JP2014079020A - Roaming method for mobile terminal in wlan, related access controller and access point device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roaming method for a mobile terminal in a wireless local area network.SOLUTION: A target access point (AP) device receives an access request for roaming from the mobile terminal, and a target access controller (AC) obtains mobility information of the mobile terminal in an original extended service set on the basis of the access request. The mobility information includes information of an AP device, an AC and a mobile agent server associated with the mobile terminal. Then the target AC determines whether the roaming for the mobile terminal is inter-IP subnet roaming or intra-IP subnet roaming on the basis of the obtained mobility information. The target AC performs mobile IP based handover when the roaming is determined as the inter-IP subnet roaming and performs Inter Access Point Protocol based handover when the roaming is determined as the intra-IP subnet roaming.

Description

  The present invention relates to wireless local area network (WLAN) technology in the communications field, and in particular, to roaming technology for mobile terminals in the WLAN.

  In recent years, wireless local area networks such as WiFi networks have been widely deployed in both private home users and public hot spots to provide broadband high-speed wireless access services to mobile terminals. In a wireless local area network, a single access point (AP) device that supports one or more mobile terminals is referred to as a basic service set (BSS), and the AP device is referred to as a basic service set ID ( Identified by BSSID). Two or more BSSs form an extended service set (ESS). Typically, an ESS is a single logical network segment (one ESS is in one IP subnet) and is identified by its service set ID.

  Common WLAN architectures can be classified as autonomous network architectures and centralized network architectures. In an autonomous WLAN architecture, AP devices are individually managed as separate network entities and have the capability to provide accessibility to mobile terminals. A centralized WLAN architecture includes an access controller (AC) that configures, manages, and controls AP devices and cooperates with the AP devices to provide wireless accessibility to mobile terminals. In a centralized WLAN architecture, the AP device is also referred to as a wireless terminal point (WTP) device. Communication between the access controller AC and the WTP device controlled by the access controller AC uses the Control and Provisioning of Wireless Access Points (CAPWAP) protocol. In the CAPWAP protocol, WTP devices in a centralized WLAN architecture are used. Two types of MAC models are defined: split MAC model and local MAC model. When the split MAC model is used, WTP devices are mainly used to receive wireless traffic and transmit the received traffic without processing, and the access controller AC performs all operations related to access. To do. When the local MAC model is used, the WTP device performs all wireless MAC functions.

  In order to allow mobile terminals to move between different AP devices, an inter-access point protocol (IAPP) has been proposed to move between AP devices to meet the increasing mobility needs of users of mobile terminals. Intended to give the mobile terminal the ability to However, the IAPP protocol is only applicable to intra-network roaming for mobile terminals between all AP devices in one ESS, and these AP devices are in the same network segment. According to the IAPP protocol, when the mobile terminal is successfully associated with the target AP device, the target AP device sends a multicast packet containing the MAC address of the mobile terminal to other AP devices in the ESS, and so on. AP devices can update their association tables.

  Since the IAPP protocol can only enable a mobile terminal to perform intra-network roaming between all AP devices in one ESS, the mobile terminal performs internetwork roaming between different ESSs. Mobile IP (MIP) technology is introduced to ensure that it can. MIP technology allows mobile terminals to roam between different IP segments using a fixed IP address. MIP technology includes a series of processes such as mobile discovery and network registration. When a mobile terminal moves from one ESS to another ESS, the original mobile agent server and the target mobile agent server need to exchange information. In general, mobile agent server is a common name for home agent (HA) server and foreign agent (FA) server. First, the HA server related to the mobile terminal needs to be found, and then the original FA server related to the mobile terminal is identified by querying the binding table of the HA server, thereby the target FA server and Communication with the original FA server is established. However, handover delay and packet loss are caused by MIP handover, thereby reducing the service quality of communication traffic (particularly real-time communication traffic).

  In order to provide a complete roaming solution for mobile terminals, the MIP technology and the IAPP protocol should be combined. In order to implement internetwork roaming, Layer 3 MIP should support the IAPP protocol. However, in a centralized WLAN architecture, the mobile agent discovery mechanism with MIP technology cannot function. As described above, communication between the AC and its WTP device is based on a Layer 3 tunnel. Therefore, the Layer 3 function should be supported in the WTP device for both the split MAC model and the local MAC model. However, in the case of MIP technology, the foreign agent should not be configured at the WTP device, but at the AC or other higher logical location. According to the standard MIP protocol, the MIP Mobile Agent Advertisement (MAA) Time To Live (TTL) is usually set to 1 to avoid multicast storm, which is the Layer of the WTP device. 3 means that the mobile terminal cannot get the MAA message sent by the FA server set up in AC. Conversely, the FA server cannot obtain a mobile agent request (MAS) message transmitted by the mobile terminal.

  In view of the above technical problems, the present invention is proposed and the object of the present invention is to provide a roaming method for a mobile terminal in a wireless local area network, which is particularly a centralized network. For WLAN with architecture, it allows mobile terminals to roam between different ESS or different subnets and provides an efficient mobile management mechanism based on MIP and IAPP protocols. In addition, the present invention also provides an associated access controller and access point device.

  According to a first aspect of the present invention, there is provided a roaming method for a mobile terminal in a wireless local area network including a plurality of extended service sets (ESS), each of the plurality of ESSs being at least one In a roaming method including an access controller (AC) and at least two access point (AP) devices, each access controller is operable to configure, control and manage at least one AP device The target AP device receives an access request for roaming from the mobile terminal, and the target AC to which the target AP device belongs acquires mobility information of the mobile terminal in the original ESS based on the access request. , Mobility information related to mobile terminal A Including device, AC, and mobile agent server information, whether the target AC is roaming for the mobile terminal based on the acquired mobility information is inter IP subnet roaming or intra IP subnet roaming The target AC performs a Mobile IP (MIP) based handover when determining roaming as inter IP subnet roaming, and the target AC when determining roaming as intra IP subnet roaming Provides a roaming method that includes performing an Inter Access Point Protocol (IAPP) based handover.

  According to a second aspect of the present invention, there is provided a roaming method for a mobile terminal in a wireless local area network (WLAN) including a plurality of extended service sets (ESS), each of the plurality of ESSs. In a roaming method comprising at least two access point (AP) devices, the target AP device receives an access request for roaming from a mobile terminal, the target AP device in the original ESS based on the access request Obtaining mobility information of a mobile terminal, the mobility information including information on an AP device and a mobile agent server related to the mobile terminal, and the target AP device for the mobile terminal based on the acquired mobility information. Roaming in the Internet Determining whether it is roaming or intra-IP subnet roaming; when determining that roaming is inter-IP subnet roaming, the target AP device performs a Mobile IP (MIP) based handover; A roaming method is provided that includes the target AP device performing an inter-access point protocol (IAPP) based handover when the roaming is determined to be intra IP subnet roaming.

  According to the third aspect of the present invention, a receiving module that receives a request for roaming for a mobile terminal from an access point (AP) device, and acquires mobility information of the mobile terminal in the original ESS based on the request A mobility information acquisition module including information on an AP device, an AC, and a mobile agent server, the mobility information relating to the mobile terminal, and roaming for the mobile terminal based on the acquired mobility information A roaming determination module for determining whether the IP is roaming for inter-IP subnet or roaming for intra IP, and mobile IP (MIP) based handover is performed when roaming is determined as inter-IP subnet roaming , B When the timing is determined that intra IP subnet roaming access controller and a handover module for implementing a handover between protocols (IAPP) based access point is provided.

  According to a fourth aspect of the present invention, there is provided a receiving module that receives an access request for roaming from a mobile terminal, and a mobility information acquisition module that acquires mobility information of the mobile terminal in the original ESS based on the request. A mobility information acquisition module in which mobility information includes information on an AP device and a mobile agent server related to the mobile terminal, and whether roaming for the mobile terminal is inter-IP subnet roaming based on the acquired mobility information, or A roaming determination module that determines whether intra-IP subnet roaming is performed, and mobile IP (MIP) -based handover is performed when roaming is determined as inter-IP subnet roaming, and roaming is performed as intra-IP subnet roaming When it is determined that the ring, the access point device and a handover module for implementing a handover between protocols (IAPP) based access point is provided.

1 is a structural diagram of a WLAN capable of implementing a roaming method for a mobile terminal in a wireless local area network according to an embodiment of the present invention. 2 is a flowchart of a roaming method for a mobile terminal in a WLAN according to an embodiment of the present invention; FIG. 3 is a structural diagram of a WLAN capable of implementing a roaming method for a mobile terminal in a wireless local area network according to another embodiment of the present invention. 6 is a flowchart of a roaming method for a mobile terminal in a WLAN according to another embodiment of the present invention; FIG. 3 is a schematic block diagram of an access controller according to an embodiment of the present invention. FIG. 2 is a schematic block diagram of an access point device according to an embodiment of the present invention.

  The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the invention, taken in conjunction with the accompanying drawings.

  FIG. 1 shows a structural diagram of a WLAN capable of implementing a roaming method for mobile terminals in a wireless local area network according to an embodiment of the present invention, which utilizes a centralized network architecture. As shown in FIG. 1, the WLAN includes multiple ESSs (only two ESSs (ESS1 and ESS2) are shown for simplicity). The ESS1 includes one access controller AC1 that controls the access point device WTP1. The ESS2 includes two access controllers AC21 and AC22. The access controller AC21 controls the access point device WTP2a, and the access controller AC22 controls the two access point devices WTP2b and WTP2c. Initially, the mobile terminal STA is in the coverage area of ESS1 and accesses via the AP device WTP1. Next, the mobile terminal STA starts moving. When the mobile terminal STA moves into the coverage area of the AP device WTP2a in the ESS2, a handover related to the mobile terminal STA from the AP device WTP1 to the AP device WTP2a is performed (first handover). When the mobile terminal STA continues to move within the coverage area of the AP device WTP2b, a handover related to the mobile terminal STA from the AP device WTP2a to the AP device WTP2b is performed (second handover). When the mobile terminal STA continues to move within the coverage area of the AP device WTP2c, a handover related to the mobile terminal STA from the AP device WTP2b to the AP device WTP2c is performed (third handover). Each of the above handovers can be performed by the following roaming method for mobile terminals in the wireless local area network described with respect to FIG.

  FIG. 2 shows a flowchart of a roaming method for a mobile terminal in a WLAN according to an embodiment of the present invention. This embodiment will be described in detail in conjunction with FIGS.

  In this embodiment, as an example, a handover (first handover) related to the mobile terminal STA from the AP device WTP1 to the AP device WTP2a in FIG. 1 will be mainly described. In this case, AP device WTP1 is the original AP device, so AC1 is the original access controller AC, ESS1 is the original ESS, AP device WTP2 is the target AP device, and thus access controller AC21 is Target AC and ESS2 is target ESS.

  As shown in FIG. 2, in step S201, the AP device WTP2a receives an access request for roaming transmitted by the mobile terminal STA. When the mobile terminal STA moves from the coverage area of the AP device WTP1 in the ESS1 to the coverage area of the AP device WTP2a in the ESS2 (corresponding to “101” in FIG. 1), the mobile terminal STA The Layer 2 connection with WTP1 (corresponding to “102” in FIG. 1) is disconnected, and a request for reassociation with AP device WTP2a (corresponding to “103” in FIG. 1) is transmitted to AP device WTP2a. For example, in the 802.11 protocol, the request is REASSOCIATE. This is a request message. When the AP device WTP2a receives the reassociation request, the AP device WTP2a performs an appropriate process according to the type of the MAC model related to the AP device WTP2a.

  When the AP device WTP2a uses the local MAC model, that is, when the AP device WTP2a performs all processing in the MAC layer, first, the AP device WTP2a receives the original AP device WTP1 related to the mobile terminal STA from the received reassociation request. Service set ID, the MAC address of the mobile terminal STA, and the like are extracted. Next, the AP device WTP2a obtains the service set ID of the original AP device WTP1 and the MAC address of the mobile terminal STA, for example, MOVE. The message is included in the request message and transmitted to the access controller AC21 (corresponding to “104” in FIG. 1). When the AP device WTP2a utilizes a split MAC model, i.e. when the AP device WTP2a is only used to transmit and receive wireless traffic. The received reassociation request is directly transferred to the access controller AC21. FIG. 1 shows only when the AP device WTP2a uses the local MAC model.

  In step S205, the access controller AC21 acquires the mobility information of the mobile terminal STA in the original ESS1 based on the received request. In this embodiment, the mobility information includes AP device, access controller, and mobile agent server information associated with the mobile terminal. Mobility information can be stored on an authentication server in the ESS and can be indexed by the MAC address of the mobile terminal. Specifically, the mobility information includes the MAC address of the mobile terminal, the MAC address and IP address of the associated AP device, the MAC address and IP address of the associated access controller, the IP address of the home agent server, and the associated It can contain the IP address of the foreign agent server.

  After the authentication server in the ESS authenticates the mobile terminal, when the mobile terminal first accesses an AP device in the ESS, the access controller AC to which the AP device belongs generates mobility information of the mobile terminal, Sent to the authentication server for storage for future roaming and handover.

  For example, the access controller AC can encapsulate mobility information as an extended attribute for transmission in an EAP message, and the mobility information attribute in the extended EAP message is as follows.

もちろん、モビリティ情報を送信用の他のメッセージにカプセル化することもできることを当業者は理解することができる。

Of course, those skilled in the art can appreciate that mobility information can also be encapsulated in other messages for transmission.

  In this embodiment, first, the access controller AC21 determines the service set of the AP device WTP1 from the received request (that is, the request processed by the AP device WTP2a or the reassociation request directly transferred by the AP device WTP2a). The ID and the MAC address of the mobile terminal STA are extracted.

  Next, the access controller AC21 performs authentication of the mobile terminal STA and transmission of mobility information of the mobile terminal STA based on the extracted service set ID of the AP device WTP1 and the MAC address of the mobile terminal STA, That is, a request is made to the authentication server in the ESS 2 (corresponding to “105” in FIG. 1).

  Specifically, the access controller AC21 includes the service set ID of the AP device WTP1 and the MAC address of the mobile terminal STA in, for example, an ACCESS-REQUEST request in the IAPP protocol, and transmits it to the local authentication server AAAL. Can do.

  After receiving the request, the local authentication server AAAL authenticates the mobile terminal STA based on the MAC address of the mobile terminal STA. In this embodiment, the authentication server is an Authentication, Authorization, and Accounting (AAA) server, and authenticates the mobile terminal STA based on Extensible Authentication Protocol (EAP). One skilled in the art can readily appreciate that other authentication protocols such as the Remote Authentication Dial in User Service (RADIUS) protocol can also be used.

  On the other hand, the local authentication server AAAL also extracts the mobility information of the mobile terminal STA in the ESS 1 based on the MAC address of the mobile terminal STA. Here, the mobility information of the mobile terminal STA in the ESS 1 includes the MAC address of the mobile terminal STA, the MAC address and IP address of the AP device WTP1, the MAC address and IP address of the access controller AC1, and the IP address of the home agent HA server. As well as the IP address of the foreign agent server FA1. For a foreign agent server, the foreign agent server can be a stand-alone device or can be integrated into an access controller. FIG. 1 shows the case where a foreign agent server is integrated into the access controller. First, the local authentication server AAAL searches for mobility information of the mobile terminal STA locally. Since the mobility information of the mobile terminal STA in the ESS1 is stored on the authentication server in the ESS1, the local authentication server AAAL cannot find the mobility information of the mobile terminal STA locally. Therefore, the local authentication server AAAL queries the authentication server in the ESS 1 for the mobility information of the mobile terminal STA based on the service set ID of the AP device WTP1 and the MAC address of the mobile terminal STA (“106” in FIG. 1). Corresponding), the mobility information of the mobile terminal STA is received from the authentication server (corresponding to “107” in FIG. 1). Next, the local authentication server AAAL supplies the received mobility information of the mobile terminal STA together with the authentication information to the access controller AC21 (corresponding to “108” in FIG. 1). Therefore, the access controller AC21 receives the authentication information and mobility information of the mobile terminal STA from the local authentication server AAAL. Further, the authentication server in the ESS 1 can delete the mobility information after supplying the mobility information of the mobile terminal STA to the local authentication server AAAL.

  Next, in step S210, the access controller AC21 determines whether roaming for the mobile terminal STA is inter-IP subnet roaming or intra-IP subnet roaming based on the mobility information obtained in step S205. To do. In this embodiment, the access controller AC21 compares whether the IP address of the AP device WTP1 and the IP address of the AP device WTP2a belong to the same network segment based on the acquired mobility information of the mobile terminal STA. When both IP addresses belong to the same network segment, roaming for the mobile terminal STA is determined as intra IP subnet roaming. When both of the IP addresses do not belong to the same network segment, the roaming for the mobile terminal STA is determined as the inter IP subnet roaming. In the first handover, the IP addresses of the AP device WTP1 and the AP device WTP2a do not belong to the same network segment. Therefore, the access controller AC21 can perform roaming for the mobile terminal STA from the AP device WTP1 to the AP device WTP2a. It can be determined that it is subnet roaming.

  Next, the access controller AC21 performs a mobile IP (MIP) based handover (step S215). In this embodiment, the foreign agent server FA21 in the AC 21 triggers a standard mobile IP process, that is, registers the IP address of the target foreign agent server FA21 with the home agent server HA, and the home agent server. Requests the server HA to update the binding. The home agent server HA updates the binding between the IP address of the original foreign agent server FA1 and the mobile terminal STA as the binding between the IP address of the foreign agent server FA21 and the mobile terminal STA. Further, the access controller AC21 establishes a data transfer tunnel between the foreign agent server FA21 and the home agent server HA (corresponding to “109” in FIG. 1). Therefore, the home agent server HA can transmit the data transmitted to the mobile terminal STA to the foreign agent server FA21 through the data transfer tunnel. Next, context information regarding the mobile terminal STA is transmitted between the target foreign agent server FA21 and the foreign agent server FA1 (corresponding to “110” in FIG. 1), and the context information is implemented in an IAPP message. can do. The context information related to the mobile terminal STA can include data related to services used by the mobile terminal STA, security information such as a user profile, a data session key, and the like. The access controller AC21 reconstructs the user environment related to the mobile terminal STA based on the context information, and indicates that the handover has been completed, for example, MOVE. The response message is used to notify the AP device WTP2a (corresponding to “111” in FIG. 1).

  Further, after handing over the mobile terminal STA to the AP device WTP2a, the access controller AC21 generates mobility information of the mobile terminal STA in the ESS2, and transmits the generated mobility information to the local authentication server AAAL for storage. .

  The second handover will be described below. In the second handover, the original AP device is changed to AP device WTP2a, the original access controller AC is changed to access controller AC21, the target AP device is changed to AP device WTP2b, and the target access controller AC is changed to Changed to AC22, both the original ESS and the target ESS are changed to ESS2.

  When the mobile terminal STA enters the coverage area of the AP device WTP2b, the mobile terminal STA disconnects the Layer 2 connection with the AP device WTP2a and transmits a reassociation request to the AP device WTP2b. After the AP device WTP2b receives the reassociation request (step S201), the AP device WTP2b extracts from the request the service set ID of the AP device WTP2a and the MAC address of the mobile terminal STA, and stores them in the access controller AC22. MOVE. With IAPP protocol to send to Encapsulate in a request message or transfer the reassociation request directly to the access controller AC22. Based on the received request, the access controller AC22 acquires the mobility information of the mobile terminal STA in the ESS2 from the local authentication server AAAL (step S205). Since the mobility information of the mobile terminal STA in the ESS 2 is already stored on the local authentication server AAAL, the local authentication server AAAL discovers the mobility information of the mobile terminal STA locally and accesses the mobility information together with the authentication information. Return to controller AC22. Here, the mobility information of the mobile terminal STA includes the MAC address of the mobile terminal STA, the MAC address and IP address of the AP device WTP2a, the MAC address and IP address of the access controller AC21, the IP address of the home agent server HA, and Contains the IP address of the foreign agent server FA21.

  The access controller AC22 compares the IP address of the AP device WTP2a with the IP address of the AP device WTP2b (step S210), and finds that they belong to the same network segment. Therefore, the access controller AC22 determines that roaming for the mobile terminal STA is intra IP subnet roaming. Next, the access controller AC22 performs an IAPP protocol-based handover (step S220).

  In step S220, first, the access controller AC22 compares the IP address of the original access controller and the IP address of the target access controller, and the access controller having the same access controller and the target access controller are the same. It is determined whether or not. During the second handover, the original access controller is access controller AC21 and the target access controller is access controller AC22. Therefore, the original access controller and the target access controller are different access controllers. In this case, the access controller AC22 receives context information regarding the mobile terminal STA from the access controller AC21, and the context information can be implemented in an IAPP message. Next, the access controller AC22 reconstructs the user environment related to the mobile terminal STA based on the received context information, and notifies the AP device WTP2b that the handover has been completed.

  Furthermore, after handing over the mobile terminal STA to the AP device WTP2b, the access controller AC22 generates new mobility information of the mobile terminal STA in ESS2, and the generated new mobility information is stored in the local authentication server AAAL for storage. Send.

  Hereinafter, the third handover will be described. During the third handover, the original AP device is changed to AP device WTP2b, the target AP device is changed to AP device WTP2c, the original access controller and the target access controller are both access controller AC22, Both the original ESS and the target ESS are ESS2.

  When the mobile terminal STA enters the coverage area of the AP device WTP2c, the mobile terminal STA disconnects the Layer 2 connection with the AP device WTP2b and transmits a reassociation request to the AP device WTP2c when the mobile terminal STA enters the coverage area of the AP device WTP2c. . After the AP device WTP2c receives the reassociation request (step S201), the AP device WTP2c extracts the service set ID BSSID of the AP device WTP2b and the MAC address of the mobile terminal STA from the request, and sends them to the access controller. MOVE. With IAPP protocol for transmission to AC22. Encapsulate in a request message or transfer the reassociation request directly to the access controller AC22. Based on the received request, the access controller AC22 acquires the mobility information of the mobile terminal STA in the ESS2 from the local authentication server AAAL (step S205). Since the mobility information of the mobile terminal STA in the ESS 2 is already stored on the local authentication server AAAL, the local authentication server AAAL discovers the mobility information of the mobile terminal STA locally and accesses the mobility information together with the authentication information. Return to controller AC22. Here, the mobility information of the mobile terminal STA includes the MAC address of the mobile terminal STA, the MAC address and IP address of the AP device WTP2b, the MAC address and IP address of the access controller AC22, the IP address of the home agent server HA, and Contains the IP address of the foreign agent server FA22.

  The access controller AC22 compares the IP address of the AP device WTP2b with the IP address of the AP device WTP2c (step S210), and finds that the two IP addresses belong to the same network segment. Therefore, the access controller AC22 determines that roaming for the mobile terminal STA is intra IP subnet roaming. Next, the access controller AC22 performs an IAPP protocol-based handover (step S220).

  In step S220, first, the access controller AC22 compares the IP address of the original access controller and the IP address of the target access controller, and the access controller having the same access controller and the target access controller are the same. It is determined whether or not. During the third handover, both the original access controller and the target access controller are the access controller AC22. They are therefore the same access controller. In this case, the access controller AC22 has already recognized the context information regarding the mobile terminal STA, and it is not necessary to reconstruct the user environment regarding the mobile terminal STA. Therefore, the access controller AC22 directly notifies the AP device WTP2c that the handover has been completed.

  Furthermore, after handing over the mobile terminal STA to the AP device WTP2c, the access controller AC22 generates new mobility information of the mobile terminal STA in ESS2, and the generated new mobility information is stored in the local authentication server AAAL for storage. Send.

  From the above description, the roaming method for the mobile terminal in the WLAN according to this embodiment can realize the global roaming for the mobile terminal in the WLAN, and the mobile terminal uses the fixed IP address and the inter-IP subnet. Application of mobile IP technology in a WLAN with a centralized network architecture, which can allow to implement roaming, can provide an efficient interworking mechanism for MIP and IAPP protocols Can be solved to solve the problem caused by.

  FIG. 3 shows a structural diagram of a WLAN capable of implementing a roaming method for a mobile terminal in the WLAN according to another embodiment of the present invention, which utilizes an autonomous network architecture. As shown in FIG. 3, the WLAN includes multiple ESSs (for simplicity, only two ESSs (ESS1 and ESS2) are shown). ESS1 includes two access point devices AP11 and AP12, and ESS2 includes two access point devices AP21 and AP22. Initially, the mobile terminal STA is in the coverage area of ESS1 and accesses the WLAN via the AP device AP12. Next, the mobile terminal STA starts moving. When the mobile terminal STA moves into the coverage area of the AP device AP21 in the ESS2, a handover related to the mobile terminal STA from the AP device AP11 to the AP device AP21 is performed (first handover). When the mobile terminal STA continues to move within the coverage area of the AP device AP22, a handover related to the mobile terminal STA from the AP device AP21 to the AP device AP22 is performed (second handover). Each of the above handovers can be performed by a roaming method for mobile terminals in a wireless local area network described below with respect to FIG.

  FIG. 4 shows a flowchart of a roaming method for a mobile terminal in a WLAN according to another embodiment of the present invention. This embodiment will be described in detail in conjunction with FIGS. The description of the same parts as those of the previous embodiment is appropriately omitted.

  In this embodiment, as an example, a handover (first handover) related to the mobile terminal STA from the AP device AP12 to the AP device AP21 in FIG. 3 will be described. In this case, the AP device AP12 is the original AP device, ESS1 is the original ESS, AP device AP21 is the target AP device, and ESS2 is the target ESS.

  As shown in FIG. 4, in step S401, the AP device AP21 receives an access request for roaming transmitted by the mobile terminal STA. When the mobile terminal STA moves from the coverage area of the AP device AP12 in the ESS1 to the coverage area of the AP device AP21 in the ESS2 (corresponding to "301" in FIG. 3), the mobile terminal STA Disconnect the Layer 2 connection with AP 12 (corresponding to “302” in FIG. 3), and send a request for re-association with AP device AP 21 (corresponding to “303” in FIG. 3) to AP device AP 21. For example, the request may be REASSOCIATE. This is a request message.

  Next, in step S405, the AP device AP21 acquires the mobility information of the mobile terminal STA in the original ESS1 based on the received request. In this embodiment, the mobility information includes access point device and mobile agent server information associated with the mobile terminal. Specifically, the mobility information includes the MAC address of the mobile terminal, the MAC address and IP address of the associated AP device, the IP address of the home agent server, and the IP address of the associated foreign agent server. In general, mobility information is stored on an authentication server in the extended service set and can be indexed by the MAC address of the mobile terminal.

  In this embodiment, first, the AP device AP21 extracts the service set ID of the AP device AP12 and the MAC address of the mobile terminal STA from the received request.

  Next, the AP device AP21 authenticates the mobile terminal STA and transmits the mobility information of the mobile terminal STA based on the extracted service set ID BSSID of the AP device AP12 and the MAC address of the mobile terminal STA. That is, a request is made to the authentication server in ESS 2 (corresponding to “304” in FIG. 3).

  Specifically, the AP device AP21 includes the service set ID BSSID of the AP device AP12 and the MAC address of the mobile terminal STA in, for example, an ACCESS-REQUEST request in the IAPP protocol, and transmits it to the local authentication server AAAL. Can do.

  After receiving the request, the local authentication server AAAL authenticates the mobile terminal STA based on the MAC address of the mobile terminal STA. In this embodiment, the authentication server is an AAA server and authenticates the mobile terminal STA based on EAP. One skilled in the art can readily appreciate that other authentication protocols such as the RADIUS protocol can also be used.

  On the other hand, the local authentication server AAAL also extracts the mobility information of the mobile terminal STA in the ESS 1 based on the MAC address of the mobile terminal STA. Here, the mobility information of the mobile terminal STA in the ESS 1 includes the MAC address of the mobile terminal STA, the MAC address and IP address of the AP device AP12, the IP address of the home agent HA server, and the IP address of the foreign agent server FA12. including. The foreign agent server can be a standalone device or can be integrated into the AP device. FIG. 3 shows the case where the foreign agent server is integrated into the AP device. First, the local authentication server AAAL searches for mobility information of the mobile terminal STA locally. Since the mobility information of the mobile terminal STA in the ESS1 is stored on the authentication server in the ESS1, the local authentication server AAAL cannot find the mobility information of the mobile terminal STA locally. Based on the service set ID BSSID of the AP device AP12 and the MAC address of the mobile terminal STA, the local authentication server AAAL queries the authentication server in the ESS 1 for mobility information of the mobile terminal STA (corresponding to “305” in FIG. 3). 3), the mobility information of the mobile terminal STA is received from the authentication server (corresponding to “306” in FIG. 3), and then the received mobility information of the mobile terminal STA is supplied to the AP device AP21 together with the authentication information (FIG. 3). Corresponds to “307”). Therefore, the AP device AP21 receives the authentication information and mobility information of the mobile terminal STA from the local authentication server AAAL.

  Next, in step S410, the AP device AP21 determines, based on the mobility information obtained in step S405, whether roaming for the mobile terminal STA is inter IP subnet roaming or intra IP subnet roaming. . In this embodiment, the AP device AP21 compares whether the IP address of the AP device AP12 and the IP address of the AP device AP21 belong to the same network segment. If the IP address belongs to the same network segment, the AP device AP21 moves If the roaming for the terminal STA is determined as intra IP subnet roaming and the IP address does not belong to the same network segment, the roaming for the mobile terminal STA is determined as inter IP subnet roaming. In the first handover, the IP addresses of the AP device AP12 and the AP device AP21 do not belong to the same network segment. Therefore, the AP device AP21 determines that the roaming for the mobile terminal STA from the AP device AP12 to the AP device AP21 is the inter-IP subnet roaming.

  Next, the AP device AP21 performs a mobile IP (MIP) based handover (step S415). In this embodiment, the AP device AP21 registers the IP address of the target foreign agent server FA21 with the home agent server HA, and requests the home agent server HA to update the binding. The home agent server HA updates the binding between the IP address of the original foreign agent server FA12 and the mobile terminal STA as the binding between the IP address of the foreign agent server FA21 and the mobile terminal STA. Further, the AP device AP21 establishes a data transfer tunnel between the foreign agent server FA21 and the home agent server HA (corresponding to “308” in FIG. 3). Therefore, the home agent server HA can transmit the data transmitted to the mobile terminal STA to the foreign agent server FA21 through the data transfer tunnel. Then, the context information regarding the mobile terminal STA is transferred between the target foreign agent server FA21 and the original foreign agent server FA12 (corresponding to “309” in FIG. 3), and the context information is the IAPP message. Can be implemented. As described above, the context information regarding the mobile terminal STA may include data regarding services used by the mobile terminal STA, security information such as a user profile, a data session key, and the like. The AP device AP21 reconstructs the user environment related to the mobile terminal STA based on such context information, thereby completing the handover.

  Further, after handing over the mobile terminal STA to the AP device AP21, the AP device AP21 generates the mobility information of the mobile terminal STA in the ESS2, and transmits the generated mobility information to the local authentication server AAAL for storage.

  The second handover process is described below. In the second handover, the original access point device is changed to the AP device AP21, the target access point device is changed to the AP device AP22, and both the original ESS and the target ESS are changed to ESS2.

  When the mobile terminal STA enters the coverage area of the AP device AP22, the mobile terminal STA disconnects the Layer 2 connection with the AP device AP21 and transmits a reassociation request to the AP device AP22. The request includes the service set ID BSSID of the AP device AP21 and the MAC address of the mobile terminal STA. After the AP device AP22 receives the reassociation request (step S401), the AP device AP22 acquires the mobility information of the mobile terminal STA in the ESS2 from the local authentication server AAAL (step S405). Since the mobility information of the mobile terminal STA in the ESS 2 is already stored on the local authentication server AAAL, the local authentication server AAAL discovers the mobility information of the mobile terminal STA locally, and the mobility information together with the authentication information is AP device. Return to AP22. Here, the mobility information of the mobile terminal STA includes the MAC address of the mobile terminal STA, the MAC address and IP address of the AP device AP21, the IP address of the home agent server HA, and the IP address of the foreign agent server FA21. .

  The AP device AP22 compares the IP address of the AP device AP21 with the IP address of the AP device AP22 and finds that the two IP addresses belong to the same network segment. Therefore, the AP 22 determines that the roaming for the mobile terminal STA is intra IP subnet roaming (step S410). Next, the AP device AP22 performs an IAPP protocol-based handover (step S420).

  In step S420, first, the AP device AP22 receives context information regarding the mobile terminal STA from the AP device AP21, and the context information can be implemented by an IAPP message. The AP device AP22 then reconstructs the user environment for the mobile terminal STA based on the received context information, thereby completing the handover.

  Further, after handing over the mobile terminal STA to the AP device AP22, the AP device AP22 generates new mobility information of the mobile terminal STA in the ESS2, and transmits the generated new mobility information to the local authentication server AAAAL for storage. To do.

  It should be noted that the mobile terminal may be any type of wireless access enabled terminal device such as a portable computer, mobile phone, personal digital assistant (PDA), etc.

  FIG. 5 shows a schematic block diagram of an access controller 500 according to one embodiment of the invention. This embodiment will be described in detail with reference to the drawings, and the description of the same parts as those of the previous embodiment will be appropriately omitted.

  As shown in FIG. 5, the access controller 500 of this embodiment includes a receiving module 501 that receives from a requesting access point device that seeks roaming for the mobile terminal, and the mobile terminal in the original ESS based on the request. A mobility information acquisition module 502 that acquires mobility information, and a roaming determination module 503 that determines whether roaming for a mobile terminal is inter-IP subnet roaming or intra-IP subnet roaming based on the acquired mobility information When the roaming determination module 503 determines that roaming is inter-IP subnet roaming, mobile IP (MIP) based handover is performed, and the roaming determination module 503 performs roaming to the intra IP subnet. Roaming and when it is judged,, and a handover module 504 to implement the IAPP-based handover.

  In the access controller 500, the reception module 501 includes the REASSOCIATE. request request and MOVE. A request related to roaming for a mobile terminal is received from an AP device controlled by the receiving module 501 such as a request request. The mobility information acquisition module 502 then acquires the mobility information of the mobile terminal in the original ESS, and the mobility information includes AP device, access controller, and mobile agent server information associated with the mobile terminal. Specifically, the mobility information includes the MAC address of the mobile terminal, the MAC address and IP address of the associated AP device, the MAC address and IP address of the associated access controller, the IP address of the home agent server, and the associated Contains the IP address of the foreign agent server.

  In the mobility information acquisition module 502, the extraction unit 5021 extracts the service set ID BSSID of the original access point device related to the mobile terminal, the MAC address of the mobile terminal, and the like from the request received by the reception module 501. Next, the request unit 5022 requests the local authentication server to authenticate the mobile terminal and transmit the mobility information of the mobile terminal based on the extracted service set ID of the original access point device and the MAC address of the mobile terminal. . The receiving unit 5023 receives the authentication information and mobility information of the mobile terminal from the local authentication server and supplies it to the roaming determination module 503. Here, the mobility information of the mobile terminal includes the MAC address of the mobile terminal, the MAC address and IP address of the original access point device, the MAC address and IP address of the original access controller, the IP address of the home agent server, As well as the IP address of the original foreign agent server.

  In the roaming determination module 503, the comparison unit 5031 sets the IP address of the original access point device and the IP address of the access point device currently receiving the reassociation request from the mobile terminal to the same network segment. Compare whether or not they belong. If the comparison result of the comparison unit 5031 is that the two IP addresses belong to the same network segment, the first determination unit 5032 determines that the roaming for the mobile terminal is intra IP subnet roaming. When the comparison result of the comparison unit 5031 indicates that the two IP addresses do not belong to the same network segment, the first determination unit 5032 determines that the roaming for the mobile terminal is the inter IP subnet roaming.

  Next, the handover module 504 performs a corresponding handover based on the result of the roaming determination module 503. When the roaming determination module 503 determines that roaming is inter-IP subnet roaming, the handover module 504 performs a MIP-based handover. Here, in the handover module 504, the registration unit 5041 registers the IP address of the target foreign agent server with the home agent server and requests the home agent server to update the binding. A tunnel establishment unit 5042 establishes a data transfer tunnel between the target foreign agent server and the home agent server. Next, the context information transmission unit 5043 transmits the context information regarding the mobile terminal between the target foreign agent server regarding the mobile terminal and the original foreign agent server. A reconstruction unit 5044 reconstructs the user environment related to the mobile terminal based on the context information. After reconstructing the user environment for the mobile terminal with the access controller 500, the notification unit 5045 notifies the current access point device that the handover is complete.

  When the roaming determination module 503 determines that roaming is intra IP subnet roaming, the handover module 504 performs an IAPP protocol based handover. Here, in the handover module 504, first, the second determination unit 5046 compares the IP address of the access controller 500 with the original access controller for the mobile terminal, so that the two are the same access controller. Determine whether or not. When the second determination unit 5046 determines that the two access controllers are different access controllers, the context information transmission unit 5043 receives context information about the mobile terminal from the original access controller. A rebuild unit 5044 then rebuilds the user environment for the mobile terminal, and a notification unit 5045 notifies the current access point device that the handover is complete.

  Further, the access controller 500 includes a mobility information generation module 505 that generates mobility information of mobile terminals in the current ESS, and a mobility information transmission module 506 that transmits the generated mobility information to a local authentication server for storage. be able to. For example, the mobility information transmission module 506 transmits mobility information by an EAP message.

  Note that the access controller 500 of this embodiment is operable to implement the roaming method for mobile terminals in the WLAN shown in FIG.

  FIG. 6 is a schematic block diagram of an access point device 600 according to one embodiment of the invention. This embodiment will be described in detail with reference to the drawings, and the description of the same parts as those of the previous embodiment will be appropriately omitted.

  As shown in FIG. 6, the access point device 600 of this embodiment includes a receiving module 601 that receives an access request for roaming from a mobile terminal, and a mobile terminal in the original ESS based on the received access request. A mobility information acquisition module 602 that acquires mobility information, and a roaming determination module 603 that determines whether roaming for a mobile terminal is inter-IP subnet roaming or intra-IP subnet roaming based on the acquired mobility information When the roaming determination module 603 determines that the roaming is the inter IP subnet roaming, the mobile IP-based handover is performed, and the roaming determination module 603 determines the roaming as the intra IP subnet roaming. When it is determined that the grayed, and a handover module 604 to implement the IAPP-based handover.

  In the access point device 600, the reception module 601 includes REASSOCIATE. An access request related to roaming transmitted by a mobile terminal, such as a request, is received. Next, the mobility information acquisition module 602 acquires the mobility information of the mobile terminal in the original ESS based on the access request. In this embodiment, the mobility information includes access point device and mobile agent server information associated with the mobile terminal. Specifically, the mobility information includes the MAC address of the mobile terminal, the MAC address and IP address of the associated access point device, the IP address of the home agent server, and the IP address of the associated foreign agent server. Including.

  In the mobility information acquisition module 602, the extraction unit 6021 first extracts the service set ID (BSSID) of the original access point device related to the mobile terminal, the MAC address of the mobile terminal, and the like from the received request. Based on the service set ID of the original access point device extracted by the extraction unit 6021 and the MAC address of the mobile terminal, the request unit 6022 performs authentication of the mobile terminal and transmission of mobility information of the mobile terminal on the local authentication server To request. The receiving unit 6023 receives the mobile terminal authentication information and mobility information from the local authentication server.

  The mobility information acquisition module 602 supplies the acquired mobility information of the mobile terminal to the roaming determination module 603, and determines whether the roaming for the mobile terminal is inter IP subnet roaming or intra IP subnet roaming. . In the roaming determination module 603, the comparison unit 6031 compares whether the IP address of the original access point device related to the mobile terminal and the IP address of the access point device 600 belong to the same network segment. When the comparison result of the comparison unit 6031 indicates that two IP addresses belong to the same network segment, the determination unit 6032 determines that the roaming for the mobile terminal is intra IP subnet roaming. When the comparison result of the comparison unit 6031 indicates that the two IP addresses do not belong to the same network segment, the determination unit 6032 determines that the roaming for the mobile terminal is the inter IP subnet roaming.

  The handover module 604 then performs a corresponding handover based on the result of the roaming determination module 603. When the roaming determination module 603 determines that roaming is inter-IP subnet roaming, the handover module 604 performs a MIP-based handover. In this case, in the handover module 604, the registration unit 6041 registers the IP address of the target foreign agent server with the home agent server and requests the home agent server to update the binding. A tunnel establishment unit 6042 establishes a data transfer tunnel between the target foreign agent server and the home agent server. On the other hand, the context information transmission unit 6043 transmits the context information regarding the mobile terminal between the target foreign agent server regarding the mobile terminal and the original foreign agent server. A reconstruction unit 6044 reconstructs the user environment related to the mobile terminal based on the context information.

  When the roaming determination module 603 determines that roaming is intra IP subnet roaming, the handover module 604 performs an IAPP protocol based handover. In this case, in the handover module 604, the context information transmission unit 6043 receives the context information regarding the mobile terminal from the original access point device regarding the mobile terminal, and supplies the context information to the reconstruction unit 6044 to move the mobile terminal. Reconstruct the user environment for the terminal.

  Further, the access point device 600 of this embodiment includes a mobility information generation module 605 that generates mobility information of a mobile terminal in the current ESS, and mobility information that transmits the generated mobility information to a local authentication server for storage. A transmission module 606. For example, the mobility information transmission module 606 can transmit mobility information by an EAP message.

  Note that the access point device 600 of this embodiment is operable to implement the roaming method for mobile terminals in the WLAN shown in FIG.

  In the above embodiment, the access controller, the access point device, and each component include a hardware circuit such as a large-scale integrated circuit and a gate array, a semiconductor such as a logic chip and a transistor, or a field programmable gate. Can be implemented with programmable hardware devices such as arrays and programmable logic devices, or can be implemented with software running on various types of processors, or a combination of the above hardware circuits and software Note that you can.

  While the roaming method for a mobile terminal in a WLAN of the present invention and the associated access controller and access point device have been described above by way of exemplary embodiments, such embodiments are not exhaustive and are not exhaustive. Various changes and modifications can be realized within the spirit and scope of the present invention. Accordingly, the invention is not limited to such embodiments, but the scope of the invention is defined only by the appended claims.

Claims (1)

A roaming method for a mobile terminal in a wireless local area network including a plurality of extended service sets (ESS), each of the plurality of ESSs comprising at least one access controller (AC) and at least two Including an access point (AP) device, wherein each access controller is operable to configure, control and manage at least one AP device, the roaming method comprising:
A target AP device receiving an access request for roaming from the mobile terminal;
A target AC to which the target AP device belongs obtains mobility information of the mobile terminal in the original ESS based on the access request, the AP information associated with the mobile terminal, AC, And mobile agent server information, and
The target AC determining whether the roaming for the mobile terminal is inter-IP subnet roaming or intra-IP subnet roaming based on the acquired mobility information;
When the target AC determines that the roaming is the inter-IP subnet roaming, the target AC performs a mobile IP (MIP) based handover;
The target AC performing an inter-access point protocol (IAPP) based handover when determining that the roaming is the intra IP subnet roaming.

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