WO2011037298A1

WO2011037298A1 - User-defined network system and mobility management method thereof

Info

Publication number: WO2011037298A1
Application number: PCT/KR2009/006756
Authority: WO
Inventors: Jong-Tae Park
Original assignee: Kyungpook National University Industry- Academic Cooperation Foundation
Priority date: 2009-09-23
Filing date: 2009-11-17
Publication date: 2011-03-31
Also published as: KR20110032620A; KR101043766B1

Abstract

A user-defined network system and a mobility management method thereof are provided. The user-defined network system enables handover between APs managed by different network managing entities through user-defined network mobility management server storing information of APs and mobility management servers managed by each designation unit networks which constitute a user-defined network. A mobile node of the user-defined network user requests CoA information of neighboring APs, when the radio signal from the current AP is below a handover preparation threshold value, stores the CoA information, chooses a New AP, and handover the New AP when the radio signal from the current AP is below a handover execution threshold value, through the stored CoA information.

Description

USER-DEFINED NETWORK SYSTEM AND MOBILITY MANAGEMENT METHOD THEREOF

The present invention relates to a user-defined network system and a mobility management method thereof, and particularly to a user-defined network system and a mobility management method thereof, which enable handover between Access Points managed by different network management entities through a user-defined network mobility management server storing mobility management server information and AP information managed by each network management entity, which constitute a user-defined network.

IP (Internet Protocol) mobility management is a function to prevent an established communication session from being intercepted even when a mobile node moves between different IP networks in a mobile communication network. The purpose of the mobility management is to transfer diverse wireless Internet services to the terminal through continuous management of the position of the subscribed terminal in the mobile communication terminal.

With the development of a low-price IEEE 802.11 wireless local area network (WLAN), the existing wired LAN has rapidly been replaced by a WLAN in the home, an office, or a factory. In particular, as an ultrahigh-speed IEEE 802.11n, which supports the bandwidth of 600 Mbps at maximum, has been approved as a formal international standard, this phenomenon will be accelerated in the future. Additionally, since the IEEE 802.11n ultrahigh-speed WLAN adopts MIMO (Multiple-Input Multiple-Output) technology, it has a wave arrival coverage that is larger than that of the existing IEEE 802.11a/b/g WLAN. However, since such a WLAN is inexpensive and can be simply installed, an individual often installs his/her own WLAN in the home, an office, a factory, or other places, in addition to a public WLAN provided in school or a city, and this phenomenon will be sharply increased in the future. As a result, there exists a complex WLAN environment where private WLANs coexist in addition to hot spots provided from schools, cities, and/or communication service providers.

In such a complex WLAN environment installed and managed by diverse private and/or public network management entities, it is required to provide a mobility management service to a user. That is, a user desires to receive a seamless wireless Internet service when the user moves through a WLAN where user authentication is possible as the user moves between hot spots in the home, a school, and/or a paid WLAN. However, the mobile IP related technology, such as MIP (Mobile IP), FMIP (Fast Mobile IP), HMIP (Hierarchical Mobile IP), and the like, which is the IP mobility management international standard established by IETF (the Internet Engineering Task Force), has the problem that it cannot provide a seamless wireless Internet connection service when a user moves between a private WLAN constructed by the user and an ISP or between different ISPs in the complex WLAN environment. This is because the IETF international standard makes only handover between access routers managed by the same ISP an object of management. That is, when a mobile node moves into an area of an access router or an access point having a different management ISP, it is impossible to secure the mobility through the handover, and it is required to re-access a new ISP after completely intercepting the access. In particular, when a mobile node moves between public WLANs using public Internet addresses in a private WLAN using a private Internet address, it cannot support the handover. This problem has become a primary factor that obstructs the activation of the mobile Internet service.

Accordingly, there is a need for a system and a mobility management method thereof, which can smoothly support handover even in the case where a mobile node moves into an area of an access router or an access point managed by a different network management entity in a user-defined network system on the assumption that the user-defined network system includes a home network defined by a user and two or more ISPs tied with the home network.

Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a user-defined network system and a mobility management method thereof, which can secure the mobility by supporting handover when a mobile node moves into an area of an access router or an access point managed by a different network management entity.

Another object of the present invention is to provide a user-defined network system and a mobility management method thereof, which can seamlessly support an application service such as VoIP (Voice over IP) that requires the support of a real-time service by supporting a quick handover capable of minimizing a handover delay time when a mobile node moves into an area of an access router or an access point managed by a different communication management entity.

Still another object of the present invention is to provide a user-defined network system and a mobility management method thereof, which can guarantee message security even when a mobile node moves into an area of an access router or an access point having a different management ISP (Internet Service Provider) and thus handover occurs.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

In order to accomplish these objects, there is provided a mobile node, which includes a handover preparation unit providing a handover preparation message which contains identification information of next AP (Access Point) candidates including other APs from which signals are received if the strength of a signal received from a currently accessed AP is below a handover preparation threshold value; an AP information storage unit storing CoA (Care-of Address) information, private or public IP addresses of the next AP candidates provided in response to the handover preparation message; and a handover processing unit accessing the next AP selected among the next AP candidates by using the CoA of the next AP stored in the AP information storage unit if the strength of the signal is below a handover execution threshold value.

In another aspect of the present invention, there is provided a user-defined network mobility management server, which includes an ISP (Internet Service Provider) and private WLAN (Wireless Local Area Network) manager information storage unit storing access information of designation unit network operating mobility management servers and identification information of designation unit network operating AP, wherein two or more said designation unit network constituting a user-defined network; a CoA request unit receiving AP identification information and inquiring of the mobility management server of the designation unit network which controls the AP, stored in the ISP and private WLAN management information storage unit, about a CoA to be allocated through the AP; and a CoA providing unit forwarding the CoA information received from the mobility management server as a response to the inquiring of the CoA request unit as a response to the reception of the AP identification information.

In still another aspect of the present invention, there is provided a user-defined network system, which includes a mobile node receiving CoA information which is private or public IP address to be allocated through next AP candidates consisting of neighboring APs, from a user-defined network mobility management server if the strength of a wireless signal received from a currently accessed AP is below a handover preparation threshold value, and accessing the AP selected as the next AP among the next AP candidates by using the received CoA information of the next AP, if the strength of the wireless signal is below a handover execution threshold value; a user-defined network mobility management server storing information of two or more designation unit networks which constitute a user-defined network, and inquiring of a mobility management server of the designation unit network that operates each next AP candidate about CoA information to be allocated through the next AP candidate by using the stored information in compliance with a request of the mobile node, and forwarding the CoA information to the mobile node; and an ISP mobility management server providing the CoA, which is set by commanding a router that controls the next AP candidates to set the CoA in advance, to the user-defined network mobility management server, if the user-defined network mobility management server inquires about the CoA information to be allocated through the next AP candidate.

In still another aspect of the present invention, there is provided a method of managing mobility of a mobile node, which includes if the strength of a signal received from a currently accessed AP is below a handover preparation threshold value, providing a handover preparation message which contains identification information data of next AP candidates consisting other APs from which signals are received, and storing CoA information about the next AP candidates received in response to the handover preparation message; and if the strength of the signal is below a handover execution threshold value, accessing the next AP selected among the next AP candidates by using the stored CoA information of the next AP.

In still another aspect of the present invention, there is provided a method of managing mobility of a user-defined network mobility management server, which includes storing access information of designation unit network operating mobility management servers and identification information of designation unit network operating AP, wherein two or more said designation unit network constituting a user-defined network; and receiving the AP identification information by inquiring of the mobility management server of the designation unit network that controls the AP, by using the stored access information of the mobility management server, about a CoA to be allocated through the AP, and forwarding the inquired CoA information as a response to the reception of the AP identification information.

In still another aspect of the present invention, there is provided a method of managing mobility of a user-defined network system, which includes storing access information of designation unit network operating mobility management servers and identification information of designation unit network operating AP, wherein two or more said designation unit network constituting a user-defined network; if the strength of a wireless signal received from a currently accessed AP is below a handover preparation threshold value, sending a signal for requesting CoA information which is private or public IP addresses to be allocated through next AP candidates consisting of neighboring APs; receiving the signal for requesting CoA information, inquiring of the mobility management servers of the designation unit network which operates next AP candidates about the CoA information to be allocated through the next AP candidates by using the stored information; preparing the CoA to be allocated through the next AP candidates in advance as the result of inquiring, and providing the prepared CoA information in response to the signal for requesting the CoA information; transferring the CoA information in response to the requesting CoA information; and if the strength of the wireless signal is below a handover execution threshold value, accessing the AP selected as the next AP among the neighboring APs by using the transferred CoA of the next AP.

According to the present invention as constructed above, even if a mobile node moves into an area of an access router or an access point having different management ISP, handover is supported to secure the mobility. Accordingly, even when a mobile node, which initially accesses a home network, enters into a communication area of an access router or an access point managed by an ISP that is different from the home network, the access state of the mobile node can be maintained.

Also, in the case of handover between access routers or access points having different management ISPs, an application service such as VoIP (Voice over IP) that requires the support of a real-time service can be seamlessly supported through support of a quick handover capable of minimizing a handover delay time.

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a conceptual view of a user-defined network according to the present invention;

FIG. 2 is a view explaining a user-defined network system according to an embodiment of the present invention;

FIG. 3 is a block diagram illustrating the configuration of a user-defined network mobility management server according to an embodiment of the present invention;

FIG. 4 is a block diagram illustrating the configuration of a mobile node according to an embodiment of the present invention; and

FIG. 5 is a flowchart illustrating a method of managing mobility of a user-defined network according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The aspects and features of the present invention and methods for achieving the aspects and features will be apparent by referring to the embodiments to be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed hereinafter, but can be implemented in diverse forms. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is only defined within the scope of the appended claims. In the entire description of the present invention, the same drawing reference numerals are used for the same elements across various figures.

The present invention will be described herein with reference to the accompanying drawings illustrating block diagrams and flowcharts for explaining a user-defined network system and a mobility management method thereof according to embodiments of the present invention. It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block or blocks.

These computer program instructions may also be stored in a computer usable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

Also, each block of the flowchart illustrations may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

First, the concept of a user-defined network according to the present invention will be described with reference to FIG. 1. FIG. 1 is a conceptual view of a user-defined network according to the present invention.

A user-defined network may be defined as a user-grounded(oriented) logical network which includes WLANs (Wireless Local Area Networks) that can be accessed through joining of a WLAN service of an ISP (Internet Service Provider) or construction of a private WLAN. Hereinafter, a network constituting the user-defined network will be called a designation unit network.

The designation unit network may include an ISP joined by a user. An ISP is a business subject that provides an Internet access service, and in the present invention, it may be limited to a business subject that provides a WLAN access service. The ISP may include a general ISP that provides a paid service and a public ISP that provides a public service to students and teaching staffs at school and so on. Also, the ISP may provide a WLAN access service in a specified area, and a shaded area where no access service is available may exist in some areas where other ISPs provide WLAN access services.

The designation unit network may include a private WLAN which is directly constructed by a user or of which an access is permitted to a user. The private WLAN may be constructed by installing an access point, and it is preferable that the private WLAN includes a wireless router providing a NAT (Network Address Translation) function, which operates as a mobility management server, and a DHCP (Dynamic Host Configuration Protocol) function. For example, the private WLAN may include an access router or a wireless router that provides the NAT function as the access point.

In FIG. 1, it is assumed that a user using a mobile node 100 can access a private WLAN 120, an ISP WLAN 122, and a public WLAN 124. The user may construct a user-defined network 126, in which the private WLAN 120, the ISP WLAN 122, and the public WLAN 124 are defined, as the designation unit network. By contrast, the user may construct a user-defined network that includes only the WLAN 120 and the ISP WLAN 122 as the designation unit network. That is, the user-defined network may be understood as a network constructed by adding a WLAN network desired by the user.

However, since the user-defined network according to the present invention aims at support of seamless mobility of a mobile node, it is preferable that one or more WLANs constituting the user-defined network have service providing areas which at least partially overlap each other.

As illustrated in FIG. 1, it is assumed that the user’s mobile node 100 constructing the user-defined network 126 successively passes through cells of AP (Access Point) 1 102, AP 2 104, AP 3 106, AP 4 108, and AP5 110. According to the user-defined network mobility management method according to the present invention, seamless data transmission becomes possible by supporting handover irrespective of the change of the network management entity that operates the APs in the event that the mobile node moves from the cell of AP 1 102 to the cell of AP 2 104 and moves from the cell of AP 3 106 to the cell of AP 4 108 as well.

Hereinafter, a mobility management system of a user-defined network according to an embodiment of the present invention will be described with reference to FIG.2 to 4.

First, the configuration and operation of the mobility management system of the user-defined network according to an embodiment of the present invention will be described with reference to FIG. 2. In FIG. 2, it is assumed that a user of a mobile node 200 has established a user-defined network 256 in which a private WLAN 250, an ISP A 252, and an ISP B 254 are defined as designation unit network. Also, it is assumed that AP 1 202 having a NAT function serves as a mobility management server of the private WLAN 250. That is, AP 1 202 may be called an access router or a wireless router.

As illustrated in FIG. 2, the mobility management system of a user-defined network according to an embodiment of the present invention includes a mobile node 200, a user-defined network mobility management server 208, and

mobility management servers

210 and 212 operated by the ISPs.

Now, explanation will be made, laying emphasis on a handover operation in the case where the mobile node positioned within the cell of AP 1 202 included in the private WLAN 250 moves into the cell of AP 3 206 operated by ISP B 254.

The mobile node 200, which is a terminal provided with a communication module, may be, for example, a notebook computer or a smart phone. The communication module may support at least one of a WLAN, 2G (Generation) mobile communications, 3G mobile communications, 3.5G mobile communications, and 4G mobile communications. The 2G mobile communications may be GSM (Global System for Mobile communications) or IS (Interim Standard)-95. The 3G mobile communications may be W-CDMA (Wideband Code Division Multiple Access) or CDMA2000. The 3.5G mobile communications may be HSDPA (High Speed Downlink Packet Access) or HSUPA (High Speed Uplink Packet Access). Also, the 4G mobile communications may be WiMAX according to IEEE 802.16 or LTE (Long Term Evolution).

If the strength of a wireless signal being received from the currently accessed AP 1 202 is below a handover preparation threshold value S250, neighboring APs are detected, and a list of next AP candidates composed of identification information of the detected APs. The AP identification information may be BSSID (Basic Service Set Identifier). The detection may be performed by broadcasting an AP probe message and obtaining identification information of the APs that respond to the AP probe message. It is assumed that the list of the next AP candidates in FIG. 2 includes AP 2 204 and AP 3 206.

The detection may not be performed only in the case where the strength of a wireless signal is below a handover preparation threshold value, but may be periodically performed. That is, the mobile node 200 may manage a list of neighboring APs by periodically broadcasting the AP probe message, or may manage the list of neighboring APs which are currently broadcasting beacon messages by receiving the beacon messages from the neighboring APs. In the case where the mobile node manages the list of neighboring APs by periodically, the list of next AP candidates can be the list of neighboring APs at the time of the strength of the received wireless signal fall down below the handover preparation threshold value S250.

Next, the mobile node 200 transmits the handover preparation message that contains the list of AP candidates to a user-defined network mobility management server 208 through AP 1 202 S252. It is preferable that the mobile node 200 stores access information of the user-defined network mobility management server 208. The access information of the user-defined network mobility management server 208 may be an IP address.

The handover preparation message is transmitted to the user-defined network mobility management server 208 through AP 1 202 and the Internet. The network mobility management server 208 stores information about the user-defined network 256, and supports the handover operation of the mobile node 200 of the subscriber constructing the user-defined network. In particular, the handover includes handover between different ISPs.

In the network mobility management server 208, designation unit network information for respective users is stored. The designation unit network information may include identification information of the operating APs and access information of the mobility management server. For example, if a subscriber X constructs a user-defined network with ISP A, ISP B, and ISP C, which are designation unit networks, the designation unit network information may include identification information of all APs operated by ISP A and access information of the corresponding mobility management server, identification information of all APs operated by ISP B and access information of the corresponding mobility management server, and identification information of all APs operated by ISP C and access information of the corresponding mobility management server.

In the case of the user-defined network 256 as illustrated in FIG. 2, the designation unit network are the private WLAN 250, ISP A 252, and ISP B 254, and thus the network mobility management server 208 stores information of APs operated by ISP A 252 and ISP B 254 and information of the corresponding mobility management servers, and information of APs included in the private WLAN 250 and access information of a device functioning as the mobility management server of the private WLAN 250.

The device functioning as the mobility management server of the private WLAN 250 may be an access router having a NAT function and a DHCP function. In the case where AP 1 202 has a NAT function and a DHCP function, it may operate as the mobility management server. In this case, access information of the mobility management server of the private WLAN 250 may be an IP address of AP 1 202.

The network mobility management server 208 may not directly store identification information of APs operated by respective designation unit network, but may include access information of a server that can inquire about the AP identification information. In this case, the waste of storage space can be prevented, and the latest AP identification information can be inquired.

The network mobility management server 208 searches for the designation unit network information of the corresponding user by using identification information of next AP) candidates included in the next AP candidate list contained in the received handover preparation message as a key. In the case of an example as illustrated in FIG. 2, the next AP candidate list would include identification information of AP 2 204 and AP 3 206. In order to search for the designation unit network operated by AP 2 204, the network mobility management server 208 searches for the designation unit network information of the user-defined network 256 of the corresponding user. In the case of an example as illustrated in FIG. 2, the network mobility management server searches for AP information included in the private WLAN 250 that is the designation unit network, AP information included in ISP A 252, and AP information included in ISP B 254. As a result, the user-defined network mobility management server 208 can recognize that the designation unit network that operates AP 2 204 is ISP B 254. In the same manner, the network mobility management server 208 can recognize that the designation unit network that operates AP 3 206 is ISP B 254.

The network mobility management server 208 transmits a signal for requesting issuance of a CoA (Care of Address) for the mobile node 200 to the mobility management server 210 of ISP A 252 that operates AP 2 204. The CoA means a temporary Internet address to be used by the mobile node as a visitor, and not only a public IP address but also a private Internet address managed by a private wireless router can be used as the CoA. The CoA issuance request signal may contain identification information of AP 2 204 and identification information of the mobile node 200, e.g. a MAC (Media Access Control) address. The MAC address of the mobile node 200 may be extracted from the handover preparation message. The mobility management server of ISP A 210 requests an access router that controls AP 2 204 to create a CoA for the mobile node 200, and transmits the CoA received as the result of request to the user-defined network mobility management server 208 S256. Hereinafter, the CoA allocated to the mobile node 200 through AP 2 204 is referred to as “CoA1.” The user-defined network mobility management server 208 also transmits a signal for requesting issuance of the CoA for the mobile node 200 to the mobility management server 212 S254, and receives the CoA as the result of request S256. Hereinafter, the CoA allocated to the mobile node 200 through AP 3 206 is referred to as “CoA2.”

If the CoA to be allocated through all

APs

204 and 206 included in the next AP candidate list is received, the network mobility management server 208 receives the CoA information to be allocate to the respective APs as a response message to the handover preparation message, and provides the CoA information to the mobile node 200 through AP 1 202. If there is an AP that is not included in the designation unit network of the user-defined network among APs included in the next AP candidate list, the network mobility management server 208 cannot inquire the designation unit network that operates the corresponding AP, and thus the CoA information to be allocated to the corresponding AP would not be set.

The mobile node, which has received the response message to the handover preparation message from the user-defined network mobility management server 208 S258, stores the CoA information, which is contained in the response message, to be allocated to the

respective APs

204 and 206. That is, the mobile node 200 stores information that the CoA to be allocated through the neighboring AP 2 204 is CoA1 and information that the CoA to be allocated through AP 3 206 is CoA2.

If it is assumed that the strength of the signal received from AP 1 202 is lowered below a handover execution threshold value when the mobile node 200 moves into a converge area of ISP B S260, the mobile node 200 selects one of AP 2 204 and AP 3 206 included in the next AP candidate list as the next AP. The basis of selecting the next AP may be, for example, the number of mobile nodes having accessed the AP or the strength of the received signal. That is, the AP corresponding to the least number of mobile nodes having currently accessed may be selected, or the AP corresponding to the received signal having the biggest strength may be selected. If it is assumed that the mobile node 200 selects AP 3 206 having the biggest signal strength between AP 2 204 and AP 3 206 as the next AP, the mobile node 200 may directly access AP 3 206 by using CoA2 to be allocated to the mobile node 200 through AP 3 206 S262.

As illustrated in FIG. 2, the currently accessed AP 202 and AP 206 selected as the next AP may be APs operated by different designation unit network. That is, handover may occur between different designation unit networks. For example, handover becomes possible even between the service areas of different ISPs included in the user-defined network 256 according to the present invention.

The mobile node 200 requests the mobility management server 212 of ISP B to update the mobility information S264, and receives a response message that contains whether the update succeeds S266. The update of the mobility information means a work of registering that the mobile node 200 is currently accessing ISP B and is positioned in a cell of AP 3 206.

Hereinafter, the detailed configuration of the user-defined network mobility management server 208 according to an embodiment of the present invention will be described with reference to FIG. 3. As illustrated in FIG. 3, the user-defined network mobility management server 208 includes a network interface 300 interfacing data transmission/reception, a CoA request unit 302, a CoA providing unit 304, an ISP and private WLAN management unit 306, and an ISP and private WLAN manager information storage unit 308.

The ISP and private WLAN manager information storage unit 308 stores access information of mobility management servers, which are operated by two or more designation unit network constituting a user-defined network, and AP identification information. It is preferable that the designation unit network constituting the user-defined network is a network operating one or more APs in neighboring positions enough to seamlessly provide a real time service even in the case where the mobile node performs handover to the AP of another designation unit network constituting the user-defined network.

The CoA request unit 302 receives the AP identification information, and inquires of the mobility management server of the designation unit network, which controls an AP stored in the ISP and private WLAN manager information storage unit 308, about a CoA to be allocated through the AP.

The CoA providing unit 304 provides the CoA information inquired from the ISP mobility management server as a response to the reception of the AP identification information.

The ISP and private WLAN management unit 306 performs at least one of a first operation to delete information about at least one designation unit network to be deleted, constituting the user-defined network, from the ISP and private WLAN manager information storage unit 308, a second operation to update information about at least one designation unit network to be updated, constituting the user-defined network, to the ISP and private WLAN manager information storage unit 308, and a third operation to store new designation unit network information, which has not been stored in the ISP and private WLAN manager information storage unit 308, in the ISP and private WLAN manager information storage unit 308. The designation unit network information includes identification information of APs included in the designation unit network and access information of mobility management servers.

The ISP and private WLAN management unit 306 may perform at least one of the first operation, the second operation, and the third operation with respect to data of a specified user. For example, it may perform at least one of the first operation, the second operation, and the third operation with respect to only data of a user X. In the case where the user X joins a new ISP and intends to add the joined ISP to the user-defined network, the ISP and private WLAN management unit 306 can perform the third operation with respect to data of the user X.

Hereinafter, the detailed configuration of the mobile node 200 according to an embodiment of the present invention will be described with reference to FIG. 4. As illustrated in FIG. 4, the mobile node 200 includes a communication module 400 supporting at least one of a WLAN, 2G (Generation) mobile communications, 3G mobile communications, 3.5G mobile communications, and 4G mobile communications, a handover processing unit 404, a signal strength measurement unit 402, a handover preparation unit 406, and an AP information storage unit 408.

The signal strength measurement unit 402 calculates an RSSI (Received Signal Strength Indication) value of the signal received form the currently accessed AP, and provides the calculated RSSI value to the handover processing unit 404 and the handover preparation unit 406. The signal strength measurement unit 402 manages a list of neighboring APs by periodically broadcasting an AP probe message, or manages a list of neighboring APs currently broadcasting beacon messages by receiving the beacon messages broadcast from the neighboring APs.

If the strength of the signal being received from the currently accessed AP is below the handover preparation threshold value, the handover preparation unit 406 provides a handover preparation message that contains identification information of next AP candidates including other APs from which signals are received. The handover preparation message may be transmitted to the user-defined network mobility management server 208 through the communication module 400. In the event that the signal strength measurement unit 402 does not periodically manage the list of neighboring APs, the handover preparation unit 406, if the signal strength is below the handover preparation threshold value, can create identification information of the next AP candidates by broadcasting the AP probe message and obtaining the corresponding AP identification information. If the event that the signal strength measurement unit 402 periodically manages the list of neighboring APs and if the signal strength is below the handover preparation threshold value, the neighboring APs become the next AP candidates.

The AP information storage unit 408 stores CoA information of the next AP candidates provided in response to the handover preparation message.

If the signal strength is below the handover execution threshold value, the handover processing unit 404 accesses the next AP selected among the next AP candidates by using the CoA of the next AP stored in the AP information storage unit 408. The currently accessed AP and the next AP may be APs included in different designation unit network. The handover processing unit 404 may select the AP having the biggest signal strength among the next AP candidates as the next AP.

Hereinafter, a method of managing mobility of a user-defined network according to an embodiment of the present invention will be described with reference to FIG. 5.

If the strength of a signal received from the currently accessed AP is below the handover preparation threshold value S500, the handover preparation message which contains identification information data of the next AP candidates including other APs from which signals are received is provided S504. The handover preparation message maybe provided to a server that stores information about two or more designation unit networks constituting the user-defined network. The information on the designation unit network may be access information of the mobility management servers operated by the designation unit network and AP identification information.

It is preferable that the information on the designation unit network can be edited. For example, the identification information of APs operated by a specified designation unit network and the access information of the mobility management servers may be deleted, updated, or additionally stored.

The server receives the identification information of the next AP candidates contained in the handover preparation message, inquires of the mobility management server of the designation unit network that controls the AP stored in the ISP and private WLAN manager information storage unit about the CoA to be allocated through the next AP candidate, and provides the inquired CoA information as a response to the reception of the AP identification information S506.

As illustrated in FIG. 5, if the signal strength is below the handover preparation threshold value, the next AP candidate may create the identification information data of the next AP candidates by broadcasting the AP probe message and obtaining the AP identification information in response to the AP probe massage S502. However, the identification information may be obtained through the neighboring APs periodically obtained irrespective of the signal strength.

The mobile node stores the CoA information of the next AP candidates received in response to the handover preparation message S508.

If the signal strength is below the handover execution threshold value S510, the next AP is selected among the next AP candidates S512. The currently accessed AP and the next AP may be APs operated by different designation unit networks. Also, the next AP may be the AP having the biggest radio signal strength among the next AP candidates S512. The mobile node accesses the next AP by using the stored CoA of the next AP S514. After the mobile node accesses the next AP, it can request update of the mobility related information of the mobile node from the mobility management server of the ISP that operates the next AP through the next AP S516.

Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

According to this invention, users of user-defined network can use seamless WLAN communication service by suppporting handover between designation unit networks, such as ISPs, by registering designation unit networks which constituting the user-defined network, to the user-defined network mobility management server.

Claims

A mobile node comprising:

a handover preparation unit providing a handover preparation message which contains identification information of next AP candidates including other APs from which signals are received if the strength of a signal received from a currently accessed AP is below a handover preparation threshold value;

an AP information storage unit storing CoA information, private or public IP addresses of the next AP candidates provided in response to the handover preparation message; and

a handover processing unit accessing the next AP selected among the next AP candidates by using the CoA of the next AP stored in the AP information storage unit if the strength of the signal is below a handover execution threshold value.
The mobile node of claim 1, further comprising a signal strength measurement unit calculating an RSSI (Received Signal Strength Indication) value of the signal received form the currently accessed AP, and providing the calculated RSSI value to the handover processing unit and the handover preparation unit.
The mobile node of claim 1, wherein the current accessed AP and the next AP are APs included in different designation unit network.
The mobile node of claim 1, wherein the handover processing unit selects the AP having the biggest signal strength among the next AP candidates.
The mobile node of claim 1, wherein if the signal strength is below the handover preparation threshold value, the handover preparation unit creates identification information of the next AP candidates by broadcasting an AP probe message and obtaining identification information of the APs that respond to the AP probe message.
The mobile node of claim 2, wherein the signal strength measurement unit manages a list of neighboring APs by periodically broadcasting an AP probe message, or manages the list of neighboring APs currently broadcasting beacon messages by receiving the beacon messages being broadcast from the neighboring APs.
A user-defined network mobility management server comprising:

an ISP and private WLAN manager information storage unit storing access information of designation unit network operating mobility management serversand identification information of designation unit network operating AP, wherein two or more said designation unit network constituting a user-defined network;

a CoA request unit receiving AP identification information and inquiring of the mobility management server of the designation unit network which controls the AP, stored in the ISP and private WLAN management information storage unit, about a CoA to be allocated through the AP; and

a CoA providing unit forwarding the CoA information received from the mobility management server as a response to the inquiring of the CoA request unit as a response to the reception of the AP identification information.
The user-defined network mobility management server of claim 7, wherein the designation unit network is a network operating one or more APs in neighboring positions enough to seamlessly provide a real time service even in the case where the mobile node performs handover to the AP of another designation unit network constituting the user-defined network.
The user-defined network mobility management server of claim 8, further comprising an ISP and private WLAN management unit that performs at least one of the following operation; first operation to delete information about at least one designation unit network, constituting the user-defined network, from the ISP and private WLAN manager information storage unit, second operation to update information about at least one designation unit network, constituting the user-defined network, to the ISP and private WLAN manager information storage unit, and third operation to store new designation unit network information, which has not been stored in the ISP and private WLAN manager information storage unit, in the ISP and private WLAN manager information storage unit.
A user-defined network system comprising:

a mobile node receiving CoA information which is private or public IP addresses to be allocated through next AP candidates consisting of neighboring APs from a user-defined network mobility management server if the strength of a wireless signal received from a currently accessed AP is below a handover preparation threshold value, and accessing the AP selected as the next AP among the next AP candidates by using the received CoA information of the next AP if the strength of the wireless signal is below a handover execution threshold value;

a user-defined network mobility management server storing information of two or more designation unit networks which constitute a user-defined network, and inquiring of a mobility management server of the designation unit network that operates each next AP candidate about CoA information to be allocated through the next AP candidate by using the stored information in compliance with a request of the mobile node, and forwarding the CoA information to the mobile node; and

an ISP mobility management server providing the CoA, which is set by commanding a router that controls the next AP candidates to set the CoA in advance, to the user-defined network mobility management server if the user-defined network mobility management server inquires about the CoA information to be allocated through the next AP candidate.
The user-defined network system of claim 10, wherein the currently accessed AP and the next AP are APs operated by the different designation unit network.
A method of managing mobility of a mobile node, comprising:

if the strength of a signal received from a currently accessed AP is below a handover preparation threshold value, providing a handover preparation message which contains identification information data of next AP candidates consisting other APs from which signals are received, and storing CoA information about the next AP candidates received in response to the handover preparation message; and

if the strength of the signal is below a handover execution threshold value, accessing the next AP selected among the next AP candidates by using the stored CoA information of the next AP.
The method of claim 12, wherein the handover preparation message is provided to a server that stores information of two or more designation unit network constituting a user-defined network.
The method of claim 12, wherein the currently accessed AP and the next AP are APs operated by the different designation unit network.
The method of claim 12, wherein the next AP is the AP having the biggest strength of a received wireless signal among the next AP candidates.
The method of claim 12, wherein the storing CoA information comprises creating identification information data of the next AP candidates by broadcasting an AP probe message and obtaining the AP identification information in response to the AP probe massage if the signal strength is below the handover preparation threshold value.
A method of managing mobility of a user-defined network mobility management server, comprising:

storing access information of designation unit network operating mobility management servers and identification information of designation unit network operating AP, wherein two or more said designation unit network constituting a user-defined network; and

receiving the AP identification information by inquiring of the mobility management server of the designation unit network that controls the AP, by using the stored access information of the mobility management server, about a CoA to be allocated through the AP, and forwarding the inquired CoA information as a response to the reception of the AP identification information.
The method of claim 17, wherein the storing further comprises deleting the identification information of the AP and access information of the mobility management server operated by a specified designation unit network and the.
The method of claim 17, wherein the storing further comprises updating the identification information of the AP operated by a specified designation unit network and the access information of the mobility management server.
The method of claim 17, wherein the storing further comprises additionally storing the identification information of the AP operated by a specified designation unit network and the access information of the mobility management server.
A method of managing mobility of a user-defined network system, comprising:

storing access information of designation unit network operating mobility management servers and identification information of designation unit network operating AP, wherein two or more said designation unit network constituting a user-defined network;

if the strength of a wireless signal received from a currently accessed AP is below a handover preparation threshold value, sending a signal for requesting CoA information which is private or public IP addresses to be allocated through next AP candidates consisting of neighboring APs;

receiving the signal for requesting CoA information, inquiring of the mobility management servers of the designation unit network which operates next AP candidates about the CoA information to be allocated through the next AP candidates by using the stored information;

preparing the CoA to be allocated through the next AP candidates in advance as the result of inquiring, and providing the prepared CoA information in response to the signal for requesting the CoA information;

transferring the CoA information in response to the requesting CoA information; and

if the strength of the wireless signal is below a handover execution threshold value, accessing the AP selected as the next AP among the neighboring APs by using the transferred CoA of the next AP.