KR20060026311A - Handover method in portable internet using explicit multi-casting scheme - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a handover method using an explicit multicasting technique in a mobile Internet.

2. The technical problem to be solved by the invention

The present invention provides a high-speed handover method that is low in loss and seamless in a portable Internet environment with frequent mobility by using an explicit multicasting technique in which a group management control procedure is simple in handling a handover in a portable Internet. For that purpose.

3. Summary of Solution to Invention

The present invention provides a handover method using an explicit multicasting technique in a mobile Internet, comprising: generating and transmitting a CAR_ADD message for registering / managing peripheral control stations of a terminal into an explicit multicasting group, and a terminal. When the UE moves to the overlapped area of the current base station and the new base station, a step of transmitting a PreHO_ON message for generating and transmitting a PreHO_ON message for transmitting a multicasting packet to the current control station and the new control station and the terminal is performed. Simultaneously receiving packets from the control station.

4. Important uses of the invention

The present invention is used in the mobile Internet system and the like.

Handover, Explicit Multicasting, Mobile IP

Description

Handover Method in Portable Internet Using Explicit Multi-casting Scheme             

1 is a diagram illustrating a process of registering peripheral control stations of a terminal as an explicit multicasting group by using a CAR_ADD message in a mobile Internet system to which the present invention is applied;

2 is a diagram illustrating a process of delivering a PreHO_ON message so that data to be received by a terminal may be explicitly multicasted according to an embodiment of the present invention.

FIG. 3 illustrates a case in which a CaCoA list is bound only to HA in a portable Internet system in which intermediate routers R1, R2, and R3 do not support explicit multicasting according to an exemplary embodiment of the present invention. A diagram illustrating a traffic transmission process of the case of transmitting only to HA and not to CN)

4 illustrates a case in which a CaCoA list is bound to HA and CN in a portable Internet system in which the intermediate routers R1, R2, and R3 do not support explicit multicasting according to an exemplary embodiment of the present invention. A diagram showing the traffic transmission process of the case where the message is transmitted to both HA and CN,

FIG. 5 illustrates a case in which a CaCoA list is bound to HA only in a mobile Internet system in which intermediate routers R1, R2, and R3 support explicit multicasting (the terminal may transmit a CAR_ADD message to the HA) according to one embodiment of the present invention. Is a diagram illustrating a process of transmitting traffic in a case of transmitting only to a network but not to a CN)

FIG. 6 illustrates a case in which a CaCoA list is bound to HA and CN in a portable Internet system in which intermediate routers R1, R2, and R3 support explicit multicasting according to an exemplary embodiment of the present invention. Is a diagram illustrating a traffic transmission process for a case where both are transmitted to HA and CN),

7 is a flowchart illustrating a process of generating and transmitting a CAR_ADD message and a PreHO_ON message by a terminal according to an embodiment of the present invention.

The present invention relates to a handover method in a portable internet, and more particularly, to a layer 3 level quick handover method using an explicit multicasting scheme in a portable internet. will be.

The handover technology is being standardized by MIP4, MIP6, and MIPSHOP working groups in the IETF, the international standardization organization, such as MIPv4 (Mobile IPv4), MIPv6 (Mobile IPv6), and Fast Handover (FMIP).                         

Since MIPv4 / 6 inherently takes several seconds to perform handover, there are many difficulties in supporting recent multimedia services.

To compensate for this significant latency problem, select a new candidate control station to service and pass the traffic to a single candidate control station through tunneling before the third-tier handover is performed, reducing losses and performing handovers quickly. An FMIP has been proposed.

However, the FMIP selects only one candidate control station in an environment in which the UE moves in various ways. Since the selection of one candidate control station may be selected differently from the actual candidate control station, the performance may be further reduced. It is implicit (see "Draft-ietf-mipshop-fast-mipv6-02.txt" in the IETF MIPSHOP Working Group).

On the other hand, there is a technique for reducing losses by managing candidate control stations in a multicasting group and transmitting traffic to the multicasting group at the same time in a research field other than the standard activities (see "Proactive seamless mobility management for future IP radio." access networks ”, Computer Communications 26 (2003), WWW.ComputerScienceWeb.com).

However, the prior art using such multicasting group management has a problem that the load of the control signal required to manage the multicasting group is quite large.

On the other hand, the explicit multicasting technique used in the present invention is a technique proposed to support small group communication, and uses IP addresses of actual group members, not multicasting addresses representing groups. Therefore, data transmission for group communication is a technique of explicitly including the address of each member in the header part of the packet and using the address information to deliver the same data to all members. It has the advantage of simplicity (see article: IETF Personal Internet Draft, "draft-ooms-xcast-basic-spec-05.txt").

The present invention has been proposed to solve the above problems, and by using an explicit multicasting technique in which the group management control process is simple in handling handover in the portable Internet, the loss and interruption in the portable Internet environment with frequent mobility are low. The purpose is to provide a fast handover method without this.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. In addition, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to achieve the above object, the present invention provides a handover method using an explicit multicasting technique in a mobile Internet, and generates and transmits a CAR_ADD message for registering / managing peripheral control stations of a terminal in an explicit multicasting group. A CAR_ADD message transmission step, a PreHO_ON message transmission step of generating and transmitting a PreHO_ON message for transmitting a multicasting packet to a current control station and a new control station when the terminal moves to an overlapped region of the current base station and a new base station; And a simultaneous packet receiving step of the terminal receiving packets simultaneously from the current control station and the new control station.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings after describing terms used herein for convenience of description.

Definitions of the main terms used in the present specification are as follows.

The CAR_ADD message is a message newly defined in the present invention and includes a CaCoA list in the order determined by the sensed signal strength and HoA (Home Address) information of the terminal. The CAR_ADD message is an extension of the MIPv6 Binding Update message. The content of this message is similar to the Binding Update message, except that the CAR_ADD message is composed of a list of CaCoA addresses.

When the terminal needs to receive data from neighboring base stations at the same time, the PreHO-ON message transmits this message to the HA and the CN to transmit explicit multicasting traffic.

CaCoA stands for "Candidate Care-of-Address", and the concept refers to a routable address of a mobile terminal having a subnet prefix of the other network when the terminal moves to another network, such as CoA of MIP. In the present invention, since it is generated in advance from the information of the neighboring control station in advance, it is called CaCoA.

HA (Home Agent) is a device name defined in the conventional MIP, in the embodiment of the present invention is used by modifying the binding table slightly.

The active set is defined in the IEEE802.16e / D4 document, which is the standard of the portable Internet, and those with excellent radio wave quality over a certain standard are called an active set.

HoA is a term defined in MIP, short for "Home address." Means the IP address originally assigned to the terminal.

The binding update message is a message defined in MIPv6. The Binding Update message transmits a CoA generated each time a terminal moves to HA and CN, such as HoA, to register and update in a binding table. As described above, the present invention extends this to define a message called CAR_ADD.

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

1 is a diagram illustrating a process of registering peripheral control stations of a terminal as an explicit multicasting group by using a CAR_ADD message in a portable Internet system to which the present invention is applied.

As shown in FIG. 1, the portable Internet system to which the present invention is applied includes a router for managing location information of a terminal, routers R1, R2, and R3 constituting a backbone network of the portable Internet, and a control station for base station management. (Control station 1, control station 2, control station 3) and base station (base station 1, base station 2, base station 3).

The terminal according to the present invention, which dynamically moves according to the IEEE802.16e MAC standard constituting the current mobile Internet standard, periodically scans neighboring base stations and measures the quality to manage the relatively good ones as an active set. Using the information of the active set base station, the corresponding control station is found and registered in the explicit multicasting group so that the same data is simultaneously transmitted to the neighboring base stations registered by the explicit multicasting technique.

In the portable Internet system, when the terminal detects the radio signal of the base station 2 gradually out of the current base station 1 propagation area, the neighbor candidate control stations are explicitly generated by generating / delivering a CAR_ADD message, which is a control signal for handover according to the present invention. The detailed process of registering as a multicasting group is as follows.

First, the corresponding control stations are searched by the Active Set information of the base station provided in the MAC layer of the terminal.

Subsequently, CaCoAs are generated from the retrieved control station information to generate a CAR_ADD message including a CaCoA list and its HoA.

At this time, the control station can be found from the base station information by using the IETF CARD protocol or the MIPSHOP group FMIP protocol. And CaCoA generation can apply IPv6 address automatic generation method.

Subsequently, the CAR_ADD message is delivered to the HA and the CN through the path as shown in FIG. 1. At this time, if the terminal is not communicating with the CN, the CAR_ADD message is only delivered to the HA.

Subsequently, the CAR_ADD received by the HA and CN having the data structure for storing the CaCoA list is bound to the HoA and CaCoA list by the same procedure as the processing of the binding update message of the existing MIPv6. Register explicit multicasting groups of neighboring candidate control stations.

2 is a diagram illustrating a process of delivering a PreHO_ON message so that data to be received by a terminal can be explicitly multicasted according to an embodiment of the present invention.

The terminal triggers the HA and CA with the PreHO_ON message transmitted through the path as shown in FIG. 2 to receive traffic from the current control station (control station 1) and at the same time receive traffic from the neighboring control station (control station 2). Can be.                     

As shown in FIG. 2, as the terminal gradually moves away from the area of the current base station (base station 1) and moves to the area of the base station 2, at a time point when the signal of the base station 2 becomes stronger than the signal of the base station 1 beyond a certain criterion, The terminal sends a PreHO_ON message to the HA and CN, respectively, to operate multicasting for smooth (seamless) handover.

At this time, the PreHO_ON message includes a list of CaCoAs corresponding to the control station with strong signal strength, and the HA and CN receiving the PreHO_ON message change the state of the terminal from a normal state to a prehandover state. Sends traffic in to explicit multicasting.

FIG. 3 illustrates a case in which a CaCoA list is bound only to HA in a portable Internet system in which intermediate routers R1, R2, and R3 do not support explicit multicasting according to an exemplary embodiment of the present invention. Is a diagram illustrating a traffic transmission process of the case of transmitting only to HA and not to CN).

As shown in FIG. 3, the CN to transmit data to the terminal first checks whether there is binding information associated with the terminal, and if there is no information, generates and transmits a packet as if it is communicating with the terminal through unicast.

The HA in the home network of the terminal intercepts the traffic transmitted from the CN because the terminal has the binding information of the terminal, and writes the CaCoA list present in the binding table entry in the explicit multicasting header according to the binding information. Transmit to explicit multicasting packet and send.

At this time, since the routers R1, R2, and R3 constituting the central network excluding the control station do not support explicit multicasting, each router forwards the packet by the same routing function as that of a general unicast packet. do.

Therefore, as shown in FIG. 3, the packet transmitted from the HA is delivered to the control station 1 through R3 and R1.

On the other hand, the control station supporting explicit multicasting calculates routing with each CaCoA address encoded in the explicit multicasting header of the packet as a destination, and then determines the next hop to be delivered, and has the same result according to the determined value. Create a new packet by binding CaCoA addresses.

At this time, if the packet has one or more CaCoA addresses, it is generated as an explicit multicasting packet, otherwise it is generated and transmitted as a unicast packet.

Therefore, the control station 1 that receives the explicit multicasting packet from R1 generates a uticast packet and transmits it to R1 at the same time as the next hop determined by the CaCoA list is R1 and base station 1 and each has only one address. The packet is transmitted to the base station 2 through the paths R1, R3, R2 and control station 2 shown in the figure.

FIG. 4 illustrates a case in which a CaCoA list is bound to HA and CN in a portable Internet system in which intermediate routers R1, R2, and R3 do not support explicit multicasting according to an exemplary embodiment of the present invention. Is a diagram illustrating a traffic transmission process for a message transmitted to both HA and CN).

When the CN attempts to transmit data to the terminal, it confirms that there is information about the terminal in its binding table, and then generates and transmits an explicit multicasting packet.

At this time, the transmission process after the R3 receiving the packet transmitted from the CN is the same as FIG.

FIG. 5 illustrates a case in which a CaCoA list is bound to HA only in a mobile Internet system in which intermediate routers R1, R2, and R3 support explicit multicasting (the terminal sends a CAR_ADD message to HA) according to an embodiment of the present invention. Is a diagram illustrating a traffic transmission process for the case where only the data transmission is carried out in the network but not in the CN).

As described above, the CN generates and transmits a unicast packet because the CaCoA list of the terminal is not bound, and the unicast packet transmitted from the CN is modified and transmitted by explicit multicasting after arriving at the HA.

In this case, since R3 supports explicit routing, the next hop is determined for each CaCoA in the header, and a Uticast packet is generated, and one is transmitted to R1 and the other to R2, as shown in FIG. 5. Similarly, data is transmitted to both base station 1 and base station 2.

FIG. 6 illustrates a case in which a CaCoA list is bound to HA and CN in a portable Internet system in which intermediate routers R1, R2, and R3 support explicit multicasting according to an exemplary embodiment of the present invention. Is a diagram illustrating a traffic transmission process for a case where both are transmitted to HA and CN).

Since the CN is bound to the CaCoA list with the CAR_ADD message received from the terminal, the CN generates data as an explicit multicasting packet and transmits it.

As shown in FIG. 6, the packets generated from the CN and arrived at R3 are all delivered to the neighboring control station to which the terminal moves through the same path as described above with reference to FIG. 5.

Therefore, as soon as the terminal arrives at the new area (the area of the candidate control station), the terminal informs the control station of its existence and immediately receives the traffic from the candidate control station that buffers and stores the explicitly multicasted traffic. Handover can be implemented.

7 is a flowchart illustrating a process of generating and transmitting a CAR_ADD message and a PreHO_ON message by a terminal according to an embodiment of the present invention.

First, when the terminal finds a neighboring base station having a predetermined signal quality (10), the information (3 layer information, IP, prefix, etc.) of the corresponding control station is obtained using the found base station information (20).

Subsequently, CaCoA is generated using the information of the control station (30), and the generated CaCoA is encoded to generate a CAR_ADD message and then transmitted to HA (40).

Subsequently, it is determined whether the CN address being communicated is known (50), and if the CN address is known, the CAR_ADD message is transmitted to the CN (60).

Subsequently, by generating a PreHO_ON message to the HA and CN when the current base station signal of the terminal falls below a predetermined criterion or when the neighboring base station signal is stronger than the current base station signal (70), the explicit multi according to the present invention described above. You will be offered a handover service using the casting technique.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention as described above, by processing the handover by using an explicit multicasting technique, there is an effect that can provide a fast handover service without loss to the mobile terminal.

In addition, the present invention as described above by inheriting the simplicity of the explicit multicasting technique, there is an effect that can provide a fast handover service with a simple control signal and the procedure for group management.

In addition, the present invention as described above has an effect that can be easily applied to the mobile Internet system by modifying the functions of the control station and the terminal by processing the handover by using an explicit multicasting technique.

In addition, the present invention as described above can provide a seamless Internet multimedia service by processing the handover by using an explicit multicasting technique, and continues handover between the base station and the base station, such as a ping-pong phenomenon. Even when a situation occurs, there is an effect that can provide a lossless data service.

Claims (8)

As a handover method using explicit multicasting technique in the mobile Internet, A CAR_ADD message transmission step of generating and transmitting a CAR_ADD message for registering / managing peripheral control stations of the terminal into an explicit multicasting group; A PreHO_ON message transmitting step of generating and transmitting a PreHO_ON message for transmitting a multicasting packet to a current control station and a new control station when the terminal moves to an overlapped area of the current base station and the new base station; And Simultaneous packet receiving step in which the terminal simultaneously receives packets from the current control station and the new control station Handover method using an explicit multicasting technique comprising a. The method of claim 1, The CAR_ADD message transmission step, A peripheral control station information obtaining step of the terminal finding a neighbor base station of a predetermined signal quality and acquiring information of the neighboring control station using the found base station information; A CaCoA list generation step of generating a CaCoA list using the information of the neighboring control station; A CAR_ADD message generation step of generating a CAR_ADD message by encoding the CaCoA list; And CAR_ADD message HA transmission step of transmitting the CAR_ADD message to HA Handover method using an explicit multicasting technique comprising a. The method of claim 2, The CAR_ADD message transmission step, Sending the CAR_ADD message CN to send the CAR_ADD message to the CN Handover method using an explicit multicasting technique further comprising. The method according to any one of claims 1 to 3, The PreHO_ON message transmission step, A handover method using an explicit multicasting technique, wherein a PreHO_ON message is generated and transmitted to the HA when the current base station signal of the terminal falls below a predetermined criterion or when a neighbor base station signal is stronger than the current base station signal. The method according to any one of claims 1 to 3, The PreHO_ON message transmission step, A handover method using an explicit multicasting technique, which generates and transmits a PreHO_ON message to a CN when a current base station signal of a terminal falls below a predetermined criterion or when a neighboring base station signal is stronger than a current base station signal. The method of claim 1, The simultaneous packet receiving step, An explicit multicasting group registration step in which the CN registers the neighboring base station as an explicit multicasting group by using the CAR_ADD message received from the terminal; Explicit multicasting packet transmission step of generating and transmitting an explicit multicasting packet to a control station registered to the explicit multicasting group after the CN receives the PreHO_ON message from the terminal. Handover method using an explicit multicasting technique comprising a. The method of claim 1, The simultaneous packet receiving step, An explicit multicasting group registration step in which the HA registers the neighboring base station as an explicit multicasting group by using the CAR_ADD message received from the terminal; After receiving the PreHO_ON message from the terminal, the explicit multicasting packet transmission step of converting the packet into an explicit multicasting packet by using the packet transmitted by the CN to the control station registered to the explicit multicasting group. Handover method using an explicit multicasting technique comprising a. The method of claim 1, The simultaneous packet receiving step, Transmitting the current control station, which converts the explicit multicasting packet received by the current control station into a unicasting packet and transmits it to the terminal and the new control station. Handover method using an explicit multicasting technique comprising a.

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