KR20070113964A - Handover control system and method for controlling 3rd layer handover of mobile node - Google Patents

Abstract

The present invention relates to a handover control system and a method for performing a third layer handover of a mobile node. By providing a data service and generating a plurality of router and handover topology maps that periodically report the base station and its environment information to the handover control system, and map the current location of the mobile node to the handover topology map. The third layer handover time can be shortened to several tens of ms or less by providing a handover control system for searching for a target router in which a node is likely to handover, and then transmitting the retrieved target router's environmental information to the mobile node. Real-time multimedia services can be interrupted while the device is moving It has the effect that without being able to offer to their subscribers.

Description

Handover control system and method for controlling 3rd layer handover of mobile node {Apparatus and Method Controlling Layer 3 Handover of Mobile Node}

1 is a block diagram showing the configuration of a typical MIPv6 network.

2 is a flowchart illustrating a handover process of a typical MIPv6 network.

FIG. 3 is an exemplary view illustrating elapsed time during a handover process of the MIPv6 network described with reference to FIG. 2. FIG.

4 is a block diagram showing the configuration of a MIPv6 network according to an embodiment of the present invention.

5 is a block diagram showing the internal structure of a handover control system according to another embodiment of the present invention.

6 is a flowchart illustrating a method for collecting handover topology information of a handover control system according to the present invention.

7 is an exemplary diagram illustrating a handover topology map managed by the handover management module of the present invention.

8 is a flowchart illustrating a handover method using a handover control system according to another embodiment of the present invention.

9 is a block diagram showing a configuration of a network for performing a duplicate address checking procedure according to another embodiment of the present invention.

FIG. 10 is a flowchart illustrating a duplicate address checking process using a handover control system in the network of FIG.

11 is a block diagram showing the internal structure of a router according to another embodiment of the present invention.

FIG. 12 is a flowchart illustrating a duplicate address checking method of the router illustrated in FIG. 11.

Figure 13 is a block diagram showing the internal structure of a mobile node according to another embodiment of the present invention.

FIG. 14 is a flowchart illustrating a third layer handover method of the mobile node illustrated in FIG. 13.

15 is an exemplary view showing a handover time required based on a handover control system according to the present invention.

16 is a block diagram illustrating a mixed network configuration of MIPv4 and MIPv6 according to another embodiment of the present invention.

17 is a block diagram showing the internal structure of a handover control system according to another embodiment of the present invention.

18 is a flowchart illustrating a method for collecting handover topology information of a handover control system according to another embodiment of the present invention.

19A is an exemplary diagram illustrating a MIPv4 handover topology map according to another embodiment of the present invention.

19B is an exemplary diagram illustrating a MIPv6 handover topology map according to another embodiment of the present invention.

20 is a flowchart illustrating a MIPv4 handover method using a handover control system according to another embodiment of the present invention.

21 is an exemplary diagram illustrating a handover time required based on a handover control system according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: mobile node 20: first router (home agent)

30: second router 40: correspondence node

50: handover control system 51: network interface module

52: topology management module 53: handover management module

54: duplicate address handling module

The present invention relates to a handover control system and method for controlling a third layer handover of a mobile node.

The current Internet is based on Internet Protocol Version 4 (IPv4). In IPv4, a source transmits a packet including a source address and a destination address to the internet in order to transmit the packet to a destination. The IP address used by IPv4 consists of 32 bits, allowing up to about 4 billion hosts to access the Internet. However, due to the use of special addresses, subnetting, and network address assignment, the number of hosts that can actually connect to the Internet is quite small. In addition, due to the generalization of the Internet and the increase of multimedia traffic, efforts have been made to access the Internet as well as computers, mobile terminals, and information appliances unlike the past. The number of information appliances such as mobile communication terminals, televisions, and refrigerators is very large, and there is a shortage of IPv4 addresses for connecting these devices to the Internet. Therefore, the Internet Protocol Version 6 (IPv6) technology has been proposed to solve the shortage of IP addresses and to improve the performance of the Internet by supplementing the inefficiency of IPv4.

IPv6 has a 128-bit addressing scheme. As a result, IP addresses are richer than in IPv4, which has a 32-bit addressing scheme. On the other hand, if the address scheme increases to 128 bits, the time required to find the appropriate route may increase by increasing the contents of the routing table, which is necessary for the router to determine the route.However, IPv6 addressing scheme has more layers than IPv4. Because of its structure, it takes less time to find the proper route from the routing table.

Since IPv6 has an improved function compared to IPv4, it can solve the performance problems of the Internet due to the rapid increase in Internet traffic and the universal use of multimedia traffic.

On the other hand, the IP address assigned to a host consists of a network identifier and a host identifier. The network identifier is information for uniquely indicating the network to which the host is connected, and the host identifier is information for uniquely identifying the host in the network. The host assigned the IP address creates a socket address using the IP address and the port number of the transport layer, and establishes a connection with other hosts using the socket address.

Therefore, once one host (first host) establishes a connection with another host (second host), the same IP address must remain static for that host while the connection is established.

However, when the first host, which is established to be connected to the second host, moves to another network, such as a mobile environment, the network identifier must be changed, so the IP address assigned to the first host must be changed. Changing the IP address means changing the socket address, so that all existing connections are released and the connection must be retried.

In order to solve the problem of disconnection when the host changes the network to access the Internet, the IETF (Internet Engineering Task Force) proposes the Mobile IPv6 protocol (hereinafter, referred to as 'MIPv6'). . The MIPv6 protocol proposes a method for maintaining a previously established connection even when a mobile node (MN) changes and moves a network. That is, in the MIPv6 protocol, even if a mobile node connected to the Internet changes its connection point while establishing a connection with an arbitrary host (CN: Correspondent Node) on the Internet, It provides a mechanism to keep the connection intact.

On the other hand, due to the development of communication technology, not only a cellular network, but also a wireless network such as a wireless LAN and a Wibro are being constructed. The wireless network described above allows a user to use various multimedia services such as Voice over Internet Protocol (VoIP), Video Phone, IP-TV, and Video on Demand (VoD) in a wireless environment. However, in a wireless environment, when a user moves and provides a base station, the service may be interrupted. Therefore, handover technology is necessary to provide a continuous service even if a user moves. The handover technique is classified into a layer 2 handover and a layer 3 handover. The second layer handover occurs when the base station to which the user is connected changes, and the third layer handover occurs when the user moves to another IP subnet. In addition, the second layer handover is a process performed by each function of the cellular network, the wireless LAN, and the WiBro network, and the third layer handover is a process performed only by using the mobile IP (MIP) described above. This is to use the received IP address as it is.

1 is a block diagram showing the configuration of a typical MIPv6 network.

As shown in FIG. 1, the MIPv6 network includes a home agent (HA) 2, a mobile node 1 equipped with a MIPv6 function, a plurality of routers 2 and 3 and subordinate base stations 5-8. And a corresponding node 4.

The mobile node 1 is a terminal for receiving a user's Internet service, and the routers 2 and 3 are devices for relaying packets to the mobile node 1. The home agent 2 has a function of managing the address of the mobile node 1, and the corresponding node 4 provides a multimedia service or the like to the mobile node as any host on the Internet.

As shown in FIG. 1, when the mobile node 1 moves a base station, a handover process is performed.

2 is a flowchart illustrating a handover process of a general MIPv6 network.

In a general MIPv6 network, the handover process is performed when the mobile node 1 is connected to the second base station 6 under the home agent 2 and then to the third base station 7 under the second router 3. It will be described assuming.

First, the mobile node 1 belonging to the management area of the first router 2 which also performs the operation of the home agent is connected to the corresponding node 4 to transmit and receive data (S201). When the user of the mobile node 1 moves from the management area of the first router to the management area of the second router 3 (S202), the mobile node 1 detects the movement of the base station (S203). Specifically, the mobile node 1 moving to the management area of the second router 3 detects the movement in the third layer state through an Old Access Reachability Check or the like.

The mobile node 1 that detects the fact that the third layer handover is required transmits a router solicitation message (RS) to the second router 3 (S204).

Upon receiving this, the second router 3 generates a Router Advertisement Message (RA) including its own prefix information and transmits it to the mobile node 1 (S205). Receiving the routing request response message, the mobile node 1 extracts the prefix information and generates a care-of-address (CoA) by itself (S206).

The mobile node 1 notifies the auxiliary address generated in step S206 by transmitting a binding update message (BU) to the home agent 2 (S207). The home agent 2 registers the auxiliary address included in the binding update message in its database, and then sends a response to the mobile node 1 by binding binding acknowledgment message (S208).

Even after the binding update procedure of S207 and S208 is performed, the correspondent node 4 still transmits data to the mobile node 1 via the home agent 2 (S209). The home agent 2 encapsulates the data transmitted from the corresponding node 4 into the new secondary address of the mobile node 1 and tunnels it to the mobile node 1 (S210).

Meanwhile, the mobile node 1 may transmit data to the corresponding node 4 via the second router 3 (S211). However, the mobile node 1 performs a binding update process with the corresponding node 4 for routing optimization to remove the tunneling process of S210 (S212). This binding update process is performed through the exchange of the binding update message of S207 and the binding update acknowledgment message of S208. After performing the binding update process, the mobile node 1 directly transmits data with the corresponding node 4 without passing through the home agent 2 (S213).

FIG. 3 is an exemplary view illustrating elapsed time during a handover process of the MIPv6 network described with reference to FIG. 2.

As shown in FIG. 3, the third layer handover process includes a motion detection process, an auxiliary address generation process, and a binding update process.

The movement detection process takes 300ms, and the secondary address generation process takes about 1 second. Finally, the binding update process takes 10ms.

In the conventional MIPv6, as described above, the third layer handover is performed after the second layer handover is completed, but there is a problem that the third layer handover time is very long (1.3 seconds or more). In this case, since most handover time is consumed for about 1 second in the auxiliary address generation process, there is a need to greatly reduce the time of the auxiliary address generation process.

Accordingly, the present invention is to solve the problem according to the prior art, a search for a router that the mobile node is likely to move in advance, by combining the address of the router and the address of the mobile node to generate an auxiliary address, The present invention provides a handover control system and a method for enabling a quick handover.

The MIP network according to an aspect of the present invention provides a data service to a plurality of mobile nodes for providing a data service to a user, a mobile node existing in an area of a base station managed by the user, and periodically the base station and its environment information. Receive a plurality of routers and the environment information of the base station and the router to generate a handover topology map, and map the current location of the mobile node to the handover topology map to the mobile node to handover After searching for a target router for which there is a possibility, the system may include a handover control system for transmitting environmental information of the found target router to the mobile node.

The environment information of the router may include a router ID, a router interface information, a router prefix, a lower base station ID of each router, location information of each base station, or coverage information of each base station.

The handover control system may generate a candidate supplementary address by combining the prefix information of the target router and the MAC address of the mobile node, and transmit the generated candidate supplementary address to the mobile node. After performing the second layer handover, the mobile node sets the candidate auxiliary address received from the handover control system to its IP address. In this case, it is preferable that the handover control system generates a candidate auxiliary address and checks whether the candidate auxiliary address is duplicated to the found target router.

To check whether the candidate auxiliary address is duplicated, the handover control system transmits a DAD request message including the candidate auxiliary address to the target router to use the candidate auxiliary address. The router receiving the DAD request message transmits a neighbor request message to a plurality of lower base stations to check whether the candidate auxiliary address is duplicated, and checks whether the neighbor request response message has been received. If the generated candidate auxiliary address is a duplicate address, the handover control system combines the router prefix and an arbitrary address to regenerate the candidate auxiliary address and transmit it to the mobile node.

Meanwhile, the handover control system may generate a handover topology map for each MIP version supported by the base station. In this case, the handover control system checks the MIP version supported by the mobile node and searches for the target router by mapping the current location of the mobile node to the handover topology map according to the MIP version supported by the mobile node.

A handover control system of a MIP network according to another aspect of the present invention generates a handover topology map by using a topology management module that collects topology information of a plurality of routers and base stations, and topology information of base stations and routers, The mobile station may include a handover management module that searches for a target router having a possibility of handover by the mobile node by mapping a current location to a handover topology map, and then transmits the environment information of the found target router to the mobile node.

The handover control system may also include a handover topology table or mobile node including an ID of a router, interface information of a router, a prefix of a router, an ID of a lower base station of each router, location information of each base station, or coverage information of each base station. May further include a secondary address table including at least one of a MAC address, a base station ID to which the mobile node is movable, a candidate secondary address, a collision occurrence secondary address, or an entry expiration period.

The handover management module sends a topology response message including an ID of the target router, a candidate secondary address, and information on whether the candidate secondary address is duplicated, with respect to the topology request message requesting target router and base station information that may be handoverd. Send to node.

The handover control system may further include a duplicate address processing module for requesting a target router to check whether the candidate auxiliary address is duplicated.

Meanwhile, the handover topology map may be generated for each MIP version supported by the base station. The handover management module checks the MIP version supported by the mobile node and searches for the target router by mapping the current location of the mobile node to the handover topology map according to the MIP version supported by the mobile node.

According to another aspect of the present invention, a router managing a plurality of base stations includes a network interface module for communicating with a network component through an IP network, a topology information collecting module for collecting topology information of a lower base station managed by the router; The neighbor request message including candidate auxiliary address information is transmitted to a plurality of base stations managed by the network interface module through the network interface module, and the candidate auxiliary address is duplicated by using a neighbor request response message for the neighbor request message. It may include a duplicate address check module for determining whether or not. When the duplicate address check module receives the neighbor request response message for the neighbor request message, it determines that the candidate auxiliary address is a duplicate.

In addition, the router may further include a candidate secondary address table for storing at least one of a secondary address entry ID, a candidate secondary address, or an expiration period.

The mobile node according to another aspect of the present invention is a handover topology request unit for requesting information on a plurality of target routers capable of handover and candidate auxiliary addresses to the handover control system, wherein the mobile node moves to one of a plurality of target routers. The layer 2 trigger detector for detecting the end of the second layer handover according to the second layer handover; and when the layer 2 trigger detector detects the end of the second layer handover, the candidate auxiliary address information received from the handover control system is read. The apparatus may include a CoA setting unit configured to set an IP address of the mobile node, and may further include a binding update unit configured to perform binding update with a corresponding node after setting an IP address of a candidate auxiliary address. In this case, the handover topology request unit transmits the MIP version supported by the handover control system to the handover control system when requesting information of a plurality of target routers and candidate auxiliary addresses.

In the MIP network handover control method according to another aspect of the present invention, the handover control system receives the environment information of the lower router and the lower base station to generate a handover topology map, the mobile node has the possibility of handover Requesting a target router and information of the target router to a handover control system, and the handover control system maps a current location of a mobile node to the handover topology map, where a target node is likely to be handed over by a mobile node; After searching for, the method may include transmitting the found environment information of the target router to the mobile node.

The router environment information includes router ID, router interface information, router prefix, lower base station ID of each router, location information of each base station, or coverage information of each base station.

The handover control system transmits the information of the target router to the mobile node, the handover control system combines the prefix information of the target router and the MAC address of the mobile node to generate a candidate secondary address, the generated candidate The secondary address is transmitted to the mobile node. In this case, the mobile node sets the candidate auxiliary address received from the handover control system as its IP address after performing the second layer handover.

Meanwhile, the handover control system may further generate a candidate auxiliary address and then check whether the candidate auxiliary address is duplicated to the found target router. The step of checking whether the candidate auxiliary address is duplicated may include transmitting, by the handover control system, a DAD request message including the candidate auxiliary address to each target router, and the target router sends a plurality of neighbor request messages to the candidate auxiliary address. Transmitting to a lower base station, and determining whether a candidate auxiliary address is duplicated by using a target router whether or not a neighbor request response message is received from the lower base station. If the candidate auxiliary address is a duplicate address, the target router may further combine the prefix and any address to regenerate the candidate auxiliary address and notify the handover control system of the candidate auxiliary address.

On the other hand, the handover topology map generation step is more preferably to generate a handover topology map indicating the coverage of the base station for each MIP version. In this case, the target router discovery step of the handover control system includes checking the MIP version supported by the mobile node, the current location of the mobile node, and the handover topology map according to the MIP version supported by the mobile node. Searching for the target router by mapping to.

Hereinafter, a handover control system and a method for controlling to perform a third layer handover according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram showing the configuration of a MIPv6 network according to an embodiment of the present invention.

As shown in FIG. 4, the MIPv6 network includes an IP network including an L2 switch, an L3 switch, and a first router 20 and a second agent serving as a home agent (HA). Router 30, a plurality of wireless base stations 21, 22, 31, 32, mobile node 10, corresponding node 40, and handover control system 50 may be configured.

Here, the topology of the other components except for the handover control system 50 may be changed. For example, the home agent 20 may be located separately from the location shown in FIG. 4.

Since the basic operations of the router, the base station, the mobile node, and the corresponding node shown in FIG. 4 are similar to those of the general MIPv6 network, a description of the basic operations will be omitted.

5 is a block diagram showing the internal structure of a handover control system according to another embodiment of the present invention.

The handover assistant system (50) includes a network interface module (NIM) 51, a topology management module (TDM) 52, and a handover management module (HTM). Module (53), and a duplicate address processing module (DPM: DAD Process Module) (54).

The network interface module 51 is responsible for the function of connecting with the network equipment. In this case, the network interface module 51 may issue control commands to network devices using protocols such as Simple Network Management Protocol (SNMP), Command Line Interface (CLI), TCP / IP, and may transmit and receive data. . The topology management module 52 collects and manages topology information of an IP network and a wireless network. The topology management module 52 may acquire topology information by communicating with network devices using the network interface module 51. The topology management module 52 may separately store and manage the information in a network topology table (not shown).

The handover management module 53 configures and manages a topology for handover of the mobile node 10, and the duplicate address processing module 54 determines whether an auxiliary address previously generated by the mobile node 10 is a duplicate address. Duplicate address handling procedure will be performed. However, an object of the present invention is to reduce the handover time by generating the auxiliary address in advance. Accordingly, the duplicate address processing module 54 is a component for more efficiently reducing the handover time, and does not correspond to an essential component.

Hereinafter, the operation of each component will be described in the MIPv6 network shown in FIG. 4.

The topology management module 52 periodically collects first and second routers 20 and 30 and subordinate base stations 21, 22, 31, and 32 information through a protocol such as SNMP of the network interface module 51. The topology management module 52 may collect the topology of the IP network for network management purposes. In this way, the topology management module 52 that collects the network topology forms a network topology table, and organizes only the router and base station information related to the handover and transmits the information to the handover management module 53.

The handover management module 53 generates a handover topology table as shown in Table 1 below. As shown in Table 1, the handover topology table includes router information (Router ID), router interface information (Router Interface ID), IPv6 prefix information (IPv6 Prefix), router sub-base station ID, base station location, and base station coverage. ) Information and the like. Of course, the handover topology table may further include information included in a handover decision algorithm or the like. Hereinafter, the data flow between components during the process of collecting handover topology information will be described.

6 is a flowchart illustrating a method for collecting handover topology information of a handover control system according to the present invention.

The collection of handover topology information of FIG. 6 corresponds to a procedure previously performed by the handover control system 50 in order to perform the third layer handover according to the movement of the mobile node 10 in advance.

First, the topology management module 52 of the handover control system 50 collects topology information from a plurality of routers existing in the IP network (S601 and S602). In this case, the topology management module 52 may use protocols such as SNMP, CLI, and TCP / IP. The topology management module 52 may generate the topology table of the entire network by using the collected topology information (S603).

The handover related topology information is transmitted to the handover management module 53 of the handover control system 50 (S604). The handover related information includes ID of router, prefix, interface information, lower base station information, and the like. The handover management module 53 generates a handover topology table by using the received handover topology information (S605).

Since the processes of S601 to S605 do not end at one time, the topology of a router or a base station may change, and the handover control system periodically repeats the procedure for collecting the handover topology information (S606).

As described above, after creating the handover topology table, the handover management module 53 creates a handover topology map. The handover topology map prepared in this way shows the position coordinates and coverage information of the base station.

The handover topology map is used by the handover control system 50 to search for the location of the base station where the mobile node 10 is located and the adjacent base station where the mobile node 10 is likely to move. In detail, neighboring base stations having overlapping coverage with the base station where the mobile node 10 is located determine that the mobile node 10 may move, and provide information on each base station to the terminal. In addition, since the network topology collection procedure of the handover control system 50 is periodically performed at regular time intervals, the handover control system 50 may update the handover topology map even if a changed network topology exists. Hereinafter, the handover topology map created by the handover management module 52 will be described in more detail.

7 is an exemplary diagram illustrating a handover topology map managed by the handover management module of the present invention.

The handover management module 51 of FIG. 5 draws a management area of each base station by checking base station IDs stored in the table of Table 1, location coordinates for each base station ID, and coverage. A map of the management area for each base station is a handover topology map.

For example, when a map is drawn for the first base station 21, the handover management module 53 detects that the coordinate of the first base station 21 is (x1, y1). Accordingly, the handover management module 53 marks a point at the (x1, y1) coordinate and indicates that the point is the first base station 21.

In addition, the handover management module 53 checks that the coverage of the first base station 21 is K1. Accordingly, the handover management module 53 draws a circle having a radius K1 around (x1, y1), which is the coordinate of the first base station 21.

The handover management module 53 performs the same operation for the second, third, and fourth base stations 22, 31, and 32 repeatedly. When the repetitive work is completed, the handover topology map shown in FIG. 6 can be obtained.

Through this, the handover management module 53 may check the area where the mobile node 10 is likely to move to another base station. For example, the hatched A1 area corresponds to an area where there is a probability that the mobile node 10 will move from the first base station 21 to the third base station 31.

In the above, a method of briefly creating a handover topology map using the coordinates and coverage information of the base station has been described. However, the present invention is not limited to such a method of creating a topology map, and a more accurate handover topology map may be created by considering surrounding buildings and surrounding environment information. It has already been described that the handover topology table of Table 1 may include such information.

8 is a flowchart illustrating a handover method using a handover control system according to another embodiment of the present invention.

The mobile node 10 of FIG. 4 performs an initial access procedure with the first base station 21 (S801). When the connection is completed, the mobile node 10 starts data transmission and reception with the corresponding node 40 (S802). The mobile node 10 transmits a handover topology request message to the handover control system in order to obtain neighbor base station information, prefix information, and the like, in which the mobile node 10 may move (S803). The handover topology request message includes a MAC address of the mobile node 10, an ID of a base station to which the mobile node 10 is connected, and the like.

Upon receiving this, the handover management module 53 of the handover control system 50 grasps the position of the mobile node 10 on the handover topology map created as shown in FIG. 7, and has a probability of moving the mobile node. Search for a router (S804). In addition, the handover management module 53 extracts the prefix information of the base station, the router address to check the duplicate address, the interface information of the router, and the like, searched on the handover topology table of Table 1.

For example, referring to the MIP network of FIG. 4, the base stations with which the mobile node 10 may be handed over are the second base station 22 and the third base station 31. However, if the mobile node 10 exists in the area A1 of FIG. 7, the handover management module 53 will select the third base station 31 as a candidate router. After the selection of the candidate router, the handover management module 53 extracts the prefix information of the third base station 31 and the like.

The handover management module 53 generates a candidate auxiliary address, and requests the duplicate address processing module 54 to check whether the candidate auxiliary address is duplicated (S805). The handover management module 53 may generate the candidate auxiliary address by combining the found router prefix with the MAC address of the mobile node 10. The handover management module 53 informs a candidate auxiliary address (CoA) to perform the duplicate address check, a router (Router ID) to which the duplicate address check is to be performed, and interface information (Interface ID) of the router.

Thereafter, the duplicate address processing module 54 transmits a DAD request message to the router requested by the handover management module 53 and its interface (S806). The DAD request message includes a secondary address (CoA) to check for duplicate addresses, interface information (I / F ID) of a router to check for duplicate addresses, and the like.

In the above example, the DAD processing module transmits a DAD request message to the third base station. Upon receiving this, the second router 30 performs a duplicate address check process (S807). The duplicate address checking procedure of the router will be described in more detail with reference to FIG. 10.

After completing such a duplicate address check process, the second router 30 generates and updates a candidate auxiliary address table (S808). The candidate secondary address table is a table that manages candidate secondary addresses of mobile nodes that the router moves to its lower part, and may be configured as shown in Table 2 below.

As shown in Table 2, the candidate auxiliary address table stores information such as an auxiliary address entry ID, a candidate auxiliary address (candidate CoA), and an expiration time. If a DAD request message for the secondary address is not received within the expiration period, the duplicate address processing module 54 deletes the secondary address entry from the candidate secondary address table. This is in case the probability that the mobile node 10 moves to this router is lowered by moving to another place.

In addition, the router deletes the auxiliary address entry on the auxiliary address table when the address of the mobile node to be newly connected to the subordinate is equal to the auxiliary address on the candidate address table.

After performing the auxiliary address table update by the above-described process, the second router 30 transmits a DAD response message to the duplicate address processing module 54 in the handover control system 50 (S809). . The DAD response message includes information such as candidate auxiliary address, router interface ID, and duplicate address check result.

The duplicate address processing module 54 transmits the DAD processing result to the handover management module 53 based on the result of the DAD response message (S810). If a duplicate address is not found and a duplicate address is not found, the duplicate address processing module 54 transmits a DAD processing result including a DAD processing request ID, a flag indicating no duplicate address, and the like to the handover management module 53. do. On the contrary, if a duplicate address is found as a result of the duplicate address check, the duplicate address processing module 54 sends information to the handover management module 53 including information such as a DAD processing request ID, a flag indicating that a duplicate address exists, and a candidate secondary address. Deliver the result of DAD processing.

Upon receiving the DAD processing result, the handover management module 53 sends a handover topology response message including information such as ID, prefix, duplicate address check result, and candidate secondary address of the candidate base station to the mobile node. Transmit to 10 (S811). According to the network of FIG. 4, the mobile node 10 receiving the handover topology response message has a base station to which it can move, a third base station, a prefix of a connected router is pf2, and currently uses an address of pf2 :: MAC1. Information such as no terminal can be known.

In addition, the mobile node 10 may perform a movement detection in advance that the prefix of the router to which it is currently connected is pf1 and the prefix of the router to which the mobile base station is connected is pf2, so that a handover of the third layer is required (see FIG. S812). The mobile node 10 may previously generate an auxiliary address CoA of pf2 :: MAC1 using information included in the handover topology response message (S812). Since the secondary address has already been checked for duplicate addresses, no additional duplicate address check procedure is necessary. Accordingly, in the present invention, unlike the conventional MIPv6, the time required for the movement detection, the auxiliary address generation, and the duplicate address check process can be reduced, thereby greatly reducing the handover time of the third layer.

Even after the above process is completed, the mobile node 10 transmits a handover topology request message to the handover management module 53 at a predetermined period T1 (S813). This process is necessary for the mobile node to cope with the topology change and periodically block the possibility of address collision by performing the duplicate address check process.

Now, the process of actually performing the third layer handover by the mobile node will be described.

The second layer of the mobile node 10 transmits a second layer handover start trigger (L2 Handover Initiate Trigger) indicating the handover start to the third or more layer (S815). Receiving this, the mobile node 10 prepares for a third layer handover. When the mobile node 10 enters the area of the third base station 31, a second layer handover is performed (S817). After performing the second layer handover, the second layer of the mobile node 10 transmits a second layer handover finish trigger (L2 Handover Finish Trigger) to a third or more layer (S818).

Receiving this, the mobile node 10 sets the auxiliary address CoA of the mobile node to pf2 :: MAC1 (S819) and transmits a binding update message to the home agent 20 (S820). Of course, the home agent 20 receives the binding update acknowledgment message to the mobile node 10 (S821).

Since the binding procedure between the mobile node 10 and the corresponding node 40 has not been performed yet, data transmitted by the corresponding node 40 is encapsulated by the home agent 20 and tunneled to the mobile node 10 to be transmitted. (S822).

Meanwhile, the mobile node 10 transmits data to the corresponding node 40 via the third base station (S823). When the mobile node 10 transmits the binding update message to the corresponding node 40 to perform the binding procedure with the corresponding node 40 (S824), direct data transmission and reception between the mobile node 10 and the corresponding node 40 is performed. (S825).

9 is a block diagram showing a configuration of a network for performing a duplicate address checking procedure according to another embodiment of the present invention.

The duplicate address processing module 54 of FIG. 5 checks whether the candidate auxiliary address generated by the handover management module 53 overlaps. Hereinafter, a network of FIG. 9 will be assumed in order to explain a duplicate address check procedure.

The network shown in FIG. 9 includes a handover control system 50, a corresponding node 40, a mobile node 10, first, second and third routers 60-62 and base stations 63-68 below the router. And the like as a component.

In the present embodiment, it is assumed that the mobile node 10 is connected to the third base station 65, and the mobile node 10 can move to the second base station 64 and the fifth base station 67 as a result of the handover topology search.

FIG. 10 is a flowchart illustrating a duplicate address checking process using a handover control system in the network of FIG. 9.

In step S803, the mobile node 10 transmits a handover topology request message to the handover management module 53 (S1001).

The handover management module 53 searches the handover topology table, and searches for a candidate router having a probability that the mobile node 10 will move (S1002). Through this process, the mobile node 10 finds out that the base stations that can be moved are the second base station 64 and the fifth base station 67. As described in step S805, the handover management module 53 generates a candidate auxiliary address, and requests the duplicate address processing module 54 to check whether there is a duplicate (S1003). At this time, the handover management module 53 notifies the candidate auxiliary address in which the prefix of the candidate router and the MAC address of the mobile node 10 are combined, the ID of the router, and its interface information. Specifically, in the present embodiment, the handover management module notifies the information of [pf1 :: MAC1, router 1, if1], [pf3 :: MAC1, router 3, if3]. The duplicate address processing module 54 checks the duplicate address by transmitting a DAD request message to the first and third routers 60 and 62 (S1004 and S1008).

First, a duplicate address check procedure in the first router 60 is as follows. The first router 60 transmits a neighbor solicitation message to the mobile nodes 10 connected to the base station first base station 63 and the second base station 64 at step S1005. If the first router does not receive a Neighbor Advertisement Message after waiting for a predetermined time, the first router 60 determines that there is no address conflict of pf1 :: MAC1 under its interface. Therefore, the secondary address entry of the candidate secondary address table is maintained as it is and the expiration period is updated (S1006). Then, a duplicate address response message (DAD Response Message) of (pf1 :: MAC1, if1, no duplicate address) is transmitted to the duplicate address processing module (S1007).

The procedure at the third router 62 is as follows. Similar to the first router 60, the third router 62 transmits the neighbor request message to the terminals of the base station fifth base station 67 and the sixth base station 68 (S1009). If a neighbor advertisement response message is received from the base station A5 67 (S1010), the third router 62 uses an address of pf3 :: MAC1 among the lower terminals of the base station fifth base station 67. The presence of the terminal can be detected. Therefore, an update is performed to delete the entry of pf3 :: MAC1 on the candidate auxiliary address table (S1011). Thereafter, the third router 62 transmits the DAD response message of (pf3 :: MAC1, if3, duplicate address) to the duplicate address processing module 54 (S1012).

Upon receiving the address conflict result, the duplicate address processing module 54 determines a candidate auxiliary address for generating an auxiliary address (CoA) of the mobile node 10 and updates it on the candidate auxiliary address table (S1013). In the above example, the duplicate address processing module 54 determines pf1 :: MAC1 as a candidate secondary address when moving to the first router for which the duplicate address is not found. On the other hand, when moving to a third router for which a duplicate address is not found, pf3 :: X may be determined as a candidate secondary address.

Table 3 below is an example of an auxiliary address table generated by using the candidate auxiliary address determined by the duplicate address processing module 54.

As shown in Table 3, the candidate auxiliary address table includes information such as the MAC address of the mobile node, the mobile base station ID, the collision occurrence auxiliary address, the candidate auxiliary address, and the entry expiration period.

If a duplicate address check request is received from the handover topology management module 53, the duplicate address processing module 54 may request [Request ID = First Router, DAD Processing Result = No Duplicate Address, Candidate Secondary Address = Null]. And the processing result of [Request ID = third router, DAD processing result = duplicate address present, candidate auxiliary address = pf3 :: X)] (S1014).

Upon receiving this, the handover topology management module 53 responds to the mobile node 10 with the handover topology response of [A2, pf1, no duplicate address, null], [(A5, pf3, duplicate address, pf3 :: X]. Deliver the message (S1015).

Receiving this, the mobile node 10 generates pf1 :: MAC1 as a candidate secondary address for the second base station 64 and pf3 :: X recommended by the handover control system for the fifth base station 67. The candidate auxiliary address is generated (S1016). Through this process, the mobile node performs mobile detection and auxiliary address generation in advance.

Yet, candidate auxiliary addresses (pf3 :: X) recommended by the duplicate address processing module 54 of the handover control system 50 correspond to that the duplicate address check process has not yet been processed. This can be solved as follows.

In step S813, the mobile node 10 transmits a handover topology request message to the handover topology management module 53 at a period of T1 (S1017). The handover topology management module 53 transmits the DAD processing request message to the duplicate address processing module 54 after the candidate base station search (S1018) (S1019). The duplicate address processing module 54 searches the candidate auxiliary address table shown in Table 3 to determine whether a candidate auxiliary address exists (S1020). Referring to the candidate auxiliary address table, an address of pf3 :: MAC1 is stored for the first router 60 and an address of pf3 :: X is stored as the candidate auxiliary address for the third router 62. Duplicate address check request messages for pf3 :: MAC1 and pf3 :: X are transmitted to the first and third routers 60 and 62, respectively (S1021 and S1022).

The duplicate address processing module 54 receives a result of repeatedly performing a duplicate address checking process using the neighbor request message and the response message from the first and third routers 60 and 62 and informs the mobile node 10 of the result. This process is the same as the above-described process S1006, S1007, S1009 to S1015 will be omitted. Through such a periodic process, a duplicate address check of pf3 :: X randomly generated by the handover control system can be performed.

In addition, such a duplicate address check process of the arbitrarily generated address may be performed by the mobile node 10 including the candidate auxiliary address in the handover topology request message. The handover management module 53 requests duplicate checks of candidate secondary addresses stored in the handover topology request message transmitted by the mobile node 10, and the duplicate address processing module 54 replaces the secondary addresses received from the DAD processing request with duplicate addresses. To check. In this case, there is an advantage that the duplicate address processing module 54 does not need to check the mapping relationship between the address of the mobile node 10 and the candidate auxiliary address through the table of Table 3.

The process of FIG. 10 describes the processes of S803 to S814 in FIG. 8 in more detail. If the handover topology management module 53 does not receive a duplicate address check request for the secondary address within the expiration period, the duplicate address processing module 54 deletes the corresponding entry.

So far, the handover method focusing on the operation of the handover control system 50 proposed in the present invention has been described. Hereinafter, the structure and operation of a router and a mobile node according to another aspect of the present invention will be described.

11 is a block diagram showing the internal structure of a router according to another embodiment of the present invention.

As shown in FIG. 11, the router 70 may include a network interface module 71, a topology information collecting module 72, a duplicate address check module 73, a candidate auxiliary address table 74, and the like.

The network interface module 71 is responsible for the function of connecting with the network equipment. In this case, the network interface module 71 may issue control commands to network devices using a protocol such as SNMP, CLI, TCP / IP, and may transmit and receive data. The router 70 transmits and receives data with the base station or the handover control system 50 through the network interface module 71.

The topology information collection module 72 is responsible for collecting topology information of the lower base station. Upon receiving the topology information request from the handover control system 50, the topology information collecting module 72 controls the network interface module 71 to communicate with the lower base station to obtain the information.

In step S806, the duplicate address check module 73 controls the duplicate address check process by using the information of the DAD request message received from the handover control system 50. When the duplicate address check process is completed, the duplicate address check module 73 updates the candidate auxiliary address table 74 and at the same time serves to return a DAD response message to the handover control system 50. Of course, when the DAD request message for the candidate auxiliary address is not received for a predetermined period of time using a timer (not shown), the entry corresponding to the candidate auxiliary address is deleted.

FIG. 12 is a flowchart illustrating a duplicate address checking method of the router illustrated in FIG. 11.

First, the router determines whether a DAD request message is received from the handover control system 50 (S1201).

The duplicate address check module 73 of the router extracts the candidate auxiliary address (CoA) and the interface ID (I / F ID) included in the DAD request message, and transmits the extracted ID to the network interface module 71 (S1202).

The network interface module 71 transmits a neighbor solicitation message for the received candidate auxiliary address to a plurality of base stations connected to the corresponding interface (S1203).

The duplicate address check module 73 checks whether a neighbor advertisement response message for the neighbor request message is received (S1204).

If the neighbor request response message is received, the duplicate address check module 73 checks whether the auxiliary address is already stored in the candidate auxiliary address table 74, and deletes the entry (S1205).

On the other hand, if the neighbor request response message is not received for a predetermined period, the duplicate address check module 73 updates to add and modify an entry of the candidate auxiliary address table 74 (S1206). Specifically, if an entry of the auxiliary address already exists, the expiration period is updated. If the auxiliary address is not registered, the entry is newly registered.

The duplicate address check module 73 ends the duplicate address check process by returning the DAD response message including the duplicate address information of the candidate auxiliary address to the handover control system 50 (S1207).

13 is a block diagram showing the internal structure of a mobile node according to another embodiment of the present invention.

As shown in FIG. 14, the mobile node 80 may include second and third layer handover modules 82 and 82 and a network interface module 81. Of course, the mobile node 80 may include a user interface and various application programs to provide wireless services to the user. However, the mobile node 80 of FIG. 14 illustrates only components related to handover.

The network interface module 81 is responsible for communicating with the base station. The second and third layer handover modules 82 and 82 are responsible for the second and third layer handovers, respectively. In particular, the third layer handover module 83 may include a CoA setting unit 84, a layer 2 trigger detecting unit 85, a handover topology requesting unit 86, and a binding updater 87.

The layer 2 trigger detector 85 is a component that detects a time point when the second layer handover ends. When the second layer handover finish trigger is detected by the second layer handover module 82, the third layer handover is started.

The handover topology request unit 86 transmits a handover topology request message to the handover control system 50 to perform a third layer handover, and receives a response thereto. The response includes a candidate supplementary address, and the CoA setting unit 84 quickly performs a third layer handover using the address.

As such, when the CoA setting unit 84 changes the third layer address of the mobile node 80, the binding update unit 87 performs a binding update procedure with the base station and the corresponding node.

FIG. 14 is a flowchart illustrating a third layer handover method of the mobile node illustrated in FIG. 13.

The mobile node 80 may move while providing a service to a user (S1401). The handover topology request unit 86 transmits a handover topology request message to the handover control system 50 (S1402), and receives a response including a candidate auxiliary address (S1403). Through this, the mobile node 80 may check the auxiliary address to be used for detecting its own movement and used in advance (S1404).

Now, the mobile node 80 moves to the management area of the new router to perform the second layer handover (S1405). The layer 2 trigger detector 85 detects a trigger that indicates the end of the handover of the second layer (S1406). If the second layer handover termination trigger is detected, the CoA setting unit 84 changes the address of the mobile node 80 to the auxiliary address confirmed in step S1504 (S1407).

Now, the binding update unit 87 of the mobile node performs a binding update procedure with the base station and the corresponding node (S1408). After the binding update procedure with the corresponding node is performed, the mobile node directly transmits and receives data with the corresponding node (S1409).

15 is an exemplary diagram illustrating a handover time required based on a handover control system according to the present invention.

As described above, when using the handover control system, the mobile node processes the movement detection and auxiliary address generation and its duplicate address detection procedure in advance.

Therefore, when the mobile node performs the second layer handover, it prepares for the third layer handover in advance, sets the IP address of the mobile node to the pre-generated auxiliary address, and sends the binding update message to the home agent and the corresponding node. do.

As shown in FIG. 11, the results of the experiment show that in the conventional MIPv6, the third layer handover time that takes 1.3 seconds or more can be shortened to several tens of ms or less.

16 is a block diagram illustrating a mixed network configuration of MIPv4 and MIPv6 according to another embodiment of the present invention.

As shown in FIG. 16, a mixed network includes an IPv4 / IPv6 core network, a plurality of IPv4 routers 114 and 115, a plurality of IPv6 routers 111 and 112, an IPv4 / IPv6 dual-use router 113, and a plurality of wireless base stations ( 121 to 130), the MIPv4 mobile node 101, the MIPv4 corresponding node 140, and the handover control system 150.

Of course, the network topology except for the handover control system 150 may be changed. For example, the locations of the MIPv4 home agent and the MIPv6 home agent may be different from those of FIG. 16.

In this case, the IPv6 routers 111 and 112 support the MIPv6 function, and the IPv4 routers 114 and 115 may perform the functions of the MIPv4 home agent or the MIPv4 phosphor agent, respectively. The IPv4 / IPv6 dual router 113 supports the functions of MIPv4 and MIPv6.

17 is a block diagram showing the internal structure of a handover control system according to another embodiment of the present invention.

The handover control system 150 may include a network interface module 151, a topology management module 152, a MIPv4 handover management module 153, a MIPv6 handover management module 154, and a duplicate address processing module 155. Can be.

The handover control system 150 illustrated in FIG. 17 has a difference in that the handover management modules 153 and 154 are configured differently for each IP version, compared to the handover control system 50 of FIG. 5.

The topology request message transmitted by the mobile nodes 101 and 102 is transmitted to the topology management module 152 through the network interface module 151. In this case, the mobile nodes 101 and 102 include the MIP version information supported by the mobile node 101 and 102 in the topology request message. For example, the MIPv4 terminal 101 transmits a topology request message including MIPv4 version information, and the MIPv6 terminal 102 transmits a topology request message including MIPv6 version information.

The topology management module 152 checks the MIP version information of the mobile nodes 101 and 102 included in the topology request message, and accordingly the search of the target router is performed by the MIPv6 handover management module 154 or the MIPv4 management module 153. Optionally) If the mobile node 101 supports MIPv4, the topology management module 152 requests the MIPv4 handover management module 153 to search for the target router.

Meanwhile, the MIPv4 handover management module 153 and the MIPv6 handover management module 154 create a handover topology table and a map for each version. The handover topology table and map will be described in more detail with reference to Tables 4 and 5. In addition, the target router is searched for by the version of the mobile node according to the request of the topology management module 152.

The MIPv4 handover management module 153 or the MIPv6 handover management module 154 transfers the topology information of the retrieved target router to the mobile nodes 101 and 102. The topology information is included in the topology response message and may be transmitted to the mobile node through the network interface module 151.

18 is a flowchart illustrating a method for collecting handover topology information of a handover control system according to another embodiment of the present invention.

The topology management module 151 in the handover control system 150 uses information such as the SNMP of the network interface module 151 to inform the IPv6 router, the IPv4 router, the IPv4 / IPv6 dual router, and the wireless base station managed by each router. Are collected periodically (S1801 to S1805). FIG. 18 illustrates a process of collecting topology information from five routers 111 to 115 and ten lower base stations 121 to 130.

The handover control system 150 performs a process of separately generating an IPv4 network topology table and an IPv6 network topology table by using the collected information of the routers 111 to 115 and the wireless base stations 121 to 130 (S1806 and S1807). ).

The handover control system 150 transmits the information of the routers 113 to 115 and the wireless base stations 125 to 130 related to the MIPv4 handover to the MIPv4 handover management module 153 (S1808) and relates to the MIPv6 handover. Information of the routers 111 to 113 and the wireless base stations 121 to 126 is transmitted to the MIPv6 handover management module 154 (S1810).

The MIPv4 handover management module 153 and the MIPv6 handover management module 154 generate the handover topology tables as shown in the following table, respectively, using the received information of the router and the wireless base station (S1809 and S1811).

As shown in Table 4, the MIPv4 handover topology table includes the router ID, whether the router supports IPv4 / IPv6, whether it has HA or FA capability, whether it supports base station interfaces, FA-CoA or C-CoA, CoA values, and base stations connected to the router. Information such as ID, location of the base station, coverage of the base station, and the like may be included.

After generating such a handover topology table, the MIPv4 handover management module 153 generates a MIPv4 handover topology map using the table. The MIPv4 handover topology map includes location and coverage information of the base stations 125 to 130 connected to the routers 113 to 115 supporting MIPv4.

When the handover control system 150 receives the handover topology information request from the mobile nodes 101 and 102 by using the handover topology map, the topology of the base station where the mobile nodes 101 and 102 are located is determined. By mapping to the map, the mobile nodes 101 and 102 can search for neighboring base stations that are likely to move.

Specifically, the base stations where the mobile nodes 101 and 102 are located and the neighboring base stations where the coverage overlaps may determine that the mobile node may move, and may provide information about each base station to the mobile nodes 101 and 102 in advance. .

The handover control system 150 may update the network topology even when a change occurs in the network topology by performing a topology collection procedure of the network at regular time intervals (S1812).

19A is an exemplary diagram illustrating a MIPv4 handover topology map according to another embodiment of the present invention, and FIG. 19B is an exemplary diagram illustrating a MIPv6 handover topology map according to another embodiment of the present invention.

The MIPv4 handover management module 153 of FIG. 19A checks base station IDs stored in the table of Table 4, location coordinates for each base station ID, and coverage to draw a management area of each base station 125 to 130 that supports MIPv4. .

Looking at the map making process for the fifth base station 125, first, the MIPv4 handover management module 153 detects that the coordinate of the fifth base station 125 is (x5, y5). The MIPv4 handover management module 153 marks the point at the (x5, y5) coordinate and indicates that the point is the fifth base station 125. In addition, the MIPv4 handover management module 153 checks that the coverage of the fifth base station 125 is K5, and draws a circle having a radius K1 around (x5, y5) according to the fifth base station 125. . The MIPv4 handover management module 153 may perform the same operation for the sixth to tenth base stations 125 to 130 repeatedly to obtain a handover topology map for the MIPv4 base station shown in FIG. 19A.

Meanwhile, the MIPv6 handover management module 154 generates a handover topology map for base stations 121 to 125 that support MIPv6 using the table of Table 5. Since the handover topology map for the MIPv6 base stations 121 to 125 is almost the same as that of the MIPv4, a detailed description thereof will be omitted.

20 is a flowchart illustrating a MIPv4 handover method using a handover control system according to another embodiment of the present invention.

The mobile node 101 supporting the MIPv4 performs an initial access procedure with the base station 7 127 (S2001). When the connection is completed, the mobile node 101 starts data transmission and reception with the MIPv4-compatible node 140 (S2002).

The mobile node 101 transmits a handover topology request message (HO Topology Request Message) to the handover control system 150 in order to obtain information on neighboring base stations and candidate auxiliary address information that it is likely to move to (S2003). . The handover topology request message includes a mobile IP version of the mobile node, a mobile node IP address, a MAC address of the mobile node, and a base station ID to which the mobile node is currently connected.

Upon receiving this, the topology management module 152 of the handover control system 150 first checks the Mobile IP version of the mobile node 101 (S2004). If the Mobile IP version is MIPv4, the mobile node 101 transmits the information of the mobile node 101 to the MIPv4 handover control module 153 (S2005).

The MIPv4 handover control module 153 searches for the base station BS7 to which the mobile node 101 is connected on the handover topology map of FIG. 19A, and finds base stations with overlapping coverage with the seventh base station 127 (S2006). . Referring to FIG. 19A, it can be seen that the base stations in which the BS7 and the coverage overlap are the fifth, eighth and ninth base stations 125, 128, and 129.

Afterwards, the MIPv4 handover control module 153 extracts the retrieved base station information on the handover topology table and transmits a handover topology response message including topology information of the base station to the mobile node 101. (S2007). The base station information included in the handover topology response message includes a MIP version, an ID of the mobile base station, a candidate auxiliary address flag of the mobile base station, and a candidate auxiliary address value. In the present embodiment, since the discovered base stations are the fifth, eighth, and ninth base stations 125, 128, and 129, the handover topology response messages are (MIPv4, BS5, C-CoA, CoA1), (MIPv4, BS8, FA-CoA, CoA2). ), (MIPv4, BS9, FA-CoA, CoA3).

Receiving the handover topology response message, the mobile node 101 is a base station to which the mobile station can move is the fifth, eight, and ninth base stations, and in each case, candidate auxiliary addresses are CoA1, CoA2, and CoA3. It can be seen that the C-CoA, FA-CoA, FA-CoA type, respectively.

The mobile node 101 then compares the subnet of the network to which it is currently connected with the candidate secondary address to determine the necessity of changing the IP subnet (S2008). If each IP subnet needs to be changed, the mobile node 101 may generate a candidate auxiliary address to be used in advance (S2009). In the example of the present invention, the mobile node 101 is connected to the seventh base station 127, and the seventh base station 127 is connected to the same IP subnet as the eighth base station 128. Therefore, the mobile node 101 needs a MIPv4 procedure by changing an IP subnet when moving to the fifth and ninth base stations 125 and 129, but only an L2 handover procedure is required when moving to the eighth base station 128. It can be seen that.

The mobile node 101 transmits a handover topology request message to the handover control system 150 at a predetermined period T1 (S2010), and repeats the processes of S2004 to S2009 (S2011).

It is now assumed that the mobile node 101 moves from the area managed by the seventh base station 127 to the area managed by the ninth base station 129. First, the mobile node 101 generates an L2 HO Initiate Trigger signal meaning that the L2 handover is started (S2012). At this time, the mobile node 101 can grasp that the mobile node 101 moves to the ninth base station 129, and prepares for setting FA-CoA = CoA3 generated in advance.

The mobile node 101 performs L2 handover from the seventh base station 127 to the ninth base station 129 (S2013). Thereafter, the mobile node 101 moves from the area of the seventh base station 127 to the area of the ninth base station 129 (S2014). As described above, the L2 layer of the mobile node 101 which has completed the L2 handover transmits the L2 HO Finish Trigger signal to the L3 or higher layer (S2015).

The mobile node 101 sets the new CoA to CoA3 (S2016), and transmits a registration request message (Registration Request) to the fifth router 115 which is a FA (S2017). Upon receiving the registration request message, the fifth router 115 updates the visitor list (S2018), and transmits an RRQ to the fourth router 114, which is an HA (S2019). The fourth router 114 receiving the RRQ makes an RRP response to the fifth router 115 (S2020), and again, the fourth router 114 forwards the RRP to the mobile node 101 to perform a MIPv4 registration process. Complete (S2021).

After that, the traffic transmitted from the correspondent node 140 is transmitted to the fourth router 114 that is the home agent (S2022). In the example of the present invention, since the ninth base station 120 uses the FA-CoA type auxiliary address, A tunnel is formed from the fourth router 114, which is a home agent, to the fifth router 115, which is a forest agent, and data of the corresponding node 140 is transferred (S2023). After receiving the data of the corresponding node 140 using the tunnel, the fourth router 114 removes the established tunnel and transmits the data to the mobile node 101 (S2024).

The data transmitted from the mobile node 101 to the corresponding node 140 may be directly transmitted or transmitted through a reverse tunnel according to the capability of the mobile node 101 and the function of the forest agent (S2025).

In FIG. 20, the handover process of the mobile node 101 supporting MIPv4 has been described. Since the handover process of the mobile node 102 supporting MIPv6 is almost the same as that of FIG. 8, a description thereof will be omitted.

21 is an exemplary view showing handover time required based on a handover control system according to another embodiment of the present invention.

As described above, when the handover control system 150 is used, the mobile nodes 101 and 102 process the movement detection and the auxiliary address generation procedure in advance. Thereafter, when the mobile nodes 101 and 102 perform the second layer handover, the mobile nodes 101 and 102 are set to the IP addresses of the mobile nodes 101 and 102 as pre-generated auxiliary addresses, and the registration procedure is performed.

As shown in FIG. 21, the time required for the third layer handover process of the conventional MIPv4 includes a movement detection and auxiliary address generation time of about 1.5 sec and a binding update time of 50 ms. However, in the present invention, since the movement detection and auxiliary address generation are performed in advance, only the registration procedure is performed in the third layer handover process, thereby reducing the third layer handover time to several tens of ms or less.

Although the present invention has been described in detail through the representative embodiments, those skilled in the art to which the present invention pertains can make various modifications without departing from the scope of the present invention. I will understand. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

As described above, according to the handover control system and method for performing the third layer handover of the mobile node according to the present invention, a router in which the mobile node is likely to move is pre-discovered, and the address of the router and the mobile node By combining the addresses of to generate a care-of address (CoA), and by checking in advance whether the generated address is a duplicate address, it is possible to reduce the third layer handover time to several tens of ms or less, Through this, it is possible to provide subscribers with real-time multimedia services such as VoIP, IP-TV, VoD, etc. constantly while the terminal moves.

Claims (33)

In a Mobile Internet Protocol (MIP) network, A plurality of mobile nodes for providing data services to users; A plurality of routers providing data services to mobile nodes existing in an area of a base station managed by the base station and periodically reporting the base station and its environment information to a handover control system; And After receiving the environment information of the base station and the router to generate a handover topology map, by searching the target router that the mobile node is likely to handover by mapping the current location of the mobile node to the handover topology map, MIP network including a handover control system for transmitting the environment information of the target router to the mobile node. The method of claim 1, Environmental information of the router, At least one of a router ID, router interface information, router prefix, each base station ID of each router, location information of each base station, or coverage information of each base station. The method of claim 1, The handover control system, MIP network system of combining the prefix information of the target router and the MAC address of the mobile node to generate a candidate secondary address, and transmits the generated candidate secondary address to the mobile node. The method of claim 3, The mobile node, MIP network for setting the candidate secondary address received from the handover control system to its own IP address after performing a second layer handover. The method of claim 3, The handover control system generates a candidate secondary address, performs a check whether the candidate secondary address is duplicated to the found target router, and then transmits the candidate secondary address to the mobile node. The method of claim 5, The handover control system, MIP network system for delivering a DAD request message including the candidate secondary address to the target router to use the candidate secondary address to check whether the candidate secondary address is duplicated. The method of claim 6, The router, In order to check whether the candidate auxiliary addresses included in the DAD request message are duplicated, a neighbor solicitation message is transmitted to a plurality of sub-base stations, and a neighbor advertisement response message is checked. MIP network. The method of claim 5, The handover control system, If the generated candidate secondary address is a duplicate address, MIP network to combine the prefix of the router and any address to regenerate the candidate secondary address and transmit it to the mobile node. The method of claim 1, The handover control system, MIP network, characterized in that for generating a handover topology map for each MIP version supported by the base station. The method of claim 9, The handover control system, The MIP network checks the MIP version supported by the mobile node and searches for the target router by mapping the current location of the mobile node to a handover topology map according to the MIP version supported by the mobile node. In the handover control system of the MIP network, A topology management module for collecting topology information of a plurality of routers and base stations; and After generating a handover topology map by using the topology information of the base station and the router, searching for a target router in which the mobile node is likely to be handed over by mapping a current location of the mobile node to the handover topology map, Handover control system comprising a handover management module for transmitting the environment information of the target router to the mobile node. The method of claim 11, The handover control system further comprises a handover topology table including at least one of the ID of the router, the interface information of the router, the prefix of the router, the ID of each base station of each router, the location information of each base station, or the coverage information of each base station. . The method of claim 11, And a secondary address table including at least one of a MAC address of a mobile node, a base station ID to which the mobile node is movable, a candidate secondary address, a collision occurring secondary address, or an entry expiration period. The method of claim 11, The handover management module, A topology response message including an ID of the target router, a candidate secondary address, and information about whether the candidate secondary address is duplicated with respect to a topology request message requesting target router and base station information having a possibility of handover. Handover control system for transmitting a response message) to the mobile node. The method of claim 14, And a duplicate address processing module requesting a target router to check whether the candidate auxiliary address is duplicated. The method of claim 11, The handover topology map, Handover control system, characterized in that for generating for each MIP version supported by the base station. The method of claim 16, The handover management module, And a target router by checking a MIP version supported by the mobile node and mapping a current location of the mobile node to a handover topology map according to the MIP version supported by the mobile node. In a router managing a plurality of base stations, A network interface module for communicating with a network component via an IP network; A topology information collection module for collecting topology information of a lower base station managed by the base station; And Transmitting a neighbor solicitation message including candidate auxiliary address information to a plurality of base stations managed by the network interface module, and receiving a neighbor advertisement message for the neighbor request message. And a duplicate address check module configured to determine whether the candidate secondary address is duplicated based on whether the candidate secondary address is duplicated. The method of claim 18, The duplicate address check module, And when the neighbor request response message for the neighbor request message is received, determine that the candidate auxiliary address is a duplicate. The method of claim 18, And a candidate secondary address table for storing at least one of a secondary address entry ID, a candidate secondary address, or an expiration period. A handover topology request unit for requesting information on a plurality of target routers capable of handover and candidate auxiliary addresses from the handover control system; A layer 2 trigger detector configured to detect termination of the second layer handover as the mobile node moves to one of the plurality of target routers; And A mobile node including a CoA setting unit configured to set candidate auxiliary address information received from the handover control system to the IP address of the mobile node when the layer 2 trigger detector detects the end of the second layer handover; The method of claim 21, And a binding update unit configured to perform a binding update with a corresponding node after setting the IP address of the candidate auxiliary address. The method of claim 21, The handover topology request unit, A mobile node for transmitting information of a plurality of target routers and MIP versions supported by a candidate auxiliary address to the handover control system. In the handover control method in a MIP network, The handover control system receives the environment information of the lower router and the lower base station to generate a handover topology map; Requesting, by the mobile node, a target router capable of handover and information of the target router to a handover control system; And The handover control system searches for a target router in which the mobile node is likely to handover by mapping a current position of the mobile node to the handover topology map, and then transmits the found environment information of the target router to the mobile node. Handover control method in a MIP network comprising. The method of claim 24, Environmental information of the router, At least one of a router ID, router interface information, router prefix, each base station ID of each router, location information of each base station, or coverage information of each base station. The method of claim 24, The handover control system transmits the information of the target router to the mobile node, And the handover control system combines the prefix information of the target router and the MAC address of the mobile node to generate a candidate auxiliary address, and transmits the generated candidate auxiliary address to the mobile node. The method of claim 26, The mobile node further comprises the step of setting the candidate secondary address received from the handover control system to its own IP address after performing a second layer handover. The method of claim 26, The handover control system further comprises the step of generating a candidate secondary address, and performing a check whether the candidate secondary address is duplicated to the searched target router. The method of claim 28, The step of checking whether the candidate secondary address is duplicated, The handover control system forwarding a DAD request message including the candidate secondary address to each target router; The target router sending a neighbor request message to a plurality of lower base stations for the candidate secondary address; And And determining, by the target router, whether the candidate secondary address is duplicated by using a neighbor request response message received from the lower base station. The method of claim 29, Determining whether the candidate secondary address is a duplicate, And if the target router receives a neighbor request response message for a predetermined period, determining that the candidate secondary address is a duplicate. The method of claim 29, The target router further comprises combining a prefix of the target router with an arbitrary address when the candidate auxiliary address is a duplicate address, and regenerating the candidate auxiliary address and notifying the handover control system of the handset in the MIP network. Over control method. The method of claim 24, The handover topology map generation step, The handover control system generates a handover topology map indicating the coverage of a base station for each MIP version. 33. The method of claim 32, The target router discovery step of the handover control system, Checking the MIP version supported by the mobile node and the current location of the mobile node; Wow And searching for a target router by mapping a current location of the mobile node to a handover topology map according to a MIP version supported by the mobile node.

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