Abstract:
Disclosed is a method and apparatus for providing wireless access in a broadband wireless access system. The apparatus authenticates an access terminal when an access of the access terminal located in a first network employing a first predetermined access scheme is detected, allocates a private Internet Protocol (IP) address to the authenticated access terminal, translates the private IP address into a public IP address when an access of the access terminal through the private IP address is detected, and controls that the access terminal accesses a second network employing a second predetermined access scheme through the public IP address.

Description:
PRIORITY 
   This application claims the benefit under 35 U.S.C. §119(a) of an application entitled “Apparatus And Method For Providing Indoor And Outdoor Wireless Access In Broadband Wireless Access Communication System” filed in the Korean Intellectual Property Office on Oct. 7, 2004 and assigned Serial No. 2004-79891, the contents of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a wireless access apparatus and method in a broadband wireless access (BWA) communication system, and more particularly to an apparatus and method for providing indoor local-area and outdoor wide-area wireless access. 
   2. Description of the Related Art 
   A wireless access communication system includes an access point (AP) in order to provide a wireless service. The access point wirelessly communicates with access terminals (ATs) so that access terminals located in a service coverage area of the access point can transmit and receive signals and connect to an external network. 
   Hereinafter, the configuration of a wireless fidelity (WiFi) system will be described with reference to  FIG. 1  as an example of a wireless local area network (WLAN) system using an access point. 
     FIG. 1  is a block diagram schematically illustrating the configuration of a typical WiFi system. 
   A WiFi indoor network area  100 , which is a WiFi area, includes an indoor network access terminal  115  and a WiFi access point  110 . The WiFi access point  110  serves as a WLAN hub or bridge in the WiFi indoor network area  100 . In addition, the WiFi access point  110  connected to an external network  120  operates as a WiFi bridge or router to connect the external network  120  and the WiFi indoor network area  100 . 
   Generally, it is assumed that the WiFi access point  110  and the external network  120  are typically connected using a hard-wired connection. That is, there is a limitation in that the WiFi access point  110  providing only indoor local-area access wirelessly must be connected to a cable network providing outdoor wide-area access. 
   Recently, however, a broadband wireless access communication system, e.g., a Mobile Worldwide Interoperability for Microwave Access (WiMAX) system, capable of providing outdoor wide-area access as well as indoor local-area access, has been proposed. The Mobile WiMAX system can provide very-high-speed internet access at a low price without regard to time and location. For example, the Mobile WiMAX system can provide a very-high-speed Internet service to a laptop, a personal digital assistant (PDA) and the like which is located in a subway train traveling underground at 60 Km/hr. 
   Therefore, the development of a new wireless access method capable of providing not only wireless access in an indoor local area but also connection to an outdoor external network is desired. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a wireless access apparatus and method capable of providing outdoor wide-area wireless access as well as indoor local-area wireless access. 
   To accomplish this object, in accordance with one aspect of the present invention, there is provided an apparatus for providing wireless access in a broadband wireless access system which includes a first network employing a first predetermined access scheme and a second network employing a second predetermined access scheme, the apparatus including: a bridge for authenticating an access terminal when an access of the access terminal located in the first network is detected, allocating a private Internet Protocol (IP) address to the authenticated access terminal, translating the private IP address into a public IP address when an access of the access terminal through the private IP address is detected, and controlling that the access terminal accesses the second network through the public IP address. 
   In accordance with another aspect of the present invention, there is provided an apparatus for providing wireless access in a broadband wireless access system which includes a first network employing a first predetermined access scheme and a second network employing a second predetermined access scheme, the apparatus including: a bridge for controlling that an access terminal is authenticated by relaying between the access terminal and the second network when an access of the access terminal located in the first network is detected, controlling that the access terminal is allocated with a public Internet Protocol (IP) address from the second network by relaying between the authenticated access terminal and the second network, and switching the public IP address to enable the access terminal to access the second network when an access of the access terminal through the public IP address is detected. 
   In accordance with still another aspect of the present invention, there is provided a method for providing wireless access in a broadband wireless access system, the method including: authenticating an access terminal when an access of the access terminal located in a first network employing a first predetermined access scheme is detected; allocating a private Internet Protocol (IP) address to the authenticated access terminal; and translating the private IP address into a public IP address when an access of the access terminal through the private IP address is detected, and controlling that the access terminal accesses a second network employing a second predetermined access scheme through the public IP address. 
   In accordance with still another aspect of the present invention, there is provided a method for providing wireless access in a broadband wireless access system, the method including: controlling that an access terminal is authenticated by relaying between the access terminal and a second network employing a second predetermined access scheme, when an access of the access terminal located in a first network employing a first predetermined access scheme is detected; controlling that the access terminal is allocated with a public Internet Protocol (IP) address from the second network by relaying between the authenticated access terminal and the second network; and switching the public IP address to enable the access terminal to access the second network when an access of the access terminal through the public IP address is detected. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a block diagram schematically illustrating the configuration of a typical WiFi system; 
       FIG. 2  is a block diagram schematically illustrating a configuration of an indoor network and an outdoor network connected to each other using a Mobile WiMAX bridge according to an embodiment of the present invention; 
       FIG. 3  is a block diagram schematically illustrating the internal configuration of the Mobile WiMAX bridge shown in  FIG. 2 ; 
       FIG. 4  is a flow diagram illustrating the wireless access service operation of the Mobile WiMAX bridge shown in  FIG. 2  when a WiFi indoor private network is provided; 
       FIG. 5  is a flow diagram illustrating the wireless access service operation of the Mobile WiMAX bridge shown in  FIG. 2  when a WiFi indoor public network is provided; 
       FIG. 6  is a flow chart illustrating operational steps for providing QoS by the Mobile WiMAX bridge shown in  FIG. 2  according to an embodiment of the present invention; 
       FIG. 7  is a signal flow diagram explaining the wireless access service operation of the Mobile WiMAX bridge shown in  FIG. 2  when a Mobile WiMAX indoor private network is provided; 
       FIG. 8  is a flow diagram illustrating the wireless access service operation of the Mobile WiMAX bridge shown in  FIG. 2  when a Mobile WiMAX indoor public network is provided; and 
       FIG. 9  is a flow chart illustrating operational steps for providing QoS by the Mobile WiMAX bridge shown in  FIG. 2  according to another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Hereinafter, one preferred embodiment according to the present invention will be described with reference to the accompanying drawings. It is to be noted that the same elements are indicated with the same reference numerals throughout the drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention. 
   The present invention proposes a wireless access apparatus and method in a broadband wireless access (BWA) communication system, such as a Mobile Worldwide Interoperability for Microwave Access (WiMAX) system. Particularly, the present invention discloses an apparatus and method for providing indoor local-area and outdoor wide-area wireless access in a Mobile WiMAX system. That is, the present invention proposes a Mobile WiMAX bridge apparatus which serves as an access point (AP) of a wireless local area network (WLAN) (e.g., a wireless fidelity (WiFi) system or Mobile WiMAX system) for an indoor network and which simultaneously serves as an access point (AP) of a Mobile WiMAX system for an outdoor network, and a method for the same. Although the Mobile WiMAX system is described herein as an example of the broadband wireless access communication system, it is obvious that the present invention can be applied to the other communication systems as well as the Mobile WiMAX system. 
     FIG. 2  is a block diagram schematically illustrating a configuration of an indoor network and an outdoor network connected to each other using a Mobile WiMAX bridge according to an embodiment of the present invention. 
   An indoor network area  200  includes an indoor network access terminal (AT)  205  and a Mobile WiMAX bridge  230 . A Mobile WiMAX outdoor network area  210  includes a Mobile WiMAX access point  215 , which can wirelessly access the Mobile WiMAX bridge  230 . Herein, the Mobile WiMAX bridge  230  serves as an access point to be used for Mobile WiMAX access, and can be allocated with an outdoor network Internet Protocol (IP) of the Mobile WiMAX bridge  230  itself, according to necessity. It should be noted that the term “indoor network” for the sake of clarity has been used to denote a corresponding part of Mobile WiMAX network and does not have to be located “indoors”. Similarly, the term Mobile WiMAX Outdoor Network denotes a corresponding part of a Mobile WiMAX Network which can be used indoors or out. 
   The internal configuration of the Mobile WiMAX bridge  230  will now be described with reference to  FIG. 3 . 
     FIG. 3  is a block diagram schematically illustrating the internal configuration of the Mobile WiMAX bridge  230  shown in  FIG. 2 . 
   The Mobile WiMAX bridge  230  includes an indoor network processing unit  310  in charge of WiFi access and Mobile WiMAX access for an indoor network, an outdoor network processing unit  320  in charge of Mobile WiMAX access for an outdoor network, and a bridge logic unit  330  for connecting the indoor network processing unit  310  with the outdoor network processing unit  320 . 
   The indoor network processing unit  310  serves as an indoor low-power WiFi/Mobile WiMAX access point in a licensed/unlicensed MiFi/Mobile WiMAX frequency band to access ATs such as personal computers (PCs), personal digital assistants (PDAs), VoIP phones, wireless phones, and other like devices. The indoor network processing unit  310  may be installed in areas such as small office(s)/home office(s), (SOHOs), large office trains, buses, taxis, airplanes, and cars, commercial spaces such as malls, factories, stores, restaurants, etc., and other areas as desired. 
   In order to achieve WiFi access, the indoor network processing unit  310  provides a service corresponding to that provided in a WLAN system such as the conventional WiFi systems and provides a service corresponding to that provided in a Mobile WiMAX system. 
   The outdoor network processing unit  320  provides an outdoor high-power Mobile WiMAX access terminal&#39;s function of accessing an outdoor network by using a licensed Mobile WiMAX frequency band. 
   The bridge logic unit  330  connects the indoor network processing unit  310  and the outdoor network processing unit  320  to each other, and basically performs a layer 2 or 3 (L2/L3) function representing a medium access control (MAC) layer or an IP layer, a switch function, a security relevant function such as authentication and/or encryption, and a function relating to Quality of Service (QoS). 
   The bridge logic unit  330  performs different operations depending on whether the indoor network is a WiFi network, or is a Mobile WiMAX network, or is allocated with an IP address different from that of an outdoor network to form a private network independent of the outdoor network, or is a public network allocated with an IP address from an exterior. The operations of the bridge logic unit  330  performed for the above cases are shown in Table 1 below. 
   
     
       
             
             
           
             
             
             
           
         
             
               TABLE 1 
             
             
                 
             
             
               Indoor Network 
               Operations of bridge logic unit 330 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               WiFi 
               private 
               Dynamic Host Configuration Protocol (DHCP) 
             
             
                 
               network 
               server/Network Address Translation (NAT) 
             
             
                 
                 
               functions, Correspond to WiFi QoS Mobile WiMAX 
             
             
                 
               public 
               Correspond to WiFi authentication Mobile WiMAX, 
             
             
                 
               network 
               Correspond to WiFi QoS Mobile WiMAX 
             
             
               Mobile 
               private 
               DHCP server/NAT functions, Correspond to 
             
             
               WiMAX 
               network 
               connection of indoor/outdoor network 
             
             
                 
               public 
               Mobile WiMAX authentication relay, Correspond 
             
             
                 
               network 
               to connection of indoor/outdoor network 
             
             
                 
             
           
        
       
     
   
   Referring to Table 1, when a private network address is allocated for indoor network access and a network is configured independently of an external network, that is, when the indoor network is a private network, user authentication for the indoor network access terminal  205  is omitted or is completed by authentication for the Mobile WiMAX bridge  230 . In this case, the Mobile WiMAX bridge  230  provides both of a DHCP server function and a NAT function. 
   Meanwhile, when the indoor network access terminal  205  is allocated with an IP address provided from an external network and receives authentication through the external network, that is, when the indoor network is a public network, the Mobile WiMAX bridge  230  transmits authentication and DHCP information transmitted from the indoor network access terminal  205  to the external network. 
   Hereinafter, wireless access service methods of the Mobile WiMAX bridge  230  in relation to the four cases shown in Table 1 will be described in detail. 
   1. Indoor Network Constructed with WiFi Network
         1-1. WiFi Indoor Private Network       

     FIG. 4  is a signal flow diagram illustrating the wireless access service operation of the Mobile WiMAX bridge  230  shown in  FIG. 2  when a WiFi indoor private network is provided. 
   In step  410 , the indoor network access terminal  205  accesses the WiFi network by using synchronization information transmitted from the Mobile WiMAX bridge  230 . In step  420 , an authentication procedure between the indoor network access terminal  205  and the Mobile WiMAX bridge  230  is performed, which may be omitted, and then an association procedure is performed therebetween in step  430 . In step  440 , the indoor network access terminal  205  acquires a private IP address and required network configuration information through a DHCP from the Mobile WiMAX bridge  230 . After this, when the indoor network access terminal  205  attempts to access an outdoor network through the Mobile WiMAX bridge  230  by means of the private IP address in step  450 , the Mobile WiMAX bridge  230  performs a NAT function for translating the private IP address into a public IP address in step  460 , and then performs access to the outdoor network  240  by using the translated public IP address in step  470 . Herein, it is assumed that the Mobile WiMAX bridge  230  has performed an authentication procedure with respect to the outdoor network  240 , and has been allocated with a public IP address in advance. 
   The operation of the above-mentioned Mobile WiMAX bridge  230  will now be described using a detailed example. 
   First, it is assumed that the Mobile WiMAX bridge  230  performs authentication of the outdoor network  240  in advance and then has been allocated with a public IP address such as, for example, 163.213.100.100. In this case, when the indoor network access terminal  205  requests allocation of a private IP address, the Mobile WiMAX bridge  230  allocates a private IP address (e.g., 192.168.10.10) to the indoor network access terminal  205  through a DHCP procedure. When an application program of the indoor network access terminal  205  generates a TCP/IP traffic packet from source port (e.g. 10000) to external server (e.g., 148.222.123.123) for port #80, the Mobile WiMAX bridge  230  performs a NAT function with respect to this TCP/IP traffic packet, translates it into source IP address 163.213.100.100 and source port 20000, and transmits the translated result to the external network. This may be simply expressed as shown in Table 2 below. 
   
     
       
             
             
             
           
             
             
             
             
             
           
         
             
               TABLE 2 
             
           
           
             
                 
             
             
                 
               Indoor network TCP/IP packet 
               Outdoor network TCP/IP packet 
             
           
        
         
             
                 
               Source 
               Destination 
               Source 
               Destination 
             
             
                 
             
             
               Address 
               192.168.10.10 
               148.222.123.123 
               163.213.100.100 
               148.222.123.123 
             
             
               Port number 
               10000 
               80 
               20000 
               80 
             
             
               number 
             
             
                 
             
           
        
       
     
   
   Similarly, in a case of a packet of the external network targeting the IP address and port, the Mobile WiMAX bridge  230  translates the target IP address and port into the IP address and port of the indoor network access terminal  205  and transmits the packet to the indoor network access terminal  205 . This also may be simply expressed as shown in Table 3 below. 
   
     
       
             
             
             
           
             
             
             
             
             
           
         
             
               TABLE 3 
             
           
           
             
                 
             
             
                 
               Outdoor network TCP/IP packet 
               Indoor network TCP/IP packet 
             
           
        
         
             
                 
               Source 
               Destination 
               Source 
               Destination 
             
             
                 
             
             
               Address 
               148.222.123.123 
               163.213.100.100 
               148.222.123.123 
               192.168.10.10 
             
             
               Port 
               10000 
               80 
               20000 
               80 
             
             
               number 
             
             
                 
             
           
        
       
     
       
       
         
           1-2. WiFi Indoor Public Network 
         
       
     
  
     FIG. 5  is a flow diagram illustrating the wireless access service operation of the Mobile WiMAX bridge  230 , shown in  FIG. 2 , when a WiFi indoor public network is provided. 
   In step  510 , the indoor network access terminal  205  accesses the WiFi network by using synchronization information transmitted from the Mobile WiMAX bridge  230 . An authentication procedure between the indoor network access terminal  205  and the Mobile WiMAX bridge  230  is performed in step  520 , and the Mobile WiMAX bridge  230  performs a relay function to transmit a message relating to the authentication procedure between the indoor network access terminal  205  and an outdoor network in step  523 . Since a WiFi authentication message has a different format from a Mobile WiMAX authentication message, the Mobile WiMAX bridge  230  performs only the function of transmitting a corresponding message to the outdoor network by using a general traffic connection identifier (CID). In step  526 , an authentication procedure between the Mobile WiMAX bridge  230  and the outdoor network  240  is performed. 
   In step  530 , an association procedure is performed between the indoor network access terminal  205  and the Mobile WiMAX bridge  230 . In steps  540  to  546 , the indoor network access terminal  205  acquires a public IP address and required network configuration information through a DHCP from the outdoor network  240 . In this case, the Mobile WiMAX bridge  230  performs the function of relaying messages. After this, when the indoor network access terminal  205  attempts to access an outdoor network through the Mobile WiMAX bridge  230  by means of the public IP address in step  550 , the Mobile WiMAX bridge  230  performs a L2/L3 switch function in step  553 , and then performs access to an outdoor network  240  by using the public IP address in step  556 . In this case, it is also assumed that the Mobile WiMAX bridge  230  has performed an access and authentication procedure with respect to the outdoor network  240 , and has been allocated with a public IP address in advance before the indoor network access terminal  205  accesses the Mobile WiMAX bridge  230 . 
   Meanwhile, the Mobile WiMAX bridge  230  distinguishes the types of QoS using a user priority field in a WiFi layer of the indoor network with respect to signals transmitted from an access terminal. To this end, the Mobile WiMAX bridge  230  utilizes existing connections of the Mobile WiMAX of the outdoor network, or establishes a specific Mobile WiMAX connection for the outdoor network. For instance, when a flow shows that a user priority value is directed to a minimum time delay, the Mobile WiMAX bridge  230  establishes a specific Mobile WiMAX connection for each user, thereby ensuring the delay time to be set within a predetermined interval. 
   The operation for providing QoS by the Mobile WiMAX bridge  230  will now be described with reference to  FIG. 6 . 
     FIG. 6  is a flow chart illustrating operational steps for providing QoS by the Mobile WiMAX bridge  230  shown in  FIG. 2  according to an embodiment of the present invention. 
   When a WiFi frame arrives at the Mobile WiMAX bridge  230  in step  610 , the Mobile WiMAX bridge  230  determines if the WiFi frame includes an outdoor network CID corresponding to a MAC/user priority in step  620 . When it is determined in step  620  that the WiFi frame includes an outdoor network CID corresponding to a MAC/user priority, the Mobile WiMAX bridge  230  utilizes an existing Mobile WiMAX connection in step  630 . 
   In contrast, if it is determined in step  620  that the WiFi frame does not include an outdoor network CID corresponding to a MAC/user priority, the Mobile WiMAX bridge  230  determines if the WiFi frame is traffic sensitive to a user priority delay in step  640 . If it is determined in step  640  that the WiFi frame is the traffic sensitive to a user priority delay, the Mobile WiMAX bridge  230  establishes a new Mobile WiMAX connection and matches a MAC/user priority with a new CID in step  650 . In contrast, If it is determined in step  640  that the WiFi frame is not traffic sensitive to a user priority delay, the Mobile WiMAX bridge  230  transmits the WiFi frame through the best effort (BE) connection of the Mobile WiMAX bridge  230  in step  660 . 
   In brief, the Mobile WiMAX bridge determines if it is necessary to set a separate connection with respect to a user priority field. When it is necessary to set the separate connection, the Mobile WiMAX bridge establishes a separate connection for each indoor network access terminal, matches the user priority of the access terminal with a corresponding CID, and maintains the matching status. In contrast, with respect to a typical best effort (BE) traffic, the Mobile WiMAX bridge may transmit the BE traffic through an outdoor network Mobile WiMAX connection without distinction of access terminals in order to provide the corresponding service, or may transmit the BE traffic through a separate Mobile WiMAX connection for each access terminal. 
   The correspondence relation between user priorities and Mobile WiMAX connections are shown in Table 4 below. 
   
     
       
             
             
             
             
           
         
             
               TABLE 4 
             
             
                 
             
             
               User 
                 
                 
               Mobile WiMAX 
             
             
               Priority 
               Meaning 
               Class # 
               Connection 
             
             
                 
             
           
           
             
               111 
               Network Critical 
               Class 7 
               Delay 10 ms security 
             
             
                 
               (Network Control) 
                 
               Connection 
             
             
               110 
               Interactive Voice (&lt;10 ms del) 
               Class 6 
             
             
               101 
               Interactive Multimedia 
               Class 5 
               Delay 100 ms security 
             
             
                 
               (&lt;100 ms del) 
                 
               Connection 
             
             
               100 
               Stream Multimedia 
               Class 4 
             
             
                 
               (Controlled load) 
             
             
               011 
               Business Critical 
               Class 3 
             
             
                 
               (Excellent Effort) 
             
             
               010 
               Standard (Spare) T 
               Class 2 
               Best effort (BE) 
             
             
               001 
               Background 
               Class 1 
               Connection 
             
             
               000 
               Best Effort (Default) 
               Class 0 
             
             
                 
             
           
        
       
     
   
   In Table 4, with respect to the traffic having the user priority of “111” or “110”, a separate connection for securing a time delay of 10 ms is established and the traffic is mapped with the separate connection. With respect to the traffic having the user priority of “101”, “100” or “011”, a separate connection for securing a time delay of 100 ms is established and the traffic is mapped with the separate connection. With respect to the traffic having the user priority of “010”, “001” or “000”, a separate connection is not established and an existing BE connection is utilized to form a correspondence relation. 
   2. Indoor Network Constructed with Mobile WiMAX
         2-1. Mobile WiMAX Indoor Private Network       

     FIG. 7  is a signal flow diagram illustrating the wireless access service operation of the Mobile WiMAX bridge  230  shown in  FIG. 2  when a Mobile WiMAX indoor private network is provided. 
   In step  710 , the indoor network access terminal  205  performs an initial ranging corresponding to indoor network Mobile WiMAX information transmitted from the Mobile WiMAX bridge  230 , and performs association in relation to a basic function. The indoor network access terminal  205  and the Mobile WiMAX bridge  230  perform respective authentication and registration procedures in steps  720  and  730 , and creates a DHCP in step  740 , so that the indoor network access terminal  205  acquires an IP address and required network configuration information from the Mobile WiMAX bridge  230 . Then, the indoor network access terminal  205  attempts to access an outdoor network through the Mobile WiMAX bridge  230  by means of the private IP address in step  750 , and the Mobile WiMAX bridge  230  performs a NAT function for translating the private IP address into a public IP address in step  760 . After that, the Mobile WiMAX bridge  230  accesses the outdoor network  240  by using the translated public IP address in step  770 . In this case, it is also assumed that the Mobile WiMAX bridge  230  has performed an access and authentication procedure with respect to the outdoor network  240  and has been allocated with a public IP address before the indoor network access terminal  205  accesses the Mobile WiMAX bridge  230 . 
     FIG. 8  is a flow diagram illustrating the wireless access service operation of the Mobile WiMAX bridge  230  shown in  FIG. 2  when a Mobile WiMAX indoor public network is provided. 
   In step  810 , the indoor network access terminal  205  performs an initial ranging for an indoor network and performs association in relation to a basic function in step  810 , and then performs an authentication procedure in step  820 . In this case, the Mobile WiMAX bridge  230  transmits messages relating to the authentication procedure to relay message between the indoor network access terminal  205  and the outdoor network  240 . In this case, a private key management (PKM) message is used for the Mobile WiMAX authentication. The Mobile WiMAX bridge  230  processes a PKM message transmitted from the indoor network access terminal  205 , and relays an authentication procedure between an authentication server (not shown) and the indoor network access terminal  205  through a Mobile WiMAX outdoor network. The PKM message is transmitted through a basic CID, but the Mobile WiMAX bridge  230  does not use the basic CID for an outdoor network when transmitting the PKM message to the outdoor network. Since the basic CID for the outdoor network has already been used for the authentication of the Mobile WiMAX bridge  230  itself, the basic CID for the outdoor network cannot be used for the authentication of the indoor network access terminal  205 . Also, an authentication procedure with respect to the outdoor network is performed to transmit a protocol message such as remote authentication dial-in user services (RADIUS) message or a Diameter message to an authentication server, so it is still unnecessary to use the basic CID. In order to achieve such processing, the Mobile WiMAX bridge  230  establishes a separate connection, which maintains security and decreases a delay, to use a CID of a corresponding connection. 
   After performing the authentication procedure as described above, the indoor network access terminal  205  performs a registration procedure with respect to the Mobile WiMAX bridge  230  in step  830 . 
   In steps  840  to  846 , the indoor network access terminal  205  acquires a public IP address and required network configuration information through a DHCP from the outdoor network  240 . In this case, the Mobile WiMAX bridge  230  performs the function of relaying messages. After this, when the indoor network access terminal  205  attempts to access an outdoor network through the Mobile WiMAX bridge  230  by means of the public IP address in step  850 , the Mobile WiMAX bridge  230  performs a L2/L3 switch function in step  853 , and then performs access to an outdoor network  240  by using the public IP address in step  856 . In this case, it is also assumed that the Mobile WiMAX bridge  230  has performed an access and authentication procedure with respect to the outdoor network  240  and the Mobile WiMAX bridge  230  has been allocated with the public IP address before the indoor network access terminal  205  accesses the Mobile WiMAX bridge  230 . 
   Meanwhile, when an indoor network access terminal requests a Mobile WiMAX connection of the indoor network for QoS security, the Mobile WiMAX bridge  230  may utilize one of the existing Mobile WiMAX connections of the outdoor network, or may establish a separate Mobile WiMAX connection for the outdoor network. For instance, with respect to a connection set-up request defined to minimize a delay time, the Mobile WiMAX bridge  230  may set a separate Mobile WiMAX connection for each indoor network access terminal to allow a delay time to be set within a range of a predetermined interval. 
     FIG. 9  is a flow chart illustrating operational steps for providing QoS by the Mobile WiMAX bridge  230  shown in  FIG. 2 , according to an embodiment of the present invention. 
   When a WiFi frame arrives at the Mobile WiMAX bridge  230  in step  910 , the Mobile WiMAX bridge  230  determines if the WiFi frame includes an outdoor network CID corresponding to an indoor network CID in step  920 . If it is determined in step  920  that the WiFi frame includes an outdoor network CID corresponding to an indoor network CID, the Mobile WiMAX bridge  230  transmits the WiFi frame through an existing Mobile WiMAX connection in step  930 . 
   In contrast, if it is determined in step  920  that the WiFi frame does not include an outdoor network CID corresponding to an indoor network CID, the Mobile WiMAX bridge  230  determines if the CID is qualified for a delay sensitive traffic in step  940 . If it is determined in step  940  that the CID is qualified for a delay sensitive traffic, the Mobile WiMAX bridge  230  sets a new outdoor network Mobile WiMAX connection and adds a new outdoor network CID as a CID for a delay sensitive traffic in step  950 . In contrast, if it is determined in step  940  that the CID is not qualified for a delay sensitive traffic, the Mobile WiMAX bridge  230  transmits the WiFi frame through the Mobile WiMAX BE connection in step  960 . 
   In brief, the Mobile WiMAX bridge determines if it is necessary to establish a separate connection in relation to a user priority field. When it is necessary to set the separate connection, the Mobile WiMAX bridge establishes a separate connection for each indoor network access terminal, matches a relevant CID with the user priority of the indoor network access terminal, and maintains the matching status. In contrast, with respect to a typical BE traffic, the Mobile WiMAX bridge may transmit the BE traffic through an outdoor network Mobile WiMAX connection without distinction of indoor network access terminals in order to provide the corresponding service, or may transmit the BE traffic through a separate Mobile WiMAX connection for each indoor network access terminal. 
   In other words, with respect to an indoor network Mobile WiMAX access having specific QoS requirements, the Mobile WiMAX bridge determines if it is necessary to establish the separate outdoor network Mobile WiMAX connection. When it is necessary to establish a separate connection, the Mobile WiMAX bridge establishes the separate connection for each indoor network access terminal, and matches the corresponding outdoor network CID with the indoor network CID of a corresponding indoor network access terminal, and maintains the matching status. In contrast, with respect to a flow transmitted through an indoor network CID for a typical BE traffic, the Mobile WiMAX bridge may transmit the flow to an external network through one outdoor network Mobile WiMAX connection without distinction of indoor network access terminals, or may transmit the flow through a separate Mobile WiMAX connection for each indoor network access terminal. 
   As described above, the present invention provides a method for providing a WiFi or Mobile WiMAX access point for an indoor network through an outdoor Mobile WiMAX network regardless of whether an outdoor cable network has been installed. According to the present invention, a user can easily access a WiFi or Mobile WiMAX indoor network wherever an outdoor network Mobile WiMAX connection is provided. 
   While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the scope of the invention is not to be limited by the above embodiments but by the claims and the equivalents thereof.