Patent Publication Number: US-2009225705-A1

Title: Apparatus and Method for Negotiating Quality of Service

Description:
TECHNICAL FIELD 
     The present invention relates to a method for negotiating a quality of service (QoS) and an apparatus using the same. Particularly, the present invention relates to a gateway and user equipment that negotiate a QoS in a network interworking system. 
     Since a digital cellular-based second generation mobile communication system has emerged, an International Mobile Telecommunication 2000 (IMT-2000) which is a third generation (3G) mobile communication was specified as the standard protocol for providing high quality worldwide multimedia services by the International Telecommunication Union (ITU). The 3G mobile communication system provides global roaming by using a consistent wireless access scheme with a single frequency bandwidth so that users can obtain services anytime and anywhere, and also provides wireless multimedia services such as a conventional voice service, images, moving pictures, a video phone, and Internet access by supporting up to 2 Mbps transmission speed with high bandwidth. 
     An initial goal of the standardization is to complete a single, worldwide system standard. Unfortunately, the process of unifying the numerous international standards has proved to be extremely difficult. The 3G mobile communication system is now broadly divided into a Universal Mobile Telecommunication System (UMTS) for Europe and Japan and a Code Division Multiple Access 2000 (CDMA-2000) for America. 
     The standardization work for CDMA-2000 is being carried out under the supervision of the Third Generation Partnership Projects 2 (3GPP2). The CDMA-2000 uses a North American Standard Interim Standard (ANSI)-41-based network protocol as a core network, and utilizes a synchronous network scheme as an interface for synchronization between base stations. 
     The standardization work for the UMTS is being carried out under the Third Generation Partnership Project (3GPP). The UMTS uses a Global System for Mobile Communications (GSM) based mobile application part (GSM-MAP) as a core network, and utilizes an asynchronous network scheme as an air interface since synchronization between base stations is not required. 
     The 3GPP uses the concept of Release in the evolution of the system standardization, and 3GPP wireless local area network (WLAN) interworking is one of the main issues that have been developed in Release 6. The purpose of the 3GPP WLAN interworking is to provide 3GPP service and functions to a user in a WLAN. Although the standardization of the 3GPP WLAN is being carried out, a QoS negotiation method in the 3-GPP WLAN interworking system has not been proposed. 
     The 3G mobile communication system provides a packet-switched service rather than a circuit-switched service. In the packet-switched network, a communication message is broken into data units, called packets. Each packet is routed through a network based on the destination address contained in each packet. Particularly, the 3G mobile communication system is an all-IP network that enables the nodes of the network to communicate with each other based on an Internet protocol (IP), and a communication message is exchanged through the IP in the 3G mobile communication system. In the packet-switched network, a communication message is broken into a plurality of packets and thus a plurality of users can share the same channel within the network. 
     In the case that the same types of packets are input to a node in the network, the node can apply the same priority or policy to the input packets or to a group of packets. This is called a best effort scheme. However, the best effort scheme cannot provide a quality of service (QoS) that is adequate for each packet since there is a limit in bandwidth extension in the present network, and different types of packets such as a video phone, broadcasting, multimedia, and voice over IP (VOIP) are handled. 
     Particularly, the 3G mobile communication service has been developed for providing various services including voice service, image and moving pictures, a video phone, and Internet access, and therefore, standardization for QoS is demanded. However, as previously mentioned, a method for negotiating a QoS in the 3-GPP WLAN interworking system has not been proposed yet. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     DISCLOSURE 
     Technical Problem 
     The present invention has been made in an effort to provide a gateway and a terminal negotiating a quality of service (QoS) in a network interworking system, and a QoS negotiation method thereof. 
     Technical Solution 
     An exemplary gateway according to an embodiment of the present invention includes a core network, a first bearer manager, a second bearer manager, a third bearer manager, and a controller. The core network connects a wireless access network and a packet switched service network, and the first, second, and third bearer managers enable communication between the core network and the packet switched service network. The first bearer manager manages a first bearer packet exchange with an end terminal included in the packet switched service network. The second bearer manager manages a second bearer for packet exchange with a terminal accessing the wireless access network. The third bearer manager manages a third bearer for packet exchange between the terminal and the end terminal. The controller determines whether to accept a first QoS requested by the terminal for establishing the third bearer through the second bearer in accordance with an available resource of the first bearer. 
     The controller determines whether to accept the first QoS in accordance with available resources of the first and second bearers. 
     An exemplary terminal according to an embodiment of the present invention exchanges a packet with a packet switched service network connected with a wireless access network through a core network, and includes a first bearer manager, a second bearer manager, and a controller. The first bearer manages a first bearer for packet exchange with an end terminal included in the packet switched service network, and the second bearer manager manages a second bearer for packet exchange with an end terminal included in the packet switched service network. In addition, the controller manages a resource allocated to the first bearer. The second bearer manager inquires to the controller whether to accept the first QoS for establishing the second bearer, the controller determines whether to accept the first QoS in accordance with an available resource of the first bearer, and the second bearer manager requests the first QoS from the gateway through the first bearer when the controller accepts the first QoS. 
     An exemplary quality of service (QoS) negotiation method according to an embodiment of the present invention is used by a gateway that enables communication between a core network and a packet switched service network, the core network connecting a wireless access network and the packet switched service network. In the method, the gateway establishes a first bearer for packet exchange with an end terminal included in the packet switched service network. Subsequently, the gateway receives a first QoS requested by a terminal for establishing a second bearer for packet exchange with the gateway, the terminal accessing the wireless access network. Then the gateway accepts the first QoS when the first QoS is adequate for a QoS of the first bearer. The gateway establishes a second bearer when the first QoS is accepted. 
     Herein, the gateway receives a second QoS requested by the terminal for establishing a third bearer for packet exchange with the end terminal through the second bearer, accepts the second QoS when the second QoS is adequate for an available resource of the first bearer, and establishes the third bearer when the second QoS is accepted. 
     An exemplary quality of service (QoS) negotiation method according to another exemplary embodiment of the present invention is used by a terminal that exchanges a packet with a packet switched service network connected with a wireless access network through a core network. The terminal requests a first QoS to the wireless access device for establishing a first bearer for packet exchange with a wireless access device included in the wireless access network. Then the terminal establishes the first bearer when the wireless access device accepts the first QoS. Subsequently, the terminal requests a second QoS to a gateway through the first bearer for establishing a second bearer for packet exchange with the gateway, wherein the gateway enables communication between the core network and the packet switched service network. Then the terminal establishes the second bearer when the gateway accepts the second QoS. 
     Herein, the terminal requests a third QoS from the gateway through the second bearer for establishing a third bearer for packet exchange with an end terminal included in the packet switched service network, and establishes the third bearer when the gateway accepts the third QoS. 
     Advantageous Effects 
     According to the present invention, WLAN user equipment exchanges a data packet with an end terminal in the 3GPP packet-switched service network through efficient QoS negotiation. 
     Particularly, the WLAN user equipment negotiates with a packet data gate for establishing an IP bearer for packet exchange with the end terminal so that efficient QoS negotiation can be achieved. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  shows A 3GPP-wireles local area network (WLAN) interworking system according to an exemplary embodiment of the present invention. 
         FIG. 2  shows a QoS management function for a WLAN 3GPP IP connection according to an exemplary embodiment of the present invention. 
         FIG. 3  is a flowchart of an IP bearer establishment process of WLAN user equipment according to an exemplary embodiment of the present invention. 
         FIG. 4  is a flowchart of a QoS negotiation process of a packet data gateway according to an exemplary embodiment of the present invention. 
         FIG. 5  is a flowchart of a QoS negotiation process of WLAN user equipment according to an exemplary embodiment of the present invention. 
         FIG. 6  shows a QoS management function for a WLAN direct IP connection according to an exemplary embodiment of the present invention. 
     
    
    
     BEST MODEL 
     An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
     In the following detailed description, only a certain exemplary embodiment of the present invention has been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiment may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive, and life reference numerals designate like elements through the specification. 
     Throughout this specification and the claims which follow, unless explicitly described to the contrary, the word “comprising” or variations such as “comprises” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
     A Third Generation Partnership Project (3-GPP) wireless local area network (WLAN) interworking system according to an exemplary embodiment of the present invention will now be described in detail with reference to  FIG. 1 . 
       FIG. 1  shows a 3GPP-WLAN interworking system according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 1 , the 3-GPP WLAN interworking system includes WLAN user equipment (WLAN UE)  100 , a WLAN access network (WLAN AN)  1 , a 3GPP core network  2 , a 3GPP packet-switched service network  3 , and an Internet (or Intranet)  4 . 
     The WLAN UE  100  is a user terminal registered with the 3GPP packet-switched service network  3  and is able to access the WLAN AN  1 . The WLAN UE  100  may access only the WLAN AN  1  or access both the WLAN AN 1  and a 3GPP access network. Herein, the 3GPP access network includes a Node-B that provides wireless code division multiplexing access (WCDMA) wireless access and a radio network controller (RNC) that controls the Node-B. A terminal that can access the 3GPP access network accesses the 3GPP packet-switched service network  3  through the 3GPP access network. The WLAN UE  100  may be provided as a mobile device, a laptop computer, a notebook computer, or a PDA having a WLAN card, or may be provided as a mobile device, a laptop computer, a notebook computer, or a PDA having a WLAN card and a 3GPP access module. 
     The WLAN AN  1  provides WLAN access to the WLAN UE  100 , and includes a plurality of WLAN access points (WLAN APs)  200 , each of which wirelessly accesses the WLAN UE  100 . The WLAN used in the present invention is based on a wireless LAN specified by the IEEE 802.11 WLAN standard, but that is not restrictive. Therefore, the WLAN AN  1  may be provided as a typical wireless access network, and the WLAN AP  200  may be provided as a base station or a wireless access terminal that corresponds to a Node-B. 
     The 3GPP core network  2  is a core network that connects the WLAN AN  1  and the 3GPP packet-switched service network  3 . The 3GPP core network  2  includes a WLAN access gateway (WAG)  300 , a packet data gateway (PDG)  40 , and a 3GPP Authentication Authorization Accounting Server (3GPP AAA Server)  60 . 
     The WAG  300  is a gateway via which data is exchanged between the WLAN access network  1  and the 3GPP core network  2 . Since the WLAN AN  1  has a protocol that is different from that of the 3GPP core network  2 , the WAG  300  changes protocols for data exchange between the WLAN AN  1  and the 3GPP core network  2 . 
     The PDG  400  is a gateway via which data is exchanged between the 3GPP core network  2  and the 3GPP packet-switched service network  3 . Since the 3GPP core network  2  has a protocol that is different from that of the 3GPP packet-switched service network  3 , the PDG  40  changes protocols for data exchange between the 3GPP core network  2  and the 3GPP packet-switched service network  3 . 
     The 3GPP packet-switched service network  3  is a standard packet-switched service network specified by the 3GPP, and provides a 3GPP packet-switched service to the WLAN UE  100 . The WLAN UE  100  is provided with the 3GPP packet-switched service from the 3GPP packet-switched service network  3  via the WLAN AN  1  and the 3GPP core network  2 , and this is typically called WLAN 3GPP IP access. An ending network node (e.g., a server) included in the 3GPP packet-switched service network  3  and providing the 3GPP packet-switched service to the WLAN UE  100  is called a 3GPP end terminal  50 . 
     The WLAN UE  100  directly accesses the Internet  4  through the WLAN AN  1  and receives IP-based services, and this is called WLAN direct IP access. The Internet  4  includes an Internet end terminal  70  that provides the IP-based service. 
     The 3GPP AAA server  60  is a server handling user authorization, service authentication, and billing data. The WLAN UE  100  is registered with the 3GPP AAA server  60  for WLAN 3GPP IP access or WLAN direct IP access. In addition, the 3GPP AAA server  60  charges for a QoS served to the WLAN UE  100  and network and bandwidth usages. 
     The Internet  4  is a packet-switched service network, and includes an Internet end terminal  700  that provides Internet services. 
     A QoS management function for establishing a WLAN 3GPP IP connection according to an exemplary embodiment of the present invention will be described with reference to  FIG. 2 . 
       FIG. 2  shows a QoS management function for establishing a WLAN 3GPP IP connection according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 2 , the WLAN UE  100  includes a WLAN bearer service manager  110 , an Interworking WLAN (I-WLAN) bearer service manager  120 , an admission and capability controller  130 , a converter  140 , and an IP bearer service manager  150 . In addition, the WLAN AP  200  includes a WLAN bearer service manager  210 , an access network manager  220 , an admission and capability controller  230 , and a Wn bearer service manager  240 . The WAG  300  includes a Wn bearer service manager  310 , an access network manager  320 , and a Wp bearer service manager  330 . The PDG  400  includes a Wp bearer service manager  410 , an I-WLAN bearer service manager  420 , an admission and capability controller  430 , a converter  440 , an IP bearer service manager  450 , and an external bearer service manager  460 . 
     Interfaces between constituent elements of the WLAN UE  100  are as follows. The I-WLAN bearer service manager  120  exchanges data with the WLAN bearer service manager  110 , the admission and capability controller  130 , and the converter  140  through an internal service primitive. The converter  140  exchanges data with the I-WLAN bearer service manager  120  and the IP bearer service manager  150  also through an internal service primitive. 
     The internal service primitive indicates an interface function for exchanging data between layer modules, and includes a request primitive, an indication primitive, a response primitive, and a confirm primitive. The request primitive is used when an upper layer requests a service from a lower layer. The indication primitive is used when the lower layer informs an arrival of a request from a communication counterpart to the upper layer. The response primitive is used when the upper layer transmits a response to the lower layer in response to the indication primitive. The confirm primitive is used when the lower layer transmits a response to the upper layer in response to the request primitive. 
     Since interfaces between constituent elements of the WLAN AP  200 , the WAG  300 , and the PDG  400  are shown in  FIG. 2 , descriptions related thereto will not be further provided. 
     A method for establishing a WLAN bearer B 110  will be described. 
     The WLAN bearer service manager  110  of the WLAN UE  100  negotiates a QoS for establishing the WLAN bearer B 110  with the WLAN bearer service manager  210  of the WLAN AP  200 . The WLAN bearer B 110  is used for packet exchange between the WLAN UE  100  and the WLAN AP  200 . The admission and capability controller  230  of the WLAN AP  200  maintains information on resources allocated to the WLAN bearer B 110  and an available resource of the WLAN bearer B 110 . When the WLAN bearer service manager  110  requests QoS negotiation for establishing the WLAN bearer B 110 , the WLAN bearer service manager  210  inquires to the admission and capability controller  230  whether the admission and capability controller  230  accepts the QoS requested by the WLAN bearer service manager  110  through the access network manager  220 . The admission and capability controller  230  determines whether to accept the request in accordance with the available resource of the WLAN bearer B 110 . When the admission and capability controller  230  rejects the request, the WLAN bearer service manager  110  and the WLAN bearer service manager  210  perform renegotiation. 
     When the admission and capability controller  230  accepts the QoS, the WLAN bearer service manager  110  and the WLAN bearer service manager  210  generate, manage, and maintain the WLAN bearer B 110  for supporting the negotiated QoS. At this time, the I-WLAN bearer service manager  120  receives information on the negotiated QoS and information on resources allocated to the WLAN bearer B 110  and transmits the received information to the admission and capability controller  130 . The admission and capability controller  130  maintains and manages information on a QoS supported by the WLAN bearer B 110  and information on the resource allocated to the WLAN bearer B 110 . 
     The Wn bearer service manager  240  of the WLAN access point  200  and the Wn bearer service manager  310  of the WAG  300  generate, manage, and maintain a Wn bearer B 120 . According to the exemplary embodiment of the present invention, a service of the Wn bearer B 120  follows a best effort scheme. According to the best effort scheme, the same priority or the same policy is applied to packets or a group of packets. 
     The Wp bearer service manager  330  of the WAG  300  and the Wp bearer service manager  410  of the PDG  400  generate, manage, and maintain a Wp bearer B 140 . In the present embodiment, a service of the Wn bearer B 140  is based on the best effort scheme. 
     The external bearer service manager  460  establishes, manages, and maintains an external bearer B 160 , used for packet exchange between the PDG  400  and the end terminal  500 . At this time, the I-WLAN bearer service manager  420  receives information on a QoS of the external bearer B 160  or information on a resource allocated to the external bearer B 160  from the external bearer service manager  460  and transmits the received information to the admission and capability controller  430 . The admission and capability controller  430  maintains and manages the information on the QoS of the external bearer B 160  or information on the resource allocated to the external bearer B 160 . 
     The access network manager  220  of the WLAN access point  200  enables communication between the WLAN bearer service manager  210  and the Wn bearer service manager  240 . That is, the access network manager  220  receives contents of a message that the WLAN bearer service manager  210  has received from the WLAN bearer service manager  110  by using an internal service primitive 
     The access network manager  220  transmits the contents received from the WLAN bearer service manager  210  to the Wn bearer service manager  240  by using the internal service primitive. Then, the Wn bearer service manager  240  generates a message that includes the received contents, and provides the message to the Wn bearer service manager  310  of the WAG  300  by using a service of the Wn bearer B 120 . Also, reversely, the access network manager  220  provides the internal service primitive transmitted from the Wn bearer service manager  240  to the WLAN bearer service manager  210 . 
     The access network manager  220  of the WLAN access point  200  interworks with the admission and capability controller  230 . That is, when receiving the internal primitive, including whether or not to accept a QoS request of the WLAN bearer service manager  110 , from the WLAN bearer service manager  210 , the access network manager  220  transmits the corresponding internal primitive to the admission and capability controller  230 . When receiving the internal primitive, including a result of the acceptance of the requested QoS, from the admission and capability controller  230 , the access network manager  220  provides the corresponding internal primitive to the WLAN bearer service manager  210 . 
     The access network manager  320  of the WAG  300  enables communication between the Wn bearer service manager  310  and the Wp bearer service manager  330 . A role of the access network manager  320  can be easily derived from the access network manager  220 , and therefore, a further description will be omitted. 
     A method for establishing an I-WLAN bearer B 150  will now be described. 
     The I-WLAN bearer service manager  120  of the WLAN UE  100  negotiates a QoS for establishing an I-WLAN bearer B 150  with the I-WLAN bearer service manager  420  and establishes the I-WLAN bearer B 150 . The I-WLAN bearer B 150  is used for packet exchange between the WLAN UE  100  and the PDG  400 . Since it is preferred that a QoS between the WLAN UE  100  and the PDG  400  does not exceed the QoS provided from the WLAN bearer, the I-WLAN bearer service manager  120  refers to a QoS of the WLAN bearer B 110  or the available resource of the WLAN bearer B 110 . 
     For this purpose, the I-WLAN bearer service manager  120  inquires to the admission and capability controller  130  whether the QoS to be negotiated with the PDG  400  is an adequate QoS or not. The admission and capability controller  130  determines adequacy of the QoS inquired by the I-WLAN bearer service manager  120  with reference to the QoS of the WLAN bearer B 110  or the available resource of the WLAN bearer B 110 . 
     When the admission and capability controller  130  accepts the inquired QoS, the I-WLAN bearer service manager  120  requests the QoS accepted by the admission and capability controller  130  to the I-WLAN bearer service manager  420 . At this time, the I-WLAN bearer service manager  120  uses a service of the WLAN bearer B 110  when negotiating the QoS with the I-WLAN bearer service manager  420 . In more detail, the I-WLAN bearer service manager  120  negotiates with the I-WLAN bearer service manager  420  by using the services of the WLAN bearer B 110 , the Wn bearer B 120 , and the Wp bearer B 140 . 
     The I-WLAN bearer service manager  420  inquires to the admission and capability controller  430  whether the admission and capability controller  430  accepts the QoS requested by the I-WLAN bearer service manager  120 . The admission and capability controller  430  determines whether to accept the QoS requested by the bearer service manager  120  with reference to the available resource of the external bearer B 160  or the QoS of the external bearer B 160  and provides an internal primitive, including the determination of the admission and capability controller  430 . 
     At this time, the admission and capability controller  430  refers to the resource allocated to the external bearer B 160  or the QoS of the external bearer B 160  because the QoS between the WLAN UE  100  and the PDG  400  depends on the QoS provided by the external bearer B 160 . When the admission and capability controller  430  rejects the requested QoS, the I-WLAN bearer service manager  120  and the I-WLAN bearer service manager  420  renegotiate the QoS. When the admission and capability controller  430  accepts the QoS, the I-WLAN bearer service manager  120  and the I-WLAN bearer service manager  420  establish an I-WLAN bearer B 150 . Then, the I-WLAN bearer service manager  120  and the I-WLAN bearer service manager  420  convert attributes of the I-WLAN bearer B 150  and maintain the I-WLAN bearer B 150 . 
     When the I-WLAN bearer B 150  is established, the I-WLAN bearer service manager  120  provides information on a QoS of the I-WLAN bearer B 150  or information on a resource allocated to the I-WLAN bearer B 150  to the admission and capability controller  130 . Also, the I-WLAN bearer service manager  420  provides the information on the QoS of the I-WLAN bearer B 150  and the information on the resource allocated to the I-WLAN bearer B 150  to the admission and capability controller  430 . 
     The IP bearer service manager  150  of the WLAN UE  100  negotiates a QoS with the PDG  400  for packet exchange between the IP bearer service manager  150  and the end terminal  500  of the external 3GPP packet-switched service network  3 . When the negotiation is successful, the IP bearer service manager  150  and the IP bearer service manager  450  establish, manage, and maintain an IP bearer B 170 . The IP bearer B 170  is used for packet exchange (i.e., end-to-end packet switch) between the WLAN UE  100  and the end terminal  500 . The WLAN UE  100  establishes a plurality of IP bearers B 170  respectively corresponding to a plurality of end terminals  500  for packet exchange. At this time, the WLAN UE  100  establishes the plurality of IP bearers B 170  by negotiating a QoS with the PDG  400 . 
     A method for QoS negotiation between the IP bearer server manager  150  of the WLAN UE  100  and the IP bearer service manager  450  of the packet data gateway  400  for establishing an IP bearer B 170  will be described. The IP bearer B 170  is used for packet exchange between the WLAN UE  100  and the end terminal  500 . 
       FIG. 3  is a flowchart of a method for a WLAN UE to establish the IP bearer B 170 . 
     The IP bearer service manager  150  inquires to the admission and capability controller  130  whether the admission and capability controller  130  accepts a QoS requested for establishing the IP bearer B 170  in step S 110 . For this purpose, the IP bearer service manager  150  provides a primitive that includes a result of the requested QoS acceptance to the converter  140 . The converter  140  converts the primitive into a primitive to be transmitted to the admission and capability controller  130 , and provides the converted primitive to the I-WLAN bearer service manager  120 . The I-WLAN bearer service manager  120  perceives that the received primitive is a primitive to be transmitted to the admission and capability controller  130 , and transmits the primitive to the admission and capability controller  130 . 
     The admission and capability controller  130  manages a resource allocated to the I-WLAN bearer B 150 . Therefore, the admission and capability controller  130  determines whether to accept the QoS requested by the IP bearer service manager  150  in accordance with an available resource of the I-WLAN bearer B 150 , in step S 120 . That is, when enough available resources of the I-WLAN bearer B 150  exist such that the requested QoS can be supported, the admission and capability controller  130  accepts the QoS requested by the IP bearer service manager  150 . 
     When the admission and capability controller  130  accepts the QoS requested by the IP bearer service manager  150 , the IP bearer service manager  150  requests the QoS accepted by the admission and capability controller  130  to the PDG  400 , in step S 130 . 
     In more detail, the IP bearer service manager  150  provides the converter  140  with a primitive that includes a request for the QoS to the PDG  400  for establishing the IP bearer B 170 . The converter  140  acknowledges that the primitive needs to be transmitted to the PDG  400 , converts the primitive into a message to be transmitted to the PDG  400 , and provides the message to the I-WLAN bearer service manager  120 . The I-WLAN bearer service manager  120  forwards the message to the I-WLAN bearer service manager  420  through the I-WLAN bearer B 150 . The I-WLAN bearer service manager  420  provides the forwarded message to the converter  440 . 
     Then, the converter  440  converts the message into a primitive in a format that can be read by the IP bearer service manager  450 , and provides the conversion result to the IP bearer service manager  450 . When the admission and capability controller  130  rejects the QoS requested by the IP bearer service manager  150 , the IP bearer service manager  150  requests a new QoS to the admission and capability controller  130 . 
     When receiving the primitive including the QoS request of the IP bearer service manager  150  from the converter  440 , the IP bearer service manager  450  inquires to the admission and capability controller  430  about whether the admission and capability controller  430  accepts the requested QoS. The admission and capability controller  430  manages information on a resource allocated to the external bearer B 160 . 
     In addition, the admission and capability controller  430  determines whether to accept the QoS request of the IP bearer service manager  150  in accordance with an available resource of the external bearer B 160  in step S 140 . At this time, the admission and capability controller  430  may determine whether to accept the QoS request of the IP bearer service manager  150  with reference to the available resource of the external bearer B 160  and the available resource of the I-WLAN bearer B 150 . The admission and capability controller  430  provides the converter  440  with a primitive including a result of the determination on the requested QoS through the I-WLAN bearer service manager  420 . The converter  440  converts the primitive into a format that can be read by the IP bearer service manager  450 , and provides the converted primitive to the IP bearer service manager  450 . 
     When the admission and capability controller  430  accepts the QoS request of the IP bearer service manager  150 , the IP bearer service manager  150  and the IP bearer service manager  450  establish, manage, and maintain an IP bearer B 170  that supports the QoS accepted by the admission and capability controller  430  in step S 150 . When the admission and capability controller  430  rejects the QoS request of the IP bearer service manager  150 , the IP bearer service manager  150  requests a new QoS to the admission and capability controller  430 . 
     A method for transmitting user packets will now be described. 
     The WLAN UE  100  and the end terminal  500  exchange user packets by using a service of the IP bearer B 170 . At this time, the IP bearer B 170  uses services of the I-WLAN bearer B 150  and the external bearer B 160 . In addition, the I-WLAN bearer B 150  uses a service of the WLAN bearer B 110 , a service of the Wn bearer B 120 , and a service of the Wp bearer B 140 . 
     A QoS negotiation method of the PDG  400  according to an exemplary embodiment of the present invention will be described with reference to  FIG. 4 . 
       FIG. 4  is a flowchart of a QoS negotiation method of a packet data gateway according to the exemplary embodiment of the present invention. 
     The external bearer service manager  460  of the PDG  400  establishes an external bearer for packet exchange with an end terminal in step S 210 . 
     Subsequently, the WLAN UE  100  requests a QoS for establishing the I-WLAN bearer B 150  from the I-WLAN bearer service manager  420 , and the I-WLAN bearer service manager  420  receives the QoS requests from the WLAN UE  100  in step S 220 . 
     Then, the admission and capability controller  430  determines whether the requested QoS is adequate for a QoS of the external bearer in step S 230 , and accepts the request when a result of the determination shows that it is adequate in step S 240 . When the requested QoS is inadequate for the QoS of the external bearer, the WLAN UE  100  and the PDG  400  renegotiate a QoS for establishing the I-WLAN bearer B 150 . 
     When the admission and capability controller  430  accepts the requested QoS of the WLAN UE  100 , the I-WLAN bearer service manager  420  establishes the I-WLAN bearer in step S 250 . 
     Subsequently, the I-WLAN bearer service manager  420  receives the QoS requested by the WLAN UE  100  for establishing the IP bearer B 170  from the WLAN UE  100  through the I-WLAN bearer in step S 260 . 
     The admission and capability controller  430  determines whether the QoS requested by the WLAN UE  100  for establishing the IP bearer B 170  is adequate for the available resource of the external bearer B 160  in step S 270  and accepts the QoS requested by the WLAN UE  100  when it is adequate in step S 280 . At this time, the admission and capability controller  430  further determines whether the QoS requested by the WLAN UE  100  is adequate for the available resource of the I-WLAN bearer B 150  and accepts the QoS request of the WLAN UE  100  when it is adequate. When the QoS requested by the WLAN UE  100  is inadequate for the available resource of the external bearer B 160 , the WLAN UE  100  and the PDG  400  renegotiate a QoS for establishing the IP bearer B 170 . 
     When the admission and capability controller  430  accepts the QoS requested by the WLAN UE  100 , the IP bearer service manager  450  establishes the IP bearer B 170  in step S 290 . 
     A method for the WLAN UE  100  to negotiate a QoS according to an exemplary embodiment of the present invention will be described with reference to  FIG. 5 . 
       FIG. 5  is a flowchart showing a method of the WLAN UE to negotiate a QoS according to an exemplary embodiment of the present invention, which will now be described. 
     The WLAN bearer service manager  110  of the WLAN UE  100  requests a QoS for establishing the WLAN bearer B 110  from the WLAN AP  200  in step S 310 . 
     When the WLAN access point  300  accepts the QoS, the WLAN bearer service manager  110  establishes the WLAN bearer B 110  for supporting the QoS in step S 320 . 
     Subsequently, the I-WLAN bearer service manager  120  requests a QoS for establishing the I-WLAN bearer B 150  from the PDG  400  by using a service of the WLAN bearer B 110  in step S 330 . At this time, the I-WLAN bearer service manager  120  determines a QoS for establishing the I-WLAN bearer B 150  in accordance with an available resource of the WLAN bearer B 110  and then requests the determined QoS from the PDG  400 . 
     When the PDG  400  accepts the QoS, the I-WLAN bearer service manager  120  establishes an I-WLAN bearer for supporting the QoS in step S 340 . 
     The IP bearer service manager  150  requests a QoS for establishing the IP bearer B 170  from the PDG  400  by using a service of the I-WLAN bearer B 150  in step S 350 . At this time, the IP bearer service manager  150  determines a QoS for establishing the IP bearer B 170  in accordance with an available resource of the I-WLAN bearer B 150  and then requests the determined QoS from the PDG  400 . 
     When the PDG  400  accepts the QoS for establishing the IP bearer B 170 , the IP bearer service manager  150  establishes the IP bearer B 170  for supporting the QoS in step S 360 . 
     A QoS management function for establishing a WLAN direct IP connection according to an exemplary embodiment of the present invention will be described with reference to  FIG. 6 . 
       FIG. 6  shows the QoS management function for establishing the WLAN direct IP connection according to the exemplary embodiment of the present invention. 
     As shown in  FIG. 6 , the WLAN UE  100  further includes an admission and capability controller  160 , a converter  170 , and an IP bearer service manager  180 . In addition, the WLAN access point  200  further includes an external bearer service manager  250 , a converter  260 , and an IP bearer service manager  270 . 
     Interfaces between constituent elements of the WLAN UE  100  are as follows. The admission and capability controller  160  communicates with the WLAN bearer service manager  110  by using an internal service primitive. The converter  170  communicates with the WLAN bearer service manager  110  and the IP bearer service manager  180  by using an internal service primitive. 
     Interfaces between constituent elements of the WLAN AP  200  are as follows. The access network manager  220  communicates with the external bearer service manager  250  and the converter  260  by using an internal service primitive. The converter  260  communicates with the IP bearer service manager  270  by using an internal service primitive. 
     The WLAN bearer service manager  110  and the WLAN bearer service manager  210  negotiate a QoS and establish a WLAN bearer B 110  for supporting the negotiated QoS in the same way as previously described. Therefore, a description related thereto will not be further provided. When the WLAN bearer B 110  is established, the admission and capability controller  160  and the admission and capability controller  230  respectively manage resources allocated to the WLAN bearer B 110 . 
     The converter  170  and the converter  260  convert a message that corresponds to an internal service primitive and an external service signaling. 
     The external bearer service manager  250  of the WLAN AP  200  establishes, manages, and maintains an external bearer B 180  used for packet exchange between the WLAN AP  200  and the end terminal  700  of the Internet. The admission and capability controller  230  manages a resource allocated to the external bearer B 180 . 
     A method for establishing an IP bearer B 190  used for packet exchange between the WLAN UE  100  and the end terminal  700  will now be described. 
     The IP bearer service manager  180  inquires to the admission and capability controller  160  about adequacy of a QoS for establishing the IP bearer B 190 . The admission and capability controller  160  determines whether the QoS requested by the IP bearer service manager  180  is adequate in accordance with an available resource of the WLAN bearer B 110 . 
     When the admission and capability controller  160  determines that the QoS is adequate, the IP bearer service manager  180  requests the determined QoS from the IP bearer service manager  270  of the WLAN AP  200 . At this time, the IP bearer service manager  180  requests the QoS from the WLAN AP  200  by using a service of the WLAN bearer B 110 , and the request is converted into an internal service primitive by the converter and transmitted to the IP bearer service manager  270 . 
     When receiving the QoS request from the IP bearer service manager  180 , the IP bearer service manager  270  inquires to the admission and capability controller  230  whether the admission and capability controller  230  accepts the requested QoS. The admission and capability controller  230  determines whether to accept the QoS in accordance with an available resource of the external bearer B 180 . At this time, the admission and capability controller  230  determines the acceptance of the QoS with further reference to the available resource of the WLAN bearer B 110 . 
     When the admission and capability controller  230  accepts the QoS for establishing the IP bearer B 190 , the IP bearer service manager  180  and the IP bearer service manager  270  establish, manage, and maintain an IP bearer B 190  for supporting the QoS. 
     The above-described exemplary embodiment of the present invention may be realized by an apparatus and a method, but it may also be realized by a program that realizes functions corresponding to configurations of the exemplary embodiment or a recording medium that records the program. 
     Such a realization can be easily performed by a person skilled in the art. 
     While this invention has been described in connection with what is presently considered to be a practical exemplary embodiment, it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.