KR20080050242A - Method and apparatus for supporting seamless handover using multiple wireless interface in mobile terminal - Google Patents

Abstract

A method and an apparatus for supporting seamless mobility using a multi-radio interface in a mobile terminal are provided to support fast handover without requesting changing or adding a function in an AR(Access Router). A main controller(110) initializes a multi-radio interface in standby state, generates active and standby tunnels and switches the active tunnel into the standby tunnel in an initiated state. A searching unit(140) periodically searches connection points connected to each interface. An interface handover processing unit(120) selects an optimum connection point from among the searched connection points, determines active and standby interfaces according to a state of each interface when the initiated state is confirmed, and requests the main controller to generate the active and standby tunnels and switch the tunnels according to a state of a radio link with respect to the determined active and standby interfaces. An interface state selection unit(124) includes functions related to an active tunnel creation request, a standby tunnel creation request and a tunnel switchover request.

Description

METHOD AND APPARATUS FOR SUPPORTING SEAMLESS HANDOVER USING MULTIPLE WIRELESS INTERFACE IN MOBILE TERMINAL}

The present invention relates to a method and apparatus for supporting Internet Protocol Version 6 (IPv6) mobility, and more particularly to a method and apparatus for supporting seamless mobility using multiple radio interfaces of different types in an IPv6 mobile terminal. It is about.

When the IPv6 terminal moves to a new network different from the old network and performs handover, the mobile terminal disconnects from the old network and connects to the new network to perform communication. However, services that must be provided in real time are interrupted due to a handoff delay before being connected to a new network. This is similar to the conventional mobile IPv6 (hereinafter referred to as MIPv6), when the mobile node searches for a new access point, the service is interrupted because the second layer (L2) handover is performed after the second layer (L2) handover is performed. It does not provide a seamless service.

Therefore, in order to reduce the handover delay in the MIPv6, the Institute for the Future (IFTF) performs IPv6 fast handover (FTP Handover for Mobile IPv6 or lower, FMIPv6) so that a three-layer handover may be performed before a two-layer handover occurs. Technology). The FMIPv6 is a protocol for reducing the overall handover delay in the L3 layer by quickly detecting the movement and acquiring a new care of address (NCoA) based on the handover prediction information in the L2 layer.

However, the IPv6 fast handover must have a function of buffering data traffic while moving and use signaling with a home agent. Therefore, the IFTF increases the complexity of the terminal for IPv6 fast handover, and the access router supports only IPv6.

However, IPv6 and IPv4 networks coexist so that support for IPv4 is required. In this regard, IFTF proposes a draft for supporting IPv4 in an access router, but it is only for supporting mobility using an IPv4 network, but because it does not consider a method for fast handover, it is heterogeneous. It is difficult to perform seamless handover between manganese.

Meanwhile, in order to support seamless handover between different heterogeneous networks, IEEE 802.21 has standardized a media independent handover (MIH) technology. It provides an event service, a command service, an information service, and the like, and the upper layer of the MIH is provided with appropriate network information through the MIH to perform an optimized handover.

However, the MIH technology has a problem in that overhead exists because a function for MIH should be added in network equipment as well as the existing mobile terminal.

Accordingly, an object of the present invention is to provide a method for supporting seamless mobility between heterogeneous networks in an IPv6 mobile terminal having heterogeneous multiple air interfaces.

In addition, an object of the present invention is to optimize the overall handover time by switching the active / standby interface according to the radio link state in the mobile terminal to reduce the second layer (L2) handover time and the third layer (L3) handover delay time To provide a seamless mobility support method for.

The method for achieving the object of the present invention, the process of performing the second layer (L2) agreement by selecting an optimal connection point of the connection points connected to a plurality of heterogeneous interfaces it has, and the state of each interface Determining an active / standby interface according to the method, configuring an internet protocol address for each interface, creating a tunnel for the determined active / standby interface, and transmitting / receiving a mobile message; Periodically searching for a radio link state of an active / standby interface, switching a tunnel for the generated active / standby interface according to the search result, and transferring a transfer message to the switched active interface It characterized in that it comprises a process.

An apparatus for achieving the objects of the present invention includes a main controller for initializing multiple air interfaces in a ready state, creating active and standby tunnels in an initiation state, and transferring the active tunnels to a standby tunnel; A search unit periodically searching for connected connection points, and selecting an optimal connection point among the connection points searched from the search unit in the ready state, and determining the active and standby interfaces according to the state of each interface when the start state is confirmed. And an interface handover processing unit for making the active and standby tunnel creation request and the tunnel switch request to the main control unit according to the determined radio link state for the active and standby interface.

As described above, the present invention sets up an active and standby tunnel using two or more IPv6 connectivity, i.e., heterogeneous air interface, in the mobile terminal to switch the active and standby tunnels according to the radio link state, thereby removing a new connection. It can be configured to switch over quickly, reduce overall handover time without having to update L3 information, and enable the access router to support fast handover without changing or adding functionality.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a block diagram showing the structure of an IPv6 mobility support system according to an embodiment of the present invention.

Referring to FIG. 1, an IPv6 mobility support system according to an embodiment of the present invention includes a mobile terminal 10 of an IPv6 client (xGMIP Mobility IPv6 Client) and an IPv6 server (xGMIP Mobility IPv6 Server) to support mobility of an IPv6 terminal. 30 is configured as an access router (ACR) 20a or an access point (AP) 20b for connecting them via an IPv4 / IPv6 network. The access router 20a connects to the mobile terminal 10 of the client through a base station (RAS) 21. The access point 20b and the base station 21 will be collectively described as a point of attachment (POA) connected to a mobile terminal.

The mobile terminal 10 of the client determines the access point according to the movement of the terminal, requests a tunnel to the server 30 using the information of the client, and transmits its IPv6 home address information as binding information to itself and the A tunnel (IPv6-over-IPv4 or IPv6-over-IPv6) between the servers 30 is established.

The mobile terminal 10 of the client may have two or more different interfaces such as WiFi, Wibro, and 3GPP. In an embodiment of the present invention, the mobile terminal has an 802.11 WiFi interface and an 802.16 WiBro interface. It will be described with an example for having an association.

Such a function of the mobile terminal 10 of the client is a function for transmitting and receiving a mobility message (Mobility Message) with the server (xGMIP Mobility Messaging Function), the current for each interface through the scanning (Scanning) for the air interface Heterogeneous Interface Scanning Function, and the IP Configuration Function to determine the active / standby interface and configure the IP information for each interface based on the collected state information of each interface.

Meanwhile, states can be defined in five steps to manage the interface in the mobile terminal 10, and these interface states will be described with reference to FIG.

The states for managing the interface are: Disabled (51), Ready (52), Initi (53), Active (54), Standby (55) Can be defined as Here, the suspended state 51 means that the interface is physically incapable of communication, and the ready state 52 is a state initialized by the terminal to determine an optimal access point (POA), and is required to obtain an IP address. The initiation state 53 means a state in which communication is possible by acquiring an IP address. In addition, the active state 54 means a state in which the terminal is communicating, and the standby state 55 means a state always ready for providing seamless mobility.

Next, a device for supporting mobility by periodically checking the interface state of the mobile terminal 10 will be described with reference to FIG. 2.

The mobility support apparatus in the mobile terminal 10 is largely divided into a main controller 110 and a heterogeneous interface handover function 120, and a dynamic host is configured in the main controller 110. The communication protocol (hereinafter referred to as DHCP) client 130 may be connected, and the search unit 140 may be connected to the interface handover processing unit 120.

The main controller 110 may include an initialization unit 111, an event receiver 112, and a tunnel manager 113, and initialize a plurality of heterogeneous interfaces owned by the mobile terminal 10. It includes function to do. The main controller 110 may maintain one active interface and a plurality of standby interfaces, and generate and transfer active and standby tunnels at the request of the interface handover processor 120. Here, the event receiver 112 includes an access point (POA) agreement (L2 agreement) event and a new address event (New_ADDR event) function. The tunnel manager 113 includes an active tunnel creation, a standby tunnel creation, and a tunnel switchover execute function.

The interface handover processing unit 120 includes an interface scanning control unit 121, an optimal connection point selecting unit 122, an IP address configuring unit 123, and an interface state selecting unit 124. Here, the interface state selector 124 includes an active tunnel creation request, a standby tunnel creation request, and a tunnel switch request function.

Meanwhile, the handover time that may occur in the mobile terminal according to an embodiment of the present invention may be represented by the sum of the L2 handover time indicated by the change of the L2 agreement and the L3 handover time indicated by the change of the L3 router.

A mobility support method using multiple air interfaces in an IPv6 mobile terminal having the structure as described above will be described in detail with reference to the accompanying drawings.

First, an operation flow for mobility support of the mobility support apparatus as illustrated in FIG. 2 will be described with reference to FIG. 4.

2 and 4, when the mobile terminal 10 is driven, the current state transitions from the suspended state 51 to the ready state 52. Then, in operation 301, the main controller 110 of the mobile terminal 10 notifies the interface handover processor 120 after performing initialization through the initialization unit 111. Here, the ready state 52 may be classified into three types, the first of which is when the agreement with the access point is not established, the second when the IP address is not obtained, and finally, the IP of the default route. If you do not know the address and MAC address. In this ready state 52, the mobile terminal 10 may transition to the next starting state 53 by checking each case and repeating the necessary operation in that step. This can be compensated for by the periodic state management of the interface for instability on the wireless link.

Therefore, in step 302, the interface handover processing unit 120 performs an initialization in the ready state 52, and then requests the interface access point search to the search unit 140. Accordingly, in step 303, the searcher 140 searches for access points of multiple heterogeneous interfaces of the mobile terminal 10, and notifies the interface handover processor 120 of the search result.

The interface handover processing unit 120 receiving the search result selects an optimal connection point among the searched connection points in step 304 and performs an L2 agreement event to the main control unit 110 in order to connect with the optimal connection point selected in step 305. Occurs. Accordingly, when the L2 agreement event is received, the event receiving unit 112 of the main control unit 110 transmits the L2 agreement event to the DHCP client 130 using the information on the optimal access point. Accordingly, the DCHP client 130 generates a new address event (NEW_ADDR event) to the event receiver 112.

Then, in step 306, the event receiver 112 of the main controller 110 transmits the new address event to the interface handover processor 120. Accordingly, in step 307, the interface handover processing unit 120 obtains a new IP address (default router address and MAC address) from a DHCP server (not shown) through a DHCP client 130 to obtain an IP address for the access point. Configure. In this process, the mobile terminal 10 transitions from the ready state 52 to the start state 53 to obtain an IP address through the L2 agreement with the selected access point.

Thereafter, when the transition to the start state 53 is confirmed, the interface handover processing unit 120 determines whether an interface of the active state 54 exists by determining whether to set an active interface. Accordingly, in operation 308, the interface handover processor 120 requests an active interface search to the searcher 140, and receives the search result from the searcher 140 in operation 309. If the active interface does not exist by checking the search result, in step 310, the tunnel management unit 130 of the main controller 110 requests the generation of an active tunnel. Accordingly, in step 311, the tunnel manager 130 determines an active interface for the selected access point, creates an active tunnel, and starts communication.

In operation 308 and 309, the interface handover processing unit 120 receives a search result from the search unit 140 by making a standby interface search request. If there is an active interface and there is no standby interface, in step 310, the interface handover processing unit 120 requests the tunnel manager 130 to create a standby tunnel. Accordingly, in step 311, the tunnel manager 130 determines a standby interface for the selected access point and creates a standby tunnel. When the standby interface is set, the main controller 110 prepares to receive the L2 event to ensure seamless mobility.

In operation 312, the interface handover processor 120 periodically receives the monitoring result of each interface from the searcher 140 to determine each interface state. Based on the result, the interface handover processor 120 makes a tunnel switch request (L2 event) to the tunnel manager 113 of the main controller 110 in step 313. Then, in step 314, the tunnel manager 113 of the main controller 110 performs the switching to change the active and standby tunnels.

A process for mobility support according to the operation of the mobility support apparatus of the mobile terminal will be described in more detail with reference to the accompanying drawings.

5 is a diagram illustrating a process for supporting mobility in a mobile terminal according to an embodiment of the present invention.

Referring to FIG. 5, in step 401, the mobile terminal 10 of the client initiates initialization of an interface, and then, in step 402, an appropriate access point (POA) is searched for each interface of the client. At this time, the connection point list is generated using the information on the found connection point. Then, in step 403, the mobile terminal 10 selects the most appropriate access point from the searched access point list and performs L2 association with the selected access point. After the L2 agreement is completed, the mobile terminal 10 notifies the IP configuration function (not shown) of the internal L2 agreement result.

Then, in step 403, the mobile terminal 10 determines the active and standby interfaces based on the interfaces possessed by the IP configuration unit, requests IP information from the server 30 in step 404, and obtains the IP from the server 30. Based on the information, a temporary address (CoA: Care-of-Address) for each interface is determined to perform interface IP configuration. In this case, since the selected access point may be IPv4 or IPv6, different methods are used for each. In this case, DHCPv4 is used for IPv4, and IPv6 stateful (DHCPv6) or stateless IP configuration method is used for IPv6.

Thereafter, in step 405, the mobile terminal 10 transmits / receives a mobile message that is a ready message for handover with the server 30 through the determined active and standby interface, and then establishes a tunnel with the server 30 to perform communication. To start. At this time, the mobile terminal 10 periodically monitors the state of each interface.

Accordingly, the mobile terminal 10 compares the radio link state of the active / standby interface with the standard threshold value through the searcher 140. This will be described with reference to FIG. 2 again.

As a result of the comparison, if the active interface radio link state falls below the standard threshold value, the searcher 140 of the mobile terminal 10 performs an active interface change triggering on the interface state selector of the interface handover processor 120. 124). Accordingly, the interface state selector 124 determines that the tunnel of the active interface needs to be switched to the standby tunnel. On the other hand, when the radio link state of the standby interface falls below the standard threshold value, the searcher 140 generates an interface interface selection point (AP) change triggering to the interface state selector 124. Accordingly, the interface state selector 124 confirms that new connection point setting is necessary. Accordingly, the interface handover processing unit 120 requests the tunnel switching through the result confirmed by the tunnel management unit 113 of the main controller 110.

Therefore, in step 406, the mobile terminal 10 checks whether the interface state selector 124 needs to establish a new connection point of the standby interface. That is, the mobile terminal 10 checks whether an optimal connection point change is necessary while transmitting data through the active tunnel. As a result of the check, if a new access point needs to be set, in step 407, the existing L2 agreement is terminated and changed to a new standby interface to perform an L2 agreement to the new access point connected to the changed standby interface, and in step 408, the IP for the new access point is determined. After configuring the address, proceed to step 409. Referring to this process again with reference to FIG. 2, when the main control unit 110 receives the L2 event requesting a new connection point setting, the tunnel management unit 113 deletes the tunnel of the standby interface, and prepares the state ( 52). At this time, since the search unit 140 periodically monitors the link state, the interface handover processing unit 120 determines that the standby interface does not exist and notifies the tunnel management unit 113 of this. Accordingly, the tunnel manager 130 sets one interface of the start state 53 among the interfaces as the standby interface. Through this setting, if both the active interface and the standby interface exist in the interface that the mobile terminal currently has, the mobile terminal 10 manages the interface in the start state 53. This is to periodically check the interface and if there is no standby interface at any moment, it is used as a standby interface to support seamless mobility at any time.

On the other hand, if the new access point is not found in step 406, the mobile terminal 10 checks whether there is an active interface change request in step 409. If there is no active interface change request, the process proceeds to step 406. On the other hand, upon receiving an active interface change request (L2 event), the mobile terminal 10 changes the state of the standby interface to the active interface and the active interface to the standby interface through the tunnel manager 113 of the main controller 110 in step 410. Perform the transfer. The mobile message is then switched to the tunnel for the changed active interface and sent to the server 20.

Thereafter, the mobile terminal 10 transmits a tunnel request message to the server 20 using the changed active interface and the standby interface. The server 20 creates a tunnel interface and transmits a tunnel response message including a BID and preference information for distinguishing an active tunnel from a standby tunnel. Accordingly, the mobile terminal 10 receives the tunnel response message, generates the changed active interface and standby tunnel, and generates a binding update message including its home address HoA through the active tunnel. To send). Then, the server 20 allocates the binding information to the generated tunnel by using the information included in the received binding update message, and then transmits a binding acknowledgment message to the mobile terminal 10. Accordingly, the mobile terminal 10 assigns binding information to the tunnel. The generated tunnel may be IPv6-over-IPv4 or IPv6-over-IPv6 in the form of CoA.

As described above, in the embodiment of the present invention, by using two or more heterogeneous interfaces, the handover time can be reduced as a result of having no new L3 handover time by using the previously set L3 information after the L2 agreement is completed. .

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a block diagram illustrating a structure of an IPv6 mobility support system according to an embodiment of the present invention;

2 illustrates an interface state transition according to an embodiment of the present invention;

3 is a diagram illustrating a structure of an apparatus for supporting mobility in an IPv6 mobile terminal according to an embodiment of the present invention;

4 is a diagram illustrating an operation flow for mobility support in a mobility support device according to an embodiment of the present invention;

5 is a diagram illustrating a process for supporting mobility in a mobile terminal according to an embodiment of the present invention.

Claims (15)

Performing a second layer (L2) agreement by selecting an optimal connection point among the connection points connected to a plurality of heterogeneous interfaces, Determining an active / standby interface according to the state of each interface; Configuring an internet protocol address for each interface; Creating a tunnel for the determined active / standby interface and transmitting / receiving a mobile message; Periodically searching for a radio link state of the determined active / standby interface; Switching the tunnel for the generated active / standby interface according to the search result; A method of supporting seamless mobility using multiple radio interfaces in a mobile terminal, comprising: transferring a mobile message to the switched active interface. The method of claim 1, wherein the determining of the active / standby interface according to the state of each interface comprises: When the interface in the initiation state is identified, confirming the presence of the active interface, And determining the interface in the initiation state as an active interface if the active interface does not exist. The method of claim 2, wherein the determining of the active / standby interface according to the state of each interface comprises: Verifying the existence of the standby interface, If the active interface exists and the standby interface does not exist, determining the interface in the initiation state as a new standby interface, characterized in that the seamless mobility support method using multiple radio interfaces in a mobile terminal. The method of claim 3, The step of confirming the existence of the standby interface compares the state of the standby interface radio link with the standard threshold value, characterized in that seamless mobility support method using multiple air interfaces in the mobile terminal. The method of claim 3, wherein the determining of the interface in the starting state as a new standby interface comprises: Deleting the tunnel for the standby interface if the standby interface radio link status drops below a standard threshold; Setting a radio link state of the standby interface to a ready state; Setting the initiating interface as the new standby interface to perform an agreement with a new access point connected to the new standby interface; And configuring an internet protocol address of the new air interface.  The method of claim 2, wherein the determining of the interface in the starting state as a new standby interface comprises: If both the active and standby interfaces are present, managing the active and standby interfaces as an interface in an initiating state, further comprising: seamless mobility support method using multiple radio interfaces in a mobile terminal. The method of claim 1, wherein the switching of the tunnel for the generated active / standby interface comprises: Comparing the radio link status of the retrieved active interface with the standard threshold value; And switching the tunnel by changing the active interface to the standby interface and the standby interface to the active interface when the radio link state falls below the standard threshold value. How to support seamless mobility. A main control unit for initializing multiple air interfaces in a ready state, creating active and standby tunnels in an initiating state, and switching the active tunnels to a standby tunnel; A search unit for periodically searching for connection points connected to the respective interfaces; In the ready state, an optimal connection point is selected among the connection points retrieved from the search unit, and when the start state is confirmed, the active and standby interfaces are determined according to the state of each interface, and the radio link to the determined active and standby interfaces is selected. And an interface handover processor for making the active and standby tunnel generation request and the tunnel switch request to the main controller according to a state. The method of claim 8, The main control unit generates an event for acquiring a new address when the second layer agreement event for connection with the optimal access point is received from the interface handover processing unit in the ready state. Seamless mobility support device using interface. The method of claim 8, The main controller changes the generated tunnel by changing the active interface to the standby interface and the standby interface to the active interface when the radio link state of the active interface falls below the standard threshold. Seamless mobility support device using wireless interface. The method of claim 8, The interface handover processing unit checks the existence of the active and standby interfaces when the interface of the initiation state is confirmed, and determines that the interface in the initiation state is the active interface when the active interface does not exist, and the active interface exists. And if the standby interface does not exist, determining the interface of the starting state as a new standby interface. The method of claim 11, The interface handover processing unit deletes the tunnel for the standby interface when the standby interface radio link state falls below a standard threshold, sets the wireless link state of the standby interface to a ready state, and sets the interface of the initiation state to the new state. And setting an air interface to perform an agreement with a new access point connected to the new air interface, and to configure an internet protocol address of the new air interface. The method of claim 11, The interface handover processor confirms the existence of the active and standby interface by comparing the active and standby interface radio link status with the standard threshold value. .  The method of claim 11, And the interface handover processing unit manages the active and standby interfaces as interfaces in an initiation state when both the active and standby interfaces exist. The method of claim 8, And the interface handover processing unit determines an optimal access point for the standby interface.

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