Method and system for WiBro network interworking in wireless terminal

Abstract

A method and system for WiBro network interworking in a wireless terminal. The method includes: setting up, by a relay station for connecting the WLAN terminal with the WiBro network, a connection through an initial process with the WiBro network; performing, by an access router, Internet connection authentication on a user of the WLAN terminal in response to a request for Internet connection from the WLAN terminal; allocating, by the access router, an IP address in response to a request for IP address allocation from the WLAN terminal, and then allocating, by a WiBro radio access station, a unique Connection IDentification (CID) corresponding to a QoS level of the terminal user in response to a request from the relay station; and mapping, by the relay station, the allocated unique CID to the IP address of the WLAN terminal and providing Internet service.

Claims

1. A method for wireless broadband (WiBro) network interworking to a wireless local area network (WLAN) terminal by a relay station configured to connect the WLAN terminal to a WiBro network, the method comprising: setting up a connection through an initial process with the WiBro network; receiving an allocated Internet Protocol (IP) address to the WLAN terminal; receiving an allocated unique Connection IDentification (CID) corresponding to a Quality of Service (QoS) level of the WLAN terminal, the allocated unique CID allocated after allocation of an IP address to the WLAN terminal; mapping the allocated unique CID to the WLAN terminal to facilitate provisioning of Internet service to the WLAN terminal via a unique virtual link identified by the unique CID; and transmitting a notification of the allocated IP address to the WLAN terminal, wherein mapping the allocated unique CID to the WLAN terminal to facilitate provisioning of Internet service to the WLAN terminal via a unique virtual link identified by the unique CID comprises: creating a new port identifier by port mapping between a source port of an application flow forwarded from the WLAN terminal and a source port of the unique virtual link identified by the unique CID; creating a mapping table comprising port mapping information between the newly created port identifier and the source port of the unique virtual link identified by the unique CID; and determining a destination port of the application flow forwarded from the WLAN terminal by port mapping between a destination port of a second packet received from a web server and the source port of the unique virtual link identified by the unique CID mapped to the destination port of the application flow.

2. The method of claim 1, wherein the IP address comprises an IP version 6 (IPv6) or public IP version 4 (IPv4) address allocated in accordance with a dynamic host configuration protocol (DHCP).

3. The method of claim 1, wherein the unique CID is identified by a source IP, a destination IP, a source port, a destination port, and a security key.

4. The method of claim 1, wherein mapping the allocated unique CID to the WLAN terminal to facilitate provisioning of Internet service to the WLAN terminal via a unique virtual link identified by the unique CID further comprises: translating the source port of the application flow into the newly created port identifier, and transmitting a first packet comprising the translated port to the web server comprising a destination port, the first packet being associated with the application flow; and translating the destination port of the second packet received from the web server into the determined destination port and transmitting the second packet comprising the translated port to an application process of the WLAN terminal.

5. The method of claim 1, wherein creating a new port identifier by port mapping between a source port of an application flow forwarded from the WLAN terminal and a source port of the unique virtual link identified by the unique CID comprises performing port mapping through an exclusive OR operation of the source port of the application flow and the source port of the unique virtual link identified by the unique CID.

6. The method of claim 1, wherein determining a destination port of the application flow forwarded from the WLAN terminal by port mapping between a destination port of a second packet received from the web server and the source port of the unique virtual link identify by the unique CID mapped to the destination port of the second packet comprises performing port mapping through an exclusive OR operation of the destination port of the second packet received from the web server and the source port of the unique virtual link identified by the unique CID mapped to the destination port of the application flow.

7. A relay station for wireless broadband (WiBro) network interworking to a wireless local area network (WLAN) terminal, wherein the relay station is configured to: set up a connection through an initial process with the WiBro network; receive an allocated Internet Protocol (IP) address to the WLAN terminal; receive an allocated unique Connection IDentification (CID) corresponding to a Quality of Service (QoS) level of the WLAN terminal, the allocated unique CID allocated after allocation of an IP address to the WLAN terminal; map the allocated unique CID to the WLAN terminal to facilitate provisioning of Internet service to the WLAN terminal via a unique virtual link identified by the unique CID; and transmit a notification of the allocated IP address to the WLAN terminal, wherein mapping the allocated unique CID to the WLAN terminal to facilitate provisioning of Internet service to the WLAN terminal via a unique virtual link identified by the unique CID comprises: creating a new port identifier by port mapping between a source port of an application flow forwarded from the WLAN terminal and a source port of the unique virtual link identified by the unique CID; creating a mapping table comprising port mapping information between the newly created port identifier and the source port of the unique virtual link identified by the unique CID; and determining a destination port of the application flow forwarded from the WLAN terminal by port mapping between a destination port of a second packet received from a web server and the source port of the unique virtual link identified by the unique CID mapped to the destination port of the application flow.

8. The relay station of claim 7, the relay station comprising: a WiBro connection manager to perform a WiBro initial process with a WiBro radio access station; a WLAN host access point (AP) to authorize association with the WLAN terminal in response to reception of a request for WiBro network connection from the WLAN terminal; a WiBro interworking setup manager to set up, in response to successful user authentication by the WLAN host AP, the WiBro network connection according to an Internet Protocol (IP) network formed between the WLAN terminal and the relay station; and a mapper to map, in response to successful set up of the WiBro network connection by the WiBro interworking setup manager, the unique CID allocated by the WiBro radio access station to the node ID of the WLAN terminal.

9. The relay station of claim 8, wherein: the IP network formed between the WLAN terminal and the relay station is an IP version 4 (IPv4) network using a private address as the second IP address; and the WiBro interworking setup manager is configured to: create a new port identifier by port mapping between a source port of an application flow forwarded from the WLAN terminal and a source port of the unique virtual link identified by the unique CID; and transmit and receive packets via utilization of a mapping table comprising port mapping information between the newly created port identifier and the source port of the unique virtual link identified by the unique CID.

10. The relay station of claim 7, wherein the relay station is further configured to: translate the source port of the application flow into the newly created port identifier and transmit a first packet comprising the translated port to the web server comprising a destination port, the first packet being associated with the application flow; and translate the destination port of the second packet received from the web server into the determined destination port and transmit the second packet comprising the translated port to an application process of the WLAN terminal.

11. The relay station of claim 7, wherein the IP address comprises an IP version 6 (IPv6) or public IP version 4 (IPv4) address allocated in accordance with a dynamic host configuration protocol (DHCP).

12. The relay station of claim 7, wherein the unique CID is identified by a source IP, a destination IP, a source port, a destination port, and a security key.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which like reference symbols indicate the same or similar components, wherein:

(2) FIG. 1 illustrates a UMTS-WLAN Interworking architecture using Network Address Translation (NAT);

(3) FIG. 2 illustrates a traffic flow in FIG. 1;

(4) FIG. 3 illustrates a BWA-UMA (Broadband Wireless Access—Unlicensed Mobile Access) Interworking architecture according to the present invention;

(5) FIG. 4 illustrates a traffic flow in FIG. 3;

(6) FIG. 5 illustrates a configuration of a relay station (RS) for BWA-UMA interworking in FIG. 3;

(7) FIG. 6 illustrates a BWA-UMA relay station connection setup sequence upon using an IPv6 and public IPv4 network according to the present invention;

(8) FIG. 7 illustrates a BWA-UMA relay station connection setup sequence upon using a private IPv4 network according to the present invention;

(9) FIG. 8 illustrates an exemplary embodiment of translation performed on only an IP address when source and destination ports given to each application of a plurality of WLAN terminals are the same as in a case where NAT is used;

(10) FIG. 9 illustrates an exemplary embodiment of translation between an IP address and a port number when a single WLAN terminal uses three different source ports with respect to one destination port for communication in a case where NAT is used; and

(11) FIG. 10 illustrates port translation using an exclusive OR (XOR) operator according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(12) Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily carry out the present invention.

(13) FIG. 1 illustrates a UMTS-WLAN Interworking architecture using Network Address Translation (NAT), and FIG. 2 illustrates a traffic flow in FIG. 1.

(14) Referring to FIG. 1, Internet service may be provided to users of a plurality of WiFi terminals 10a, 10b, and 10c via a Network Address Translation (NAT)-based wireless Access Point (AP) 30, which is in wireless communication with a WiBro base station (BS) 20.

(15) In particular, the NAT-based wireless AP 30 provides a NAT function to translate private IP addresses of the WiFi terminals into a public IP address so that the WiFi terminals may access a public IP network (e.g., the Internet) via the single public IP address.

(16) All traffic flows transmitted by the WiFi terminals 10a, 10b, and 10c via various user applications are transmitted to a WiBro system under control of the NAT-based wireless AP (Access Point), as shown in FIG. 2.

(17) FIG. 3 illustrates a BWA-UMA (Broadband Wireless Access—Unlicensed Mobile Access) Interworking architecture according to the present invention, and FIG. 4 illustrates a traffic flow in FIG. 3.

(18) Referring to FIG. 3, the BWA-UMA Interworking architecture of the present invention includes a plurality of WiFi WLAN terminals 100a, 100b, and 100c; a relay station (RS) 200; a WiBro radio access station (RAS) 300 and an access router (ACR) 400.

(19) The WLAN terminals 100a, 100b, and 100c use an unlicensed band. Internet service (Unlicensed Mobile Access (UMA), also known as Generic Access Network (GAN)) is provided to the WLAN terminals 100a, 100b, and 100c via the RS 200.

(20) The RS 200 builds a BWA network such as WiBro/WiMAX with the WLAN terminals 100a, 100b, and 100c, which use the unlicensed band, to provide the Internet service to the WLAN terminals 100a, 100b, and 100c.

(21) The WiBro RAS 300 provides Internet service to the WiFi terminals as well as the WiBro terminals. When a WiFi terminal makes a request for a UMA Internet connection, the RS 200 requests the WiBro RAS 300 to allocate a unique Connection IDentification (CID) number to the WiFi terminal. In response to the RS's request, the WiBro RAS 300 allocates the unique CID number to the WiFi terminal.

(22) The access router 400 is in wireless communication with a plurality of WiBro RASs in the WiBro network. In particular, the access router 400 allocates a public IP address to the relay station 200 in response to a request from the relay station 200 in a WiBro initial process.

(23) Also, the access router 400 performs UMA connection authentication on the WiFi terminal in response to the request from the relay station 200, which responds to the request for UMA connection from the WiFi terminal.

(24) In the BWA-UMA Interworking architecture of the present invention, the WiFi WLAN terminals 100a, 100b, and 100c can transmit and receive various traffic service flows, such as service flow 1, service flow 2, and service flow 3, on user applications via CID-based virtual tunnels CID 1, CID 2, and CID 3, as shown in FIG. 4.

(25) FIG. 5 illustrates a configuration of the relay station (RS) 200 for BWA-UMA Interworking in FIG. 3.

(26) Referring to FIG. 5, the relay station 200 of the present invention includes a BWA connection manager 210, a WLAN host AP 220, a CID-UMA terminal 1:1 mapper 230, and a BWA-UMA connection initiation manager 240.

(27) The BWA connection manager 210 performs a WiBro initial process with the WiBro RAS 300 so that the Internet service is provided to the WiFi terminal via the WiBro system.

(28) Here, the WiBro initial process includes ranging, SS (subscriber station) basic capability, authentication, registration, and service addition, which will be described in detail below.

(29) When there is a request for WiBro network association from the WiFi terminal, the WLAN host AP 220 authorizes the association with the WiFi terminal.

(30) In other words, when the WiFi terminal transmits an association request message to the WLAN host AP 220 in order to access the WiBro network, the WLAN host AP 220 authorizes the association with the WiFi terminal. The association request message includes a MAC address that is user information of the WiFi terminal.

(31) If the WiFi terminal association is successful, the WLAN host AP 220 transmits to the WiBro network an access request message including the user information (MAC address) via the BWA-UMA connection initiation manager 240.

(32) Upon receipt of the access request message from the WLAN host AP 220, the BWA-UMA connection initiation manager 240 interworking with the BWA connection manager 210 transmits a user authentication request message including the user information (MAC address) to the WiBro network in order to make a request for user authentication. When the user authentication is successful, the BWA-UMA connection initiation manager 240 receives a response message from the WiBro network and notifies the WiFi terminal of the successful authentication.

(33) When the user authentication is successful, the BWA-UMA connection initiation manager 240 also sets up a connection for BWA-UMA Interworking dependent on an IP network in use. Here, the connection for BWA-UMA Interworking is set up in a different manner depending on whether the IP network in use is a public IP network or a private IP network, as described in detail with reference to FIGS. 6 and 7.

(34) In particular, if the IP network is an IPv4 network using a private address, a port mapping unit for allowing for several service flows of one user over an established unique virtual link CID is further required, as described in detail with reference to FIG. 10.

(35) The BWA-UMA connection initiation manager 240 includes a BW (Band-Width) negotiator 241 for bandwidth negotiation upon transmission and reception of IP packets, and a QoS controller 242. The BWA-UMA connection initiation manager 240 may be implemented in a BWA core network component in light of efficiency.

(36) The CID-UMA terminal 1:1 mapper 230 performs CID-UMA mapping between the virtual link CID allocated by the WiBro RAS 300 and the WiFi terminal in a one-to-one correspondence when the BWA-UMA Interworking connection is set up by the BWA-UMA connection initiation manager 240.

(37) Of course, the CID-UMA terminal 1:1 mapper 230 may also map a plurality of different CID number groups to one UMA.

(38) A connection setup process performed based on a used IP for BWA-UMA Interworking will now be described in detail with reference to FIGS. 6 and 7.

(39) FIG. 6 illustrates a BWA-UMA relay station connection setup sequence upon using an IPv6 and public IPv4 network according to the present invention.

(40) Referring to FIG. 6, the relay station 200 first performs a connection setup process S10 with a WiBro core network to obtain a basic/primary/secondary ID for transmission and reception of MAC management messages, a transport ID (TID) for transmission and reception of data, and an IP address. This connection setup process is the same as a connection setup process for data communication of a portable subscriber station (PS).

(41) In such a WiBro initial process, a ranging (RNG) process S11 by a RNG-REQ/RNG-RSP message transmission and reception between the relay station 200 and the WiBro RAS 300 is first performed and then an SS basic capability (SBC) process S12 by SBC-REQ/SBC-RSP message transmission and reception is performed.

(42) Subsequently, an authentication process S13 by PKM-REQ/PKM-RSP (PKM: privacy key management protocol) message transmission and reception between the relay station 200 and the WiBro RAS 300 is performed and a registration (REG) process S14 by REG-REQ/REG-RSP message transmission and reception is performed.

(43) Subsequently, a service addition process S15 by DSA-REQ/DSA-REP/DSA-ACK (DSA: dynamic service addition) message transmission and reception between the relay station 200 and the WiBro RAS 300 is performed and a DHCP REQ/DHCP RSP (DHCP: dynamic host configuration protocol) message transmission and reception process (S16 and S17) for public IP address allocation of the relay station itself is performed.

(44) The relay station 200, after completing the WiBro initial process, waits for a UMA request from the WLAN terminal 100.

(45) When the WLAN terminal 100 transmits an association REQ message to the relay station 200 in order to access the WiBro network (S20), the WLAN host AP 220 of the relay station 200 authorizes the association with the WLAN terminal 100 by transmitting the association REQ message. Here, the association REQ message includes MAC address information that is user information of the WiFi terminal 100 transmitting the association REQ message.

(46) In the relay station 200, the WLAN host AP 220 then transmits an access REQ message including the MAC address information of the WLAN terminal 100 to the BWA connection manager 210 via the BWA-UMA connection initiation manager 240 (S30).

(47) The BWA connection manager 210 of the relay station 200 then transmits a UMA authentication REQ message including the MAC address information of the WLAN terminal 100 to the access router 400 of the WiBro network in order to make a request for user authentication (S40).

(48) If the user authentication is successful, the access router 400 of the WiBro network transmits a UMA authentication REP message to the relay station 200 as a response message to the UMA authentication REQ message (S50).

(49) The relay station 200 transmits an access REP message in response to the access REQ message in order to notify that the user authentication was successful (S60), and transmits an association REP message in response to the association REQ message to the WLAN terminal 100 (S70).

(50) After the WiBro initial process and the user UMA authentication process are completed, the WLAN terminal 100 transmits a DHCP REQ (IPv6 or public IPv4) message to the access router (ACR) 400 of the WiBro network in order to make a request for IPv6 or public IPv4 address allocation using a dynamic host configuration protocol (DHCP) (S80).

(51) In response to the address allocation request from the WLAN terminal 100, the ACR 400 of the WiBro network allocates the IPv6 or public IPv4 address and transmits a DHCP REP-to-RS (IPv6 or public IPv4) message including the allocated IP address information to the relay station 200 (S90).

(52) After the IP address allocation to the WLAN terminal 100 is successful, the relay station 200 transmits a dynamic service addition request (DSA-REQ) MAC management message to the WiBro RAS 300 in order to make a request for allocation of a unique Connection IDentification (CID) number corresponding to a QoS level of the WLAN terminal 100 (S100).

(53) In response to the unique CID number allocation request of the relay station 200, the WiBro RAS 300 allocates the unique CID number corresponding to the QoS Level of the WLAN terminal 100 and transmits a DSA-REP message including the allocated unique CID number information to the relay station 200 (S110).

(54) Upon receipt of the DSA-REP message from the WiBro RAS 300, the relay station 200 transmits a DSA-ACK message to the WiBro RAS 300 (S120).

(55) After the unique CID number allocation to the WLAN terminal 100 has been completed, the relay station 200 performs a CID-UMA mapping process between the allocated unique CID number and the WLAN terminal 100 (S130).

(56) Finally, the relay station 200 relays and transmits a DHCP REP (IPv6 or public IPv4) message, which is a response message to the DHCP REQ (IPv6 or public IPv4) message, to the WLAN terminal 100 in order to notify that the IP allocation has been completed (S140).

(57) As described above, since each WiFi terminal is allocated the unique public IP upon using the IPv6 and public IPv4 network, the user management is possible by mapping the private virtual link CID to the allocated public IP without implementing an additional function, such as packet processing. The user management is also possible through CID-MAC mapping between the private virtual link CID and the unique MAC address of the WLAN terminal 100.

(58) The BWA-UMA relay station connection setup sequence upon using an IPv6 and public IPv4 network has been described so far. A BWA-UMA relay station connection setup sequence upon using a private IPv4 network will be described with reference to FIG. 7.

(59) FIG. 7 illustrates a BWA-UMA relay station connection setup sequence upon using a private IPv4 network according to the present invention.

(60) Referring to FIG. 7, the relay station 200 performs a WiBro initial process (S10) and waits for a UMA request from the WLAN terminal 100, as in the use of the IPv6 and public IPv4 network. Since the WiBro initial process has been described above, a description thereof will be omitted.

(61) When the WLAN terminal 100 transmits an association REQ message to the relay station 200 in order to access the WiBro network (S20), the WLAN host AP 220 of the relay station 200 authorizes the association with the WLAN terminal 100 transmitting the association REQ message. Here, the association REQ message includes MAC address information that is user information of the WLAN terminal 100 transmitting the association REQ message.

(62) In the relay station 200, the WLAN host AP 220 then transmits an access REQ message including the MAC address information of the WLAN terminal 100 to the BWA connection manager 210 via the BWA-UMA connection initiation manager 240 (S30).

(63) The BWA connection manager of the relay station 200 then transmits a UMA authentication REQ message including the MAC address information of the WLAN terminal 100 to the access router 400 of the WiBro network in order to make a request for user authentication (S40).

(64) When the user authentication is successful, the access router (ACR) 400 of the WiBro network transmits a UMA authentication REP message to the relay station 200 as a response message to the UMA authentication REQ message (S50).

(65) The relay station 200 transmits an access REP message in response to the access REQ message in order to notify that the user authentication was successful (S60), and transmits an association REP message in response to the association REQ message to the WLAN terminal 100 (S70).

(66) After the WiBro initial process and the user UMA authentication process are completed, the WLAN terminal 100 transmits a DHCP REQ (private IPv4) message to the relay station 200 in order to make a request for private IPv4 address allocation using a dynamic host configuration protocol (DHCP) (S800).

(67) In response to the private IPv4 address allocation request from the WLAN terminal 100, the relay station 200 allocates the private IPv4 address, and then transmits a dynamic service addition request (DSA-REQ) MAC management message to the WiBro RAS 300 in order to make a request for allocation of a unique Connection IDentification (CID) number corresponding to a QoS level of the user of the WLAN terminal 100 (S900).

(68) In response to the number allocation request of the relay station 200, the WiBro RAS 300 allocates the unique CID number corresponding to the QoS Level of the WLAN terminal 100 and transmits a DSA-REP message including the allocated unique CID number information to the relay station 200 (S1000).

(69) Upon receipt of the DSA-REP message from the WiBro RAS 300, the relay station 200 transmits a DSA-ACK message to the WiBro RAS 300 (S1100).

(70) After the unique CID number allocation to the WLAN terminal 100 has been completed, the relay station 200 performs a CID-UMA mapping process between the allocated unique CID number and the WLAN terminal 100 (S1200).

(71) Finally, the relay station 200 relays and transmits a DHCP REP private IPv4 message, which is a response message to the DHCP REQ private IPv4 message, to the WLAN terminal 100 in order to notify that the IP allocation has been completed (S1300).

(72) As such, the use of private IPv4 network necessitates the Network Address Translation (NAT) function, unlike the use of the IPv6 or public IPv4 network.

(73) In other words, the translation is performed with respect to the IP Packet of each WLAN terminal by using the public IP of the relay station 200 allocated in the WiBro initial connection process of the relay station 200.

(74) In particular, a unique virtual link CID that the relay station 200 obtains using DSA-REQ in the above process is identified by five tuple (Quintuple or Pentuple), which includes a source IP, a destination IP, a source port, a destination port and a security key. A source port and a destination port for each CID are uniquely given by the relay station 200.

(75) However, when several WLAN terminals attempt to access the network as in FIG. 8, the allocation of one CID to each WLAN terminal for management causes the following problems, as described in detail with reference to FIG. 8.

(76) FIG. 8 illustrates an exemplary embodiment of the translation performed on only an IP address when source and destination ports (sp and dp) given to each application of a plurality of WiFi WLAN terminals are the same as in a case where NAT is used.

(77) In FIG. 8, source and destination ports for each flow given to applications of the first and second WiFi WLAN terminals 100a and 100b are the same between the first and second WLAN terminals 100a and 100b. Here, {SPn, DPn} are source and destination port numbers given to the CID by the relay station 200, and {spn, dpn} are source and destination port numbers given for each service flow of the WLAN terminals.

(78) When the first and second WLAN terminals 100a and 100b simultaneously forward IP packets having the same source and destination ports for each flow via the first CID A and the second CID B, respectively, incoming IP packets are received as a response to such outgoing IP packets and have the same source and destination ports. Accordingly, the incoming IP packets are indistinguishable from each other, which makes it difficult to determine whether any one of the first CID A and the second CID B is used for packet transmission. Here, the incoming packets have the destination port corresponding to the source port of the outgoing packets and the source port corresponding to the destination port of the outgoing packets.

(79) FIG. 9 illustrates an exemplary embodiment of translation between an IP address and a port number when a single WiFi WLAN terminal uses three different source ports with respect to one destination port for communication in a case where NAT is used.

(80) As shown in FIG. 9, a WiFi LAN terminal 100a forwards a user application flow having three different source ports sp1, sp2, and sp3 with respect to one destination port dp1 via a CID C. Here, {SPn, DPn} are source and destination port numbers given to the CID by the relay station 200, and {spn, dpn} are source and destination port numbers given for the service flow of each WiFi user.

(81) When the WLAN terminal 100a forwards the user application flow having the three different source ports sp1, sp2, and sp3 with respect to one destination port dp1 via the CID C by translating the three different source ports sp1, sp2, and sp3 into the source port SP1 of the CID C, incoming flows are received as a response to such an outgoing flow and have the same source and destination ports. Accordingly, the incoming flows are indistinguishable from each other, which make it difficult to determine whether any application flow is used for packet transmission.

(82) Meanwhile, the port translation may also be performed by using a separate port rather than the port allocated to the CID. In this case, however, relatively complex management of states, such as a currently used port, a previously used port and CID mapping, is required since one cannot know a CID to be mapped for an incoming packet.

(83) FIG. 10 illustrates port translation using an exclusive OR (XOR) operator according to the present invention. An XOR port mapper is required for performing port mapping of a source port (spn) of a user application flow, and a source port (SPn) of a unique virtual link CID by using the exclusive OR operator, on an upper layer of the network in order to solve problems with existing NAT exploitation.

(84) Referring to FIG. 10, the WiFi WLAN terminal 100a forwards the user application flow having the three different source ports sp1, sp2, and sp3 with respect to one destination port dp1 via the CID(D) having the source port and the destination port of {SP1, DP1}.

(85) The XOR port mapper 250 performs port mapping for each flow. For example, the XOR port mapper 250 maps the source port sp1 of the flow forwarded via the CID D to the source port SP1 of the CID D to generate a new port number xsp1.

(86) The XOR port mapper 250 transmits the IP packet having the translated port to a web server with a destination port on the Internet, and manages a mapping table of a source port SP1 of the CID D and the newly generated port number xsp1.

(87) After transmitting the IP packet to the web server on the Internet, the XOR port mapper 250 receives an IP packet as a response, which has the destination port of xsp1 and the source port of dp1.

(88) The XOR port mapper 250 recognizes, from the mapping table, that the received IP packet should be sent to the CID of the port SP1 mapped to the destination port xsp1 of the received IP packet, and creates sp1 through XOR operation of xsp1 and SP1 to deliver sp1 to the application process at a side of the WLAN terminal 100a.

(89) According to the present invention, user-oriented Internet connectivity is provided to a user using an unlicensed band in the WiBro/WiMAX-based Broadband Wireless Access (BWA) environment, thereby achieving user management, such as QoS/traffic control and billing, even though the user uses the unlicensed band.

(90) While the present invention has been described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the present invention as defined by the following claims.