KR100943515B1 - Address Management Method for Vertical Handoff - Google Patents

Abstract

The present invention relates to an address management system and method for heterogeneous handoff.

To this end, the present invention generates a message including the information of the first access router to perform the handoff and transmits to the second access router, the unassigned of the first access router to perform the handoff When one of the prefixes is selected, the state is changed to a temporary assignment state, the corresponding information is transmitted to the terminal, and when a handoff request is received from the terminal, the second access router sends a handoff initialization message for tunnel establishment. Generate and transmit to the first access router, and when a handoff response message including the result of validating the prefix is received from the first access router, the second access router changes the state of the selected prefix to the assigned state and changes information. A method of managing an address in a second access router for handoff between heterogeneous networks for transmitting a message to a terminal Ball.

According to the present invention, there is an effect that the address allocation policy can reduce delay and packet loss even when handoff between different heterogeneous networks.

Fast Handoff, Heterogeneous Network, Address Management, FBU, PAR, NAR, Prefix

Description

Address Management Method for Vertical Handoff

The present invention relates to an address management system and method for heterogeneous handoff. In particular, the present invention relates to an address management method in a system that performs handoff using a prefix assigned to each terminal in order to support fast handoff between heterogeneous networks having different address assignment methods.

As users want to be provided with voice call services or wireless Internet services on the go, wireless communication services are rapidly evolving in various ways.

Users who want to support such wireless communication services can use WCDMA or 1X EV-DO-based 3GPP wireless access network, 3GPP-Wireless LAN access network based on 3GPP connection, IEEE 802.11-based wireless LAN access network and WiBro. It may be connected to a portable Internet network or the like, and may receive a wireless communication service through the corresponding communication network.

1 is a diagram schematically illustrating a network for providing a wireless communication service.

3GPP wireless access network, 3GPP-WLAN access network, wireless LAN access network and portable Internet network providing wireless communication service includes an access router for connection with other networks. That is, the 3GPP wireless access network is referred to as an access gateway (AGW), the 3GPP wireless LAN access network is called a packet data gateway (PDG: PDG), and the wireless LAN access network is Routers and portable Internet networks each include an access control router (ACR).

As a user who is located in a specific cell of the wireless communication system and receives a wireless communication service using a terminal moves, a handoff is performed to another cell or a heterogeneous network in the same access network. At this time, in order to maintain a wireless communication service serviced at a high speed, a fast handoff between access routers of heterogeneous networks is required.

2 is a signal flowchart illustrating a fast handoff method used in a conventional wireless communication system.

A terminal connected to a previous access router (PAR: hereinafter referred to as a 'PAR') before a handoff may search for a target to perform a handoff and request a router (RtSolPr :) including searched wireless access identification information. Router Solicitation for Proxy or Router Solicitation for Proxy Advertisement (hereinafter referred to as RtSolPr) message is transmitted.

When the PAR receives the RtSolPr message, information of an access router managing radio access identification information received from the terminal, that is, an access router (NAR: New Access Router (NAR) hereinafter called 'NAR') to which the terminal accesses after handoff is received. A Proxy Router Advertisement (PrRtAdv) message including network prefix information, IP address of the NAR, link layer address information of the NAR, and the like is transmitted to the terminal as a response to the RtSolPr message.

When the UE receiving the PrRtAdv message is determined to handoff a network, the UE generates a new address (NCoA: New Call of Address (NCoA)) to be used after the handoff, using the information of the corresponding NAR. The terminal transmits a binding request (FBU: Fast Binding Update) message including NCoA to the PAR.

Upon receiving the FBU message, the PAR selects a NAR related to the NCoA generated by the terminal, and initializes a handoff (HI: Handover Initiate, hereinafter 'HI') for overlapping inspection of the NCoA and setting up a tunnel between the PAR and the NAR with the selected NAR. It sends a message).

The NAR validates the NCoA included in the HI message and delivers the validation result to the PAR through a handoff acknowledgment (HAck) message.

After receiving the HAck message, the PAR delivers the result of the validation to the terminal through a binding response message (FBAck: FBAck). At this time, a tunnel is created between the terminal and the PAR.

Packets transmitted to the previous address (PCoA) (hereinafter referred to as 'PCoA') are tunneled from the PAR to NCoA and forwarded to the NAR.Unsolicited Neighbor Advertisement (UNA) messages are sent from the terminal to the NAR. Until it is buffered in the NAR. At this time, tunneling between the PAR and the terminal lasts for several seconds.

The high speed handoff method used in the conventional wireless communication system is a shared media application technology based on the IEEE environment, and all terminals connected to the router must share the prefix of the router. Accordingly, there is a problem that packet loss and delay may occur in fast handoff between heterogeneous networks having different address allocation methods.

An object of the present invention is to provide an address management method for supporting high speed handoff between heterogeneous networks with different address allocation methods in order to reduce delay and packet loss due to handoff.

To this end, the address management method according to the first embodiment of the present invention is an address management method for a router before a handoff to which a terminal is connected to support handoff between heterogeneous networks of the terminal, and (a) a hand from the terminal. Receiving a message containing information of a first access router to access via off; (b) selecting one of the prefixes of the first access router and transmitting information of the selected prefix to the terminal; (c) generating a message including information of the selected prefix and transmitting the message to the first access router according to a handoff request from the terminal, and receiving a message including a result of validating the selected prefix; And (d) notifying the terminal of the possibility of handoff by transmitting a message including allocation information of the selected prefix to the terminal.

The address management method according to the second embodiment of the present invention is an address management method for supporting a handoff between heterogeneous networks of a terminal by a router before the handoff to which the terminal is connected, and (a) a hand from the terminal. Receiving a message containing information of a first access router to access via off; (b) selecting one of the prefixes of the first access router and transmitting information of the selected prefix to the terminal; (c) generating a message including information of the selected prefix and transmitting the message to the first access router according to a handoff request from the terminal, and receiving a message including a result of validating the selected prefix; And (d) if it is confirmed that the prefix information of the terminal included in the handoff request message transmitted through the first access router is identical to the prefix received through the handoff response message, a message indicating successful termination of the handoff is received. Transmitting to the first access router.

In addition, the address management method according to the third embodiment of the present invention is an address management method for supporting a handoff between heterogeneous networks of the terminal by a router before the handoff to which the terminal is connected, and (a) a hand from the terminal. Receiving a message containing information of a first access router to access via off; (b) selecting one of the prefixes of the first access router and transmitting information of the selected prefix to the terminal; (c) Upon receipt of the handoff request from the first access router, a handoff initialization message including information of the prefix assigned to the terminal is generated and transmitted to the first access router, and the first to the prefix assigned to the terminal. Receiving prefix status information of the access router; And (d) sending a binding response message to the first access router indicating the successful end of the handoff.

According to the present invention, since the fast handoff is performed regardless of whether the handoff request message and the response message between the PAR and the NAR are received, even when a handoff between heterogeneous networks having different address assignment policies is performed, the handoff is performed. Fast handoff techniques can be used to reduce delays and packet loss due to this.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have.

Since the message flow of the fast handoff does not occur sequentially with the handoff procedure of the link layer, the message flow can be classified into three types according to the state of the link.

In the first case, the PAR forwards the handoff request to the NAR in advance and receives a response. In the second case, the PAR forwards the handoff request from the PAR to the NAR in advance. In the third case, the handoff request cannot be transmitted from the PAR to the NAR.

3 is a flowchart illustrating an address management method when a terminal executes handoff after receiving a response by transmitting a handoff request before handoff according to the first embodiment of the present invention.

The terminal connected to the PAR searches for a target to be handed off (S302), and transmits an RtSolPr message including the found radio access identification information (S304).

Receiving the RtSolPr message, the PAR generates a NAR list corresponding to the radio access identifier, and distinguishes NARs using the IP prefix allocation mechanism for each terminal among NARs included in the NAR list. At this time, the prefix of the NAR using the IP prefix assignment mechanism may be displayed as 'temporarily assigned', 'allocated' or 'unallocated'. Among the prefixes of the NAR using the IP prefix assignment mechanism, one of the prefixes whose status is 'unallocated' is selected (S306). Then, the state of the selected prefix is changed to 'temporary allocation' state and the corresponding terminal identifier is stored. This altered 'temporary allocation' state is only maintained for a certain preset time, for example a few seconds. Then, when the predetermined time expires in advance, the state is changed to 'unassigned' again (S308).

The PrRtAdv message including the prefix information and the NAR information changed to the 'temporary allocation' state is transmitted to the terminal as a response to the RtSolPr message (S310).

When the UE receiving the PrRtAdv message is determined to handoff the network, the UE generates a FBU message including the selected NAR information and transmits the generated FBU message to the PAR (S312). Send a message. At this time, the HI message includes the information of the prefix changed to the 'temporary allocation' state (S314).

When the NAR determines that the prefix changed to the 'temporary allocation' state included in the HI message is valid by checking the validity, the NAR changes the prefix to the 'temporary allocation' state (S316).

When the validity of the corresponding prefix is verified and the state change is completed, the NAR generates a HAck message including a successful result and sends it to the PAR (S318), and the PAR receiving the HAck message 'allocates' the state of the prefix. Change to (S320).

When the state of the prefix is changed to 'assigned', the PAR transmits the prefix allocation result to the terminal through the FBAck message (S322). Upon receipt of the FBAck message, a tunnel is created between the UE and the PAR (S324).

The NAR may confirm that the terminal is connected through the UNA message transmitted from the terminal (S326), and change the state of the prefix changed to the 'temporary allocation' state in step S316 to 'assigned' (S328).

Through this address management method, fast handoff support is possible after the terminal receives a response by transmitting a handoff request before handoff.

4 is a flowchart illustrating a method for managing an address when a handoff request is previously transmitted from a PAR to a NAR but no response is received, thereby making a handoff request again through the NAR according to the second embodiment of the present invention. to be.

In the address management method according to the second embodiment of the present invention, in response to a handoff request of the terminal, the PAR selects one of the prefixes of the 'unassigned' state and changes it to the 'temporary allocation' state, and the NAR is received. As the state of the prefix is changed to 'temporary allocation' state through the HI message, the steps S402 to S420 of changing the state of the prefix to the 'assigned' state are described above with reference to S302 to S320 of FIG. 3. Since the steps are the same, detailed description is omitted.

At this time, when a fast handoff is performed in the link layer of the terminal, the terminal accesses a new link and transmits a UNA message to the NAR in a state in which the FBAck message is not received (S422).

The NAR may check the access of the terminal through the received UNA message, and change the state of the prefix, which has been changed to the 'temporary allocation' state according to the access of the terminal, to 'assigned' (S424).

Since the terminal has not received the FBAck message, and transmits the FBU message back to the PAR. At this time, since the terminal is connected to the NAR, the FBU message transmitted from the terminal is delivered to the PAR via the NAR (S426).

The PAR receiving the FBU message checks that the corresponding IP prefix is in the 'assigned' state, and checks whether the terminal to which the prefix is assigned and the terminal to which the FBU message is transmitted use the same terminal identifier (S428).

When the confirmation of the status of the prefix and whether the same terminal identifier is used, a FBAck message indicating the success of the handoff is generated and transmitted to the terminal. At this time, the FBAck message generated in the PAR is transmitted to the terminal through the NAR (S430).

Through this address management method, it is possible to support fast handoff of a terminal not receiving the FBAck after transmitting the FBU.

5 is a flowchart illustrating an address management method when a UE transmits an FBU after performing a handoff according to the third embodiment of the present invention.

In the address management method according to the third embodiment of the present invention, in response to the transmission of the RtSolPr message for the handoff request of the terminal, the PAR is changed to a 'temporary assignment' state by selecting one of the prefixes of the 'unallocated' state. In addition, since the steps S502 to S510 for transmitting the PrRtAdv message including the prefix information and the NAR information changed to the 'temporary allocation' state are the same as the steps S302 to S310 of FIG. 3, detailed description thereof will be omitted.

At this time, when a fast handoff is performed in the link layer of the terminal, the terminal accesses a new link and transmits a UNA message to the NAR without transmitting the FBU message (S512).

When the NAR confirms the access of the terminal through the received UNA message, the NAR checks whether the prefix requested by the terminal is assignable. When the allocation of the requested prefix is confirmed, the state of the prefix is changed to a 'temporary allocation' state (S514).

The terminal then transmits an FBU message to the PAR. At this time, since the terminal is connected to the NAR, the FBU message transmitted from the terminal is delivered to the PAR through the NAR (S516).

Upon receiving the FBU message, the PAR transfers the HI message including the fast handoff request of the UE to the NAR (S518). The NAR receiving the HI message changes the state of the corresponding IP prefix to an 'assigned' state (S520).

When the state change of the prefix is completed, a HAck message including a successful result is generated and transmitted to the PAR (S522), and the PAR receiving the HAck message changes the state of the prefix to 'assigned' (S524).

The PAR generates an FBAck message indicating the success of the handoff and transmits it to the terminal. At this time, the FBAck message generated in the PAR is transmitted to the terminal through the NAR (S526).

Through such an address management method, it is possible to support fast handoff for a UE transmitting an FBU after performing the address management method.

6 is a flowchart illustrating a prefix request and response method between a PAR and a NAR according to an embodiment of the present invention.

Prefixes whose status is set to 'allocated' among IP prefixes in PAR and NAR cannot be allocated to other terminals.

The PAR may not be allocated for a few seconds with respect to a prefix that may not be allocated to a terminal among the prefixes included in the PAR, and thus may be deleted while maintaining a 'temporary allocation' or 'assigned' state.

On the other hand, the NAR can confirm the disconnection of the terminal through interworking with the terminal connection management function. As such, the NAR can explicitly predict that a particular prefix will no longer be used.

According to the characteristics of the PAR and the NAR, the PAR may generate and transmit a prefix information request message requesting additional prefix information to the NAR (S602), and the NAR receiving the prefix information request message is added to a prefix that is no longer used. A prefix information response message including information about the generated information may be generated and provided to the PAR.

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram schematically illustrating a network for providing a wireless communication service;

2 is a signal flowchart for explaining a fast handoff method used in a conventional wireless communication system;

3 is a flowchart illustrating a method for managing an address when a terminal executes handoff after receiving a response by transmitting a handoff request before handoff according to the first embodiment of the present invention;

4 is a flowchart illustrating a method for managing an address when a handoff request is previously transmitted from a PAR to a NAR but no response is received, thereby making a handoff request again through the NAR according to the second embodiment of the present invention. ,

5 is a flowchart illustrating an address management method when a UE transmits an FBU after performing a handoff according to a third embodiment of the present invention;

6 is a flowchart illustrating a prefix request and response method between a PAR and a NAR according to an embodiment of the present invention.

Claims (17)

In the address management method for supporting the handoff between the heterogeneous network of the terminal by the router before the handoff that the terminal is connected, (a) receiving a message from the terminal, the message including information of a first access router to access through the handoff; (b) selecting one of the prefixes of the first access router and transmitting information of the selected prefix to the terminal; (c) generating a message including information on the selected prefix and transmitting the message to the first access router according to a handoff request from the terminal, and receiving a message including a result of validating the selected prefix; And (d) sending a message including allocation information of the selected prefix to the terminal to inform the handoff of possible handoff; Address management method comprising a. The method of claim 1, Step (b) is (b1) selecting one prefix of an unassigned state among the prefixes of the first access router and changing the state of the selected prefix to a temporary allocation state; And (b2) transmitting a proxy router advertisement message including information of the prefix changed to the temporary allocation state and information of the first access router to the terminal; Address management method comprising a. The method of claim 2, Step (d) is (d1) changing the state of the selected prefix from the temporary assignment state to an assignment state; And (d2) transmitting a binding response message including information of the prefix changed to the assigned state to the terminal; Address management method comprising a. The method of claim 1, Step (c) is, (c1) upon receipt of a handoff request from the terminal, generates a handoff initialization message for establishing a tunnel with the first access router, where the handoff initialization message includes information of the selected prefix; Making; (c2) sending the handoff initialization message to the first access router, such that the state of the selected prefix is changed to a temporary allocation state at the first access router; And (c3) receiving a handoff response message containing a result of validating the selected prefix from the first access router; Address management method comprising a. The method of claim 4, wherein After step (d) above, Changing the state of the selected prefix from the temporary allocation state to an allocation state when the first access router confirms connection of the terminal; Address management method further comprising. In the address management method for supporting the handoff between the heterogeneous network of the terminal by the router before the handoff that the terminal is connected, (a) receiving a message from the terminal, the message including information of a first access router to access through the handoff; (b) selecting one of the prefixes of the first access router and transmitting information of the selected prefix to the terminal; (c) generating a message including information on the selected prefix and transmitting the message to the first access router according to a handoff request from the terminal, and receiving a message including a result of validating the selected prefix; And (d) if it is confirmed that the prefix information of the terminal included in the handoff request message transmitted through the first access router and the prefix received through the handoff response message are notified, the successful termination of the handoff is performed. Sending a message to the first access router Address management method comprising a. The method of claim 6, Step (b) is (b1) selecting one prefix of an unassigned state among the prefixes of the first access router and changing the state of the selected prefix to a temporary allocation state; And (b2) transmitting a proxy router advertisement message including information of the prefix changed to the temporary allocation state and information of the first access router to the terminal; Address management method comprising a. The method of claim 7, wherein Step (c) is, And changing the state of the selected prefix from the temporary allocation state to the allocation state upon receipt of a handoff response message including a result of validating the selected prefix transmitted from the first access router. The method of claim 8, Step (d) is, (d1) checking the prefix of the terminal included in the handoff request message transmitted through the first access router and whether the prefix changed to the assigned state in step (c) is the same; And (d2) if it is determined that the prefix of the terminal and the prefix changed to the assigned state are identical, transmitting a binding response message indicating the successful end of the handoff to the terminal. Address management method comprising a. The method of claim 6, Step (c) is, And send the handoff initialization message to the first access router such that the selected prefix state at the first access router is changed to a temporary assignment state. The method of claim 10 Between the step (c) and the step (d), Changing the state of the selected prefix from the temporary allocation state to an allocation state when the first access router confirms connection of the terminal; Address management method further comprising. In the address management method for supporting the handoff between the heterogeneous network of the terminal by the router before the handoff that the terminal is connected, (a) receiving a message from the terminal, the message including information of a first access router to access through the handoff; (b) selecting one of the prefixes of the first access router and transmitting information of the selected prefix to the terminal; (c) in response to receiving the handoff request from the first access router, generates a handoff initiation message including information of the prefix assigned to the terminal and transmits the generated handoff initialization message to the first access router, and the prefix assigned to the terminal. Receiving prefix status information of a first access router for a; And (d) sending a binding response message to the first access router indicating the successful end of the handoff. Address management method comprising a. The method of claim 12, Step (b) is And selecting a prefix that is in an unassigned state among the prefixes of the first access router, and then changing the state of the selected prefix to a temporary assignment state. The method of claim 13, Step (c) is, (c1) generating a handoff initialization message including information of a prefix assigned to the terminal when a handoff request sent from the terminal is received through the first access router; (c2) sending the handoff initialization message to the first access router; And (c3) receiving a handoff response message sent from the first access router, wherein the handoff response message includes prefix status information of the first access router with respect to the prefix assigned to the terminal; Address management method comprising a. The method of claim 14, After the step (c3), And changing the state of the selected prefix from the temporary allocation state to the allocation state by using the state information of the prefix included in the handoff response message received from the first access router. The method of claim 12, Between step (b) and step (c), Changing the prefix set in the connected terminal to a temporary allocation state when the first access router determines that the terminal is connected; Address management method further comprising. The method of claim 15, Step (c) is, Changing a state of a prefix assigned to the terminal from a temporary allocation state to an allocation state by a first access router receiving the handoff initialization message; Address management method further comprising.

Images