Abstract:
The present invention relates to a mobile communication network, and more particularly to a method for the allocation and registration of a suitable generic access network (GAN) controller for the location of a terminal when the terminal moves in the mobile communication network. The mobile communication network comprises: a terminal, which transmits the location information thereof to the mobile communication network, makes a new request for GAN controller information under instructions from the mobile communication network and performs GAN registration again based on the GAN controller information provided from the mobile communication network; a mobility management entity, which receives a location registration request from the terminal, changes WCDMA/GSM location information from the location information of the terminal in the current LTE service area and sends the changed information to the terminal, instructs the terminal to do GAN re-registration and notifies the GAN controller of the change in the location information of the terminal; and the GAN controller, which processes the GAN registration from the terminal and assigns suitable GAN control information for the current location of the terminal.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a mobile communication network and, in particular, to a method for assigning and registering with a GAN controller appropriate for the location of the UE on the move within the mobile communication network. That is, the present invention allows the UE to re-register with a GAN controller covering the area where the UE is currently located without involvement of the user when a UE moves out of the service area of the GAN (Generic Access Network) controller within the EPS (Evolved Packet System) network providing voice services with GAN. 
         [0003]    2. Description of the Related Art 
         [0004]    GAN (generic access network) is a system which is conventionally referred to as UMA (unlicensed mobile access) network. The system supports seamless handover between a cellular network and an IP access network while the UE are transmitting any, both, or nothing of voice and data. That is, the GAN system allows the mobile phone user to take advantages of the fixed broadband network. 
         [0005]    The GAN system is an architecture component of the GERAN/UTRAN network and includes a GAN controller. The GAN controller is identical with the base station controller (BSC) of a legacy network in functional view. However, the GAN controller differs from the legacy base station controller in that it is connected to an IP access network at its front end and communicates with the UE via the interface (referred to as Up interface) using dedicated protocol for GAN. The GAN controller is responsible for converting the Up interface messaging to legacy BSC/core network interface protocol for supporting signaling and data communication between UE and network. 
         [0006]      FIG. 1  is a diagram illustrating a mobile communication network including the PS (Packet Switched) domain with the GAN controller (Generic Access Network Controller, GANC) and the CS (Circuit Switched) domain with Mobile Switching Center (MSC). 
         [0007]    In  FIG. 1 , the User Equipment (hereinafter, referred to as UE) accesses the voice call service of the Internet Protocol (hereinafter, referred to as IP) network. 
         [0008]    Reference numbers  101 ,  103 , and  105  denote the Core Network (Non-Access Stratum) and the Access Network (Access Stratum) evolved from GPRS/UMTS (General Packet Radio Service/Universal Mobile Telecommunications System) as European 2.5 and 3 rd  generation mobile communication standards. 
         [0009]    The enhanced Node B (hereinafter, referred to as eNB)  101  manages radio access. 
         [0010]    The Mobility Management Entity (hereinafter, referred to as MME)  103  is responsible for authentication and registration of the UE  110  which attempts to connect to the mobile communication network, processing service request from the UE  110 , and guaranteeing the mobility of the UE  110  between eNBs  101 . 
         [0011]    The Serving Gateway (hereinafter, referred to as SGW)  105  provides the bearer service for transferring the user&#39;s service data such as voice information to the eNB  101 . 
         [0012]    The Packet Data Network Gateway (hereinafter, referred to as PDN GW)  105  assigns an IP address to the UE  110  connected to the mobile communication network and provides IP Connectivity. In the IP network, the PDN GW  105  operates in the same way as IP router. 
         [0013]    The SGSN (Serving GPRS Service Node) (not shown) is responsible for authentication and registration of the UE  110  which attempts to connect to the mobile communication network via a GERAN/UTRAN, processing the service request from the UE  110 , and guaranteeing the mobility of the UE  110  which moves between BSs or NodeBs. 
         [0014]    The Mobile Switching Center (hereinafter, referred to as MSC)  115  is a switchboard providing the UE with circuit switching call processing, mobility management, and GSM service. Here, the service includes all of voice, data, FAX, and SMS. 
         [0015]    The Home Subscriber Server (hereinafter, HSS)  109  stores the subscription information and authentication information of the subscriber and retains the address of the MCS  115 , SGSN, or MME  103  with which the subscriber is registered in the mobile communication network. 
         [0016]    The GAN controller  117  is a device which converts signaling such that the UE can communicate with the mobile communication network via an IP access network rather than the cellular network. The GAN controller  117  is identical with the Base Station Controller (hereinafter, referred to as BSC) of the legacy GERAN network or the Radio Network Controller (hereinafter, referred to as RNC) of the UTRAN network in functional view. However, the GAN controller  117  differs from the BSC/RNC in that the GANC is connected to the UE via IP access network and can communicates with the UE using the dedicated protocol for GAN. 
         [0017]    Although the GAN controller  117  is applied to the representative IP access network such as wireless LAN or WiFi,  FIG. 1  shows the case where the Evolved Packet System (hereinafter, referred to as EPS) including eNB  101 , MME  103 , and S-GW/P-GW  105 . 
         [0018]    The GAN controller  117  includes a Security Gateway (hereinafter, referred to as SEGW) for providing decoded communication channel in order to maintain communication security between the UE  110  and GAN controller  117 . 
         [0019]      FIG. 2  is a diagram illustrating signaling of the procedure for registration and deregistration of the UE with the GAN controller  117  when the UE moves in or out a GAN service area. 
         [0020]    The UE  110  enters the service area of the GAN controller  117  at step  201 . The UE  110  makes a query to the DNS server for the IP address of the SEGW  119  for establishing a secure IP tunnel with the SEGW  119  and acquires the IP address at step  203 . Next, the UE  110  establishes the secure IP tunnel with the SEGW  119  with the IP address of the SEGW  110  at step  205 . Next, the UE  110  acquires the IP address of the GAN controller  117  from the DNS server of the GAN via the secure IP tunnel established with the SEGW  119  at step  207 . 
         [0021]    The UE  110  sends a GAN registration request message (hereinafter, interchangeably used with the term “GA-RC REGISTER REQUEST message”) to the IP address of the GAN controller  117  so as to request for the GAN service registration at step  209 . The GAN registration request message includes a CID (Cell ID), a LAI (Location Area Id), and an IMSI (International Mobile Subscriber Identity). 
         [0022]    The GAN controller  117  which has received the GAN registration request message from the UE sends a GAN registration accept message (hereinafter, interchangeably used with the term “GA-RC REGISTER ACCEPT message) to the UE to notify of the completion of the GAN service registration at step  211 . At this time, the GA-RE REGISTER ACCEPT message includes the system information of the GAN. 
         [0023]    After the completion of the GAN service registration, the UE  110  initiates the Location Area Update process by sending a Location Area Update request message to the MSC  115  via the GAN controller  117  at step  213 . Afterward, the incoming call received by the MSC  115  is sent to the UE  110  via the GAN controller  117 . 
         [0024]    If the UE  110  moves out of the service area of the GAN controller  117 , the UE  110  sends a GAN Deregistration message (hereinafter, interchangeably used with the term “GA-RC DEREGISTER message”) to the GAN controller  117  for GAN deregistration at step  217 . Once the GSN service is deregistered, the UE  110  initiates Location Area Update process by sending a Location Area Update request message to the MSC via the BSS or RNS for receive an incoming call directly from the MSC  115  by means of A or Iu message of the BSS or RNS at step  219 . Afterward, the UE  110  receives the incoming call sent by the MSC  115  via the BSS or RNS. 
         [0025]    In case that the GAN service is provided by means of wireless LAN, the GAN service area is confined by the area centering around an access point such that the GAN service is provided within a Hot Zone. Accordingly, when the UE moves out of the Hot Zone, the GAN service is deregistered according to the steps following step  215  of  FIG. 2 ; and when the UE moves in another Hot Zone, the GAN service registration procedure is initiated from the first step. As a consequence, there is no need for the UE  110  to roam between Hot Zones while maintaining the GAN service registration, and the UE switches between GAN controllers as roaming from one to another Hot Zone. 
       SUMMARY OF THE INVENTION 
     Problem to be Solved 
       [0026]    The present invention provides a method and apparatus for maintaining registration with a GAN controller appropriate for the location of the UE in the mobile communication network supporting voice services by means of GAN service especially when the UE registered with a GAN controller moves to an EPS network in a LTE area. 
       Means for Solving the Problem 
       [0027]    In order to solve the above problems, a method for changing GAN controller in a mobile communication network supporting GAN (Generic Access Network) terminal includes transmitting, a location change of the terminal is detected, a Location Area Update Request (LAU Request) message from the terminal to a GAN controller with which the terminal is registered; determining, at the GAN controller, whether the terminal is necessary to change the GAN controller; and transmitting, when the terminal is necessary to change the GAN controller, a GAN control registration change indication message (GA-RC REGISTER REDIRECT) from the GAN controller to the terminal. 
         [0028]    In accordance with another aspect of the present invention, a method for changing GAN controller in a mobile communication system supporting GAN (Generic Access Network) terminal includes instructing, at a mobility management entity when change of location of a terminal is detected, the terminal to relocate the GAN controller (GANG relocation Required); requesting, at the terminal, the GAN controller with which the terminal is registered for GAN registration update (GA-RC REGISTER UPDATE UPLINK); and transmitting, when the request is received, information on a new GAN controller from the registered GAN controller to the terminal. 
         [0029]    In accordance with still another aspect of the present invention, a method for changing GAN controller in a mobile communication network supporting GAN (Generic Access Network) terminal includes transmitting, when a mobility management entity detects change of location area of the terminal, a Location Area (LA) change of the terminal to a GAN controller with which the terminal is registered; determining, at the GAN controller, whether the terminal is necessary to change GAN controller; and transmitting, when the terminal is necessary to change GAN controller, a GAN controller registration change instruction (GA-RC REGISTER REDRICT) message from the GAN controller to the terminal. 
       Advantageous Effects 
       [0030]    According to the present invention, the UE receiving the voice call service with the GAN controller in an LTE service area can receive the incoming call, without notifying the mobile communication network of the current location, when the UE crosses between LTE service area and WCDMA/GSM service area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  is a diagram illustrating a communication network including a PS domain with a GAN controller and a CS domain with a Mobile Switching Center (MCS). 
           [0032]      FIG. 2  is a diagram illustrating signaling of the procedure for registration and deregistration of the UE with the GAN controller  117  when the UE moves in or out a GAN service area. 
           [0033]      FIG. 3  is a diagram illustrating signaling for registering the UE with a new GAN controller according to the first embodiment of the present invention. 
           [0034]      FIG. 4  is a diagram illustrating signaling for registering the UE with a new GAN controller according to the second embodiment of the present invention. 
           [0035]      FIG. 5  is a diagram illustrating signaling for registering the UE with a new GAN controller according to the third embodiment of the present invention. 
           [0036]      FIG. 6  is a flowchart illustrating operations for the MME to instruct the UE for GAN controller re-registration request according to the first embodiment of the present invention. 
           [0037]      FIG. 7  is a flowchart illustrating operations for the MME to instruct the UE for GAN controller re-registration request according to the second embodiment of the present invention. 
           [0038]      FIG. 8  is a flowchart illustrating operations for the MME to instruct the UE for GAN controller re-registration request according to the third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0039]    Exemplary embodiments of the present invention are described with reference to the accompanying drawings in detail. Detailed description of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present invention. The following terms are defined in consideration of functions in the present invention, and the meanings thereof may vary according to the intention of a user or an operator or according to usual practice. Therefore, the definitions of the terms must be interpreted based on the entire content of the present specification. 
         [0040]    Although the description is directed to the embodiments of the present invention with an exemplary case of EPS (Evolved Packet System) core network as the core network evolved based on the 3GPP, the procedure for providing the GAN service in the present invention can be applied to any type of mobile communication networks in the same manner. 
         [0041]    In the following, the description is made of the first to third embodiments differentiated by the method for a UE to register with a new GAN controller.  FIGS. 3 and 6  are the drawings for illuminating the first embodiment,  FIGS. 4 and 6  for illuminating the second embodiment, and  FIGS. 5 and 8  for illustrating the third embodiment. 
         [0042]      FIG. 3  is a diagram illustrating signaling for registering the UE  110  with a new GAN controller when the UE  110  registered with a certain GAN controller  310  moves into the service area of an EPS core network and registers its current location with the EPS core network, while moving out of the service area of the current GAN controller  117 , according to the first embodiment of the present invention. 
         [0043]    The UE  110  moves into a new tracking area (hereinafter, referred to as TA) which is not included in the registered Tracking Area List (hereinafter, referred to as TA list) at step  301  of  FIG. 3 . The UE  110  sends a Tracking Area Update request message to request the MME  103  for registering the new location. 
         [0044]    The MME  103  processes the location registration request of the UE  110  and replies by sending a Tracking Area Update Accept message to the UE  110  at step  303 . 
         [0045]    The MME  103  determines that the UE  103  registered with a certain GAN  310  moves out of the service area of the currently registered GAN controller  310  at step  305 . Here, the MME  103  sends the UE  110  a S 1  connection release message with the cause of GAN controller Relocation Required (hereinafter, interchangeably used with the term “GANC Relocation Required”) to request the UE  110  for GAN registration. 
         [0046]    For example, the MME  103  manages the mappings between the TA of the UE  110  and the Location Area (hereinafter, referred to as LA) such that, when the UE  110  moves out of the LA served by the GAN controller  310 , the MME  103  determines the registration of the UE  110  with a new GAN controller  320 . 
         [0047]    The eNB  101  sets the cause of the RRC connection release message to “GANC relocation required” so as to notify the UE  110  of the necessity of switching of the GAN controller  310 , at step  307 . 
         [0048]    In order to update the GAN controller registration, the UE  110  sends a Service Request message to the GAN controller  310  to establish a radio bearer for transmitting data and transitions to the active state, at step  308 . 
         [0049]    The UE  110  sends a GAN registration update uplink message (hereinafter, interchangeably used with the term “GA-RC REGISTER UPDATE UPLINK message”) to the old GAN controller  310  with which the UE is currently registered in order to request for the GAN registration update at step  309 . In this case, the UE transmits the LAI (Location Area Identifier) as its location identifier in the GAN registration update uplink message. The old GANC  310  identifies the current location of the UE  110  based on the LAI transmitted by the UE  110  and determines registration with a new GAN controller  320 , at step  311 . 
         [0050]    Next, the old GAN controller  310  sends a GAN registration reconfiguration message (hereinafter, interchangeably used with the term “GA-RC REGISTER REDIRECT message”) containing the information on the new GAN controller  320  to the UE  110 . Here, the information on the new GAN controller  320  includes the IP address of the new GAN controller  320 . 
         [0051]    The UE  110  receives the information on the new GAN controller  320  from the old GAN controller  310  at step  311  and establishes a secure tunnel for secure communication with the new GAN controller  320  at step  313 . According to an embodiment of the present invention, the secure tunnel can be an IPSec tunnel as an example. 
         [0052]    The UE  110  transmits the GA-RC REGISTER REQUEST message to the new GAN controller  320  via the secure tunnel (established at step  313 ) to requests for registration with the new GAN controller  320  at step  315 . The new GAN controller  320  processes the GAN registration request message of the UE  110  at step  317 . The GAN registration is successful, the UE  110  requests the MSC  115  for location registration via the new GAN controller  320  at step  319 . 
         [0053]      FIG. 4  is a diagram illustrating signaling for registering the UE  110  with a new GAN controller when the UE  110  registered with a certain GAN controller moves into the service area of an EPS core network and registers the current location of the UE  110  with the EPS core network, while moving out of the service area of the current GAN controller, according to the second embodiment of the present invention. 
         [0054]    As the UE  110  moves into a new TA which is not included in the registered TA list (Tracking Area List), it sends the Tracking Area Update request to MME  103  for new location registration at step  401 . The MME  103  processes the location registration request from the UE  110  and replies by sending a Tracking Area Update Accept message to the UE  110 . At this time, the MME  103  sends the LA identity information (LAI) corresponding to the TA in which the UE  110  is located using the information on the mappings between TA and LA which is managed by the MME  103 . 
         [0055]    The UE  110  receives the LAI transmitted by the MME  103  and compares the received LAI with the LAI received from the GAN controller  310  with which the UE  110  has been registered previously, at step  403 . 
         [0056]    In case that the two LAIs differ from each other, the UE  110  establishes a radio bearer for transmitting the Location Area Update Request message (LAU request message) to request for the location registration update of the MSC  115 , at step  405 . 
         [0057]    The UE  110  sends the LAU request message to the GAN controller  310  with which the UE  110  is previously registered, at step  407 . Upon receipt of the LAU request message, the GAN controller  310  checks that the UE  110  is currently located out of the its service area and determines the necessity of the GAN controller switching. The GAN controller  310  sends the GA0RC REGISTER REDIRECT message to the UE  110  to instruct to switch to the new GAN controller  320 . The GA-RC REGISTR REDIRECT message includes the information on the IP address of the new GAN controller  320 . 
         [0058]    The UE  110  receives the information on the new GAN controller  320  from the old GAN controller  310  at step  409  and establishes a secure tunnel for security communication with the new GAN controller  320  at step  411 . 
         [0059]    The UE  110  sends the GA-RC REGISTER REQUEST message to the new GAN controller  320  via the secure tunnel established at the previous step to request for the new registration at step  413 . The new GAN controller  320  processes the new registration of the UE  110  at step  415 . If the new registration is successful, the UE  110  requests the MSC  115  for the location registration again via the new GAN controller  320 . 
         [0060]      FIG. 5  is a diagram illustrating signaling for registering the UE  110  with a new GAN controller when the UE  110  registered with a certain GAN controller moves into the service area of an EPS core network and registers the current location of the UE  110  with the EPS core network, while moving out of the service area of the current GAN controller, according to the third embodiment of the present invention. 
         [0061]    The UE  110  moves into a new TA which is not included in the registered TA list at step  501  of  FIG. 5 . In this case, the UE  110  sends the Tracking Area Update request to the MME  103 . 
         [0062]    Next, the MME  103  determines whether the UE  110  is registered with a certain GAN controller. If the UE  110  is registered with a GAN controller, the MME  103  detects the change of the LA where the UE  110  is located using the mapping information between TA and LA under its management and notifies a certain GAN controller  310  of the LA change by sending the Location Area Change message (LA change message) at step  503 . At this time, the LA change message includes the LAI acquired by mapping the IMSI (Internal Mobile Subscriber Identity) as the identifier of the UE  110  and TA. 
         [0063]    The GAN controller  310  replies by transmitting the location area change ask (LA check ask) message to the MME  103  at step  505 . 
         [0064]    After completing the location registration of the UE  110 , the MME  103  replies by sending the TAU accept message to the UE  110  at step  507 . 
         [0065]    Meanwhile, the GAN controller  310  receives the LAI information of the UE  110  from the MME and determines that the UE  110  is out of its service area, at step  503 . The GAN controller  310  sends the GA-RC REGISTER REDIRECT message to the UE  110  to instruct the UE  110  to update the GAN registration with the new GAN controller  320  at step  509 . The GA-RC REGISTER REDRICT message includes the information on the IP address of the new GAN controller  320 . 
         [0066]    The UE  110  receives the information on the GAN controller from the old GAN controller  310  at step  509  and establishes a secure tunnel for secure communication with the new GAN controller  320 . 
         [0067]    The UE  110  sends the GA-RC REGISTER REQUEST message to the new GAN controller  320  via the secure tunnel established at the previous step in order to request for new registration at step  513 . The new GAN controller  320  processes the new registration request of the UE  110  at step  515 . If the new registration is successful, the UE  110  requests the MSC  115  for location registration again via the new GAN controller  320  at step  517 . 
         [0068]      FIG. 6  is a flowchart illustrating operations for the MME to instruct the UE for the GAN controller re-registration request when the UE registered with a certain GAN controller transmits the TAU request message to the MME, according to the first embodiment of the present invention. 
         [0069]    Referring to  FIG. 6 , the MME  103  receives the TAU request form the UE  110  at step  601 . Upon receipt of the TAU request, the MME  103  processes the TAU request at step  603  and sends the UE  110  the TAU response message at step  605 . 
         [0070]    Next, the MME  103  checks whether the UE  110  is registered with the GAN at step  607  and checks the LA from the current TA of the UE when the UE  110  is registered with the GAN. Next, the MME  103  checks whether the LA is included in the service area of the GAN controller  310  with which the UE is currently registered. The MME  103  can determine whether the checked LA is included in the service area of the GAN controller  310  by using the mapping relationship between the TA of the UE  110  and the LA. 
         [0071]    If the LA is included in the service area of the GAN controller  310  or changed, the MME  103  sets the SI connection release cause to GANC relocation request so as to instruct the UE  110  to reconfigure the GAB registration via the RRC release cause at step  611 . The MME  103  releases the S 1  connection at step  613 . Accordingly, the UE  110  can perform registration with the new GAN controller  320  according to the following procedure. 
         [0072]      FIG. 7  is a flowchart illustrating operations for the MME to notify the UE of the current LA in response to the TAU request message transmitted by the UE according to the second embodiment of the present invention. 
         [0073]    Referring to  FIG. 7 , the MME  103  receives the TAU request from the UE  110  at step  701  and processes the TAU request at step  703 . Next, the MME  103  determines whether the UE  110  is registered with a certain GAN, at step  705 . If the UE is registered with a specific GAN, the MME  103  checks the LA using the current TA of the UE and generates the LAI as the location area identifier of the current location of the UE  110  at step  707 . Next, the MME  103  adds the generated LAI to the TAU accept response message. The MME  103  sends the TAU accept message to the UE  110  at step  709 . The UE  110  can perform registration with the new GAN controller  320  based on the information carried in the TAU accept message. 
         [0074]      FIG. 8  is a flowchart illustrating operations for the MME to instruct the UE to perform GAN re-registration by notifying the GAN controller of the change of the LA of the UE when the UE registered with a certain GAN controller has sent the TAU request message to the MME, according to the third embodiment of the present invention. 
         [0075]    Referring to  FIG. 8 , the MME  103  receives the TAU request from the UE  110  at step  801  and processes the TAU request at step  803 . The MME  103  determines whether the UE  110  is registered with a GAN, at step  805 . If the UE  110  is registered with a GAN, the MME  103  checks the LA from the LA of the UE  110  to determine whether the LA is changed, at step  807 . If the LA is changed, the MME  103  sends a LA change message to the GAN controller  301  with which the UE  110  is currently registered. If an LA change acknowledgement message is received from the GAN controller  310  in response to the LA change message, the MME  103  sends a TAU accept response message to the UE  110  at step  811 . The UE  110  can perform the procedure for registration with the new GAN controller  320  based on the TAU accept response message afterward. 
         [0076]    The embodiments disclosed in the specification and drawings aim only to help understand but not limit the present invention. Meanwhile, persons ordinarily skilled in the art would make modifications in terms of specific embodiments and application scopes without departing from the concepts of the present invention.