KR20080012243A - Apparatus and method for processing hand-off in wireless telecommunication system - Google Patents

Abstract

An apparatus and a method for processing handoff in a wireless communication system are provided to prevent the loss of packets in advance by making an ACR(Access Control Router) bicast packets to both a serving RAS(Radio Access Station) and a target RAS when handoff is ongoing and unicast packets only to the target RAS if handoff is completed. An apparatus for processing handoff in a wireless communication system comprises a subscriber session management part(110) and a routing processing part(120). The subscriber session management part(110), if a handoff request message is received, requests the routing processing part(120) to modify routing information so that packets can be transmitted to both a serving RAS and a target RAS. If a handoff complete message is received, the subscriber session management part(110) requests the routing processing part(120) to modify routing information so that packets can be transmitted only to the target RAS. The routing processing part(120) stores the routing information, modifies the routing information according to a request from the subscriber session management part(110), and transmits packets on the basis of the modified routing information.

Description

Apparatus and method for processing hand-off in wireless telecommunication system

The present invention relates to an apparatus and method for handoff processing in a wireless communication system. More particularly, in a wireless communication system conforming to the IEEE 802.16e standard, a control station simultaneously transmits a packet to a serving base station and a target base station during handoff. A handoff processing apparatus and method for transmitting a packet only to a target base station when the handoff is completed.

Recently, with the development of electronic / communication technology, various communication services such as mobile communication and portable internet using wireless network are provided, and the user controls by carrying a portable subscriber station (MSS) or mobile station (PSS). Various communication services provided through an access control router (ACR) and a base station (RAS) can be used.

1 is a diagram illustrating a hierarchical structure of a wireless communication system, which illustrates a portable Internet system, which is a terminal (PSS) for providing a portable Internet service to a user, and transmits and receives data through a wireless interface with the terminal. A base station (RAS), a control station (ACR) that controls the terminal and the base station and routes an Internet Protocol (IP) packet, a home agent (HA; Home Agent) that supports IP mobility of the terminal in a home network, and a user; It consists of an authentication server (AAA; Authentication, Authorization, Accounting) that performs authentication, authorization verification, and billing for the terminal, and the IP network of the individual operator connected to the control station, home agent, authentication server, etc. is a public IP network. By connecting to the Internet, it is possible to provide a mobile Internet service that can be connected to the Internet around the world.

On the other hand, when the user moves away from the base station as the mobile terminal moves away from the base station to reduce the signal quality of service (QoS; Quality of Service) is reduced, in order to prevent this, the currently serving base station (hereinafter, 'Serving (Serving) When the signal strength of the base station falls below a certain level, the radio link is switched to a new base station (hereinafter referred to as a 'target base station') to perform hand-off / handover.

Such handoff methods include hard hand-off and soft hand-off. Hard hand-off is performed after a terminal disconnects communication with a serving base station currently serving. The soft handoff is a method of connecting to the target base station and communicating with the serving base station and the target base station simultaneously during the handoff by connecting with the target base station before ending the connection with the serving base station.

In relation to the above handoff, the IEEE 802.16e system is designed to calculate hard handoff as a basic model so that the user can be provided with smooth communication service while on the move, whereas in the case of soft handoff, the currently defined subchannel There is a problem that it is difficult to apply the (Sub-Channel) allocation method as it is.

Therefore, in the case of the IEEE 802.16e system, in the prior art, as shown in FIG. 2, the control station 10 performs a core network 50 while the handoff is performed from the serving base station 20 to the target base station 30. Uni-casting the packet transmitted from the serving base station 20 only (see Fig. 2a), and after the handoff is completed (Uni-casting) the packet (Uni-casting) to the target base station 30 (Fig. 2b).

However, when handoff is performed in this manner, especially in the current IEEE 802.16e system in which it is difficult to apply soft handoff without changing the subchannel allocation scheme, since only packets are transmitted to the serving base station during handoff, serving is performed. When a handoff is completed from the base station to the target base station, a packet may be lost.

The present invention was devised to solve the above problems, and an object of the present invention is to transmit a packet to a serving base station and a target base station during a handoff process by a control station, which is a component of a wireless communication system, and then target the target after completion of the handoff. The present invention provides a handoff processing apparatus and method capable of preventing loss of a packet by transmitting a packet only to a base station.

Another object of the present invention is to perform a L3 handoff to a serving base station and a target base station by a control station performing an L3 handoff so that a base station performing L2 handoff in a wireless communication system can support both hard handoff and soft handoff. A handoff processing apparatus and method for bi-casting a packet are provided.

Another object of the present invention is to provide an apparatus and method for handoff processing in which a soft handoff can be easily performed regardless of a subchannel allocation scheme in a system supporting IEEE 802.16e.

For this purpose, a handoff processing apparatus in a wireless communication system according to the present invention, the serving base station for transmitting and receiving a packet with a mobile terminal; A target base station to be handoff target of the mobile terminal; And a serving control station that transmits a packet to a serving base station and a target base station when receiving a handoff request message from the serving base station, and transmits the packet to the target base station when the handoff is completed.

The handoff processing method in the wireless communication system according to the present invention includes a) transmitting a packet from a serving control station to a serving base station and a target base station when a handoff is requested; and b) the serving when the handoff is completed. And transmitting, by the control station, the packet to the target base station.

In addition, a handoff processing method in a wireless communication system according to the present invention includes the steps of: a) when a handoff is requested, a serving control station transmitting a packet to a serving control station and a target control station managing a target base station; b) And when the handoff is completed, the serving control station transmitting a packet to the target control station managing the target base station.

Accordingly, the present invention has the effect that the control station, which is a component of the wireless communication system, prevents packet loss during handoff by bi-casting the packet to the serving base station and the target base station during the handoff process. .

Further, according to the present invention, the control station performing the L3 handoff bi-casts the packet to the serving base station and the target base station during the handoff process, so that the base station performing the L2 handoff is hard handoff and soft. It has the advantage of supporting both handoffs.

In particular, according to the present invention, a soft handoff can be easily performed regardless of a subchannel allocation scheme in a system supporting IEEE 802.16e.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments. For reference, in the following description, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention are omitted.

3 is a block diagram of a handoff processing apparatus according to the present invention. For reference, the handoff processing apparatus according to the present invention controls L3 (Layer 3) handoff in an Open Systems Interconnection (OSI) 7 Layer model. In addition, the handoff processing apparatus according to the present invention may be implemented as a control station itself or as part of a control station in a wireless communication system.

Referring to FIG. 3, the handoff processing apparatus 100 according to the present invention includes a routing switch unit (CSBA) that performs a routing and switching function for an IP packet (hereinafter referred to as a 'packet'). And a Subscriber Session Management Assembly (SSMA) 120 that performs inter-working and session management functions with the base station.

In detail, the routing processor 120 includes a routing table in which routing information for transmitting a received packet to a destination is stored, and a base station corresponding to the corresponding destination is controlled based on the routing information. Send to the station.

In addition, the subscriber session manager 110 interworks with a routing processor, transmits and receives a handoff related message (eg, a handoff request message, a handoff complete message, etc.) with a base station through the routing processor, and transmits to the handoff related message. The subscriber session is managed by instructing the routing processing unit to change the routing information.

Specifically, when the subscriber session manager receives the handoff request message, the subscriber session manager reads the IP address, the serving base station ID, and the target base station ID of the handoff progress terminal included in the handoff request message, and a destination address is set to the terminal. Instructs the routing processor to change the routing information so that the packet is transmitted to the serving base station and the target base station.

Then, the routing processor changes the routing table such that the packet is bi-casted to the serving base station and the target base station according to the instruction of the subscriber session management unit. By changing the forwarding table included in the packet, the packet to be transmitted to the terminal is transmitted to the serving base station and the target base station. For example, the routing processor changes and sets an output link corresponding to the IP address of the handoff target terminal from a serving base station to a serving base station and a target base station in a forwarding table, and when a packet having the corresponding IP address as a destination address is transmitted, the serving base station. And bicast to the target base station. To do this, the routing processor reads the field values of the packet header input (which includes the destination address and the destination address), and then refers to the forwarding table to determine the output link corresponding to the corresponding destination address (that is, the output link to be forwarded). If there are a plurality of output links (bycasting to a serving base station and a target base station), the corresponding input links are directly connected to the plurality of corresponding output links or the packets are copied to generate the same packet, respectively. Forward to the output link of.

On the other hand, the subscriber session manager stops packet transmission to the serving base station upon receiving the handoff completion message and instructs the routing processor to change the routing information so that the packet is transmitted only to the target base station. Then, the routing processor changes the routing information stored in the routing table so that the packet is transmitted only to the target base station according to the instruction of the subscriber session manager, and transmits the packet to the destination corresponding to the changed routing information. That is, the routing processor changes and sets the output link corresponding to the IP address of the terminal from the serving base station and the target base station to the target base station in the above-described forwarding table, and if a packet including the corresponding IP address (destination address) is received, the target Uni-casting only to the base station (transmit packets to only one base station).

Hereinafter, a handoff processing method according to a first embodiment of the present invention will be described with reference to FIGS. 4 and 5. For reference, this embodiment is a handoff process between a serving base station and a target base station belonging to the same control station.

First, FIG. 4 is a diagram illustrating a communication connection state between a control station, a serving base station, and a target base station while handoff is performed.

4A is a state before handoff commencement, the routing processing unit of the control station 100 performs packet transmission and reception between the core network 50 and the serving base station 200 based on preset routing information. In addition, the serving base station 200 performs packet transmission and reception with respect to a user terminal (not shown).

Subsequently, when the subscriber session manager of the serving control station 100 receives the handoff request message through the routing processing unit, the serving base station 200 corresponding to the serving base station ID and the target base station ID included in the message is processed by processing the received message. And routing information of the routing processing unit to bi-cast the packet to the target base station 300. Then, the routing processor simultaneously transmits the same packet to the serving base station 200 and the target base station 300 according to the changed routing information.

After that, when the handoff is completed and the subscriber session manager of the serving control station 100 receives the handoff complete message, routing of the routing processor to forward the packet transmitted from the core network 50 to only the corresponding target base station 300. After changing the information, the routing processing unit of the serving control station 100 performs unicasting to transmit the packet only to the target base station 300 as shown in FIG. 4C. Thereafter, the terminal communicates with the target base station 300.

FIG. 5 illustrates a flow of messages transmitted between components of a wireless communication system in relation to a handoff processing method according to a first embodiment of the present invention.

For reference, the handoff processing method illustrated in FIG. 5 illustrates a Fast Base Station Swithcing (FBSS) Anchor Update (FBSS) using a Channel Quality Indicator Channel (CQICH) of a Fast Feedback Channel (FFCH) of a portable Internet. will be.

Meanwhile, the configuration of the base station used in this embodiment in connection with the handoff will be described briefly. The base station according to the present invention performs a baseband processor (BBP) for performing a call access function, a packet scheduling function, and the like. And a RAS Management Processor (hereinafter referred to as 'RMP') that performs an L2 handoff function.

The RMP includes a communication unit for communication with a control station, an operation management unit for base station state management, an access processing unit for call connection processing, an authentication processing unit for user authentication, a handover processing unit for handover processing of a subscriber station, and service charging. It consists of a billing processing unit, a memory unit for storing the DB necessary for call control, and a control unit for controlling the operation of each unit according to the signal input through the communication unit as a whole.

The communication unit transmits and receives data using an element management system (EMS) (not shown), which is a control station and a network management system, using a user datagram protocol (UDP) / stream control transmission protocol (SCTP), and a MAC (Media) with a channel card. Send and receive data using Access Control.

The operation management unit builds all the DBs to be managed based on channel card information, its base station information and neighbor base station information, and performs functions related to operation, management and maintenance of the base station based on these DBs. The base station management function is performed through operations (Operations, Administration and Maintenance, OAM Task) described below.

The access processing unit performs access processing for the subscriber station, and establishes network connection information, service flow information, and link information as a DB and controls the call state of the subscriber station based on these DBs. State control is achieved through an admission task described below.

Meanwhile, the authentication processing unit performs authentication and user authentication of the subscriber station through an authentication task (Public Key Manager Task, PKM Task), and the handover processing unit performs handover processing of the subscriber station through a mobility task (Mobility Task). The charging processing unit performs a service charging process through an accounting task. Hereinafter, the operation management task, the admission task, the authentication task, the moving task, and the charging task will be described in detail.

When the base station is initialized, the base station configures all channel cards belonging to the base station, and receives the radio parameter information from the network management system (EMS) and sets the radio parameter of the channel card to be managed based on it. Channel card information DB.

In more detail, the operation management task may include downlink-mobile aplication protocol (DL-MAP) information, uplink-mobile aplication protocol (UL-MAP) information, and cell synchronization (cell sync) for resource allocation. Uplink Channel Descriptor (UCD) information, Downlink Channel Descriptor (DCD) information, and NBR-ADV information for handover are received from the control station management system (EMS), and the channel card information DB is built based on this. An example of the channel card information DB thus constructed is shown in FIG. 4.

As shown in FIG. 4, the channel card information DB (CHANNEL CARD INFO) contains various information about the channel card held by the base station, for example, a media access control address (CCMacAddress), a frequency area ID (Frequency Area ID): Information such as FAID) and sector ID (SectorID) are stored.

In addition, the operation management task builds the base station global information DB based on its base station information, neighbor base station information and control station information, and stores it in the memory unit, and based on this, fault management, performance management, and statistical processing of the base station. As shown in FIG. 4, the base station global information DB (RAS GLOBAL INFO) stores control station information (ACRinfo), its own base station information (Myinfo), neighbor base station information (NeighborRASinfo), and the like.

In addition, the operation management task performs a DB management function for the Simple Network Management Protocol (SNMP) related to network monitoring.

That is, the operation management task builds all the DBs to be managed based on channel card information, its base station information and neighbor base station information, and performs functions related to the operation, management, and maintenance of the base station.

The admission task is for controlling the access processing and service flow for the subscriber station 11, and the function of the admission task will be described in more detail as follows.

The subscriber station attempts to enter the network by performing downlink synchronization (DL sync) and uplink synchronization (UL synchronization).

Next, the admission task receives the access request (RNG-REQ) from the subscriber station, finds the MAC address of the subscriber station, and if the ranging request is successful, the admission task (RNG-RSP). ), And then stores the MAC address of the terminal in the authentication information space.

After the above ranging procedure, the admission task performs a basic function negotiation procedure for the subscriber station (hereinafter referred to as "SBC negotiation"), which is first performed by the subscriber station to the base station for basic function negotiation. When the basic function negotiation request message (SBC-REQ) is transmitted, the admission task receives it and sends a response (SBC-RSP) to the subscriber station, and the network entry procedure for the subscriber station is completed according to the SBC negotiation. .

Meanwhile, the admission task generates a user agent context DB based on the contents of a network-entry procedure. The user agent context DB (UAContext) includes a MAC address (PSSMacAddress) assigned to a subscriber station. , User ID (userID), call connection status (BasicCID) for sending delay-sensitive messages, primaryCID for sending messages that are relatively less sensitive, ranging information (RangingInfo), Information such as basic function negotiation information (SBCInfo), registration information (RegistInfo), handover status information (handoverStatus), and the like are stored.

The admission task notifies the control station when the service addition / change message (DSA / DSC-REQ) is transmitted from the subscriber station, and sends a response message (DSA / DSC-RSP) to the subscriber station, and transmits the service to the subscriber station. It creates a service link information DB for a transmission convergence context DB and a service link so that a corresponding service can be provided to a subscriber station based on these DBs.

The transport convergence context DB (TCContext) contains information about its own transport convergence (myTCContextPoolID), transaction ID (transactionld), service status (statusj), downlink transport (downLinkTransport), and uplinkTransport (upLinkTransport). In the service link information DB (LinkInfo), the service flow CID (Service Flow CID, SFID), the connection identifier (Connection ID, CID), the IP source address (IPSourceAddress), the IP target address (IPDestAddress), and the source port (SourcePort). ), The target port (destPort) and the like are stored.

Here, since the information related to the service flow is stored in the transmission convergence context DB, the transmission convergence context DB may be understood as the same meaning as the service flow information DB.

On the other hand, when the service deletion request message (DSD-REQ) is received from the subscriber station, the base station notifies the control station and deletes the transmission convergence context DB and link information DB for the corresponding service flow through the admission task to stop the service. do.

That is, the admission task controls the service flow for the subscriber station 11 by creating / modifying / deleting the transmission convergence context DB (TCContext) and the link information DB (LinkInfo) according to the creation / modification / deletion of the service flow. Perform.

Meanwhile, when the handover is completed, the admission task of the current base station deletes the user agent context DB (UAContext), the transmission convergence context DB (TCContext), and the link information DB (LinkInfo), and the assignment task on the target base station is a new user agent context. A DB (UAContext), a transport convergence context DB (TCContext), and a link information DB (LinkInfo) are generated.

In addition, if a registration cancellation request message (DEREG-REQ) is received from the subscriber station due to handover or power off, the admission task may include a user agent context DB (UAContext), a transmission convergence context DB (TCContext), and a link information DB (LinkInfo). While deleting the registration, the registration termination result is transmitted to the subscriber station 11 and the control station to complete the registration termination procedure.

The authentication task is for authentication and user authentication of the subscriber station, and controls the authentication policy and key exchange between the subscriber station and the control station.

When the subscriber station first transmits the subscriber authentication request message (PKM-REQ) to the base station, the authentication task receives the authentication task through the AAA server 14, which is an authentication server, and then sends the subscriber authentication response message (PKM-REQ). Send to the subscriber terminal.

Then, when the subscriber station transmits a registration request message (REG-REQ, Registration Request) to the base station, the authentication task receives it and registers the subscriber station in the network and transmits a registration response message (REG-RSP) to the subscriber station. .

Then, if it is confirmed that registration with the subscriber station is successful, the subscriber station transmits a Trivial File Transfer Protocol-CPLT message for the file download path, and the base station sends a response message (TFTP-RSP) thereto. Send to subscriber station to complete call setup for subscriber station.

The billing task is for performing billing processing. When a new service is requested from the subscriber station, the billing task forwards a message (AccountStart) informing of the billing start to the control station 13 or the billing server (not shown). The charging information message for each service flow is transmitted to the control station 13 or the charging server (not shown) according to the charging report interim.

The mobile task is to perform handover processing of the subscriber station. When a handover is requested from the subscriber station, the mobile task performs handover processing in consideration of the current environment and conditions.

In more detail, when the subscriber station enters another cell area beyond the cell area in which the subscriber station is currently serving, the mobile task may change its current environment and condition according to its base station information, neighbor base station information, control station information, and mobile information. By performing a handover process suitable for the mobile station, and after the handover is completed, the call context between the source base station and the target base station is exchanged, and then the handover complete message is transmitted to the subscriber station. Ensure that current services are provided seamlessly.

In the above, the call context exchange between the source base station and the target base station means that the mobile task of the current base station is transmitted to the mobile task of the target base station 12 by the user agent context DB (UAContext), transmission convergence context DB (TCContext), And link information DB (LinkInfo), so that the network entry procedure and authentication procedure as described above can be omitted and the service can be provided immediately.

As described above, various functions related to call control in the base station are implemented in the form of tasks, and tasks that can be processed in the base station, for example, operation management of the base station, access of subscriber stations, user authentication, service charging , And handover procedures by the respective tasks, it is possible to distribute the traffic concentrated in the control station to the base station.

Referring back to FIG. 5, when an anchor ID for handoff request is transmitted from the terminal PSS to the BBP of the serving base station through the FFCH, the BBP of the serving base station transmits a switching request message for updating the anchor base station ( MSG_RM_ABS_SWITCH_REQ) is transmitted to the RMP of the serving base station.

The RMP of the serving base station receiving the switching request message transmits a first anchor update request message (MSG_IR_ANCHOR_UPDATE_REQ) requesting the anchor base station update to the RMP of the target base station, and also sends a handoff request message (MSG_AS_HO_PERFORM_REQ) to the control station (ACR). Send it. In this case, the handoff request message includes IDs of the serving base station and the target base station for bi-casting packets to the serving base station and the target base station (S501).

The subscriber session management unit of the control station receiving the handoff request message requests the routing processing unit to change the routing information so as to transmit a packet to the serving base station and the target base station, and the routing processing unit changes the routing information of the routing table and then changes the routing information. The packet is bicasted to the BBP of the serving base station and the BBP of the target base station based on (for details related to the change of the routing table, refer to the foregoing description with reference to FIG. In addition, in response to the handoff request message, the control station transmits a handoff performance response message (MSG_AS_HO_PERFORM_RSP) indicating that the handoff is in progress to the RMP of the serving base station (S502).

Meanwhile, the RMP of the target base station receiving the anchor update request message transmits a handoff preparation request message (MSG_RM_HO_RSV_REQ) requesting to receive a handoff to the BBP of the target base station (S503), and the BBP of the target base station performs a handoff. In step S504, a handoff preparation response message MSG_RM_HO_RSV_RSP is transmitted to the RMP of the target base station.

The RMP of the target base station receiving the handoff preparation response message transmits a first anchor update response message (MSG_IR_ANCHOR_UPDATE_RSP) to the RMP of the serving base station, and the RMP of the serving base station receiving the handoff response message (MSG_RM_ABS_SWITCH_RSP) to the BBP of the serving base station ). The BBP of the serving base station that receives the switching response message from the RMP of the serving base station transmits anchor base station switching information (Anchor_Switch_IE) through the uplink map UL_MAP (S505).

Then, the mobile terminal transmits a CQI report (CQI Report) to the BBP of the target base station, and the received BBP of the target base station transmits a management indication message (MSG_RS_MGMT_IND) for channel management to the RMP of the target base station, The RMP transmits a second anchor update request message (MSG_AS_ANCHOR_UPDATE_REQ) requesting unicasting (bycasting stop) to the control station (S506).

Upon receiving the second anchor update request message, the control station changes routing information to unicast the packet only to the target base station, and transmits the packet to the BBP of the target base station based on the changed routing information (Uni-Casting). The control station transmits a second anchor update response message (MSG_AS_ANCHOR_UPDATE_RSP) indicating that unicasting is performed to the RMP of the target base station (S507).

Then, the RMP of the target base station transmits a resource allocation stop message (MSG_IR_IMHOST_OF) to the serving base station's RMP in order to prevent waste of radio resources of the serving base station, and the serving base station's RMP transmits a handoff end request message to the serving base station's BBP. The base station transmits MSG_RM_END_REQ, and the BBP of the serving base station transmits the handoff end response message MSG_RM_END_RSP to the RMP of the serving base station to complete the handoff (S508).

Hereinafter, a handoff processing method according to a second embodiment of the present invention will be described with reference to FIG. 6. For reference, this embodiment is a handoff process between a serving base station and a target base station belonging to different control stations.

FIG. 6A illustrates a state before handoff initiation, and the routing processing unit of the serving control station 100 performs packet transmission and reception to the corresponding serving base station 200 based on preset routing information. In addition, the serving base station 200 performs packet transmission and reception with respect to a user terminal (not shown).

Subsequently, when the subscriber session manager of the serving control station 100 receives the handoff request message through the routing processor, the subscriber session manager processes the received message and transmits the packet to the serving base station 200 and the target base station 300 included in the message. The routing information of the routing processor is changed to bi-casting. In this case, if the target base station 300 belongs to another control station 400, the routing processing unit of the serving control station 100 is bicasting the received packet to the serving base station 200 and the target control station 400. The routing table is changed so that the same packet is simultaneously transmitted to the serving base station 200 and the target control station 400 according to the changed routing information (see FIG. 4B). Then, the target control station 400 receiving the packet transmits it to the target base station 300.

After that, when the handoff is completed and the subscriber session manager of the serving control station 100 receives the handoff complete message, the routing information of the routing processor is changed to be routed only to the target base station 300 through the target control station 400. The routing processing unit of the serving control station 100 performs unicasting to transmit a packet to the target base station 300 via the target control station 400 as shown in FIG. 4C. Thereafter, the terminal communicates with the target base station 300. Of course, as shown in FIG. 4D, the target control station 400 may directly connect with the core network 50 without the previous serving control station 100 to relay packets to and from the terminal.

On the other hand, with regard to the message flow, except for the case that the handoff process between the base stations belonging to different control stations, the message transmission between the serving control station and the target base station is carried out through the target control station. Since it is substantially the same as the message flow described with reference to, the detailed description thereof will be omitted.

Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art to which the present invention pertains can implement the present invention in other specific forms without changing the technical spirit or essential features, The examples are to be understood in all respects as illustrative and not restrictive.

In addition, the scope of the present invention is specified by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention. Should be interpreted as

1 is a diagram illustrating a hierarchical structure of a wireless communication system.

2 is a view for explaining a handoff processing scheme according to the prior art.

3 is a block diagram of a handoff processing apparatus according to the present invention.

4 is a diagram illustrating a handoff processing method according to a first embodiment of the present invention, and shows a handoff processing procedure between base stations belonging to the same control station.

FIG. 5 is a diagram illustrating a flow of a message transmitted between components of a wireless communication system in relation to a handoff processing method according to a first embodiment of the present invention.

6 is a diagram illustrating a handoff processing method according to a second embodiment of the present invention, and shows a handoff processing procedure between base stations belonging to different control stations.

Claims (22)

A handoff processing method in a wireless communication system, a) if a handoff is requested, the control station sending a packet to the serving base station and the target base station; And b) when the handoff is complete, the control station sending a packet to the target base station. The method of claim 1, Step a) is a-1) if the handoff is requested, the control station changing routing information to bicast the packet to a serving base station and a target base station; And a-2) transmitting, by the control station, the same packet to a serving base station and a target base station based on the changed routing information. The method of claim 2, Step a-1) is, a-1-1) the control station receiving a handoff request message from the serving base station; And a-1-2) changing the routing information so that the control station bicasts the packet to the serving base station and the target base station corresponding to the serving base station ID and the target base station ID included in the handoff request message. A handoff processing method in a wireless communication system. The method of claim 3, Step a-2), a-2-1) the control station transmitting a handoff performance response message to the serving base station in response to the handoff request message. The method of claim 1, Step b), b-1) when the handoff is complete, changing, by the control station, routing information to unicast a packet to the target base station; And b-2) the control station transmitting a packet to the target base station based on the changed routing information. The method of claim 5, Step b-1), b-1-1) the control station receiving an anchor update request message from the target base station; And b-1-2) modifying routing information such that the control station unicasts the packet to the target base station. The method of claim 6, Step b-2), b-2-1) the control station transmitting an anchor update response message to the target base station in response to the anchor update request message. A handoff processing method in a wireless communication system, a) if a handoff is requested, the serving control station sends a packet to the serving base station and the target control station, and the target control station transmits the packet to the target base station; And b) when the handoff is complete, the serving control station stops transmitting the packet to the serving base station, and the target control station transmits the packet only to the target base station. The method of claim 8, Step a) is a-1) When a handoff is requested, the serving control station changes routing information of the serving control station to bicast the packet to the serving base station and the target control station, and the target control station to unicast the packet to the target base station. Changing routing information of the target control station; And a-2) the serving control station bicasts the packet to the serving base station and the target control station based on the changed routing information of the serving control station, and the target control station targets the based on the changed routing information of the target control station. And unicasting the packet to the base station. The method of claim 9, Step a-1) is, a-1-1) the serving control station receiving a handoff request message from the serving base station; a-1-2) The serving control station reads the serving base station ID and the target base station ID included in the handoff request message, and the serving base station corresponding to the serving base station ID and the target base station corresponding to the target base station ID Changing routing information of the serving control station to bicast the packet to the belonging target control station; And a-1-3) changing the routing information of the target control station so that the target control station unicasts the packet to the target base station corresponding to the target base station ID. Treatment method. The method of claim 10, Step a-2), a-2-1) the serving control station transmitting a handoff response message to the serving base station in response to the handoff request message. The method of claim 8, Step b), b-1) when the handoff is complete, the serving control station changing routing information of the serving control station to stop packet transmission to the serving base station; And b-2) the target control station transmitting a packet to the target base station based on the changed routing information of the target control station. The method of claim 12, Step b-1), b-1-1) the target control station receiving an anchor update request message from the target base station; And b-1-2) changing the routing information of the second control station so that the target control station unicasts the packet to the target base station. The method of claim 13, Step b-2), b-2-1) the control station transmitting an anchor update response message to the target base station in response to the anchor update request message. A handoff processing apparatus in a wireless communication system, When the handoff request message is received, the routing processor requests the routing processor to change the routing information so as to transmit the packet to the serving base station and the target base station. When the handoff completion message is received, the routing information is transmitted to the routing processor. A subscriber session manager requesting a change; And And a routing processor configured to store the routing information, change routing information according to a request of the subscriber session manager, and transmit a packet based on the routing information. The method of claim 15, And the routing processing unit comprises a routing table in which routing information is stored in a table form. The method according to claim 15 or 16, The handoff request message includes a serving base station ID and a target base station ID, The subscriber session manager reads the serving base station ID and the target base station ID, and requests a routing processor to change the routing information to bicast the same packet to the serving base station and the target base station corresponding to the serving base station ID and the target base station ID. Hand off processing apparatus for a wireless communication system, characterized in that. The method according to claim 15 or 16, And said handoff processing apparatus is a control station. The method according to claim 15 or 16, The handoff processing apparatus is a handoff processing apparatus in a wireless communication system, characterized in that for supporting IEEE 802.16e. As a handoff processing system, A serving base station communicating with the terminal before initiating handoff; A target base station communicating with the terminal after the handoff is completed; And A control station interworking with the serving base station and the target base station and controlling packet transmission and reception; The control station bicasts the packet to the serving base station and the target base station when receiving the handoff request message from the serving base station, and when receiving the handoff completion message from the target base station, the control station UTcasts the packet only to the target base station. Handoff processing system. The method of claim 19, The serving control station, A subscriber session manager for processing the received handoff request message to change routing information to bicast to a serving base station and a target control station; And a routing processing unit which simultaneously transmits the same packet to the serving base station and the target control station by the changed routing information. The method of claim 21, The subscriber session management unit changes the routing information to unicast to the target base station when the handoff is completed and receives the second anchor update request message requesting unicasting to the target control station. And the routing processor transmits a packet to a target control station according to the changed routing information.

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