KR20050058775A - Apparatus and method of packet forwarding for handoff in wireless access network - Google Patents

Abstract

The present invention relates to an apparatus and method for packet forwarding according to handoff in a wireless access network.

According to the present invention, when a mobile node performing data communication in a wireless access network performs a handoff, when a previous access router performs F tag marking on a packet forwarded to a new access router, and the mobility management origin completes a path change, Stop routing to the access router, forwarding information about the last message to the previous access router and forwarding it to the new access router, and the new access router preferentially sends F-tag packets to the mobile node until it receives the information about the last message. The new packet is transmitted after receiving the last message so that the packet can be transmitted without changing the order of the packets.

Description

Apparatus and method of packet forwarding for handoff in wireless access network

The present invention relates to packet forwarding during handoff in a wireless access network, and more particularly, to an apparatus and method for packet forwarding according to handoff in a wireless access network for sequential packet forwarding during handoff in a mobility management origin domain.

Mobile IP and Mobile IPv6, which provide global mobility in both Internet Protocol (IP) and IPv6 (IP version 6) networks, are geographically remote even when the mobile node moves inside the wireless access network. Since the move information must be registered in the home agent (hereinafter referred to as HA) of the mobile node, it takes a lot of time to move the mobile node, which dramatically reduces the throughput of data communication.

Therefore, a local mobility support protocol has been proposed to process internal movement within a wireless access network without informing the outside of the wireless access network. In particular, HMIPv6 (Hierarchical Mobile IP version 6) is a technique for managing mobility in a region by having one or more mobility management points in an IPv6 wireless access network.

However, when a mobile node moves and hands off within a domain managed by a Mobile Anchor Point in an HMIPv6 wireless access network, packets forwarded to the new access router are forwarded to the new access router. However, the order of the received packets may be changed due to the late order packets which are transmitted on the new path and arrive first, and the forward order packets which are forwarded through the previous path and arrive late.

In this case, when the transport layer protocol is a transmission control protocol (hereinafter referred to as TCP), the packet change caused by the handoff is determined to be lost, and the packet determined to be lost is retransmitted by performing a congestion control mechanism. Halve the packet rate. If the number of lost packets is large, TCP will perform congestion control again from slow-start, causing serious effects on performance.

In order to solve the above problem, Korean Patent Laid-Open Publication No. 2003-50897 (Handoff Method in a Wireless Access Network Accessing an Internet Protocol Network) proposes a method for improving cellular IP semi-soft handoff. This paper proposes a technique that targets cellular IP networks configured with a tree structure of routers and instructs mobile nodes in handoff time points so that there is no loss of received packets.

In addition, the above-mentioned technique notifies the mobile node of the time when the mobile node receives all the packets transmitted to the previous path so that the network can start the handoff, and the data to the new path is buffered at the new access router. When the off is completed, the buffered data is transmitted to the mobile node. Therefore, the old access router does not forward the packet to the new access router.

Since the cellular IP semi-soft handoff method is used after the mobile node first handoffs the care of address (CoA) received when the mobile node first enters the cellular IP network, the IPv6 network in which the mobile node has a different local address for each handoff is used. Not available in. In addition, if the network itself does not allow semi-soft handoff, that is, in a network that does not allow the process of attempting and disconnecting with a new access router for a while before the actual handoff, the cellular IP semi-soft handoff improvement method may be used. There is a problem that can not be.

Currently, a method of using packet forwarding according to handoff is a seamless handoff architecture for mobile IP (INFOCOM 2003).

1 is a flowchart illustrating a method of packet forwarding during handoff in a conventional S-MIP.

Referring to FIG. 1, the handoff using the S-MIP method is performed between the mobile node 110, the new access router 121, the old access router 122, the mobility management origin 130, and the mobility management decision node 140. This is done by sending and receiving packets.

The mobile node 110 recognizes the need for a handoff and requests a new access router address from the previous access router 122-currently accessing (S101).

The mobility management determining node 140 determines a router to which the mobile node 110 newly connects based on the access mobility node information for each access router, and transfers the determined address of the new access router to the previous access router 122-currently connected. And informs the neighboring router (new connection router 121) to transmit (S102).

The previous access router 122-currently connecting transmits a PrRtAdv (Proxy Router Advertisement) message and a HN (Handoff Notification) message including the address of the new access router received from the mobility management decision node 140 to the mobile node 110. (S103), an address of the new access router 121 is informed and instructed to hand off.

The mobile node 110 creates a new care of address (NCoA), which is a new address to have after handoff, based on the address of the new access router 121, and an address currently connected to the previous access router 122-currently connected. The packet forwarding is requested by sending a binding modification request message (F-BU; Fast Binding Update) between the (on-link CoA) and the NCoA (S104).

When the previous access router (122-currently connected) receives the binding modification request message, it sends a Scast (Simulcast) message to the mobility management node 130, and sends a packet to be transmitted from the mobility management point to the mobile node. Medium) and the new access router 121 to transmit the S tag attached at the same time (S105).

In addition, the previous access router 122-currently connected to the mobile node 110 directly sends a fast binding acknowledgment (F-BAck) message to inform the result of the binding modification request (S106a), and the mobile node 110 has already sent the message. In case the handoff is initiated and the F-BAck is not received, the F-BAck message is also sent to the new access router 121 to be transmitted to the mobile node 110 (S106b).

When the mobile node 110 is performing the handoff, when the previous access router 122 receives the packet transmitted from the mobile management origin 130 to the mobile node 110 after the step S106a (or S106b), The F tag is attached to the new access router 121 to indicate that the packet is a forwarding packet, and then transmitted (S107). After the mobile management origin 130 receives the Scast (S105), the packet is transmitted to the mobile node 110 after receiving the Scast (S105). The tag is copied, and the packet is copied and transmitted to the old access router 122 and the new access router 121 simultaneously (S108). In this case, the previous access router 122 does not forward the packet tagged with the S tag.

After receiving the F-BAck message in step S106b, the new access router 121 buffers the packets to be sent to the mobile node in the F buffer and the S buffer. In this case, it can be seen that all the access routers have an S buffer and an F buffer for buffering packets to be transmitted to the mobile node during handoff. The F buffer is also for packets forwarded from the previous access router 122.

Then, the mobile node 110 disconnects from the previous access router 122 (S109), resumes connection with the new access router 121 (S110), and confirms its new address F_NA (Fast Neighbor). Advertisement) is sent to the new access router 121 to complete the handoff (S111).

The new access router 121 receives the F_NA message, confirms that the connection with the mobile node has been resumed, and transmits a packet in the F buffer first among the packets to be sent to the mobile node (S112), and sends it to the mobile management originating station 130. The Soff (Seamless off) message to stop sending the S packet is transmitted (S113). The movement management origin 130 notifies the movement management decision node 140 by transmitting a Soff message indicating that the S packet is transmitted (S115).

Then, the new access router 121 transmits all the packets of the F buffer, and then transmits the packets of the S buffer (S114).

Thereafter, the mobility management origin 130 stops marking the S tag on the packet after receiving the Soff message, and performs packet delivery only to the new access router 121 (S116).

The above-described method can reduce the order entanglement of packets due to packet forwarding during handoff providing mobility in a region in a generally used manner.

However, since the forwarding packet is more than the S-packet, it goes through the MO-PG-MOP pass, so when the mobile node handoffs and delivers all the packets in the F buffer at the new AP, it is still old. There is a problem that an F packet on a path from an access router to a new access router may be being transferred. The S-MIP scheme directly transfers the contents of the S buffer to the mobile node without considering this case.

In this case, late arriving F packets are transmitted to the mobile node after the packets of the S buffer, and the order is reversed. This causes a problem of dropping the transmission rate by judging packet loss as in the case of TCP. 140 simultaneously copies the S packet and transmits it to the old access router 122 and the new access router 121, resulting in unnecessary waste of bandwidth.

In order to solve the above problem, the present invention transmits a packet to a mobile node without entanglement when forwarding packets are forwarded to a new access router during handoff in a wireless access network connecting to an IPv6 network. It is an object of the present invention to provide a packet forwarding apparatus and method according to the handoff in a wireless access network that can continue the sequential packet communication.

Packet forwarding apparatus according to a handoff in a wireless access network according to an aspect of the present invention,

In the packet forwarding apparatus for handoff of a mobile node in a wireless access network performing wireless data communication with the mobile node, when the mobile node performs wireless channel communication and the mobile node performs handoff, the mobile node A second access router which indicates that the packet to be transmitted to the mobile node is a forwarding packet until the packet transmission path to the network is changed, and that the mobile node newly accesses a message indicating that the packet is forwarded when the packet transmission path is changed. A first access router for forwarding; Storing a forwarding packet transmitted from the first access router, transmitting a forwarding packet to the mobile node until receiving a message indicating forwarding of the last packet, and then receiving a message indicating forwarding of the last packet Thereafter, a second access router for transmitting a new packet to the mobile node; A mobile management originating point for transmitting a packet to the mobile node through the first access router and the second access router, and changing a packet transmission path according to a handoff of the mobile node; And a mobility management determination node for determining a new access router of the mobile node according to the handoff request of the mobile node and informing the first access router and the second access router of the determined new access router address information.

In this case, the first access router and the second access router, a forwarding buffer for storing the packet forwarded according to the handoff of the mobile node; And a general buffer for storing the new packet transmitted to the mobile node by the mobility management origin.

Packet forwarding method according to the handoff in a wireless access network according to an aspect of the present invention,

A first access router and a second access router configured to perform wireless data communication with the mobile node; A mobility management originating point for transmitting a packet to the mobile node through the first access router and the second access router; A method of packet forwarding when a mobile node is handed off in a wireless access network comprising a mobile management network that determines and manages a router to which the mobile node is connected when the mobile node is handed off. A second access router, which is currently in wireless communication, transmits a handoff request message due to the movement of the mobile node from the mobile node to the mobility management decision node, and the mobile node newly connects from the mobility management decision node. Receiving an address of the; (b) the first access router transmits a packet transmission path change request message including the second access router information to be handed off by the mobile node to the mobility management origin, and marks a forwarding packet on a packet to be transmitted to the mobile node. Forwarding to the second access router; (c) receiving a response message for the packet transmission path change request message transmitted from the first access router to the mobility management origin, and indicating that the last packet is the last message of the packet to be forwarded to the second access router. Transmitting to a two access router; And (d) transmitting a packet with a forwarding packet indication to the mobile node until the second access router receives a packet indicating that the message is the last message from the first access router, and receiving the packet indicating the last message. And transmitting the newly received packet after transmitting the packet to the mobile node.

The second access router stores a packet transmitted from the mobility management origin to the mobile node, and transmits a forwarding packet forwarded from the first access router to the mobile node first.

A recording medium according to one aspect of the present invention,

A recording medium storing a function for packet forwarding when a mobile node is handed off in a wireless access network performing wireless data communication with a mobile node, the method comprising: (a) a first access router to which the mobile node is currently wirelessly communicating; Transmitting a handoff request message due to movement of a mobile node from the mobile node to the mobility management decision node, and receiving an address of a second access router to which the mobile node newly connects from the mobility management decision node; (b) the first access router transmits a packet transmission path change request message including the second access router information to be handed off by the mobile node to the mobility management origin, and marks a forwarding packet on a packet to be transmitted to the mobile node. Forwarding to the second access router; (c) receiving a response message for the packet transmission path change request message transmitted from the first access router to the mobility management origin, and indicating that the last packet is the last message of the packet to be forwarded to the second access router. Transmitting to a two-connected router; And (d) transmitting a packet with a forwarding packet indication to the mobile node until the second access router receives a packet indicating that the message is the last message from the first access router, and receiving the packet indicating the last message. And a function of transmitting a newly received packet after transmitting the packet to the mobile node.

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 accompanying drawings, parts irrelevant to the description of the present invention are omitted in order to clearly describe the present invention, and the same or similar parts are denoted by the same reference numerals.

2 is a block diagram illustrating a connection structure between a wireless access network and an IPv6 network according to an embodiment of the present invention.

Referring to FIG. 2, the wireless access network connecting to the IPv6 network 200 includes a mobility management origin point 230, a mobility management decision node 240, a new access router 221, and an old access router 222. The mobile node 210 communicates wirelessly with the new access router 221 and the previous access router 222. The mobile node 210 communicates by accessing the IPv6 network 200 through a wireless access network when communicating with the counter node 250.

The previous access router 222 indicates a router to which the mobile node 210 is currently connected, and indicates that the previous access router 222 becomes when handoff is performed.

The new access router 221 indicates a router to which the mobile node newly connects from the previous access router 222 at the time of handoff.

When the mobile node 210 starts to perform a handoff, the previous access router 222 sets the F tag on the packet to be transmitted to the mobile node 210 and forwards it to the new access router 221, and the new access router 221. ) Temporarily stores the forwarded F packet.

The new access router 221 also temporarily stores new packets transmitted from the mobility management origin 230 to the mobile node 210 due to handoff.

To this end, the new access router 221 and the old access router 222 include a forwarding (F) buffer for performing handoff and a general buffer.

The F-buffered packet is stored in the F buffer, and the general buffer stores a packet for newly receiving from the mobility management origin 230 and transmitting to the mobile node 210.

In addition, when the mobile node 210 finishes the handoff, the previous access router 222 forwards the packet and finally displays the End of Old Flow (EoOF) indicating that the packet is the last forwarding packet, and the EoOF mark is displayed. Upon receiving the packet, the new access router 221 starts to transmit the packet stored in the F buffer to the mobile node 210, transmits all the packets stored in the F buffer, and then transfers the packet in the general buffer to the mobile node 210. So that the order of the packets is not reversed.

The mobility management decision node (DE) 240 determines a router to which the mobile node 210 connects at the time of handoff, and the mobility management origin point 230 transmits a packet transmitted to the mobile node 210 to the corresponding mobile node. Transmit to the router 210 is connected to.

3 is a flowchart illustrating a packet forwarding method according to handoff in a wireless access network according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the mobile node 210 recognizes the need for handoff by comparing the beacon signal strength of the currently connected router with the beacon signal strength of another access router during data communication with the currently connected router. In step S301, a new access router address is requested from the previous access router (222-currently connected).

The mobility management decision node 240 determines a router to which the mobile node 210 newly connects based on the access mobile node information for each access router, and transfers the determined address of the new access router to the previous access router (222-currently connected). And informs by transmitting to the adjacent router (S302).

The old access router (222-currently connected) sends a PrRtAdv (Proxy Router Advertisement) message and a HN (Handoff Notification) message including the address of the new access router 221 received from the mobility management decision node 240. (S303), an address of the new access router 221 is informed and instructed to hand off.

The mobile node 210 creates a new care of address (NCoA), which is a new address to have after handoff, based on the address of the new access router 221, and an address currently connected to the previous access router 222-currently connected. The packet forwarding is requested by sending a binding modification request message (F-BU; Fast Binding Update) between the (on-link CoA) and the NCoA (S304).

When the previous access router (222-currently connected) receives the binding modification request message, the transport access point change request message for changing the transmission path of the packet transmitted to the mobile node 210 to the new access router 222 may be transmitted. 230, and transmits the F-BAck message for binding confirmation directly through the new access router 222 or to the mobile node 210 (S306a, S306b).

In addition, the mobility management origin 230 changes the path for transmitting the packet to the mobile node 210 from the previous access router 222 to the new access router 221 according to the transmission path change request message in step S305. In operation S307, the router 222 informs the previous access router 222 of the transmission path change complete message.

Thereafter, the movement management origin 230 transmits the packet transmitted to the mobile node 210 to the new access router 221 (S308).

In addition, the previous access router 222 marks the F tag on a packet to be transmitted to the mobile node 210 received while the mobile node 210 is handing off and forwards it to the new access router 221 (S309). At this time, the new access router 221 separates and buffers each of the F buffer having an F tag for buffering the packet marked with the F tag and a general buffer for buffering the new packet.

After receiving the transmission path change complete message from the mobility management origin 230, the previous access router 222 transmits all packets marked with the F tag and finishes packet forwarding (EoOF; End of Old Flow). Is sent to the new access router (221) (S310).

The mobile node 210 terminates the connection with the previous access router 222 (S311), resumes connection with the new access router 221 through a handoff process (S312), and confirms its new address. A Fast Neighbor Advertisement (F_NA) message is transmitted to the new access router 221 (S313).

The new access router 221 confirms the normal handoff of the mobile node 210 according to the F_NA message transmitted by the mobile node 210, and first transmits F packets in the F buffer to the mobile node 210 sequentially. (S314).

After receiving the EoOF message indicating that the message is the last message from the previous access router 222 and transmitting all the packets of the F buffer, the forwarding completion notification message indicating the completion of the transmission of the F packet is transmitted to the mobility management decision node 240. (S315).

Thereafter, the new access router 221 transmits a new packet to the mobile node 210 (S316).

As described above, when the mobile node performing data communication in the wireless access network connecting to the IPv6 network performs a handoff, F tag marking is performed on the packet forwarded by the previous access router to the new access router, and the mobility management origin path When the change is complete, stop routing to the old access router, forwarding the information about the last message to the old access router, and forwarding it to the new access router. The new access router forwards the F tag packet until it receives the information about the last message. First, it transmits to the mobile node and transmits a new packet after receiving the last message, thereby enabling transmission without changing the order of packets.

In addition, due to the above effects, compared to the method in which the mobile management origin used in the S-MIP scheme copies packets and simultaneously transmits the packets to the old access router and the new access router, bandwidth waste can be reduced, thereby expanding the wireless access network. It has an effect of increasing sex.

Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited thereto, and various other changes and modifications are possible.

In addition, the method of the present invention as described above may be implemented as a program and stored in a recording medium-CD-ROM, RAM, floppy disk, hard disk, magneto-optical disk, etc. in a computer-readable form.

As described above, the packet forwarding apparatus and method according to the handoff in the wireless access network according to the present invention is a mobile node after the handoff regardless of the relative distance difference between the new access router and the old access router from the mobility management origin Since the next packet of the data packet received just before the handoff can be immediately received from the new access router, packet loss is prevented, so that the TCP connection can maintain performance even after the handoff.

1 is a flowchart illustrating a method of packet forwarding during handoff in a general S-MIP.

2 is a block diagram illustrating a connection structure between a wireless access network and an IPv6 network according to an embodiment of the present invention.

3 is a flowchart illustrating a packet forwarding method according to handoff in a wireless access network according to an exemplary embodiment of the present invention.

Claims (5)

A packet forwarding apparatus for handoff of a mobile node in a wireless access network performing wireless data communication with the mobile node, the apparatus comprising: When the mobile node communicates with the mobile node and the mobile node performs handoff, it indicates a forwarding packet to a packet to be transmitted to the mobile node until the packet transmission path to the mobile node is changed. If is changed, the first access router for transmitting a message indicating that the forwarding of the last packet to the second access router that the mobile node newly connected; Storing a forwarding packet transmitted from the first access router, transmitting a forwarding packet to the mobile node until receiving a message indicating forwarding of the last packet, and then receiving a message indicating forwarding of the last packet Thereafter, a second access router for transmitting a new packet to the mobile node; A mobile management originating point for transmitting a packet to the mobile node through the first access router and the second access router, and changing a packet transmission path according to a handoff of the mobile node; And A mobile management determination node for determining a new access router of the mobile node according to the handoff request of the mobile node and informing the first access router and the second access router of the determined new access router address information. Packet forwarding apparatus according to the handoff in a wireless access network comprising a. The method of claim 1, The first connection router and the second connection router, A forwarding buffer for storing a packet forwarded according to the handoff of the mobile node; And a general buffer for storing a new packet transmitted to the mobile node by the mobile management origin point. A first access router and a second access router configured to perform wireless data communication with the mobile node; A mobility management originating point for transmitting a packet to the mobile node through the first access router and the second access router; A packet forwarding method for handoff of a mobile node in a wireless access network comprising a mobile management network that determines and manages a router to which the mobile node will access when the mobile node is handed off. (a) a first access router to which the mobile node is currently wirelessly communicating transmits a handoff request message resulting from the movement of the mobile node from the mobile node to the mobility management decision node, and from the mobility management decision node; Receiving an address of a second access router to which a new connection is made; (b) the first access router transmits a packet transmission path change request message including the second access router information to be handed off by the mobile node to the mobility management origin, and marks a forwarding packet on a packet to be transmitted to the mobile node. Forwarding to the second access router; (c) receiving a response message for the packet transmission path change request message transmitted from the first access router to the mobility management origin, and indicating that the last packet is the last message of the packet to be forwarded to the second access router. Transmitting to a two access router; And (d) transmitting a packet with a forwarding packet indication to the mobile node until the second access router receives a packet indicating that the message is the last message from the first access router, and receiving the packet indicating the last message. Transmitting the newly received packet after transmitting the packet to the mobile node Packet forwarding method according to a handoff in a wireless access network indicating a. The method of claim 3, wherein In the step (d), In the wireless access network, the second access router stores a packet transmitted from the mobility management origin to the mobile node, and transmits a forwarding packet forwarded from the first access router to the mobile node first. Packet forwarding method according to handoff. A recording medium storing a function for packet forwarding when handoff of the mobile node in a wireless access network performing wireless data communication with the mobile node, (a) a first access router to which the mobile node is currently wirelessly communicating transmits a handoff request message resulting from the movement of the mobile node from the mobile node to the mobility management decision node, and from the mobility management decision node; Receiving an address of a second access router to be newly connected; (b) the first access router transmits a packet transmission path change request message including the second access router information to be handed off by the mobile node to the mobility management origin, and marks a forwarding packet on a packet to be transmitted to the mobile node. Forwarding to the second access router; (c) receiving a response message for the packet transmission path change request message transmitted from the first access router to the mobility management origin, and indicating that the last packet is the last message of the packet to be forwarded to the second access router. Transmitting to two access routers; And (d) transmitting a packet with a forwarding packet indication to the mobile node until the second access router receives a packet indicating that the message is the last message from the first access router, and receiving the packet indicating the last message. A function that transmits a newly received packet after transmitting the packet to the mobile node Recording medium for storing a program comprising a.