KR100612703B1 - Handover method between rass in wibro system - Google Patents

Abstract

A handover method between base stations in a WiBro system is provided.

In the handover method of the present invention, as the mobile communication terminal requests a handover to the control station through the access base station, the control station determines a handover type, and determines a target base station, wherein the handover type is a hard hand between base stations. In case of over, requesting the target base station to check the quality of service for the mobile communication terminal. As the target base station reports that the service quality is satisfied to the control station, the control station requests handover to the mobile communication terminal through the access base station. Transmitting a response message to the controller; driving the timer; as the mobile communication terminal instructs the handover to the control station through the access base station; instructing the control station to handover to the target base station; as the timer expires. The accessing base station and the control station initiating buffering for the packet data; Delivering the packet data received from the target base station to the target base station and completing the registration of the mobile communication terminal and reporting that the handover is completed to the control station. Can be.

Mobile Internet, Base Station, Handover

Description

Handover Method Between RASs in WiBro System

1 is a block diagram of a portable Internet system to which the present invention is applied;

2 is a flowchart for explaining an inter-base station handover method according to an embodiment of the present invention;

3 is a flowchart illustrating an embodiment of a handover decision process illustrated in FIG. 2;

4 is a flowchart for explaining an embodiment of an anchor base station update process shown in FIG. 3;

FIG. 5 is a flowchart illustrating an embodiment of an active set update process illustrated in FIG. 4;

6 is a flowchart for explaining another embodiment of an anchor base station update process shown in FIG. 3;

7A to 7C are diagrams illustrating examples of types of parameters included in main messages used in the handover process and types, lengths, and parameter values of each parameter.

<Description of the symbols for the main parts of the drawings>

100: mobile communication terminal 210, 212: base station

220: control station 230: home agent

240: authentication center 250: location management server

The present invention relates to a handover method in a mobile communication system, and more particularly, to a handover method between base stations in a mobile Internet (WiBro) system.

Recently, wireless Internet service using a mobile communication terminal is provided by a communication method such as CDMA 1x EV-DO, WCDMA, and the like, and the demand thereof is increasing. However, the mobile communication terminal has a small screen size and low resolution. However, due to the low data rate, multimedia content is not suitable. In addition, there is a limitation as a general means for accessing the Internet due to the burden on the information usage fee due to the high wireless Internet usage fee.

Overcoming the limitations of the existing system, a portable Internet service has been developed as a wireless Internet service capable of high-speed Internet access even when stationary or on the move with high service quality and cost. Portable Internet service is defined as a service that enables high-speed wireless Internet access anytime, anywhere, even while stationary and mobile. The portable Internet service enables the use of the Internet service even when the vehicle is stationary, while walking, or while the vehicle is moving. Since the portable Internet service is an open service, there is an advantage of using various contents.

The portable Internet service should guarantee the mobility of the user. At present, there is no alternative for providing continuous service when the access base station is changed by the user. Therefore, connection disconnection may occur while using the service. there is a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a technical problem to propose a handover scheme for a mobile communication terminal moving between base stations of a portable Internet system.

In the inter-base station handover method of the present invention for achieving the above technical problem, as the mobile communication terminal requests a handover to the control station through the access base station, the control station determines the handover type, and determines the target base station A first step of making; A second step of requesting a target base station to check a quality of service for a mobile communication terminal when the handover type is hard handover between base stations; As the target base station reports that the quality of service is satisfied to the control station, the control station transmits a response message for the handover request to the mobile communication terminal through the access base station, and the control station and the access base station A third step of driving a timer; A fourth step of the control station instructing a handover to the target base station as the mobile communication terminal instructs a handover to the control station through the access base station; A fifth step in which the access base station and the control station start buffering packet data as the timer driven in the third step ends; A sixth step of transmitting, by the control station, the packet data received from the access base station to the target base station as the access base station transmits the buffered packet data to the control station; And a seventh step of the target base station completing registration of the mobile communication terminal and reporting that the handover is completed to the control station.

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

1 is a block diagram of a portable Internet system to which the present invention is applied.

As illustrated, the portable Internet system transmits and receives data to and from a mobile communication terminal (PSS) 100 through a wireless interface, and supports a plurality of base stations (RAS) that support radio resource management and control, a downlink multicast function, and a handover function. 210, 212), a data core network infrastructure system for providing a mobile Internet service, is connected to a plurality of base stations to manage the base stations, and includes data packet routing, diameter authentication requests, billing data collection and transmission, and operation maintenance. A control station (ACR) 220 that performs information collection and transmission function, and a configuration node for providing a mobile IP service, assigns an address to the mobile communication terminal 100 and performs an IP according to the mobile IP request of the control station 220. And a home agent (HA) 230 for transmitting and receiving packet data to the control station 220, the control station 220, the home agent 230 and a mobile communication packet network component ( Packet authentication center (AAA, 240) that performs user authentication, authorization authentication, and billing at the request of packet data service node and interworking unit, and location management server (LMS, 250) for managing status information and location information of subscribers. It includes.

In the present invention, the handover support function is added to the base stations 210 and 212 and the control station 220 to provide continuous services for mobile communication terminals moving between base stations.

For this purpose, the interface between the base stations is defined as an A-interface, and the interface between the base station and the control station is called an IR-interface, and the A-interface is a mobile terminal initial access, authentication, authorization, verification, location registration, service flow management, and hand. It is an interface for call processing signals such as over, and the IR-interface is an interface for call processing signals such as neighboring control station map management and handover between control stations.

2 is a flowchart illustrating a method for handover between base stations according to an embodiment of the present invention. The base station and the control station mentioned in the following description are defined as follows to clarify the division according to their roles.

RAS_ _S : A base station currently being serviced by a mobile communication terminal

-RAS_ _T : Target base station to be handed over by mobile communication terminal

RAS_ _C : Candidate base station to be handed over

The mobile communication terminal (PSS) requests a handover to the RAS_ _S when a handover is necessary because the received signal strength from the access base station RAS_ _S is lower than a specified threshold (MOB-MSSHO-REQ) ( S101), and this RAS_ _S requests a handover to the ACR (a-MOB-MSSHO- REQ) (S103) in accordance with.

Accordingly, the ACR determines the handover type required for the PSS requesting the handover, and determines the handover target RAS (S105). The handover type and the target RAS determination process will be described later with reference to FIG. 3.

Is determined RAS liver in the same ACR result of executing the steps S105 to require a handover, when the target RAS to determine, ACR is requested to check whether the service quality of the PSS to perform handover to RAS_ _T more than the specified level, and (A -MOB-MSSHO-AR-REQ) (S107), RAS_ T , according to the ACR request when the quality of service for hand-over to a specified level or more PSS transmits a response message indicating this to the ACR (a-MOB-HO- AR-RSP) (S109).

Accordingly, ACR transmits a response message (A-MOB-BSHO-RSP) for handover request to RAS_ _S to perform handover, and each of ACR and RAS_ _S is assigned to a packet to be transmitted to PSS during handover. The timer for starting the buffering is driven (S111). In addition, RAS_ _S transmits a response message to the handover request to the PSS to perform handover (MOB-BSHO-RSP) (S113).

On the other hand, PSS instructs a handover to the ACR through a RAS_ _S, and (A-MOB-HO-IND ) (S115, S117), ACR indicates handover to _{RAS_ T (A-MOB-HO} -AR- IND) (S119).

As later, as the switching time of the drive in step S111 the arrival, that is, the timer expires RAS_ _S and ACR discloses a buffer for the packet data (S121). RAS_ _S transmits a transmit and receive (A_PKT_RPT) (S123), ACR is the packet data buffered in the data packet to the ACR _{RAS_ T (A_PKT_AR_RPT) (S125)} .

On the other hand, PSS will report that the request to register to RAS_ _T and (RNG_REQ) (S127), RAS_ T is to complete the registration by sending a response message thereto in PSS hand (RNG_RSP) (S129), the registration is completed to the ACR (A_RNG_NOTI) (S131).

Since, as the PSS sends the serving base station information is changed to _{RAS_ T (SN_RPT (SN + 1} )) (S133), RAS_ T is reporting that handover is completed in the ACR, and (A_SWITCH_END) (S135), transmits the packet data asked to and (A_PKT_REQ) (S137), thereby ACR is to be a handover process is completed by sending (A_PKT_RSP) (S139) the packet data to the RAS_ _T. In addition, RAS_ _T is the subsequent service to occur to resume data transmission to the PSS.

As described above, in the present invention, the ACR determines the target RAS according to the handover request of the mobile communication terminal, buffers the packet data during handover to the corresponding RAS, and transmits the packet data to the mobile communication terminal when the handover is completed. In addition, it can provide a continuous service to the mobile communication terminal to move between RAS.

FIG. 3 is a flowchart for explaining an embodiment of the handover decision process illustrated in FIG. 2.

While the PSS is connected to the ACR through a RAS_ _{S, S} RAS_ by sending the neighboring base station information, and downlink / uplink information to the PSS for each specified period and to be used when a handover is required. In this state, if the handover is required because of a decrease in received signal strength from RAS_ _S PSS requests handover to RAS_ _S, and requests the handover by receiving the RAS_ _S in the ACR.

Accordingly, the ACR checks whether the PSS requesting the handover is in an active state, determines which handover is applied in the active state, and performs an anchor base station update procedure when it is not in the active state (S201). The anchor base station update procedure may be performed using a feedback message or may be performed using a MAC message, which will be described later with reference to FIGS. 4 and 6.

When the anchor base station update is completed, the ACR determines what handover should be performed (S203). At this time, if all neighboring base stations are sectors in the current RAS, it is determined as sector handover. In addition, SHO / FBSS (Soft Handover / Fast Base Station Switching) support ID is 1, the terminal meets the SHO condition, optional diversity is supported in ACR, adjacent base stations are in the same ACR, soft add or If the drop condition is met, soft handover is determined. If the SHO / FBSS is supported by the base station and the control station, and the terminal can also support this function, it is determined as FBSS. If all of the above conditions are not satisfied, a hard handover is determined. Here, Fast Base Station Switching (FBSS) is a type of handover defined in IEEE802.16e, which is one of the methods for reducing the switching time during handover.

In the present invention, and assuming the hard handover, it will be described a case where the candidate RAS contained in ACR_ _S.

Accordingly ACR is whether the hand-over of a plurality of RAS_ _C candidate RAS That is, in transmitting the message to determine how your quality of service, and (A-HO-PRECHECK) transmitting a response, from (S205), RAS_ _C According to (A-HO-PRECHECK-RSP) (S207), one target RAS having excellent service quality is determined (S209). Then, the target RAS is notified that it is selected as a handover target (A-MOB-MSSHO-AR-REQ) (S211).

FIG. 4 is a flowchart illustrating an embodiment of an anchor base station update process illustrated in FIG. 3, and illustrates an anchor base station update process using a feedback message.

To update the anchor base station, first update the active set. (S301). When the active set update has been completed, the PSS selects the best performance among the base stations in the active set, and transmits to the _S RAS_ using a feedback channel to the base station information (base station ID) to be switched (S303). Accordingly, the RAS_ _S transmits a base station ID to the ACR to request switching (A-FBSS-HO-REQ) (S305), and the ACR refers to the base station ID included in the switching request message to service the PSS with the corresponding RAS_ _T. Request to confirm and report quality (A-FBSS-HO-AR-REQ) (S307).

RAS_ _T will make sure to support the quality of service required by the current PSS according to the ACR request, supported if possible and report it to the ACR (A-FBSS-HO- AR-RSP) (S309). Thus, ACR sends a response message to the switching request to the PSS (A-FBSS-BSHO- RSP) (S311, S313) through a RAS_ _S.

Now, the PSS instructs the ACR to update the anchor base station to the ACR through the RAS_ _S using the feedback channel (A-FBSS-HO-IND) (S315, S317), and the ACR is the anchor base station to the RAS_ _T to update to the anchor base station. An update is instructed (A-FBSS-HO-AR-IND) (S319). At this time, the ACR also transmits the RAS PSS context.

RAS_ _S will accordingly request to initiate a switch to the ACR, and (A-FBSS-START) ( S321), RAS_ S and ACR will start the buffering of the data packet (S323). When the buffering is started, RAS_ _S transmits the data packet to the ACR, and (A-FBSS-PKT-RPT ) (S325), ACR received it passes the packet data to the _{RAS_ T (A-FBSS-PKT} -AR- RPT) (S327).

Thereafter, the PSS transmits channel information to the anchor base station RAS_ _T using a feedback channel (Feedback (CQI)) (S329), and the RAS_ _T reports that the anchor base station update process is completed to the ACR (A-FBSS-END). ) (S331), if PSS to report information to the base station RAS_ _T by using the feedback channel (SN-RPT (SN + 1 )) (S333), by RAS_ _T requests a packet data transfer to the ACR (a-FBSS- PKT-REQ) packet data is received (A-FBSS-PKT-RSP) (S335, S337).

Then, the RAS_ _T has received the packet data, the anchor BS updating procedure is completed by resuming the transfer of data to the PSS.

FIG. 5 is a flowchart for explaining an embodiment of an active set update process illustrated in FIG. 4.

PSS determines whether the handover request and the handover to the ACR through a RAS_ _S accordingly (A-MOB-MSSHO-REQ ), if necessary, ACR is to update the active set (S401). That is, it is to check whether the base stations included in the base station list transmitted in the handover request message need to be added or deleted differently from the active set currently managed by the ACR.

If it is determined to be necessary to update the active set, ACR sends a response message for the handover request to the PSS through the _{RAS_ S (A-MOB-BSHO} -RSP) (S403, S405). Accordingly, the PSS instructs the ACR to update the active set through RAS_ _S (A-MOB-HO-IND) (S407, S409), and accordingly, the ACR sends the active set to the RAS_ _T to be added as the active set. Instructs to update (A-MOB-AR-IND) (S411).

Now, RAS_ _T generates the context of the PSS (S413), and as the PSS requests registration with RAS_ _T (RNG-REQ) (S415), after RAS_ _T sends a response message to the PSS to the registration request (RNG-RSP) (S417) The ACR reports that the update of the active set and the PSS registration have been completed (A-RNG-NOTI) (S419).

FIG. 6 is a flowchart illustrating another embodiment of the anchor base station update process shown in FIG. 3 and illustrates an anchor base station update process using a MAC message.

PSS determines whether the handover request and the handover to the ACR through a RAS_ _S accordingly (A-MOB-MSSHO-REQ ), if necessary, ACR is to update the anchor base station (S501). The update of the anchor base station is performed when the neighbor base station list received from the PSS requesting the handover is the same as the active set managed by the ACR, and there is a base station that performs better than the current receiving power of the anchor base station.

Step verification of S501 results if the anchor base necessary updates, ACR is a base station RAS_ _T current request (A-MOB-MSSHO-AR -REQ) to confirm that the PSS can support the quality of service needs to be updated in the anchor base station (S503), RAS_ _T transmits a response message if it can support the quality of service (a-MOB-MSSHO-AR -RSP) (S505).

Thus, ACR is the anchor BS to the ACR through a RAS_ through _S transmits a response message for the handover request to the PSS, and (A-MOB-BSHO-RSP ) (S507, S509), PSS has received this, RAS_ _S instructing to update, and (a-MOB-HO-IND ) (S511, S513), ACR is instructed to perform the anchor BS updating to _{RAS_ T (a-MOB-HO} -AR-IND) (S515).

Thereafter, the RAS_ _S notifies the ACR to start switching when the specified switching time arrives (A-SWITCH_START) (S517), and the RAS_ _S and ACR respectively start buffering (S519). And, RAS_ _S transmits the packet data to the ACR (A-FBSS-PKT-RPT) (S521), and the received ACR transmits the packet data to the RAS_ _T (A-FBSS-PKT-AR-RPT) ( S523).

Now, the PSS reports base station information to RAS_ _T (SN-RPT (SN + 1)) (S525), and after receiving this, RAS_ _T reports that anchor base station update is completed to ACR (A-SWITCH-END). (S527), packet data is requested (A-FBSS-PKT-REQ) (S529). Thus, ACR then transmits the packet data buffered in _{RAS_ T (A-FBSS-PKT} -RSP) (S531).

Then, the anchor base station, the update process is completed by RAS_ _T to resume data transmission to the PSS.

7A to 7C illustrate examples of types of parameters included in the main message used in the handover process and types, lengths, and parameter values of each parameter.

In the present invention, by supporting the handover between RASs in the same ACR according to the PSS handover request using the A-interface, which is an interface between the RAS and the ACR, the portable Internet user moving between the RASs can use the continuous service. .

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

According to the present invention, handover between base stations of the portable Internet system can be performed, thereby ensuring a seamless service, improving service quality, and providing a more stable service to secure the number of subscribers of the portable Internet service. There is an advantage that can be created.

Claims (15)

An inter-base station handover method in a portable Internet system including a base station and a control station, A first step of the control station determining a handover type and determining a target base station as the mobile communication terminal requests a handover to a control station through an access base station; A second step of requesting a target base station to check a quality of service for a mobile communication terminal when the handover type is hard handover between base stations; As the target base station reports that the quality of service is satisfied to the control station, the control station transmits a response message for the handover request to the mobile communication terminal through the access base station, and the control station and the access base station A third step of driving a timer; A fourth step of the control station instructing a handover to the target base station as the mobile communication terminal instructs a handover to the control station through the access base station; A fifth step in which the access base station and the control station start buffering packet data as the timer driven in the third step ends; A sixth step of transmitting, by the control station, the packet data received from the access base station to the target base station as the access base station transmits the buffered packet data to the control station; And A seventh step of the target base station completing registration of the mobile communication terminal and reporting that the handover is completed to the control station; A base station handover method in a mobile Internet system comprising a. The method of claim 1, After the seventh step, the target base station further performs an eighth step of requesting packet data transmission to the control station and transmitting the packet data to the target base station by the target base station. To handover method. The method of claim 2, And after the eighth step, the target base station further performs a ninth step of resuming a service by transmitting packet data to the mobile communication terminal. The method of claim 1, The first step includes the control station checking whether the mobile communication terminal is active as the mobile communication terminal requests a handover; Performing an anchor base station update procedure when the mobile communication terminal is not in an active state; If the control station does not satisfy the sector handover condition, the soft handover condition, and the fast base station switching condition by referring to the neighbor base station information included in the handover request message received from the mobile communication terminal, it is determined that it is a hard handover. step; Requesting the control station to confirm a quality of service to a handover candidate base station; Determining, by the candidate base station, a target base station having the highest quality of service as the quality of service is reported to the control station; And Notifying the target base station that the target base station has been selected as a handover target; A base station handover method in a mobile Internet system comprising a. The method of claim 4, wherein The sector handover condition is a base station handover method in the mobile Internet system, characterized in that all neighboring base stations of the mobile communication terminal is present in the sector in the base station. The method of claim 4, wherein The soft handover condition is a soft handoff / high-speed base station switching (SHO / FBSS) support ID of 1, the mobile communication terminal meets the soft handover condition, selective diversity is supported at the control station, The inter-base station handover method in a mobile Internet system, wherein the mobile station is located in the same control station and meets soft add or drop conditions. The method of claim 4, wherein The high speed base station switching condition is a case where a soft handover / high speed base station switching (SHO / FBSS) function is supported in the base station, the control station and the mobile communication terminal. The method of claim 4, wherein The anchor base station update procedure may include updating, by the control station, an active set; As the mobile communication terminal selects a base station having the best performance among the active sets, and transmits base station information to be switched to the access base station using a feedback channel, the access base station information to the control station to the switching base station information Transmitting a request for switching; Requesting, by the control station, to check the quality of service for the mobile communication terminal from the switching target base station with reference to the base station information; Reporting, by the switching target base station, the quality of service to report to the control station when the quality of service is satisfied; Transmitting, by the control station, a response message for the switching request to the mobile communication terminal through the access base station; Instructing the control station to update the anchor base station to the switching target base station as the mobile communication terminal instructs the control station to update the anchor base station through the access base station using a feedback channel; In response to the access base station requesting to initiate switching to the control station, the access base station and the control station initiating buffering for packet data; Forwarding, by the control station, packet data received from the access base station to the switching target base station; And Reporting, by the switching target base station, that the anchor base station update is completed to the control station as the mobile communication terminal transmits channel information to the switching target base station; A base station handover method in a mobile Internet system comprising a. The method of claim 8, And instructing the control station to update the anchor base station to the switching target base station further comprises transmitting a context of the mobile communication terminal. The method of claim 8, After the switching target base station reports completion of anchor base station update to the control station, the switching target base station transmits packet data to the control station as the mobile communication terminal reports base station information to the switching target base station. Requesting and receiving packet data from the control station. The method of claim 8, The updating of the active set may include: checking whether the control station satisfies an active set update condition as the mobile communication terminal requests a handover; Transmitting, by the control station, a response message for a handover request to the mobile communication terminal through the access base station when the active set update condition is satisfied; Instructing the control station to update an active set to a target base station to which the control station is to be added as an active set as the mobile communication terminal instructs to update the active set to the control station through the access base station; Generating, by the active set addition target base station, a context of the mobile communication terminal; As the mobile communication terminal requests registration to the base station to be added to the active set, the base station to be added to the active set registers the mobile terminal, and updates the active set to the control station and registers the mobile terminal is completed. Reporting; A base station handover method in a mobile Internet system comprising a. The method of claim 11, The active set update condition is a case where the base stations included in the base station list transmitted when the mobile communication terminal requests a handover is different from the active set currently managed by the control station. . The method of claim 4, wherein The anchor base station update procedure may include: checking whether the control station satisfies the anchor base station update condition according to a handover request of the mobile communication terminal; When the anchor base station needs to be updated, requesting, by the control station, to confirm the quality of service required by the current mobile communication terminal to a target base station to be updated to the anchor base station; When the update target base station measures the quality of service and satisfies the quality of service, and transmits a response message to the control station, the control station sends a response message for the handover request to the mobile communication terminal through the access base station. Transmitting; Instructing the control station to perform the anchor base station update to the update target base station as the mobile communication terminal instructs the control station to update the anchor base station through the access base station; The access base station requesting switching to the control station, and the access base station and the control station initiating buffering for packet data; Forwarding, by the control station, packet data received from the access base station to the update target base station; And As the mobile communication terminal reports base station information to the update target base station, the updating target base station reporting that the anchor base station update is completed to the control station; A base station handover method in a mobile Internet system comprising a. The method of claim 13, The anchor base station update condition is a case where a base station list received from the mobile communication terminal requesting the handover is the same as the active set managed by the control station, and there is a base station that performs better than the current reception power of the anchor base station. A base station handover method in a portable internet system. The method of claim 13, After the updating target base station reports that the anchor base station update is completed to the control station, as the updating target base station requests packet data to the control station, the control station transmits the buffered packet data to the updating target base station. Transmitting handover between base stations in a portable Internet system, characterized in that it further comprises the step of transmitting.

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