KR20080011003A - Method for handoff in a wireless communication system using mobile ip and the system thereof - Google Patents

Abstract

A handoff method in a wireless communication system using a mobile IP and the system are provided to reduce overhead and minimize a loss of data in performing handoff in wireless communication system using mobile IPV6. When an MS(Mobile Station)(111) that communicates enters in a state that a call is maintained, a target router requests handoff information from a source router and receives it, transmits data bicast-set binding update to an HA(Home Agent)(101) of the MS(111), receives a binding response, and completes handover. A source router provides handoff information when the MS(111) requests the handoff information as it moves out of a communication area, and when a pre-set time lapses after providing the handoff information, the source router transmits binding update with a CoA(Care of Address) and life time expiration to the HA(101). When the binding update message requesting data bicast is received from the target router, the HA(101) simultaneously transmits packets to the MS until it receives the binding update.

Description

Method for handoff in wireless communication system using mobile IP and system therefor {METHOD FOR HANDOFF IN A WIRELESS COMMUNICATION SYSTEM USING MOBILE IP AND THE SYSTEM THEREOF}

1 is a schematic configuration diagram of a wireless communication system to which the present invention is applied;

2 is a control flowchart when a handoff of a mobile terminal is supported in a T-PDSN according to the present invention;

3 is a control flowchart when a handoff of a mobile terminal is supported in an HA according to the present invention;

4 is a signal flow diagram when handover of a mobile terminal when using Proxy Mobile IPv6 according to the present invention;

The present invention relates to a handoff method and system therefor, and more particularly to a handoff method and system in a wireless communication system using a mobile IP.

In general, a wireless communication system has been developed as a system for enabling communication while extending the range of activities of users. Such wireless communication systems have been gradually evolving from the center of providing voice services to the system of providing data services. Currently, wireless communication systems that can provide data services include 3GPP and 3GPP2 systems, wireless LAN (WLAN) systems, and Wibro systems.

Since all the above systems perform wireless communication, basically, the communication area is expanded by using a handoff method to provide continuous communication. That is, there are base stations covering a specific area, and the wireless terminals perform communication in the area of the base stations. If the wireless terminal communicating in the area of a specific base station moves to the outside of the base station, the communication channel is switched to a better base station with reference to signal signals received from other base stations. This series of processes is called handoff.

The handoff is not only a process of establishing a channel between the wireless terminal and the base station, but also a connection of a currently established call must be smoothly performed in the system. In detail, all of the wireless communication systems include base stations performing direct communication with a terminal and higher nodes controlling a plurality of base stations. In this case, the handoff between the base stations may result in the handoff of the upper node. Therefore, when a handoff occurs in a higher node, handover of a call connected between higher nodes is necessary, and this process is also included in the handoff process.

Meanwhile, due to the rapid development of wireless communication systems, various systems for rapidly providing data services rather than voice services are being developed. Among the wireless communication systems, the interest in data service to a mobile terminal is increasing in the case of a wireless LAN service that is rapidly increasing.

In the case of the wireless LAN service, a mobile IP (Internet Protocol) technology used in the Internet is used to manage the location of the mobile terminal and provide seamless communication even during handoff. The Mobile IP technology includes Mobile IPv4 and Mobile IPv6 technologies depending on the version. The mobile IP protocol has an effect of providing data without changing the existing IP or disconnection in data transmission.

However, this mobile IP technology has a lot of overhead. Therefore, there is a problem in that a lot of overhead of the protocol itself to use in a mobile communication network, such as 3GPP2.

Therefore, in order to reduce such overhead, a technology called proxy mobile IP has been discussed. The technology for Proxy mobile IPv6 has no standard to date, and efforts are being made to create a standard. Particularly, 3GPP2 camp among mobile communication systems intends to use proxy mobile IP to improve handover performance, and active research is being conducted to determine the standard.

However, there are no specific plans for handover using proxy mobile IP yet.

In the case of mobile IPv6, which is the basis of proxy mobile IPv6, data loss may occur when using mobile IPv6 in the handoff process according to the current standard. Therefore, when using proxy mobile IPv6 as a variant of mobile IPv6 in a mobile communication system that wants to use proxy Mobile IPv6, a method for supporting the protocol is required.

Accordingly, an object of the present invention is to provide a method and system for reducing overhead in handover in a wireless communication system using proxy mobile IPv6.

Another object of the present invention is to provide a method and a system capable of simultaneously providing data between routers during handover in a wireless communication system.

Another object of the present invention is to provide a method and system for reducing data loss during handover in a wireless communication system.

A method of the present invention for achieving the above objects, a method for performing a handoff using a proxy mobile IP in a router of a wireless communication system, the terminal communicating using the IP enters while the call is maintained And performing a context transfer with the source router of the terminal, and transmitting a binding update for setting data by-cast to the home agent of the terminal, receiving a binding response, and then completing a handover.

The system of the present invention for achieving the above objects is a system for performing a handoff of a terminal using a proxy mobile IP in a wireless communication system, the terminal communicating using the IP enters a state where the call is maintained A target router requesting and receiving handoff information with a source router of the terminal, transmitting a binding update for setting data bicast to a home agent of the terminal, receiving a binding response, and completing a handover; When the handoff information is requested from the target router while leaving this communication area, the handoff information is provided, and when the set time elapses after the handoff information is provided, a binding update for setting a care-of address and a survival time expiration is transmitted to the home agent. A data bicast from a source router and the target router And a home agent that simultaneously transmits a packet to be transmitted to the terminal when a binding update message requested by the network is received until a binding update is received from a source router.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users or operators, and the definitions should be made based on the contents throughout the present specification.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, in order to solve the problem described in the prior art to inform the information required in the process of sending a proxy binding update (proxy binding update), by using the information from the home agent (home agent) two or more tunnels for a predetermined time In this case, we introduce a method that maintains only one tunnel when the handoff is finally completed. This process and information will be described below.

1 is a schematic configuration diagram of a wireless communication system to which the present invention is applied. Hereinafter, a configuration and connection relationship of a wireless communication system to which the present invention is applied will be described with reference to FIG. 1. In addition, the wireless communication system of FIG. 1 assumes a 3GPP2 system, but should not be construed as limited thereto, and unnecessary components are not illustrated in describing the present invention in the 3GPP2 system.

In FIG. 1, S means a source and T means a target. Therefore, the nodes on the side that perform the initial communication are source nodes and are shown with S in the drawing, and the nodes on the call transfer side are target nodes and are shown with T in the drawing.

The mobile station (MS) 111 communicates with a radio network (hereinafter referred to as "RN") via a wireless link. Herein, the mobile terminal 111 is a terminal that performs data communication. Accordingly, a radio network collectively refers to a base station (BTS), a base station controller (BSC) and a packet control function unit (PCF) for packet data communication. The RN is connected to a higher packet data service node (PDSN). The PDSN corresponds to an end node having a routing function for transmitting packet data to a specific network in a 3GPP2 mobile communication system.

In the present invention, the mobile terminal 111 to be examined communicates by using a mobile IP and is a case where a handoff is performed. Therefore, the first mobile terminal 111 communicates with the S-PDSN 103 via the S-RN 107. Accordingly, the mobile terminal 111 performs data communication with the home agent (hereinafter referred to as "HA") 101 through the S-PDSN 103. At this time, the S-PDSN 103 communicates with the HA 101 using proxy Mobile IPv6. The connection between the S-PDSN 103 and the T-PDSN 105 is not established.

When the mobile station 111 moves as shown by reference numeral 120 and moves to the T-RN 109 during the communication as described above, the mobile station 111 establishes a new channel according to the change of the RN and PDSN. The T-PDSN 105 then establishes a P-P interface with the S-PDSN 103 and communicates with the HA 101 using proxy Mobile IPv6. Here, the type of data transmitted through the PP interface may be various, but only the extent to which IP address information and security information transmitted from the Layer 2 (L2) is included is mentioned here. Shall be. In this case, the present invention provides a method for minimizing loss of packet data transmitted to the mobile terminal 111. A detailed operation of the present invention will be described in more detail with reference to the control flowcharts of FIGS. 2 and 3 and the signal flowchart of FIG. 4.

Meanwhile, the environment described in the present invention uses proxy Mobile IPv6 between the S-PDSN 103 and the HA 101 and between the T-PDSN 105 and the HA 101 as described above, and the S-PDSN (103). ) And the T-PDSN 105 use the PP interface. However, the mobile terminal 111 may use simple IP or may use Mobile IP. That is, it operates independently from the proxy Mobile IP used in PDSN.

2 is a control flowchart when a T-PDSN supports handoff of a mobile terminal according to the present invention. Hereinafter, a control process for minimizing the loss of data transmitted to the mobile terminal during handoff of the mobile terminal in the T-PDSN according to the present invention will be described in detail with reference to FIG. 2.

When the T-PDSN 105 detects that the mobile terminal 111 communicating with the S-PDSN 103 moves to its own area while communicating with the S-PDSN 103, the T-PDSN 103 performs an S-PDSN 103. From the T-PDSN 105). When the handoff is necessary as described above, the T-PDSN 105 transmits a message requesting a context transfer to the S-PDSN 103 in step 201. Thereafter, in step 203, context transfer data is received from the S-PDSN 103. The context transfer data refers to data of the second layer as described above. In the embodiment of the present invention, the process of requesting and receiving the context transfer data is illustrated and described, but only handoff related information suitable for the purpose of the present invention is transmitted / received between the S-PDSN 103 and the T-PDSN 105. It can also be configured to receive. In the following description, only context transfer data is transmitted / received for convenience of description. Then, the T-PDSN 205 checks whether data transmitted to the mobile station 111 can be delivered for a certain time to reduce data loss through S-PDSN as well as its PDSN. First, the data transmitted to the mobile terminal 111 is delivered for a certain time to reduce data loss not only through its PDSN but also through the S-PDSN. In the following description, "data bicast" " The data bicast check can be performed by determining whether the connection with the HA 101 and the connection between the S-PDSN 103 and the HA 101 can support Proxy Mobile IPv6. In addition, even if the S-PDSN 103 and the HA 101 support Proxy Mobile IPv6, if the S-PDSN 103 and the HA 101 cannot support the function according to the present invention, such a function cannot be provided. However, if all PDSNs and HAs can perform the functions of the present invention, they can be configured to require data bicast immediately without such checking.

The T-PDSN 105 performs the inspection based on the above information. For this inspection, the T-PDSN 105 and the S-PDSN 103 may be confirmed by transmitting and receiving specific signals between the T-PDSN 105 and the HA 101, and may be configured to know in advance. . In the present invention, it is assumed that step 205 is performed by using the above-described information, and no specific limitation is given thereto.

If the bicast of the test result data of step 205 is possible, the T-PDSN 105 proceeds to step 207 and transmits a proxy binding update (Proxy BU) to the HA 101. At this time, S bit is transmitted to Proxy BU. These S bits are in accordance with the present invention and simultaneously transmit data to the S-PDSN 103 and the T-PDSN 105 when the mobile terminal 111 is handed off, thereby transmitting the S-PDSN 103 and the T-PDSN 105. In order to be able to transmit data to the mobile terminal 111 at the same time through. This will be described in more detail with reference to FIG. 4 described later. In addition, the S bit is to use one bit among bits that are reserved bits in the Proxy BU. Thereafter, the T-PDSN 105 receives a binding acknowledgment (BA) from the HA 101 in step 209. As such, when receiving the BA, the T-PDSN 105 completes the handoff in step 211 and then proceeds to step 221 to control the flow of packet data to be transmitted from the HA 101 to the mobile terminal 111. .

On the other hand, if it does not support the scheme according to the present invention, the T-PDSN 105 proceeds to step 215 and transmits the proxy BU to the HA 101 without the S bit. Thereafter, the T-PDSN 105 receives the BA from the HA 101 in step 217, and proceeds to step 221 to control the flow of packet data to be delivered to the mobile terminal 111. Therefore, in step 215, the T-PDSN 105 and the S-PDSN 103 may not simultaneously provide data transmitted to the mobile terminal 111.

Referring to FIG. 2 briefly described above, when the handoff is performed to the S-PDSN 103 and the T-PDSN 105 in order to minimize the loss of data transmitted to the mobile terminal in the environment described in FIG. This is to allow binding to both sides simultaneously for a certain time. This is to minimize the loss of packet data to be delivered to the mobile terminal (111).

3 is a control flowchart when a handoff of a mobile terminal is supported in an HA according to the present invention. Hereinafter, a control process will be described in detail when the mobile terminal supports handoff in the HA according to the present invention with reference to FIG. 3.

When the HA 101 receives the BU from the T-PDSN 105 in step 301, the HA 101 proceeds to step 303 and checks whether an S bit is set in the received BU. If the S bit is set in the check result BU in step 303, the HA 101 proceeds to step 305 to transmit a BA to the T-PDSN 105. Thereafter, the HA 101 proceeds to step 307 and bicasts the packet data to be transmitted to the mobile station 111 to the S-PDSN 103 and the T-PDSN 105 for a predetermined time. As such, a predetermined time period during which the bicsat transmission is performed is performed until the BU set to "life time expiration (life time = 0)" is received from the S-PDSN 103. That is, when the HA 101 receives the BU set to “life time expiration (life time = 0)” from the S-PDSN 103 as in step 309, the HA 101 proceeds to step 311 and performs a BA to the S-PDSN 103. In step 313, the S-PDSN 103 and the T-PDSN 105 transmit data to the T-PDSN 105 only. That is, the HA 101 switches a tunnel from the S-PDSN 103 to the T-PDSN 105. The HA 101 proceeds to step 321 to receive the BU from the mobile terminal 111.

On the other hand, when the HA 101 bit is not set in the BU, the UE 101 proceeds to step 317 to transmit a BA to the T-PDSN 105, and proceeds to step 319 to transmit the T in the S-PDSN 103. Switch the tunnel to PDSN 105. Accordingly, the steps 317 to 319 may not be transmitted to both the S-PDSN 103 and the T-PDSN 105 as described in the present invention.

4 is a signal flowchart when handover of a mobile terminal when using Proxy Mobile IPv6 according to the present invention. Hereinafter, the signal flow and the operation of each node when handover of a mobile terminal when using Proxy Mobile IPv6 according to the present invention will be described in detail with reference to FIG. 4. In addition, in FIG. 4, RNs that are not particularly related to the present invention are not shown, and description thereof will be omitted.

First, the mobile terminal 111 initiates communication by transmitting a BU to the HA 101 in step 401. In step 403, the mobile terminal 111 communicates with the HA 101 through the S-PDSN 103. When the mobile station 111 moves from the S-PDSN 103 to the T-PDSN 105 during communication in this manner, that is, a handoff may occur. 4 illustrates a case where such a handoff occurs.

When handoff of the mobile terminal occurs, as shown in step 405, information related to handoff between the S-PDSN 103 and the T-PDSN 105 may be context transferred to support handoff. When the context transfer is performed as described above, the T-PDSN 105 transmits the BU to the HA 101 in step 407. This BU is different from case to case as described above. If the S bit is set and transmitted, step 413 is performed without the dotted line shown in FIG. 4. If the S bit is transmitted without setting the S bit, step 413 is shown with the dotted line. Is not performed.

When receiving the BU, the HA 101 transmits a BA to the T-PDSN 105 in step 409. The T-PDSN 105 then completes the handoff in step 411. Then, the HA 101 performs steps 415 and 417 together if the S bit is set in the received BU. That is, the HA 101 simultaneously transmits packet data to be transmitted to the mobile terminal 111 to the T-PDSN 105 and the S-PDSN 103. In FIG. 4, steps 415 and 417 are sequentially shown due to difficulty of expression, but it should be noted that the processes are performed simultaneously.

Thereafter, the HA 101 uses the care-of-address 0 (CoA0) and the life time expiration (life time = 0) used by the S-PDSN as shown in step 419 from the S-PDSN 103. If a BU having a value of "" is received, the process proceeds to step 421 to transmit a BA to the S-PDSN 103. Then, the HA 101 terminates the tunnel to the S-PDSN 103 in order to transmit data to the mobile terminal 101 only to the T-PDSN 105 as shown in step 423. That is, the S-PDSN 103 no longer transmits data to be transmitted to the mobile terminal 111.

If the above process is made, the handover is completed. Accordingly, in step 425, the HA 101 communicates with the mobile station 111 through the T-PDSN 105. Thereafter, the mobile terminal 111 transmits the BU to the HA 101 in step 427.

As described above, the present invention has an advantage of minimizing data loss that may occur during handoff while reducing overhead during handoff in a wireless communication system using Mobile IPv6.

Claims (6)

A method for performing handoff using a proxy mobile IP in a router of a wireless communication system, Requesting and receiving handoff information from a source router of the terminal when the terminal communicating with the IP enters a state where a call is maintained; And transmitting a binding update for setting data by-cast to the home agent of the terminal, receiving a binding response, and completing a handover. The method of claim 1, When the tunneling from the home agent of the terminal handover in the wireless communication system using a mobile IP characterized in that it further comprises the step of transmitting the packet data transmitted and received between the terminal and the home agent through the set tunnel. Off way. A method for performing handoff using a proxy mobile IP in a router of a wireless communication system, Providing a handoff information from another router while the terminal communicating with the IP leaves the communication area with the router; In the wireless communication system using a mobile IP, if the set time elapses after providing the handoff information, transmitting a binding update that sets a care-of address and a survival time expiration to the home agent of the terminal. Handoff method. A method for performing a handoff using a proxy mobile IP in a home agent of a system connected to a wireless communication system and configured with a home agent using a mobile IP, the method comprising: Checking whether data bicast is required when a binding update message of a UE registered in the home agent is received from a target router; And simultaneously transmitting packets to be transmitted to the terminal when the data bicast is requested, until a binding update is received from a source router. The method of claim 4 And receiving a binding response from the source router and switching a tunnel to a target router when receiving the binding update. A system for performing handoff of a terminal using a proxy mobile IP in a wireless communication system, When a terminal communicating with IP enters a state where a call is maintained, it receives and requests handoff information from the source router of the terminal, and transmits and binds a binding update that sets data by-cast to the home agent of the terminal. A target router that completes the handover after receiving the response; When the terminal leaves the communication area and the handoff information is requested from the target router, it provides the request, and if the set time elapses after the provision of the handoff information, the binding update is set to the home agent. The source router to send, And a home agent that simultaneously transmits a packet to be transmitted to the terminal when a binding update message requesting data bicast is received from the target router until a binding update is received from a source router.

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