Abstract:
The present invention relates to a device for interworking a wireless local area network (WLAN) and a portable Internet. The device establishes a first wireless data path following a first wireless communication protocol with a first network, and establishes a plurality of the second wireless data paths through the first wireless data paths. Here, the plurality of the second wireless data paths follow a second wireless communication protocol and respectively correspond to a plurality of terminal devices. Subsequently, the device establishes a plurality of first network links respectively corresponding to the plurality of terminal devices with the first network, and stores mapping information for the first network link corresponding to a relationship between the plurality of terminal devices and the plurality of first network links.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2006-0120598 filed in the Korean Intellectual Property Office on Dec. 1, 2006, and 10-2007-0035627 filed in the Korean Intellectual Property Office on Apr. 11, 2007, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to an apparatus for interworking a wireless local area network (WLAN) and a portable Internet, and a method thereof. Particularly, the present invention relates to an apparatus for interworking a WLAN and a portable Internet so that a subscriber subscribing to a WLAN Internet service may receive an Internet service through the portable Internet, and a method thereof. 
         [0004]    This work was supported by the IT R&amp;D program of MIC/IITA[2006-S-009-01, The Development of WiBro Service and Operating Standard]. 
         [0005]    (b) Description of the Related Art 
         [0006]    Conventional techniques for interworking a wireless local area network (WLAN) with networks including a wireless broadband Internet (WiBro), a universal mobile telecommunications system (UMTS), and a code division multiple access (CDMA) have been suggested. However, in the techniques, methods for connecting the WLAN and a public network through the above respective networks in a narrow area supporting the WLAN have been suggested or signal processes performed by WLAN terminals and the interworked network have been suggested. 
         [0007]    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. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention has been made in an effort to provide a method for providing a service provided from a wireless local area network (WLAN) service provider to WLAN terminals through a portable Internet. 
         [0009]    In an exemplary interworking method according to an embodiment of the present invention, a first wireless data path following a first wireless communication protocol is established with a first network, a plurality of second wireless data paths that respectively correspond to a plurality of terminal devices and follow a second wireless communication protocol are established through the first wireless data path, a plurality of first network links respectively corresponding to the plurality of terminal devices are established with the first network, and mapping information for the first network link that corresponds to a relationship between the plurality of terminal devices and the plurality of first network links is stored. 
         [0010]    Here, the first wireless communication protocol supports a handover operation, and the second wireless communication protocol does not support a handover operation. 
         [0011]    When the plurality of first network links are established, a bandwidth of each first network link is allocated according to a service grade of each terminal device. 
         [0012]    When the mapping information is stored, the mapping information for the plurality of terminal devices respectively corresponding to the plurality of first network links is stored. 
         [0013]    In the interworking method, a packet is received and the packet is transmitted according to the mapping information. 
         [0014]    When the packet is transmitted, the packet is received through one among the plurality of first network links, and the packet is transmitted to the terminal device corresponding to the first network link among the plurality of terminal devices according to the mapping information. 
         [0015]    The packet follows the first wireless communication protocol. When the packet is transmitted, the packet is received through one of the plurality of first networks, the packet is converted into a packet following the second wireless communication protocol, and the packet following the second wireless communication protocol is transmitted to the terminal device corresponding to the first network among the plurality of terminal devices according to the mapping information. 
         [0016]    When the packet is transmitted, the packet is received through the second wireless data path from one terminal device among the plurality of terminal devices, and the packet is transmitted through the first network link corresponding to the terminal device among the plurality of first network links according to the mapping information. 
         [0017]    The packet follows the second wireless communication protocol. When the packet is transmitted, the packet is received through the second wireless data path from one terminal device among the plurality of terminal devices, the packet is converted into a packet following the first wireless communication protocol, and the packet following the first wireless communication protocol is transmitted through the first network corresponding to the terminal device among the plurality of first network links according to the mapping information. 
         [0018]    When the first wireless data path is established, a wireless link following the first wireless communication protocol is established with a base station of the first network, an authentication message is transmitted to an authentication server of the first network through the wireless link so that the authentication server of the first network performs an authentication process according to the authentication message, and the first wireless data path following the first wireless communication protocol is established with the first network when the authentication process is finished. 
         [0019]    When the plurality of second wireless data paths are established, a wireless link following the second wireless communication protocol is established with each terminal device, an authentication message is received through the wireless link, the authentication message is transmitted to an authentication server of the second network through the first wireless data path so that the authentication server of the second network performs an authentication process according to the authentication message, and the second wireless data path following the second wireless communication protocol is established with the terminal device when the authentication process is finished. 
         [0020]    In another exemplary interworking method according to an embodiment of the present invention, a first wireless data path following a first wireless communication protocol is established with a first network, an authentication message is received from a terminal device through the first wireless link, the authentication message is transmitted to an authentication server of a second network through the first data path to receive a service grade of the terminal device, and a first network link following the first wireless communication protocol is established according to the service grade of the terminal device. 
         [0021]    In the interworking method, a second wireless data path following a second wireless communication protocol is established according to the service grade of the terminal device. 
         [0022]    In the interworking method, data are received through the first network link and the data are transmitted through the second wireless data path. 
         [0023]    In the interworking method, data are received through the second wireless data path, and the data are transmitted through the first network link. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a schematic diagram of a wireless Internet. 
           [0025]      FIG. 2  is a diagram of a system for interworking a wireless local area network (WLAN) and a portable Internet according to an exemplary embodiment of the present invention. 
           [0026]      FIG. 3  is a schematic diagram of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention. 
           [0027]      FIG. 4  is a schematic diagram of a portable Internet matching unit of an interworking device according to the exemplary embodiment of the present invention. 
           [0028]      FIG. 5  is a schematic diagram of a WLAN matching unit according to the exemplary embodiment of the present invention. 
           [0029]      FIG. 6  is a schematic diagram of an interworking unit according to the exemplary embodiment of the present invention. 
           [0030]      FIG. 7  is a flowchart representing a signaling method of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention. 
           [0031]      FIG. 8  is a flowchart representing a data exchanging method of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0032]    In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
         [0033]    In addition, unless explicitly described to the contrary, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. The terms “module”, “unit”, and “block” used herein mean one unit that processes a specific function or operation, and may be implemented by hardware, software or a combination thereof. 
         [0034]    An apparatus and method for interworking a wireless local area network (WLAN) and a portable Internet according to an exemplary embodiment of the present invention will be described with reference to the figures. 
         [0035]    A configuration of a wireless Internet will be described with reference to  FIG. 1 . 
         [0036]      FIG. 1  is a schematic diagram of the wireless Internet. 
         [0037]    As shown in  FIG. 1 , the wireless Internet includes an Internet  10  and a WLAN access point (AP)  20 , and communicates with a WLAN terminal  30  through a radio channel. 
         [0038]    The Internet  10  is a wire-based Internet connected to the WLAN AP  20 . The Internet  10  includes an authentication, authorization, and accounting (AAA) server  11  for authenticating the WLAN terminal  30 , and a dynamic host configuration protocol (DHCP) server  13  for allocating an Internet protocol (IP) address to the authenticated WLAN terminal  30 . 
         [0039]    The WLAN AP  20  has an IP address of the AAA server  11  and a DHCP relay function to perform authentication and address allocation functions for all the WLAN terminals  30  accessed to the WLAN AP  20 . 
         [0040]    The WLAN terminal  30  accesses the WLAN AP  20  through a wireless link, and communicates with the WLAN AP  20  according to a WLAN communication standard. 
         [0041]    A system including an interworking device for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention will be described with reference to  FIG. 2 . 
         [0042]      FIG. 2  is a diagram of a system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention. 
         [0043]    As shown in  FIG. 2 , the system including the interworking device includes an Internet  100 , a portable Internet  200 , a base station  300 , and an interworking device  400 , and communicates with a WLAN terminal  500  through the wireless link. 
         [0044]    The Internet  100  is a wire-based Internet that provides an e-mail service, a telnet service, a file transfer protocol (FTP) service, a Gopher service, and a World Wide Web (WWW) service. 
         [0045]    The portable Internet  200  communicates to the Internet  100  through a wired link, and provides a high speed wireless Internet service to a portable Internet terminal whether the portable Internet terminal stops or moves. The portable Internet  200  may be referred to as “wireless portable Internet”, “wireless wideband Internet”, “wireless high speed Internet”, and wireless broadband Internet (WiBro)” 
         [0046]    The base station  300  transmits/receives a signal according to a control operation of the portable Internet  200  through a radio channel. The base station  300  has an own communication area, and may perform a handover operation with a neighboring base station  300 . 
         [0047]    The interworking device  400  communicates with the portable Internet  200  through the base station  300 . In this case, the portable Internet  200  may acknowledge the interworking device  400  as a portable Internet terminal. 
         [0048]    The WLAN terminal  500  communicates with the interworking device  400  through the wireless link. In this case, the WLAN terminal  500  may acknowledge the interworking device  400  as a WLAN AP. 
         [0049]    The system including the interworking device for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention will be described in further detail with reference to  FIG. 3 . 
         [0050]      FIG. 3  is a schematic diagram of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention. 
         [0051]    As shown in  FIG. 3 , the system for interworking the WLAN and the portable Internet includes the Internet  100 , the portable Internet  200 , the base station  300 , and the interworking device  400 , and communicates with the WLAN terminal  500 . 
         [0052]    The Internet  100  includes a WLAN authentication server  110  and a WLAN DHCP server  130 . The WLAN authentication server  110  authenticates the WLAN terminal  500 , and the WLAN DHCP server  130  allocates a network address for the WLAN terminal  500 . 
         [0053]    The portable Internet  200  includes a portable Internet authentication server  210  and a portable Internet DHCP server  230 . The portable Internet authentication server  210  authenticates the portable Internet terminal, and the portable Internet DHCP server  230  allocates a network address for the portable Internet terminal. 
         [0054]    The base station  300  has an own wireless communication area, and transmits/receives a signal to/from the portable Internet terminal within the wireless communication area according to a control operation of the portable Internet  200  through a radio channel. The base station  300  performs a handover operation with a neighboring base station when the portable Internet terminal moves into the wireless communication area of the neighboring base station  300 . 
         [0055]    The interworking device  400  includes a portable Internet matching unit  410 , a WLAN matching unit  430 , and an interworking unit  450 . The portable Internet matching unit  410  accesses the portable Internet  200  and operates as the portable Internet terminal for the portable Internet  200 . When the WLAN terminal  500  is accessed, the WLAN matching unit  430  operates as the WLAN AP for the WLAN terminal  500  and communicates with the WLAN terminal  500 . The interworking unit  450  interworks the portable Internet matching unit  410  and the WLAN matching unit  430 . 
         [0056]    The WLAN terminal  500  includes a WLAN authentication client  510 , a WLAN DHCP client  530 , and an IP application unit  550 . The WLAN authentication client  510  uses a WLAN authentication message to request a service provider to authenticate the WLAN terminal  500 . The WLAN DHCP client  530  uses WLAN DHCP message to request the service provider to allocate the network address for the WLAN terminal  500 . The IP application unit  550  transmits/receives a data packet. 
         [0057]    The portable Internet matching unit of the interworking device according to the exemplary embodiment of the present invention will be described with reference to  FIG. 4 . 
         [0058]      FIG. 4  is a schematic diagram of the portable Internet matching unit of the interworking device according to the exemplary embodiment of the present invention. 
         [0059]    As shown in  FIG. 4 , the portable Internet matching unit  410  includes a transmitting/receiving antenna  411 , a modulation/demodulation unit  413 , a portable Internet protocol processing unit  415 , an interworking processing unit  417 , and a mapping table  419 . 
         [0060]    The transmitting/receiving antenna  411  transmits/receives a signal through the radio channel. 
         [0061]    The modulation/demodulation unit  413  demodulates an analog signal received through the transmitting/receiving antenna  411  into a digital signal and modulates the digital signal into the analog signal to transmit the signal through the transmitting/receiving antenna  411 . 
         [0062]    The portable Internet protocol processing unit  415  processes the portable Internet protocol. 
         [0063]    The interworking processing unit  417  interworks with the WLAN matching unit  430 . 
         [0064]    The mapping table  419  stores link information. 
         [0065]    The WLAN matching unit of the interworking device according to the exemplary embodiment of the present invention will be described with reference to  FIG. 5 . 
         [0066]      FIG. 5  is a schematic diagram of the WLAN matching unit according to the exemplary embodiment of the present invention. 
         [0067]    As shown in  FIG. 5 , the WLAN matching unit  430  includes a transmitting/receiving antenna  431 , a modulation/demodulation unit  433 , a WLAN protocol processing unit  435 , and an interworking processing unit  437 . 
         [0068]    The transmitting/receiving antenna  431  transmits/receives a signal through the radio channel. 
         [0069]    The modulation/demodulation unit  433  demodulates an analog signal received through the transmitting/receiving antenna  431  and modulates the digital signal to the analog signal to transmit the signal through the transmitting/receiving antenna  431 . 
         [0070]    The WLAN protocol processing unit  435  processes the WLAN protocol. 
         [0071]    The interworking processing unit  437  interworks with the portable Internet matching unit  410 . 
         [0072]    The interworking unit of the interworking device according to the exemplary embodiment of the present invention will be described with reference to  FIG. 6 . 
         [0073]      FIG. 6  is a schematic diagram of the interworking unit according to the exemplary embodiment of the present invention. 
         [0074]    As shown in  FIG. 6 , the interworking unit  450  includes a portable Internet authentication client  451 , a portable Internet DHCP client  453 , a WLAN authentication relay  455 , a WLAN DHCP relay  457 , and an IP relay  459 . 
         [0075]    The portable Internet authentication client  451  requests the portable Internet  200  to authenticate the portable Internet matching unit  410  of the interworking device  400 . In this case, the portable Internet authentication client  451  may use a portable Internet authentication message to request the portable Internet  200  to perform an authentication operation. 
         [0076]    The portable Internet DHCP client  453  requests the portable Internet  200  to allocate a network address for the portable Internet matching unit  410  of the interworking device  400 . In this case, the portable Internet DHCP client  453  may use a DHCP message to request the portable Internet  200  to allocate the network address. 
         [0077]    The WLAN authentication relay  455  transmits the WLAN authentication message transmitted from the WLAN authentication client  510  to the portable Internet  200 . 
         [0078]    The WLAN DHCP relay  457  transmits the WLAN DHCP message transmitted from the WLAN DHCP client  530  to the portable Internet  200 . 
         [0079]    The IP relay  459  transmits the data packet transmitted by the IP application unit  550  to the portable Internet  200 , and transmits the data packet transmitted by the portable Internet  200  to the IP application unit  550 . 
         [0080]    A signaling method of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention will be described with reference to  FIG. 7 . 
         [0081]      FIG. 7  is a flowchart representing the signaling method of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention. 
         [0082]    As shown in  FIG. 7 , the portable Internet matching unit  410  of the interworking device  400  establishes a portable Internet wireless link with the base station  300  of the portable Internet  200  in step S 101 . In this case, the portable Internet wireless link follows the portable Internet communication protocol defined by IEEE 802.16, and the portable Internet communication protocol supports a terminal handover operation. 
         [0083]    The interworking device  400  establishes a portable Internet data path with the portable Internet  200  through the portable Internet wireless link, and the portable Internet  200  allocates a network address to the portable Internet matching unit  410  of the interworking device  400  in step S 103 . The portable Internet data path follows the portable Internet communication protocol defined by IEEE 802.16. The portable Internet authentication client  451  of the interworking unit  450  transmits the portable Internet authentication message to the portable Internet authentication server  210  of the portable Internet  200  through the portable Internet wireless link, and the interworking device  400  establishes the portable Internet data path with the portable Internet  200  according to the portable Internet authentication response message when the portable Internet authentication server  210  performs the authentication operation according to the portable Internet authentication message and transmits the portable Internet authentication response message. In addition, the portable Internet DHCP client  453  of the interworking unit  450  transmits the portable Internet DHCP message to the portable Internet DHCP server  230  through the portable Internet data path, and the portable Internet DHCP server  230  allocates the network address to the portable Internet matching unit  410  according to the portable Internet DHCP message. 
         [0084]    The WLAN terminal  500  establishes a WLAN wireless link with the WLAN matching unit  430  of the interworking device  400  in step S 105 . The WLAN wireless link follows the WLAN communication protocol defined by IEEE 802.11, and the WLAN communication protocol does not support a handover operation. 
         [0085]    The WLAN authentication client  510  of the WLAN terminal  500  transmits a WLAN authentication message to the WLAN matching unit  430  of the to interworking device  400  through the WLAN wireless link in step S 107 . 
         [0086]    The WLAN authentication relay  455  of the interworking unit  450  performs a relay function in step S 109  so that the WLAN authentication message is transmitted to the WLAN authentication server  110  of the Internet  100 . In this case, the WLAN authentication relay  455  transmits the WLAN authentication message to the portable Internet matching unit  410  so that the WLAN authentication message is transmitted to the WLAN authentication server  110  of the Internet  100  through the portable Internet  200 . 
         [0087]    The portable Internet matching unit  410  of the interworking device  400  transmits the WLAN authentication message to the WLAN authentication server  110  of the Internet  100  through the portable Internet  200  in step S 111 . In this case, the interworking unit  450  may transmit the WLAN authentication message to the WLAN authentication server  110  through the portable Internet  200  in the portable Internet wireless link or the portable Internet data path. 
         [0088]    The WLAN authentication server  110  of the Internet  100  performs the authentication process according to the WLAN authentication message in step S 113 . In this case, the authentication process performed by the WLAN authentication server  110  may vary according to characteristics of the Internet  100 . 
         [0089]    When the authentication process is finished, the WLAN authentication server  110  of the Internet  100  transmits a WLAN authentication response message to the interworking device  400  in response to the WLAN authentication message in step S 115 . The WLAN authentication response message includes service grade information for the WLAN terminal  500 . In this case, the WLAN authentication server  110  may transmit the WLAN authentication response message to the interworking device  400  through the portable Internet  200  in the portable Internet wireless link or the portable Internet data path. 
         [0090]    When the portable Internet matching unit  410  of the interworking device  400  receives the WLAN authentication response message, the interworking unit  450  of the interworking device  400  establishes a WLAN data path between the WLAN terminal  500  and the WLAN matching unit  430  of the interworking device  400  in step S 117 . The WLAN data path follows the WLAN communication protocol defined by IEEE 802.11. In this case, the interworking unit  450  may establish the WLAN data path according to the service grade information for the WLAN terminal  500 . 
         [0091]    The interworking unit  450  of the interworking device  400  establishes a portable Internet link between the portable Internet  200  and the portable Internet matching unit  410 , and writes the portable Internet link information in the mapping table  419  of the portable Internet matching unit  410  in step S 119 . The portable Internet link follows the portable Internet communication protocol defined by IEEE 802.16. The interworking unit  450  may establish the portable Internet link by allocating a traffic parameter and a bandwidth of the portable Internet link based on the service grade information for the WLAN terminal  500 . The portable Internet link corresponds to the WLAN data path for the WLAN terminal  500 , and mapping information between the portable Internet link and the WLAN data path is stored in the mapping table  419  of the portable Internet matching unit  410 . 
         [0092]    When the portable Internet link is established to transmit IP traffic, the WLAN DHCP client  530  of the WLAN terminal  500  transmits the WLAN DHCP message to the WLAN matching unit  430  of the interworking device  400  through the WLAN data path in step S 121 . The WLAN DHCP message is used to request the network address for the WLAN terminal  500  from the WLAN DHCP server  130  of the Internet  100 . 
         [0093]    The WLAN DHCP relay  457  of the interworking unit  450  performs a relay function in step S 123  so that the WLAN DHCP message is transmitted to the WLAN DHCP server  130  of the Internet  100 . In this case, the WLAN DHCP relay  457  transmits the WLAN DHCP message to the portable Internet matching unit  410  so that the WLAN DHCP message is transmitted to the WLAN DHCP server  130  of the Internet  100  through the portable Internet  200 . 
         [0094]    The portable Internet matching unit  410  of the interworking device  400  transmits the WLAN DHCP message to the WLAN DHCP server  130  of the Internet  100  through the portable Internet  200  in step S 121 . In this case, the WLAN DHCP relay  457  of the interworking unit  450  may transmit the WLAN DHCP message to the WLAN DHCP server  130  of the Internet  100  through the portable Internet  200  in the portable Internet data path. In addition, the WLAN DHCP relay  457  may transmit the WLAN DHCP message to the WLAN DHCP server  130  through the portable Internet link, and in this case, the WLAN DHCP relay  457  may transmit the WLAN DHCP message through the portable Internet link corresponding to the WLAN terminal  500  by using the mapping table  419 . 
         [0095]    The WLAN DHCP server  130  of the Internet  100  allocates the network address of the WLAN terminal  500  according to the WLAN DHCP message in step S 123 . The WLAN DHCP server  130  may allocate the IP address corresponding to the network address. 
         [0096]    The WLAN DHCP server  130  of the Internet  100  transmits a WLAN DHCP response message corresponding to the WLAN DHCP message to the interworking device  400  through the portable Internet  200  in step S 125 . In this case, the WLAN DHCP response message includes the network address of the WLAN terminal  500  allocated by the WLAN DHCP server  130 . 
         [0097]    When the WLAN DHCP response message is received through the portable Internet matching unit  410 , the WLAN DHCP relay  457  of the interworking unit  450  performs the relay function in step S 127  so that the WLAN DHCP response message is transmitted to the WLAN terminal  500 . In this case, the WLAN DHCP relay  457  transmits the WLAN DHCP response message to the WLAN matching unit  430  so that the WLAN DHCP response message is transmitted to the WLAN terminal  500  through the WLAN data path. 
         [0098]    A data exchanging method of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention will be described with reference to  FIG. 8 . 
         [0099]      FIG. 8  is a flowchart representing the data exchanging method of the system for interworking the WLAN and the portable Internet according to the exemplary embodiment of the present invention. 
         [0100]    As shown in  FIG. 8 , when the data packet is transmitted to the Internet  100  of the WLAN terminal  500 , the IP application unit  550  of the WLAN terminal  500  transmits a WLAN data packet following a WLAN standard to the WLAN matching unit  430  of the interworking device  400  through the WLAN data path in step S 301 . In this case, the WLAN data packet includes a data link address or a network address of the WLAN terminal  500 . 
         [0101]    The interworking device  400  uses the mapping table  419  of the portable Internet matching unit  410  to establish the portable Internet link allocated for the WLAN terminal  500  as a data packet path in step S 303 . The interworking device  400  searches the mapping table  419  based on the data link address or the network address of the WLAN terminal  500 , and establishes the portable Internet link corresponding to the WLAN terminal  500  as the data packet path according to the mapping table  419 . 
         [0102]    The interworking device  400  converts a WLAN data packet type into a portable Internet type in step S 305 . The interworking device  400  converts the WLAN data packet into the portable Internet type so that the WLAN data packet passes through the portable Internet  200 . The interworking processing unit  437  of the WLAN matching unit  430  and the interworking processing unit  417  of the portable Internet matching unit  410  are interworked to convert the WLAN data packet into a portable Internet data packet following the portable Internet standard. 
         [0103]    In this case, when the IP relay  459  of the interworking unit  450  operates in a tunneling mode that provides a transparent data path from the interworking device  400  to the Internet  100 , the interworking device  400  may capsulate the data packet. 
         [0104]    In addition, when the IP relay  459  operates in a routing mode that determines a path, the interworking device  400  allows a header of the data packet to include the network address of the portable Internet  200  so that the data packet may be transmitted to the Internet  100  through the portable Internet  200 . 
         [0105]    Further, when the IP relay  459  operates in the routing mode, the interworking device  400  receives the network address of the WLAN matching unit  430  from the WLAN DHCP server  130  of the Internet  100 , and receives the network address of the portable Internet matching unit  410  from the portable Internet DHCP server  230  of the portable Internet  200 . The WLAN matching unit  430  and the portable Internet matching unit  410  respectively operate as routers, and the interworking device  400  has two interfaces. 
         [0106]    The IP relay  459  of the interworking unit  450  performs the relay function in step S 307  so that the portable Internet data packet is transmitted to the Internet  100 . The IP relay  459  controls the portable Internet matching unit  410  to transmit the portable Internet data packet to the Internet  100  through the portable Internet  200 . 
         [0107]    The interworking device  400  transmits the portable Internet data packet to the Internet  100  in step S 309 . The portable Internet matching unit  410  maps the portable Internet data packet into the portable Internet link allocated for the WLAN terminal  500  so that the portable Internet data packet is transmitted to the Internet  100  through the portable Internet  200  in the portable Internet link. Since it receives the portable Internet data packet, the Internet  100  receives the WLAN data packet transmitted from the WLAN terminal  500 . 
         [0108]    When the Internet  100  transmits the data packet to the WLAN terminal  500 , the Internet  100  transmits the data packet to the portable Internet  200  in step S 311 . In this case, the data packet includes the data link address or the network address of the WLAN terminal  500  that corresponds to a destination. 
         [0109]    The portable Internet  200  converts a type of the data packet in step S 313 . The portable Internet  200  generates the portable Internet data packet following the portable Internet standard by converting the type of the data packet to transmit the data packet through the portable Internet link. 
         [0110]    The portable Internet  200  transmits the portable Internet data packet to the portable Internet matching unit  410  of the interworking device  400  through the portable Internet link in step S 315 . The portable Internet  200  transmits the portable Internet data packet through the portable Internet link allocated for the WLAN terminal  500  corresponding to a destination of the data packet. In this case, the portable Internet  200  may include information of the WLAN terminal  500  and the portable Internet link. 
         [0111]    The interworking device  400  uses the mapping table of the portable Internet matching unit  410  to the map WLAN terminal  500  corresponding to the portable Internet link to which the portable Internet data packet is transmitted in step S 317 . 
         [0112]    The interworking device  400  converts a type of the portable Internet data packet into a type of the WLAN terminal in step S 319 . The interworking device  400  converts the portable Internet data packet into the WLAN type so that the portable Internet data packet is transmitted to the WLAN terminal  500  through the WLAN data path. The interworking processing unit  417  of the portable Internet matching unit  410  and the interworking processing unit  437  of the WLAN matching unit  430  are interworked to convert the portable Internet data packet into the WLAN data packet following the WLAN standard. 
         [0113]    The IP relay  459  of the interworking unit  450  performs the relay function in step S 321  so that the WLAN data packet is transmitted to the WLAN terminal  500 . The IP relay  459  controls the WLAN matching unit  430  to transmit the WLAN data packet to the WLAN terminal  500  through the WLAN data path. 
         [0114]    In step S 323  the interworking device  400  transmits the WLAN data packet to the WLAN terminal  500 . The WLAN matching unit  430  transmits the WLAN data packet to the WLAN terminal  500  corresponding to the portable Internet link. Since it receives the WLAN data packet, the WLAN terminal  500  receives the data packet transmitted from the Internet  100 . 
         [0115]    When the WLAN terminal  500  cancels the access, the WLAN terminal  500  releases the WLAN data path in step S 325 , and transmits a WLAN data path release message to the interworking device  400  through the WLAN wireless link in step S 327 . 
         [0116]    In step S 329 , the interworking device  400  releases the portable Internet link allocated for the WLAN terminal  500  according to the WLAN data path release message. 
         [0117]    Subsequently, the interworking device  400  modifies the mapping table  419  in step S 331 . The portable Internet matching unit  410  deletes the mapping information for the WLAN terminal  500  canceling the access from the mapping table  419 . 
         [0118]    In the exemplary embodiment of the present invention, the WLAN and the portable Internet are interworked, but it is not limited thereto. In addition, in another exemplary embodiment of the present invention, a network for supporting a handover and a network that does not support a handover may be interworked. 
         [0119]    The above-described methods and apparatuses are not only realized by the exemplary embodiment of the present invention, but, on the contrary, are intended to be realized by a program for realizing functions corresponding to the configuration of the exemplary embodiment of the present invention or a recording medium for recording the program. 
         [0120]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
         [0121]    As described above, according to the exemplary embodiment of the present invention, the WLAN terminal may receive a WLAN service by accessing the WLAN AP without any changes, and it may receive an Internet service in a moving state by using mobility of the portable Internet.