  600   b  in the same LA. 
         [0087]    Referring to  FIG. 5 , the UE  700  that moves to the target eNB  600   b  transmits a measurement report to the source eNB  600   a  in operation  501  and the source eNB  600   a  checks whether current location information (TAI) about the UE  700  is included in an LA PDN context in operation  503 . In an embodiment of the present disclosure, it is assumed that the current location information (TAI) about the UE  700  is included in the LA PDN context. 
         [0088]    In operation  505 , the source eNB  600   a  transmits a handover request message including an LA PDN handover context to the target eNB  600   b . The LA PDN handover context includes an LA PDN context and an LA PDN bearer context. The LA PDN context includes an LA ID and a TA list, and the LA PDN bearer context includes related bearer IDs (for example, Evolved Radio Access Bearer (E-RAB) IDs). 
         [0089]    A bearer configuration is modified and a communication path is switched from the source eNB  600   a  to the target eNB  600   b  in operations  507  to  523  according to a known X2 handover procedure of the3GPP EPS. Therefore, operations  507  to  523  are not described herein in detail. 
         [0090]      FIG. 6  is a diagram illustrating a signal flow for a procedure for transmitting an LA PDN context during S1 handover according to an embodiment of the present disclosure. It is assumed herein that the UE  700  in connected state moves from the source eNB  600   a  to the target eNB  600   b  in the same LA. 
         [0091]    Referring to  FIG. 6 , the UE  700  that moves to the target eNB  600   b  transmits a measurement report to the source eNB  600   a  in operation  601 , and the source eNB  600   a  checks whether current location information (TAI) about the UE  700  is included in an LA PDN context in operation  603 . In an embodiment of the present disclosure, it is assumed that the current location information (TAI) about the UE  700  is included in the LA PDN context. 
         [0092]    In operation  605 , the source eNB  600   a  transmits a handover request message including an LA PDN handover context to the target eNB  600   b . The LA PDN handover context includes an LA PDN context, an LA PDN bearer context, and a bearer information list (for example, a System Architecture Evolution (SAE) Bearer Information List in the EPS). The LA PDN context includes an LA ID and a TA list. 
         [0093]    Table 1 below illustrates a transparent container including the LA PDN handover context of operation  605 . 
         [0000]    
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 IE/Group 
                   
                   
                 IE type and 
                 Semantics 
                   
                 Assigned 
               
               
                 Name 
                 Presence 
                 Range 
                 reference 
                 description 
                 Criticality 
                 Criticality 
               
               
                   
               
             
             
               
                 RRC 
                 M 
                   
                 OCTET 
                   
                 — 
                 — 
               
               
                 Container 
                   
                   
                 STRING 
               
               
                 SAE 
                 M 
                   
                   
                   
                 YES 
                 Ignore 
               
               
                 Bearers 
               
               
                 information 
               
               
                 List 
               
               
                 &gt; SAE 
                   
                 1 to &lt;max 
                   
                   
                 EACH 
                 Ignore 
               
               
                 Bearers 
                   
                 no of 
               
               
                 information 
                   
                 SAE 
               
               
                 item 
                   
                 bearers&gt; 
               
               
                 &gt;&gt; SAE 
                 M 
                   
                 BIT 
                   
                 — 
                 — 
               
               
                 Bearer ID 
                   
                   
                 STRING 
               
               
                   
                   
                   
                 (SIZE(8)) 
               
               
                 &gt;&gt; DL 
                 O 
                   
                 9.2.3.14 
               
               
                 forwarding 
               
               
                   
               
             
          
         
       
     
         [0094]    Handover-related signaling is performed between the source eNB  600   a  and the target eNB  600   b  and between a source MME  300   a  and a target MME  300   b  in operations  607  to  633  according to a known S1 handover procedure of the3GPP EPS. Therefore, operations  607  to  633  are not described herein in detail. 
         [0095]    Now, a description will be given of an LA PDN disconnection procedure according to an embodiment of the present disclosure. 
         [0096]    When the UE  700  moves in an idle state or performs a handover procedure in a connected state, the LA PDN disconnection procedure may be performed. The UE  700  and the network perform a TAU procedure during the LA PDN disconnection procedure. 
         [0097]      FIG. 7  is a diagram illustrating a signal flow for an LA PDN disconnection procedure according to an embodiment of the present disclosure. 
         [0098]    Referring to  FIG. 7 , the UE  700  starts a TAU procedure for LA PDN disconnection in operation  701  and transmits a TAU request message to the eNB  600  in operation  703 . In operation  705 , the eNB  600  transmits a TAU request message to the MME  300 . The TAU procedure is performed along with an S-GW change, as defined in section 5.3.3.1 of3GPP TS 23.401 in operation  707 . 
         [0099]    In operation  709 , the MME  300  checks whether the current location information (TAI) about the UE  700  is included in an LA PDN TA list. In the absence of the current location information (TAI) about the UE  700  in the LA PDN TA list, the MME  300  triggers LA PDN disconnection. Thus, the MME  300  transmits a delete session request message to the S-GW  400  in operation  711 . The S-GW  400  transmits a delete session request message to the L-GW  500  in operation  713 . When the L-GW  500  deletes a session, the L-GW  500  transmits a delete session response message to the S-GW  400  in operation  715  and then performs a PCC function along with the session deletion in operation  717 . Upon receipt of the session delete response message in operation  715 , the HSS  200  transmits a session delete response message to the MME  300  in operation  719 . In operation  721 , the MME  300  transmits a TAU accept message to the UE  700 . The UE  700  transmits a TAU complete message to the MME   300  in operation  723 . 
         [0100]    An LA PDN disconnection procedure according to an embodiment of the present disclosure will be described below. 
         [0101]    The MME  300  and the UE  700  may maintain an LA PDN context until expiration of an LA PDN context retain timer, rather than release an LA PDN connection according to an embodiment of the present disclosure. In the present disclosure, this operation mode is defined as LA PDN away mode. 
         [0102]      FIG. 8  is a diagram illustrating a signal flow for a deferred LA PDN disconnection procedure according to an embodiment of the present disclosure. 
         [0103]    Referring to  FIG. 8 , operations  801  to  807  are performed in the same manner as operations  701  to  707  of  FIG. 7  and thus will not be described herein. In operation  809 , the MME  300  determines whether current location information (TAI) about the UE  700  is included in an LA PDN TA list. In the absence of the current location information (TAI) about the UE  700 , the MME  300  determines to switch to the LA PDN away mode and performs one of the following operations 1), 2), and 3) in relation to deferred LA PDN disconnection according to the state of the LA PDN context retain timer.
       1) Registration of the LA PDN context retain timer: if the deferred LA PDN disconnection is enabled, the MME  300  defers release of an LA PDN connection. That is, the MME  300  registers the LA PDN context retain timer instead of releasing the LA PDN connection.   2) Deletion of the LA PDN context retain timer: if the UE  700  completes a TAU procedure before expiration of the LA PDN context retain timer in an LA, the MME  300  deletes the LA PDN context retain timer.   3) Expiration of the LA PDN context retain timer: if the LA PDN context retain timer expires without the TAU procedure of the UE  700  in the LA, the MME  300  performs the LA PDN disconnection procedure.       
 
         [0107]    The MME  300  transmits a TAU accept message to the UE  700  in operation  811  and the UE  700  transmits a TAU complete message to the MME  300  in operation  813 . The TAU accept message includes an LA PDN context retain command and information about the LA PDN context retain timer. The UE  700  may be aware that the deferred LA PDN disconnection procedure is performed by checking the information included in the TAU accept message. 
         [0108]    If the embodiment of  FIG. 8  is implemented, even though the UE  700  moves out of the LA, when the MME  300  decides to maintain the LA PDN connection, the MME  300  may set the state of the LA PDN context to the LA PDN away mode. In this case, the MME  300  may transmit the TAU accept message with, for example, an LA PDN maintain action code indicator as the LA PDN context retain command and the value of the timer as the information about the LA PDN context retain timer to the UE  700  in operation  811 . 
         [0109]    In an embodiment of the present disclosure, if the UE  700  returns to the LA in the LA PDN away mode, an LA PDN reconnection procedure may be performed. Then the MME  300  transmits an LA PDN context and a stored LA PDN bearer context during handover of the UE  700  in connected state or upon receipt of a service request from the UE  700  in idle state. 
         [0110]      FIG. 9  is a diagram illustrating a signal flow for an LA PDN reconnection procedure according to an embodiment of the present disclosure. The LA PDN reconnection procedure is initiated by a service request from the UE  700  in the idle state. 
         [0111]    Referring to  FIG. 9 , the UE  700  returns to an LA in the LA PDN away mode and thus performs a service request procedure to the eNB  600  in operation  901 . The eNB  600  transmits a service request of the UE  700  to the MME  300  in operation  903 . As an example, the service request is transmitted by NAS signaling. In operation  905 , the MME  300  and the HSS  200  perform an authentication security procedure. If the MME  300  determines that an LA PDN connection is still in the LA PDN away mode in an embodiment of the present disclosure, the MME  300  transmits an S1 initial context setup request message including the LA PDN context and the LA bearer context to the eNB  600  in operation  907 . 
         [0112]    In operation  911 , the UE  700  and the eNB  600  perform a radio bearer setup procedure related to an LA PDN connection. The eNB  600  transmits an initial context setup complete message to the MME  300  in operation  913  and the MME transmits a bearer modify request message for LA PDN reconnection to the S-GW  400  in operation  915 . In operation  917 , the S-GW  400  transmits the bearer modify request message to the L-GW  500 . The L-GW  500  performs a PCC function for the LA PDN reconnection in operation  919  and transmits a response message to the bearer modify request message to the S-GW  400  in operation  921 . The S-GW  400  transmits a response message to the bearer modify request message received in operation  915  to the MME  300  in operation  923 . 
         [0113]      FIG. 10  is a diagram illustrating a signal flow for an LA PDN reconnection procedure according to an embodiment of the present disclosure. In the embodiment of  FIG. 10 , the LA PDN reconnection procedure is triggered by handover of the UE  700  in the connected state. 
         [0114]    Referring to  FIG. 10 , as the UE  700  returns to the LA in the LA PDN away mode, the UE  700  performs a handover procedure in connected mode in operation  1001 . The handover procedure is performed from a source eNB (S-eNB) outside the LA to a target eNB (T-eNB) within the LA, including a TAU procedure. In operation  1003 , the MME  300  determines whether current location information (TAI) about the UE  700  is included in an LA PDN context before expiration of the LA PDN context retain timer. In the presence of the current location information (TAI) about the UE  700  in the LA PDN context, the MME  300  determines whether the state of an LA PDN is the LA PDN away mode. If both of the conditions are satisfied, the MME  300  decides to reconfigure (reconnect) an LA PDN bearer. If the MME  300  decides to reconfigure the LA PDN bearer in operation  1003 , the MME  300  transmits a bearer setup request message including an LA PDN context and an LA bearer context to the T-eNB  600   b  in operation  1005 . Subsequently, an RRC reestablishment procedure is performed between the UE  700  and the T-eNB  600   b  in operations  1007  and  1009 . In operation  1011 , the T-eNB  600   b  transmits a bearer setup response message indicating the bearer reconfiguration to the MME  300 . 
         [0115]      FIG. 11  is a block diagram of a UE according to an embodiment of the present disclosure. 
         [0116]    Referring to  FIG. 11 , the UE includes a transmitter  1110  and a receiver  1130 , which respectively transmit and receive messages according to the various embodiments of the present disclosure illustrated in  FIGS. 1A to 10  in order to establish, maintain, release, or reestablish an LA PDN connection with an eNB through a wireless network. The UE further includes a controller  1150  that controls the transmission and reception of messages according to the various embodiments of the present disclosure illustrated in  FIGS. 1A to 10  to and from an eNB in order to establish, maintain, release, or reestablish an LA PDN connection and provides overall control to the UE so that the UE may conduct communication in each communication state of an LA PDN. 
         [0117]      FIG. 12  is a block diagram of an eNB according to an embodiment of the present disclosure. 
         [0118]    Referring to  FIG. 12 , the eNB includes a first communication interface  1210  for transmitting and receiving messages to and from a UE through a wireless network according to the various embodiments of the present disclosure illustrated in  FIGS. 1A to 10  during establishment, maintenance, release, or reestablishment of an LA PDN connection in the UE  700 , and a second communication interface  1230  for transmitting and receiving signals to and from other network entities of an EPS system such as another eNB or an MME via a predetermined communication interface. The eNB further includes a controller  1250  that controls the transmission and reception of the various messages as described above. The eNB transmits and receives messages for establishment, maintenance, release, or reestablishment of an LA PDN connection in the UE  700  in predetermined procedures and participates in procedures such as current location information check, TAU, bearer establishment, and handover of a UE in the LA PDN based on the transmitted and received messages according to the various embodiments of the present disclosure illustrated in  FIGS. 1A to 10 . 
         [0119]    While not shown, an MME may also be configured to include a communication interface for transmitting and receiving messages to and from a UE through a wireless network according to the various embodiments of the present disclosure illustrated in  FIGS. 1A to 10  during establishment, maintenance, release, or reestablishment of an LA PDN connection in the UE, and a controller for controlling related operations. 
         [0120]    While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.