KR100964614B1 - Method for controlling handover signaling in hybrid indoor/outdoor wibro system and handover message configuration method in its - Google Patents

Abstract

The present invention relates to a handover control method and a method for constructing a handover message therefor in a portable internet system including an indoor / outdoor base station. A handover control method capable of reducing handover latency and message overhead, and a method for constructing a handover message therefor, are provided.

To this end, the present invention, in the handover control method in the base station, when the terminal performs a first handover from the outdoor base station to the indoor serving base station, the step of storing the connection information with the outdoor base station; ; When the terminal searches for the outdoor base station and requests a handover from the indoor serving base station to the outdoor base station when the second handover is required, the handover is requested to the indoor serving base station including the search result of the outdoor base station. Transmitting, by the indoor serving base station, the confirmation result of the handover candidate base station to the terminal; And as the terminal selects a handover target base station, the outdoor base station selected as the handover target base station to ensure handover of the terminal using the connection information.

Handover, Indoor Base Station, Outdoor Base Station, Mobile Internet

Description

Method for controlling handover signaling and method for constructing handover message in portable internet system including indoor / outdoor base station in hybrid indoor / outdoor wibro system and handover message configuration method in its}

The present invention relates to a handover control method and a method for configuring a handover message therefor in a portable internet system including an indoor / outdoor base station, and more particularly, to a hand of a terminal in a portable internet system including an indoor / outdoor base station. The present invention relates to a handover control method capable of reducing handover latency and message overhead, and a method for constructing a handover message therefor.

Wireless Broadband (WiBro) systems provide Internet services in a wireless environment, such as Wi-Fi, and provide broadband Internet access, such as high-speed Internet services. In terms of transmission speed, mobility, cell radius, etc., it can supplement the advantages and disadvantages in terms of transmission distance and transmission speed of current mobile communication and wireless LAN. It is a representative mobile communication technology.

The portable Internet system can obtain or utilize various information and contents by accessing the Internet at a high speed transmission speed anytime, anywhere using a portable wireless terminal (portable Internet terminal). Accordingly, like many existing cellular mobile communication systems, the portable Internet system supports a handover to guarantee mobility of mobile terminals. In addition, the portable Internet system is a complementary relationship between a cellular mobile communication system having nationwide wide area and high speed mobility and a wireless LAN system supporting high speed transmission speed indoors.

However, in the portable Internet system, various kinds of base stations are located at the same time. These various types of base stations can be broadly divided into indoor base stations and outdoor base stations, which are divided into cell coverage perspectives and main installation sites and applications.

In general, handover includes a communication path (base station ↔ terminal communication path) so that a mobile terminal can maintain communication when entering a cell area of another base station out of the cell area of a serving base station currently communicating. This refers to changing to a target base station located in the movement direction of the terminal.

The portable Internet should be able to continuously provide QoS guaranteed services on the go. To this end, the handover technology used in the mobile Internet uses a hard handover technology that breaks an existing call line and connects to a new base station, but recently, two or more base stations are used for reliability. Soft handover technology that can support high handover is being considered. The handover technique may be divided into a network topology acquisition procedure for periodically measuring parameter values required for handover determination and a procedure for determining and performing a handover.

In general, a portable Internet system in an indoor environment supports a handover as in an outdoor environment in order to provide seamless communication to a portable Internet terminal located in a specific area of an indoor environment. When the handover control procedure of the outdoor portable Internet system is applied to the base station, the target base station (target base station) includes not only the indoor base station but also the adjacent outdoor base station, and the base station to be handed over is selected according to the signal strength. .

However, if the adjacent outdoor base station is included in the base station to be handed over according to the above method, the handover is performed from the indoor base station to the adjacent outdoor base station or from the adjacent outdoor base station to the indoor base station when the terminal located in the area of the indoor base station moves. When a handover occurs from an indoor base station to a neighboring outdoor base station or from an adjacent outdoor base station to an indoor base station, the core router (ACR) is changed to perform a network reentry procedure. There is a problem that a transmission delay and a communication disconnection occur.

Then, the existing handover control process in the outdoor portable Internet network will be described with reference to FIGS. 1 to 8, and the existing handover control process cannot be applied as it is to the portable Internet network composed of indoor / outdoor base stations. Let's look at it.

1 is a diagram illustrating a configuration of a general outdoor portable Internet (WiBro) network.

In an outdoor portable Internet system, a handover occurs when the portable Internet terminal (MS) 11 moves to another cell (BS1 → BS2) (1a). That is, in the outdoor portable Internet system, only a handover exists between the outdoor serving base station BS1 12-1 and the outdoor target base station BS2 12-2.

That is, the base station BS serviced by the mobile Internet terminal 11 in the process of moving the mobile Internet terminal 11 from cell 1 to cell 2 is an outdoor target in the outdoor serving base station BS1 12-1. (Target) It is switched to the base station (BS2) 12-2 (1a). This process is a handover control process in the existing outdoor portable Internet system. In the existing outdoor portable Internet system, there is only a single handover scenario from the BS1 12-1 that is currently being serviced to the new BS2 12-2 of the cell.

However, if the indoor portable Internet system is combined with the outdoor portable Internet system (portable Internet system composed of indoor / outdoor base stations 12 and 13 in FIG. 2), the outdoor handover control procedure [outdoor base station 1 (12-1)) In addition to the handover control procedure to the outdoor base station 2 (12-2), the indoor handover control procedure (that is, the handover control procedure between the outdoor base station 12 to the indoor base station 13, the indoor base station 13). -Handover control procedure between indoor base station 13] must be added separately.

That is, as shown in FIG. 2, in the portable Internet system composed of the outdoor base station 12 and the indoor base station 13, not only the handover 2a between the outdoor base stations 12, but also the indoor base station 13 and The handovers 2b to 2d between the outdoor base stations 12 and the handover 2e between the indoor base stations 13 exist.

The indoor base station 13 in the portable Internet system may operate as a single base station, but several indoor base stations 13 may be gathered in a building or an area to form one indoor base station group 2f.

In a mobile Internet system, cells and cells are not clearly distinguished, and cells overlap each other. That is, the base stations 12 and 13 are not uniformly arranged at a certain distance. Therefore, when the portable Internet terminal (MS) 11 moves and performs handover, one or more candidates of the target base station (BS) exist. Therefore, for handover, one base station must be selected from a plurality of target base stations, and at this time, the target base station is evaluated with a signal strength.

For example, the handover control procedure in the outdoor portable Internet network (see FIG. 1) that conforms to the IEEE 802.16e standard is illustrated in FIG. 3.

In FIG. 3, when a mobile Internet terminal (MS) 11 moves in an outdoor portable Internet network and a handover occurs, an outdoor base station (BS) 12 and a portable Internet terminal (MS) 11 defined in the IEEE 802.16e standard are generated. Follow the message format and procedure.

Referring to FIG. 3, referring to a handover control procedure in an outdoor portable internet network, first, the serving base station 12-1 provides MOB_NBR informing neighbor BS information for handover of the portable Internet terminal 11. Broadcasts a Mobile Neighbor Advertisement (ADV) message (IEEE 802.16e neighbor advertisement message, the serving base station periodically advertises network attributes for the serving base station and neighboring base stations) (see FIG. 4) (see FIG. 4). 301). Therefore, when the mobile Internet terminal 11 receives the MOB_NBR-ADV message periodically advertised from the base station (serving base station) 12-1 to which it belongs, it acquires IDs, QoS parameters, and channel information of neighboring base stations. This information can be used to perform a quick handover.

Referring to FIG. 4, the MOB_NBR-ADV message includes information such as a PHY profile ID, FA index, BS EIRP, BSID, etc. for N neighbor base stations, including a 24-bit operator ID. Able to know. Therefore, the size of this message increases in proportion to the number of neighboring base stations.

Subsequently, the portable Internet terminal 11 performs a task of scanning neighboring base stations as needed, and thus, the signal strength of the neighboring base stations can be known (302). In this case, the scanning operation transmits a MOB_SCN-REQ message to the serving base station 12-1 by the portable Internet terminal 11 requesting an interval between the scanning interval and the MOB_SCN-RSP message. It is assigned through. During the scanning interval, the portable Internet terminal 11 searches whether several neighboring base stations are suitable for handover.

That is, the mobile Internet terminal 11 may manage the list of candidate base stations to perform handover by obtaining a list of IDs of neighbor base stations through a MOB_NBR-ADV message and selecting an appropriate base station based on real-time link information acquired through scanning. have.

However, the handover may be initiated by the portable Internet terminal 11 (303) or by an outdoor serving base station (BS) 12-1 (308).

First, referring to the case where the portable Internet terminal 11 starts the handover, after the scanning process is finished, the portable Internet terminal 11 sends a MOB_MSHO-REQ message [MS → BS1, the portable Internet terminal 11] to start the handover. IEEE 802.16e handover request message) is transmitted to the serving base station 12-1 (303), in which the MOB_MSHO-REQ message includes the carrier to interference and noise ratio (CINR) of neighbor base stations received through the MOB_NBR-ADV message. Contains a value.

When the handover request is received from the portable Internet terminal 11 (303), the serving base station 12-1 is the candidate base stations recommended by the portable internet terminal 11 through the backbone network (target base station 12- 2), and informs the information of the mobile Internet terminal 11 through the message HO_notification (304), and can proceed or not handover from the candidate base station (including the target base station 12-2) Whether or not a response message (HO_notification_response) is received (305).

After receiving the response (305), the serving base station 12-1 checks with the recommendable handover target base station 12-2 (306), and then the MOB_BSHO-RSP message [BS1 → MS, serving base station 12]. IEEE 802.16e handover response message -1), including the recommended base station list (adjacent base station list), is transmitted to the portable Internet terminal 11 (307).

Thereafter, the portable Internet terminal 11 determines the final handover target base station 12-2 from among the target base stations recommended by the serving base station 12-1, and sends a MOB_HO-IND message (MS) to the serving base station 12-1. BS1, IEEE 802.16e handover execution message) is sent to finally notify the handover (309).

In the above, steps "303" to "307" represent a handover preparation process, and "309" represents an initial process of handover execution.

During the handover preparation process (303 to 307), the portable Internet terminal 11 determines the optimal target base station 12-2 by comparing the signal strength and QoS parameters of the neighboring base stations previously obtained. That is, the portable Internet terminal 11 compares the quality of service and signal strength provided from the serving base station 12-1 with a list of base stations capable of handover to the serving base station 12-1 in a MOB_MSHO-REQ message. The serving base station 12-1 transmits 303, and the serving base station 12-1 includes a list of recommended base stations (candidate base station) in the MOB_BSHO-RSP message and returns 307. At this time, the serving base station 12-1 notifies the handovers to the candidate base stations (one of which becomes the target base station 12-2) through the backbone network to advance the session and setting information of the portable Internet terminal 11 in advance. By transmitting 304, the handover execution time can be shortened later.

After the mobile Internet terminal 11 receives the MOB_BSHO-RSP message and determines the target base station 12-2, the mobile Internet terminal 11 sends a MOB_HO-IND message to the serving base station 12-1 to finally notify the handover [hand Overrun initial process] (309), immediately perform the handover [handover execution process] (310 ~ 316). The handover execution process will be described in more detail below.

Meanwhile, in the handover preparation process, the serving base station 12-1 may start the handover process by first transmitting the MOB_BSHO-REQ message to the portable Internet terminal 11.

Specifically, when the serving base station 12-1 starts handover, the mobile Internet terminal (MOB_BSHO-REQ message [BS1 → MS, IEEE 802.16e handover request message of the serving base station 12-1]) 11), where the MOB_BSHO-REQ message includes a list recommended by the serving base station 12-1 (candidate base station list), and the mobile Internet terminal 11 transmits the recommended base station to the MOB_NBR-ADV message. The handover is notified by transmitting the MOB_HO-IND message to the serving base station 12-1 by evaluating the information obtained through the discovery and the information through the base station discovery (309).

Now, referring to the handover execution process, the serving base station 12-1 receiving the MOB_HO-IND message disconnects from the portable Internet terminal 11 after the resource retention time and stops the service. At this time, since the MOB_HO-IND message is transmitted, the portable Internet terminal 11 can no longer transmit / receive packets through the serving base station 12-1, and then quickly reenter the network after moving to a new network (Network Re-entry). The procedure must be performed. At this time, if the target base station 12-2 receives the information of the portable Internet terminal 11 on the performance capability and authentication, etc. from the serving base station 12-1, the portable Internet terminal 11 performs the process during the network entry process; It can be omitted to shorten the handover process. If the network entry process is successfully completed, the target base station 12-2 starts a service to the portable Internet terminal 11.

In detail, the new serving node, the target base station 12-2, transmits a fast_ranging IE to the portable Internet terminal 11 (310), and the portable Internet terminal 11 transmits a CDMA ranging code. A ranging code is transmitted to the target base station 12-2 (311). [Transmission Parameter Acquisition Process]

Referring to the transmission parameter acquisition process (310,311), the target base station 12-2 transmits UL-MAP (Uplink Map), DL-MAP (Downlink Map) message to the portable Internet terminal 11 every frame, DCD ( The downlink channel descriptor (UCD) and the uplink channel descriptor (UCD) are periodically transmitted according to the configuration of the target base station 12-2, and the portable internet terminal 11 receives the frame and checks the delivery information. Here, the DCD message includes a transmission / reception time, a center frequency, a mobility support function, a base station identification information, a radio signal calculation method, and a downlink burst profile information for the duplex method. In addition, the UCD message includes uplink burst profile information, contention-based reservation timeout, ranging related information, information for power signal adjustment, and the like.

Thereafter, the portable Internet terminal 11 performs a network re-entry procedure to the target base station 12-2, which is a new serving node (312 to 315). At this time, the entry procedure into the new network is largely ranging, ranging (312), basic capability negotiation process (313), terminal authentication and key exchange process (314), registration process (315), connection establishment process, IP This can be seen as an address assignment process. In each process, the portable Internet terminal 11 transmits the REQ message to the target base station 12-2, and receives the RSP message from the target base station 12-2. When the portable Internet terminal 11 enters a new network, the handover procedure is completed, and after completing the handover procedure, the new serving node, the target base station 12-2, transmits data to the portable Internet terminal 11. (316).

In the above description, the ranging process 312 is described in detail. The portable Internet terminal 11 targets a burst profile and media access control (MAC) information of the terminal through a ranging request (RNG-REQ) message. The target base station 12-2 responds with a ranging response (RNG-RSP: Ranging Response) message (312). In this case, the RNG-RSP message includes information such as ranging status, burst profile, MAC address of the portable Internet terminal 11, and connection identifier (CID).

After performing the ranging (RNG) process 312, the mobile Internet terminal 11 transmits a basic capability negotiation request (SBC-REQ: SS Basic Capability Request) message to the target base station 12-2, and the target base station 12-2, a basic capability negotiation response (SBC-RSP: SS Basic Capability Response) message is transmitted to the portable Internet terminal 11 to exchange information for using radio resources (313). [Basic Capability Negotiation Process] At this time, the SBC message includes transmission / reception switching time, maximum power, current transmission power, and information related to orthogonal frequency division multiple (OFDM) according to the time division duplex (TDD) method of the portable Internet terminal 11. Included.

After performing the basic capability negotiation (SBC) process 313, the portable Internet terminal 11 requests a privacy key management (PKM) request message to the target base station 12-2 [EAP transmission request]), and a PKM response. It receives the message and manages the encryption key required to protect the information [EAP transmission response] (314). [Terminal authentication and key exchange process]

After performing the terminal authentication and key exchange process 314, the portable Internet terminal 11 transmits a registration request message (REG-REQ: Registration Request) to the target base station 12-2, and the target base station 12 -2) transmits a registration response (REG-RSP) message to the portable Internet terminal 11 (315). [Registration Process] At this time, the registration request message includes information such as the number of up / down CIDs, the type of packet (CS: Convergence Sublayer), maximum classification information, service flow, etc. to be used in Internet communication.

After performing the registration process 315, although not shown in the drawing, the target base station 12-2 additionally transmits a dynamic service addition (DSA) request message for establishing a traffic connection to the portable Internet terminal 11, If the mobile Internet terminal 11 responds with a DSA-RSP (DSA Response) message, it checks with a DSA-ACK (DSA Acknowledge) message. [Connection establishment process] At this time, the DSA message processes the up / down service flow using the transaction identification number.

In addition, after performing the connection setup process, although not shown in the figure, in the case of IPv4 additionally according to the IP version automatically using the DHCP (Dynamic Host Configuration Protocol) v4 IP address to be used in the mobile Internet terminal 11 Set it. In the case of IPv6, an address to be used by the portable Internet terminal 11 is automatically set using DHCPv6 or an automatic setting function. [IP Address Allocation Process]

In summary, the serving base station 12-1 first transmits the MOB_NBR-ADV message containing the surrounding base station information to the portable Internet terminal 11. The portable Internet terminal 11 and the serving base station 12-1 exchange MOB_SCN-REQ message and MOB_SCN-RSP message, and in this process, the portable Internet terminal 11 may change the target base station 12 according to signal strength and QoS characteristics. -2) will be selected. Subsequently, when the portable Internet terminal 11 selects the target base station 12-2, it enters a handover preparation step. As a preprocessing step for performing the handover, when the MOB_MSHO-REQ message, the MOB_BSHO-RSP message, or the MOB_BSHO-REQ message is exchanged with the current serving base station 12-1, the handover preparation step ends.

Thereafter, the portable Internet terminal 11 performs the actual handover. To this end, the portable Internet terminal 11 transmits the MOB_HO-IND message to the serving base station 12-1. Subsequently, the serving base station 12-1 receiving the MOB_HO-IND message releases the resources allocated to the portable Internet terminal 11 and performs security functions and authentications with the target base station 12-2.

As described above, handover may be initiated by the portable Internet terminal 11 (303) or by the serving base station 12-1 (308).

5 and 6, when the portable Internet terminal 11 starts handover, the handover control process of the portable Internet terminal 11 and the base stations 12-1 and 12-2 is separated. Let's take a look.

Referring to FIG. 5, the portable Internet terminal 11 receives a MOB_NBR-ADV message (see FIG. 4) periodically broadcasted from the serving base station 12-1 to inform neighbor BS information (see FIG. 4). 501, if it is determined that scanning of neighboring base stations is necessary (502), the MOB_SCN-REQ message is transmitted to the serving base station 12-1 to request a scanning interval and an iteration ( 503). Subsequently, the mobile Internet terminal 11 receives the MOB_SCN-RSP message from the serving base station 12-1 (504), and scans neighbor base stations in earnest. Accordingly, the portable Internet terminal 11 searches through hand scanning whether it is suitable for handover (searches whether neighboring base stations are suitable for handover during the scanning interval), and thus, the signal strength of neighboring base stations can be known (505).

If the portable internet terminal 11 determines that handover should be performed (506), the portable internet terminal 11 includes candidate base stations including neighboring base stations (target base station 12-2) to start the handover. The MOB_MSHO-REQ message is transmitted to the serving base station 12-1, including the CINR value of () (507).

Subsequently, when the mobile Internet terminal 11 receives the MOB_BSHO-RSP message including the candidate base station list recommended by the serving base station 12-1 from the serving base station 12-1 (508), the portable Internet terminal 11 The handover target base station 12-2 is finally determined according to the signal strength, and the final handover target base station 12-2 is informed to the serving base station 12-1 through the MOB_HO-IND message (509). At this time, since the MOB_HO-IND message is transmitted, the portable Internet terminal 11 can no longer transmit or receive a packet through the serving base station 12-1. (Network Re-entry) procedure (Ranging process, basic capability negotiation process, terminal authentication and key exchange process, registration process, connection establishment process, IP address allocation process, etc.) must be performed (510-518). However, if the target base station 12-2 receives the information of the portable Internet terminal 11 on the performance capability and authentication, etc. from the serving base station 12-1, the portable Internet terminal 11 performs the corresponding process during the network entry process. It can be omitted to shorten the handover process.

That is, when the initial handover execution process ends, the portable Internet terminal 11 performs a network reentry procedure. Accordingly, when the mobile internet terminal 11 receives the Fast_Ranging_IE from the target base station 12-2 (510), the mobile internet terminal 11 transmits an RNG-REQ message to the target base station 12-2 (511). In response to the RNG-RSP response message (512), the fast ranging operation is completed.

Thereafter, the portable Internet terminal 11 transmits the SBC-REQ message to the target base station 12-2 (513), and receives the SBC-RSP message from the target base station 12-2 in response (514). The basic capability is negotiated. The mobile Internet terminal 11 transmits the PKM-REQ message to the target base station 12-2 (515), receives the PKM-RSP message from the target base station 12-2 in response (516), Terminal authentication and key exchange Finally, the mobile Internet terminal 11 transmits the REG-REQ message to the target base station 12-2 (517), and receives the REG-RSP message from the target base station 12-2 in response thereto (518). After completing the Registration process (which may involve connection setup process, IP address assignment process, etc.), complete the network re-entry process to complete the entire handover procedure.

As such, when the network entry process is successfully completed, the portable Internet terminal 11 may receive a service from the target base station 12-2.

Meanwhile, referring to FIG. 6, the serving base station 12-1 transmits a MOB-NBR-ADV message including neighbor BS information to the portable Internet terminal 11 (601), and the portable Internet terminal ( 11, when a MOB_SCN-REQ message requesting a scanning interval and an iteration is received (602), the MOB_SCN-RSP message is carried by allocating a scanning interval and an iteration. It transmits to the Internet terminal 11 (603).

Subsequently, the serving base station 12-1 may include a MOB_MSHO-REQ message (that is, a CINR value of neighboring base stations recommended by the portable Internet terminal 11 (ie, candidate base stations including the target base station 12-2)). When the terminal receives the message including the search results of the target base stations in the message (604), the mobile Internet terminal 11 recommends the candidate base station (including the target base station 12-2) as the backbone. The handover of the portable Internet terminal 11 is notified through the network (605). If a response is received from the recommended target base stations (the candidate base station including the target base station 12-2) (606), the serving base station 12-1 based on the response, the serving base station 12-1 can be recommended again. 2) and confirms handover to the selected recommended target base station 12-2 through message exchange using a backbone network (608).

Next, the serving base station 12-1 includes the recommended target base station list in the MOB_BSHO-RSP message in response to the MOB_MSHO-REQ message transmitted by the mobile internet terminal 11 and transmits it to the mobile internet terminal 11 ( 609).

Subsequently, as the serving base station 12-1 determines the target base station 12-2 at the portable Internet terminal 11, a MOB_HO-IND message is received from the portable Internet terminal 11 to receive final notification of handover. In operation 610, the connection with the portable Internet terminal 11 is disconnected after resource retention time (611).

7 and 8, when the serving base station 12-1 starts handover, the handover control process in the portable Internet terminal 11 and the base stations 12-1 and 12-2 is performed. Let's look at it separately.

Referring to FIG. 7, the portable Internet terminal 11 receives a MOB_NBR-ADV message (see FIG. 4) periodically broadcasted from the serving base station 12-1 to inform neighbor BS information (see FIG. 4). 701), when receiving a MOB_BSHO-REQ message including a recommended target base station list from the serving base station 12-1 (702), a signal from the recommended neighbor base station (a candidate base station including the target base station 12-2) is received. The handover target base station 12-2 is finally determined according to the strength, and the serving base station 12-1 is finally notified of the handover fact through the MOB_HO-IND message (703).

At this time, since the MOB_HO-IND message is transmitted, the portable Internet terminal 11 can no longer transmit or receive a packet through the serving base station 12-1. (Network Re-entry) procedure (Ranging process, basic capability negotiation process, terminal authentication and key exchange process, registration process, connection establishment process, IP address allocation process, etc.) must be performed (704-712). However, if the target base station 12-2 receives the information of the portable Internet terminal 11 on the performance capability and authentication, etc. from the serving base station 12-1, the portable Internet terminal 11 during the network entry process By omitting the handover process can be shortened.

Therefore, when the portable Internet terminal 11 receives the Fast_Ranging_IE from the target base station 12-2 (704), the portable Internet terminal 11 transmits the RNG-REQ to the target base station 12-2 (705), and the RNG In response to the RSP response (706), the fast ranging operation is completed.

Thereafter, the mobile Internet terminal 11 undergoes a basic capability negotiation process with the target base station 12-2 through the SBC-REQ message and the SBC-RSP message (707,708), and the terminal through the PKM-REQ message and the PKM-RSP message. By performing authentication and key exchange process (709,710), and finally performing registration process (711,712) through REG-REQ message and REG-RSP message to complete network reentry process (connection establishment process, IP address allocation process, etc.) May be accompanied) complete the entire handover procedure.

As such, when the network entry process is successfully completed, the portable Internet terminal 11 may receive a service from the target base station 12-2.

Meanwhile, referring to FIG. 8, the serving base station 12-1 transmits a MOB_NBR-ADV message including neighbor BS information to the portable Internet terminal 11 (801) and determines that handover is necessary. In operation 802, the candidate base stations (including the target base station 12-2) are exchanged with the candidate base stations in advance via the backbone network to the candidate base stations (803).

Subsequently, when the mobile base station 11 transmits the MOB_BSHO-REQ message including the target base station list recommended by the serving base station 12-1 to the mobile internet terminal 11 (804), the mobile internet terminal 11 recommends candidate base stations (targets). If the handover target base station 12-2 is finally determined according to the signal strength among the base station 12-2), and finally the serving base station 12-1 is notified to the serving base station 12-1 through the MOB_HO-IND message (805) The serving base station 12-1 disconnects from the portable Internet terminal 11 and stops the service after the resource retention time (806).

When the handover control method according to the prior art as described above is applied to the outdoor / indoor portable internet system as it is (when the handover control procedure of the outdoor portable internet system is used in the indoor portable internet system), the following problems This will occur.

The mobile Internet terminals 11 may access the indoor / outdoor base stations 12 and 13 having two different characteristics and receive a service through a base station suitable for a subscriber's own environment such as mobility of the terminal. . Therefore, in the new environment, such as a mobile Internet system in which the various base stations 12 and 13 are arranged more than the existing cellular mobile communication system, the base station 12 or the terminal 11 transmits messages required for handover in a conventional manner. In this case, the overhead of the handover message is increased such that the size of the MOB_NBR-ADV message, which contains information of neighboring base stations broadcast by the base station 12, increases in proportion to the number of neighboring base stations. This can cause a decrease in system transmission efficiency. In addition, the size of various messages MOB_SCN-REQ, MOB_SCN-RSP, MOB_SCN-REP, MOB_MSHO-REQ, MOB_BSHO-REQ, and MOB_BSHO-RSP messages, which are required for the terminal 11 and the base station 12 to proceed with the handover procedure. In addition, since the number increases in proportion to the number of adjacent base stations, the system transmission capacity cannot be effectively utilized.

Handover of the terminal 11 proceeds through a number of procedures, each of which has a message that the terminal / base station to transmit to each other. In addition, most messages include information of several neighboring base stations. Therefore, compared to the existing cellular mobile communication system, in a portable Internet system composed of a plurality of indoor / outdoor base stations 12 and 13, the size of such a message increases in proportion to the increased number of base stations, and the terminal 11 has a plurality of base stations. Since the nodes 12 and 13 must be searched, a handover latency problem and a message overhead problem occur.

In addition, compared to the existing cellular mobile communication system, a handheld Internet system in which a plurality of base stations exist in the same area is frequently handed out by the terminal, so handover delay may affect the service. Therefore, the importance of handover technology for maintaining communication with the base stations 12 and 13 even when the terminal 11 is mobile is very important, and handover for maintaining seamless communication of the terminal 11 during the handover procedure. It is very important to reduce the delay as much as possible.

Accordingly, the present invention provides a handover control method and a handover method for reducing handover latency and message overhead during handover of a terminal in a mobile Internet system in which indoor / outdoor base stations exist. Its purpose is to provide a way of constructing messages.

That is, in the present invention, in a mobile Internet system environment in which a larger number of base stations exist in the same area than existing cellular mobile communication systems, it is possible to efficiently utilize system transmission capacity by minimizing the MOB_NBR-ADV message overhead broadcasted by each base station periodically. Make sure In addition, the present invention minimizes system performance degradation due to an increase in handover delay and an increase in handover message overhead caused by an increase in the handover frequency of a terminal in an indoor / outdoor portable Internet system environment in which various types of base stations are mixed. I would like to.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, 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.

According to an aspect of the present invention, there is provided a method for constructing a handover message in a wireless communication system including an indoor base station and an outdoor base station, wherein the cell area provided by the outdoor base station is located at a location where the indoor base station is disposed. Dividing the indoor base station into an inner base station or an outer base station, and dividing the indoor base station in a cell area of the outdoor base station into a single base station indoor group or a group base station indoor base station according to the configuration form of the base station base station; And configuring, by the indoor serving base station, a neighboring base station information related message for handover based on the deployment information and configuration information of the indoor base station.

Meanwhile, the present invention provides a method for controlling a handover in a base station, comprising: storing, by the outdoor base station, connection information with the terminal when the terminal performs a first handover from an outdoor base station to an indoor serving base station; When the terminal searches for the outdoor base station and requests a handover from the indoor serving base station to the outdoor base station when the second handover is required, the handover is requested to the indoor serving base station including the search result of the outdoor base station. Transmitting, by the indoor serving base station, the confirmation result of the handover candidate base station to the terminal; And as the terminal selects a handover target base station, the outdoor base station selected as the handover target base station to ensure handover of the terminal using the connection information.

In addition, the present invention, in the handover control method in the base station, when the terminal performs the first handover from the outdoor base station to the indoor serving base station, the indoor serving base station configuration information and configuration information of the indoor base station Constructing and broadcasting a neighbor base station information related message for handover based on the broadcast; The terminal searches for the outdoor base station and the indoor base station based on previously stored information of the outdoor base station and 'information of the same group of indoor base stations acquired through the neighbor base station information related message'. When the indoor serving base station requests a handover to the indoor serving base station, including a result of the base station search when the second handover is needed from the indoor serving base station, the indoor serving base station receives the confirmation result of the handover candidate base station. Transmitting to the terminal; And as the terminal selects a handover target base station, performing the second handover by the indoor serving base station to the selected handover target base station.

Meanwhile, the present invention provides a method for controlling a handover in a terminal, the method comprising: storing information about the previously connected outdoor base station by the terminal after performing a first handover from an outdoor base station to an indoor serving base station; Performing, by the terminal, searching for an outdoor base station based on information about the outdoor base station previously stored; When the terminal needs a second handover from the indoor serving base station to the outdoor base station, requesting a handover to the indoor serving base station including a search result of the outdoor base station, and handing over from the indoor serving base station. Receiving a confirmation result of the candidate base station; And selecting, by the terminal, a handover target base station and performing a handover to the outdoor base station.

The present invention also provides a method for controlling a handover in a terminal, after the terminal performs a first handover from an outdoor base station to an indoor serving base station, and stores information about the previously connected outdoor base station, and Receiving, from an indoor serving base station, a message related to neighbor base station information for handover based on configuration information and configuration information of the indoor base station; Searching, by the terminal, the outdoor base station and the indoor base station based on previously stored information about the outdoor base station and 'information of the same group of indoor base stations acquired through the neighbor base station information related message'; When the terminal needs a second handover from the indoor serving base station to the other indoor base station, requesting a handover to the indoor serving base station including a result of the base station search, and a handover candidate from the indoor serving base station. Receiving a confirmation result of the base station; And selecting, by the terminal, a handover target base station and performing the second handover to the selected handover target base station.

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In the present invention as described above, when the existing handover scheme is applied to the portable Internet system, the broadcasting overhead problem of the MOB_NBR-ADV message caused by the increase in the number of neighboring base station handover candidates due to the increase in the density of the base stations. There is an effect to reduce.

When the handover is performed from the indoor base station to the outdoor base station due to the decrease of the MOB_NBR-ADV message, the messages necessary for each handover procedure (MOB_SCN-REQ, MOB_SCN-RSP, MOB_SCN-REP, MOB_MSHO-REQ, MOB_BSHO-REQ). , The amount of base station information included in the MOB_BSHO-RSP message) is reduced, thereby increasing the system transmission capacity. Also, as the number of neighbor base stations to be searched is reduced, there is an advantage that the neighbor base station search time, which is most of the time required for handover delay, can be greatly reduced. Therefore, it is possible to shorten the processing time of the corresponding messages of the terminal and the base station and to reduce the transmission message size, and to reduce the number of neighbor base station search times, thereby reducing the base station search time.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

9 is an exemplary configuration diagram of an indoor / outdoor portable Internet (WiBro) network to which the present invention is applied.

As shown in FIG. 9, in the portable Internet system including indoor / outdoor base stations, outdoor base stations 12-1 to 12-3 are disposed in the center of a cell, and outdoor base stations 12-1 to 12-3 are provided. Indoor base stations 13-1, 13-7-13-9 are independent (13-1, 13-7-13-9) or groups 13-5, 13-6 in a cell area provided by; ) 9f is arranged. In addition, indoor base stations 13-2 to 13-4 are located at overlapping portions of two or more cell regions.

9 illustrates a hierarchical ID structure of outdoor base stations 12-1 to 12-3 and indoor base stations 13-1 to 13-9 in a portable Internet system.

That is, in FIG. 9, the outdoor base stations 112-1 to 12-3 are set to "BS", the indoor base stations 13-1 to 13-9 are set to "Inner_BS", the terminal is set to "MS", and indoors. The base station group is designated as "G". In addition, BS and Inner_BS, MS, and G are distinguished by attaching numbers such as BS1, Inner_BS1, MS1, or G1, and indoor base station 1 (Inner_BS1) (13-1) belonging to outdoor base station 1 (BS1) 12-1. ) Is designated as "BS1.Inner_BS1". In addition, indoor base station 5 (Inner_BS5) 13-5 and indoor base station 6 (Inner_BS6) 13-6, which constitute a group 9f belonging to the outdoor base station 2 (BS2) 12-2, are respectively " BS2.G1.Inner_BS5 "and" BS2.G1.Inner_BS6 ".

10 and 11 are explanatory views showing a handover control process in a cell inner region according to an embodiment of the present invention, and FIGS. 12 to 15 are handover control processes in a cell outer region according to an embodiment of the present invention. It is an explanatory diagram showing.

10 shows that the mobile path of the terminal 11 performs handover from the cell area of the outdoor base station 1 12-1 to the cell area 10 d of the indoor base station 1 13-1 in a single configuration; 10a), the mobile station 11 moves from the cell area 10d of the single configured indoor base station 1 13-1 (10b) and receives service, and then the cell area of the same outdoor base station 1 12-1. (10c) shows a scenario (outdoor base station 1 → single configuration indoor base station 1 → outdoor base station 1 handover scenario (scenario where an indoor base station is located in a cell)).

In FIG. 10, the cell areas that can be serviced by a single configured indoor base station 1, 2 (13-1, 13-2) existing in the cell area of the outdoor base station 1 12-1 are equal to “10d” and “10e”. .

FIG. 11 shows that the mobile path of the terminal 11 performs handover from the cell area of the outdoor base station 1 12-1 to the cell area of the indoor base station 1 13-1 composed of the group 11d. (11a), and then move within the same group (10d) (11b) to handover to another indoor base station 3 (13-3), and then to the same cell area of the same outdoor base station 1 (12-1) A moving 11c scenario (outdoor base station 1 → group configuration indoor base station 1 → group configuration indoor base station 3 → outdoor base station 1 handover scenario (scenario in which an indoor base station group is located inside a cell)) is shown.

In FIG. 11, cell areas that can be serviced by indoor base stations 13-1 to 13-3 (13-4 and 13-5) configured as a group are equal to "11d" and "11e".

FIG. 12 shows that the mobile path of the MS 11 is handed over from the cell region of the outdoor base station 12-1 to the cell region 12d of the single configured indoor base station 2 13-2 located in the outer region of the cell. (12a), the mobile station 11 is moved (12b) in the cell area (12d) of a single configured indoor base station 2 (13-2) located in the outer cell area receiving the service, and then the same outdoor base station A scenario (12c) of moving to the cell area of (12-1) (outdoor base station 1 → single configuration indoor base station 2 → same outdoor base station 1 handover scenario (scenario where indoor base station is located outside of cell)) is shown.

In FIG. 12, a single configured indoor base station 1, 2, 3, 4 (13-1 to 13-4) located in a cell outer region of an outdoor base station 1 12-1 and an outdoor base station 2 12-2 is serviced. Possible cell regions are as follows: "12d", "12e", "12f", "12g".

FIG. 13 shows the movement path of the MS 11 from the cell area of the outdoor base station 1 12-1 to the cell area 13d of the single configured indoor base station 2 13-2 located in the outer cell area. After performing the over (13a), the mobile station 11 is moved (13b) in the cell area (13d) of a single configured indoor base station 2 (13-2) located in the cell outside area (13b), and then the other outdoor use A scenario (13c) of moving to the cell area of the base station 2 (12-2) [indoor base station 1 → single-organized indoor base station 2 → other outdoor base station 2 handover scenario (scenario where indoor base station is located outside of room)] is shown. will be.

In FIG. 13, a single configured indoor base station 1, 2, 3, 4 (13-1 to 13-4) located in a cell outer region of an outdoor base station 1 12-1 and an outdoor base station 2 12-2 is serviced. Possible cell regions are as follows: "13d", "13e", "13f", and "13g".

FIG. 14 shows a cell path of an indoor base station 1 (13-1) in which a mobile path of a terminal (MS) 11 is composed of a group 14d located in a cell outer area from a cell area of an outdoor base station 1 12-1. Perform a handover (14a), then move within the same group 14d (14b) and proceed handover to another indoor base station 2 (13-2) (14b), and then the same outdoor base station 1 ( 12-1) Moving to the Cell Area (14c) Scenario [Outdoor Base Station 1 → Group Configuration Indoor Base Station 1 → Group Configuration Indoor Base Station 2 → Same Outdoor Base Station 1 Handover Scenario (Scenario where an indoor base station is located outside a cell) )].

In FIG. 14, cell areas that can be serviced by indoor base stations 13-1 to 13-3 (13-4 to 13-6) (13-7 to 13-9) configured as groups are "14d" and "14e. Is equivalent to "14f".

FIG. 15 shows a cell path of an indoor base station 1 (13-1) in which a mobile path of a terminal (MS) 11 is composed of a group 15d located in a cell outer area from a cell area of an outdoor base station 1 12-1. Perform a handover (15a), then move within the same group (15d) (15b) to proceed with the handover to another indoor base station 2 (13-2), and then different outdoor base station 2 (12-2) (15c) a scenario (outdoor base station 1 → group configuration indoor base station 1 → group configuration indoor base station 2 → other outdoor base station 2 handover scenario (scenario with indoor base station located outside the cell)) It is shown.

In FIG. 15, cell areas that can be serviced by indoor base stations 13-1 to 13-3 (13-4 to 13-6) and 13-7 to 13-9 in groups are "15d" and "15e. Is equivalent to "15f".

10, 12, and 13, the cell area of the unitary indoor base station 13 is an indoor base station installed in a small area, such as a home portable Internet system.

11, 14, and 15, the cell area of the grouped indoor base station 13 is a case where indoor base stations are grouped for artificial purposes in a specific company or a business place, such as an enterprise portable Internet system, This means that the cell areas of the base stations overlap.

As shown in FIGS. 10 and 11, when the indoor base station 13 exists in the cell inner region, the handover is performed again to the outdoor base station 12-1 that has been previously connected by the movement of the terminal 11. It is possible. That is, unless a situation in which handover to the previously connected outdoor base station 12-1 is not possible due to a problem of the outdoor base station 12-1, most of the terminals 11 are connected to the outdoor base station 12- Proceed to handover to 1).

12 to 15, when the indoor base station 13 is located in the cell outlying region, the terminals 11 which have performed the handover to the indoor base station 13 may use the same outdoor device as previously connected. The handover is performed again to the base station 12-1 or handover to another adjacent outdoor base station 12-2. That is, most of the terminals if the handover is inevitable that the handover cannot proceed to the previously connected outdoor base station 12-1, or if the progress direction of the terminal 11 is not the direction of the outdoor base station 12-1 previously connected. 11, it is advantageous to proceed with the handover to the existing outdoor base station 12-1 due to the cell structure.

In such an environment, when the base stations transmit the MOB_NBR-ADV message, which is a message transmitted by including information of neighboring base stations to help the terminal prepare for handover, the handover method of the existing cellular mobile communication system is applied to the mobile Internet system. In this case, the message size is considerably increased because it transmits not only the information of the outdoor base stations 12 but also the information of a number of indoor base stations 13, and thus, the overhead of broadcasting the handover message. A problem arises.

Accordingly, in the present invention, the indoor base station 13 proposes a MOB_NBR-ADV message configuration through a new policy in order to reduce such broadcasting overhead problem. Through this, it is possible to reduce the broadcasting overhead problem of MOB_NBR-ADV message generated when the handover method used in the existing cellular mobile communication system is applied in the portable Internet system.

That is, in the present invention, the configuration of the MOB_NBR-ADV message utilizes the placement information of the base stations 12 and 13. That is, the cell area provided by the outdoor base station 12 is divided into an inner / outer area, and the MOB_NBR-ADV message is composed of the indoor base station 13 located inside the cell and the indoor base station 13 located outside the cell. Separate In addition, between the indoor base stations 13, indoor base stations such as indoor base stations used at home independently operate, and indoor base stations such as indoor base stations used in businesses are operated in groups. Distinguish MOB_NBR-ADV messages.

The IDs of the indoor base stations 13 are a hierarchical structure in which the IDs of the outdoor base stations 12 are configured as a superset. The hierarchical structure ID is a terminal 11 when a base station 12 or 13 composes a MOB_NBR-ADV message in a mobile Internet system in which various indoor / outdoor base stations 12 and 13 are mixed, and receives a MOB_NBR-ADV message. It is a good structure to distinguish this base station ID.

The base stations 12 and 13 include information of neighbor base stations required for handover of the terminal 11 when constructing the MOB_NBR-ADV message. In this case, in the case of the indoor base station 13, the terminal 11 directly moves from the indoor base station 13 to the indoor base station 13 between the independently operating indoor base stations 13 that are separated from each other. Since the scenario that proceeds over cannot occur, when the indoor base station 13 constructs a MOB_NBR-ADV message, only the indoor base station 12 including the information of the indoor base stations 12 including itself and the information of the indoor base stations forming the group are included. Construct a message. In addition, when there is only a handover scenario from the indoor base station 13 to the specific outdoor base station 12 in the moving path of the terminal 11, the mobile station 11 of the terminal 11 is not broadcasted. Only when the request exists, the UE 11 may unicast the MOB_NBR-ADV message.

That is, as shown in FIG. 10, when the indoor base station 1 13-1 is located in the cell inner region of the outdoor base station 1 (BS1) 12-1 and is configured as a single indoor base station BS1.Inner_BS1, The indoor base station 1 13-1 may broadcast only the information of the outdoor base station 1 12-1 including its cell area 10d in the MOB_NBR-ADV message or may not transmit the MOB_NBR-ADV message. have.

However, as shown in FIG. 11, indoor base stations 1 to 3 (13-1 to 13-3) are located in the cell inner region of the outdoor base station 1 (BS1) 12-1 and constitute a group 11d. In the case of the base stations BS1.G1.Inner_BS1, BS1.G1.Inner_BS2, BS1.G1.Inner_BS3, the indoor base station 1 13-1 is the other indoor base stations of the group 11d to which it belongs. (13-2, 13-3) and information of the outdoor base station 1 (12-1) including its cell area are broadcasted in the MOB_NBR-ADV message or other indoors of the group 11d to which it belongs. Only the information of the base stations 13-2 and 13-3 configures and broadcasts a MOB_NBR-ADV message.

12 and 13, the indoor base station 2 (13-2) is located outside the cell of the outdoor base station 1 (BS1) 12-1 and the outdoor base station 2 (BS2) 12-2. If located at and configured as a single indoor base station (BS1 / BS2.Inner_BS2), indoor base station 2 (13-2) is an outdoor base station 1 (12-1) and an outdoor base station including its cell area (12d or 13d). The information of 2 (12-2) may be included in the MOB_NBR-ADV message and broadcasted, or the MOB_NBR-ADV message may not be transmitted.

However, as shown in Figs. 14 and 15, indoor base stations 1 to 3 (13-1 to 13-3) are the outdoor base station 1 (BS1) 12-1 and the outdoor base station 2 (BS2) 12-2. In the case of the indoor base station (BS1 / BS2.G1.Inner_BS1, BS1 / BS2.G1.Inner_BS2, BS1 / BS2.G1.Inner_BS3) located in the cell outer region of the The base station 1 (13-1) is an outdoor base station 1 (12-1) including its cell area with other indoor base stations (13-2, 13-3) of the group (14d or 15d) to which it belongs And broadcast the information of the base station 2 (12-2) for outdoor use in the MOB_NBR-ADV message or only with information of other indoor base stations (13-2, 13-3) of the group (14d or 15d) to which it belongs. Constructs and broadcasts a MOB_NBR-ADV message.

As shown in FIG. 10 to FIG. 15, when the terminal 11 performs a handover from the outdoor base station 12 to the indoor base station 13, the terminal 11 includes base station information of the existing outdoor base station 12. And the outdoor base station 12 stores the connection (Session) information with the terminal (11). Through this, it is possible to shorten the time required for the handover procedure, and it is possible to ensure whether the handover of the terminal 11 which has handed over to the indoor base station 13 in its cell area is possible.

Here, the information of the existing outdoor base station 12 stored by the terminal 11 is items corresponding to the base station specific information included in the MOB_NBR-ADV message of the outdoor base station 12 previously connected, in which case the indoor When the base station 13 does not include the information corresponding to the outdoor base station 12 in the MOB_NBR-ADV message or does not transmit the MOB_NBR-ADV message at all, the scanning process for the outdoor base station 12 is performed (a search procedure). ), The handover process is possible, and the hand of the outdoor base station 12 previously connected using the result of the base station discovery process in the target base station selection process (step “1603” of FIG. 16A) is performed. When there is no difficulty in the over progress, the outdoor base station 12 corresponding to the stored unique ID may be selected as the target base station to ensure faster re-handover.

The terminal-related connection information stored in the outdoor base station 12 includes a handover confirmation process (step 1606 of FIG. 16A) and a network reentry process (steps 1621 ˜ 1624 of FIG. 16B). A unique ID, a CDMA ranging code, and an authentication and registration information message corresponding to each terminal 11 for performing handover to the indoor base station 13 for use in PKM-RSP / REG-RSP message). As such, the outdoor base station 12 includes basic information (unique ID, CDMA ranging code), PKM-RSP / REG-RSP message, etc. of each terminal 11 that has performed the handover to the indoor base station 13. When the set of connection information is stored, the outdoor base station 12 may omit the message exchange process for authentication and registration of the authentication and registration server and the terminal 11 through the backbone network. In addition, when the terminal 11 performs the handover to the indoor base station 13 included in its cell area, the terminal 11 will handover to its cell area again after an appropriate time. Therefore, the outdoor base station 12 may store the corresponding terminal information set and may ensure that a problem does not occur in the handover process of the terminal 11 in preparation for the terminal 11 to proceed with the handover.

Referring to FIGS. 16A and 16B, the handover control procedure when the terminal 11 performs handover in such a scenario is as follows. 16A and 16B, after the terminal 11 hands over from the outdoor base station 12 to the indoor base station 13, the indoor base station (which becomes the serving base station) 13 is another indoor base station (a target base station). And handover from the indoor base station (serving base station) 13 to the same outdoor base station (which becomes the target base station) or another outdoor base station (which becomes the target base station).

Typically, the outdoor serving base station is a MOB_NBR-ADV message (IEEE 802.16e neighbor advertisement message, which informs neighbor BS information) for handover of the terminal 11, and serves network attributes for the serving base station and neighbor base stations. The base station broadcasts periodically] (see FIG. 4). Therefore, when the terminal 11 receives the MOB_NBR-ADV message periodically advertised from the serving base station to which it belongs, the terminal 11 acquires ID, QoS parameter, and channel information of neighbor base stations and performs this information in order to perform a faster handover later. It is available.

However, in the present invention, when the indoor serving base station transmits a smaller number of neighbor base station information in the MOB_NBR-ADV message as described above (1601) or the indoor serving base station does not transmit the MOB_NBR-ADV message at all. Is present. That is, the indoor serving base station may broadcast only the information of the outdoor base station including its cell area in the MOB_NBR-ADV message (1601) or may not transmit the MOB_NBR-ADV message (FIGS. 10, 12, and 12). 13]. In addition, the indoor serving base station 1 (13-1) broadcasts (1601) information of other indoor base stations of the group to which it belongs and the outdoor base station including its cell area in the MOB_NBR-ADV message; It configures and broadcasts the MOB_NBR-ADV message only with information of other indoor base stations in the group to which it belongs (see Figs. 11, 14, and 15).

Subsequently, if it is determined that the UE 11 needs to search for neighbor BSs, the UE 11 stores a part of the MOB_NBR-ADV message (1602) and the MOB_NBR-ADV message transmitted by the serving BS whether the neighbor indoor base station exists. In operation 1604, the neighboring base station is searched using the neighboring base station information received from the MOB_NBR-ADV message of the outdoor serving base station stored in the terminal 11 and the current indoor serving base station. 1603,1605).

For example, as shown in FIG. 10, when the terminal 11 hands over from the outdoor base station 1 12-1 to the indoor base station 1 13-1, the terminal 11 is an outdoor base station 1 12-1. ), And the outdoor base station 1 12-1 stores connection information of the corresponding terminal 11. Therefore, the indoor serving base station (which becomes the indoor base station 1 13-1) broadcasts only the information of the outdoor base station 12-1 including its cell area in the MOB_NBR-ADV message (1601) or MOB_NBR. You may not send ADV messages. Therefore, the terminal 11 may receive the same outdoor base station information as the information of the outdoor base station 12-1 stored by the indoor serving base station through the MOB_NBR-ADV message or may not receive the MOB_NBR-ADV message. In this case, the terminal 11 determines whether there is previously stored outdoor base station information (1602), and since information on the outdoor base station 1 12-1 exists, whether the outdoor base station 1 12-1 is suitable for handover. Search (1603).

However, as shown in FIG. 11, when the terminal 11 hands over from the outdoor base station 1 12-1 to the indoor base station 1 13-1, the terminal 11 is connected to the outdoor base station 1 12-1. Information is stored, and the outdoor base station 1 12-1 stores connection information of the corresponding terminal 11. Therefore, the indoor serving base station (which becomes the indoor base station 1 (13-1)) includes the information of the other indoor base station 2 (13-2) of the group to which it belongs and its outdoor base station 12- The information of 1) may be included in the MOB_NBR-ADV message and broadcasted (1601), or only the information of another indoor base station 2 (13-2) of the group to which it belongs may be included in the MOB_NBR-ADV message and broadcasted (1601). ). Therefore, the terminal 11 receives outdoor base station information and indoor base station 2 (13-2) information identical to the information of the outdoor base station 12-1 stored by the indoor serving base station through the MOB_NBR-ADV message, Indoor base station 2 (13-2) information may be received from the indoor serving base station via the MOB_NBR-ADV message. In this case, the terminal 11 determines whether there is already stored outdoor base station information (1602) and determines whether or not indoor base station search is necessary (1604), and information about the outdoor base station 1 (12-1) is present and Since information about the indoor base station 2 (13-2) is also present, the outdoor base station 1 (12-1) and the indoor base station 2 (13-2) are searched for handover (1603, 1605).

That is, as shown in FIGS. 10 and 11, the terminal 11 stores information about the outdoor base station 12 when performing a handover from the outdoor base station 12 to the indoor base station 13, and thus, the indoor base station ( When the handover is performed from 13) to the outdoor base station 12 again, even when the indoor serving base station does not include the outdoor base station information in the MOB_NBR-ADV message or transmits the MOB_NBR-ADV message, the previously stored outdoor base station information is used. The existing outdoor base station 12 can be selected as a target base station (included in the search target).

In the above, the discovery process (1603, 1605) is performed by the terminal 11 sends the MOB_SCN-REQ message to the indoor serving base station scanning interval (interval) and the inter- Iteration) and is allocated through the MOB_SCN-RSP message from the indoor serving base station. During the scanning interval, the terminal 11 searches whether several neighboring base stations are suitable for handover. However, such a discovery process is not a necessary process, and since there is no previous outdoor base station information stored in the terminal 11 and the indoor serving base station does not transmit the MOB_NBR-ADV message, the terminal 11 has information about the neighbor base station. If not determined, the terminal 11 may not perform the pre-search process of the neighbor base stations. In this case, the terminal 11 transmits a MOB_MSHO-REQ message that does not include a search result to the indoor serving base station in the handover request.

However, if the terminal 11 that does not have the information of the outdoor base station including the indoor serving base station connected to the indoor serving base station for fast handover progress feels that the search for the outdoor base station is necessary, the terminal 11 searches. The indoor serving base station requests the indoor serving base station information, and the indoor serving base station transmits a MOB_NBR-ADV message to the terminal 11 to perform a fast handover process through a pre-search process.

When the terminal 11 requires a handover (1606), the mobile station transmits a MOB_MSHO-REQ message to the indoor serving base station to start the handover (1607). In this case, if the UE 11 performs the pre-neighbor base station search process, the search result is included in the MOB_MSHO-REQ message. If the UE 11 does not perform the pre-search process, the MOB_MSHO does not include the search result. Send a REQ message.

As such, the handover may be initiated by the terminal 11 (1607), but may be performed by the indoor serving base station (1612) as another example. However, when the indoor serving base station starts handover, the UE 11 may not be able to handover to neighboring target base stations previously searched or MOB_MSHO-REQ in which the discovery result is not included in step "1607" below. Assume a message is received.

Then, referring to the case where the terminal 11 starts the handover, after the discovery process is finished, the terminal 11 sends a MOB_MSHO-REQ message [MS → BS. The IEEE 802.16e handover request message of the terminal 11] is transmitted to the indoor serving base station (1607). In this case, the MOB_MSHO-REQ message includes CINR values of neighbor base stations received through the MOB_NBR-ADV message. That is, the CINR value of the candidate base station is transmitted through the MOB_MSHO-REQ message.

When the handover request is received from the terminal 11 (1607), the indoor serving base station notifies the candidate base stations recommended by the terminal 11 through the backbone network of information of the terminal to be handed over (handover to the target base station). Informs the information of the terminal 11 through the message HO_notification] (1608), and receives a response message (HO_notification_response) from the candidate base stations (target base station) through the response message (HO_notification_response) (1609). .

After receiving the response (1609), the indoor serving base station confirms the recommendable handover target base station (1610), and then the MOB_BSHO-RSP message [BS → MS. IEEE 802.16e handover response message of the indoor serving base station] includes information on the recommended base station list and transmits the information to the terminal 11 (1614 and 1615).

Thereafter, the UE 11 receiving the MOB_BSHO-RSP message from the indoor serving base station selects a final handover target base station (1616), and sends the MOB_HO-IND message containing information of the corresponding target base station to the indoor serving base station [MS → BS]. . IEEE 802.16e handover execution message] is transmitted to finally notify the handover (1617).

However, when the UE 11 cannot handover to the neighboring target BSs previously searched (1611) or when the MOB_MSHO-REQ message is not included in the search result in step 1616 (1611), indoors The serving base station sends the terminal 11 a MOB_BSHO-REQ message [BS → MS. IEEE 802.16e handover request message of indoor serving base station] is transmitted (1612). In this case, the MOB_BSHO-REQ message includes a list recommended by the indoor serving base station (candidate base station list), that is, information of other alternative neighboring base stations to which the terminal 11 can perform a handover. (11) searches for the base stations using the information of the alternative neighbor base stations included in the message (1613), selects the final target base station using the result (1616), and then the MOB_HO-IND message containing the information of the target base station Transmit to indoor serving base station (1617).

When the handover target base station (target base station) is determined as described above, when the terminal 11 performs handover from the outdoor base station 12 to the indoor base station 13, the outdoor base station 12 performs terminal-related connection information [terminal of the terminal]. Since the connection information set consisting of basic information (unique ID, CDMA ranging code) and PKM-RSP / REG-RSP message] is stored, a message indicating that the terminal 11 requests handover is transmitted from the indoor serving base station. When received, the outdoor base station (which becomes the target base station) 12 may ensure whether the handover of the corresponding terminal is possible using the stored information of the corresponding terminal. In this case, the message exchange process for authentication and registration required in the handover process may be omitted using the stored connection information (simplification of the network re-entry procedures 1621 to 1624).

In the above, steps "1607" to "1615" represent a handover preparation process, and "1617" represents an initial process of handover execution.

During the handover preparation process (1607 ~ 1615), the terminal 11 determines the optimal target base station by comparing the signal strength and QoS parameters of the neighboring base stations obtained previously. That is, the terminal 11 compares the service quality and signal strength provided from the pre-stored or indoor serving base station with the list of base stations capable of handover in the MOB_MSHO-REQ message and transmits it to the indoor serving base station (1607). In step 1615, the indoor serving base station returns a list of recommended base stations (candidate base station) among them in the MOB_BSHO-RSP message. At this time, the indoor serving base station notifies the handover to the candidate base stations (one of which becomes the target base station) through the backbone network, and transmits the session and configuration information of the terminal 11 in advance (1608). Can be shortened.

Then, when the terminal 11 receives the MOB_BSHO-RSP message and determines the target base station (1616), it sends a MOB_HO-IND message to the indoor serving base station to finally notify the handover [handover execution initial process] ( 1617), a handover is immediately performed (handover execution process) (1619-1625).

Referring to the handover execution process, the indoor serving base station receiving the MOB_HO-IND message disconnects from the terminal 11 and stops the service after the resource retention time (1618). At this time, since the UE 11 can no longer transmit / receive packets through the indoor serving base station from the time of transmitting the MOB_HO-IND message, it must perform a network re-entry procedure quickly after moving to a new network. do. At this time, if the target base station receives the information of the terminal 11 on the performance capability, authentication, etc. from the indoor serving base station, the terminal 11 may shorten the handover process by omitting the corresponding process during the network entry process. If the network entry process is successfully completed, the target base station starts the service to the terminal (11).

Specifically, the new serving node, the target base station, transmits Fast_Ranging IE to the terminal 11 (1619), and the terminal 11 transmits a CDMA ranging code to the target base station (1620). [Transmission Parameter Acquisition Process] That is, the target base station transmits a UL-MAP, DL-MAP message to the terminal 11 every frame, periodically transmits DCD and UCD according to the setting of the target base station, and the terminal 11 Receives the frame and checks the delivery information.

Thereafter, the terminal 11 performs a network re-entry procedure to the target base station, which is a new serving node (1621 ~ 1624). At this time, the entry procedure to the new network is largely ranging (Ranging) process (1621), basic capability negotiation process (1622), terminal authentication and key exchange process (1623), registration process (1624), connection establishment process, IP This can be seen as an address assignment process. In each process, the terminal 11 transmits a REQ message to the target base station and receives an RSP message from the target base station. When the terminal 11 enters a new network, the handover procedure is completed, and after completing the handover procedure, the new serving node, the target base station, transmits data to the terminal 11 (1625).

In detail, the ranging process 1621, the terminal 11 sends a burst profile, MAC information, etc. of the terminal to the target base station through a ranging request (RNG-REQ) message, and the target base station sends a ranging response. Reply (RNG-RSP) message (1621). In this case, the RNG-RSP message includes ranging status, burst profile, MAC address of the terminal 11, CID, and the like.

After performing the ranging (RNG) process 1621, the terminal 11 transmits a basic capability negotiation request (SBC-REQ) message to the target base station, and the target base station transmits a basic capability negotiation response (SBC-RSP) message. It receives and exchanges information for using a radio resource (1622). Basic Skills Negotiation Process

After performing the basic capability negotiation (SBC) process 1622, the terminal 11 requests the PKM request message to the target base station [EAP transmission request], and receives the PKM response message to manage encryption keys necessary for information protection. [EAP Transmission Response] (1623). [Terminal authentication and key exchange process]

After performing the terminal authentication and key exchange process 1623, the terminal 11 transmits a registration request message (REG-REQ) message to the target base station, and the target base station transmits a registration response (REG-RSP) message to the terminal. And transmits to (11) (1624). [Registration Process]

After performing the registration process 1624, the target base station transmits a DSA request message for establishing a traffic connection to the terminal 11, and if the terminal 11 responds with a DSA-RSP message, the target base station sends a DSA-ACK message. You can check it. [Connection setup process]

In addition, after performing the connection setup process, according to the IP version, in case of IPv4, the IP address to be used by the terminal 11 is automatically set using DHCPv4, and in case of IPv6, the terminal (using DHCPv6 or automatic setting function) is used. The address to be used in 11) can be set automatically. [IP Address Allocation Process]

17 and 18 illustrate a handover control process of the terminal 11 and the indoor serving base station when the terminal 11 performs handover from the indoor base station 13 to the outdoor base station 12 in the portable Internet system. It is shown.

First, referring to FIG. 17, when the terminal 11 starts handover, the handover control process in the terminal 11 will be described.

Referring to FIG. 17, the terminal 11 receives a MOB_NBR-ADV message [see FIG. 4] periodically broadcasted from an indoor serving base station (1701) to inform neighbor BS information (1701). If it is determined that the scanning is necessary (1702), and transmits the MOB_SCN-REQ message to the indoor serving base station to request the scanning interval (Interference) (Iteration) (1703). Thereafter, the terminal 11 receives the MOB_SCN-RSP message from the indoor serving base station (1704), and scans neighboring base stations in earnest. Accordingly, the terminal 11 searches for whether it is suitable for handover (scanning whether neighboring base stations are suitable for handover during the scanning interval), and thus, the signal strength of the neighboring base stations can be known (1705).

If the terminal 11 determines to perform the handover (1706), the terminal 11 sends a MOB_MSHO-REQ message to the CINR values of the neighbor base stations (the candidate base stations including the target base station) in order to start the handover. Including it, it transmits to the indoor serving base station (1707).

Subsequently, when the terminal 11 receives a MOB_BSHO-RSP message including the list of candidate base stations recommended by the indoor serving base station from the indoor serving base station (1709), the terminal 11 finalizes the handover target base station according to the signal strength. Determine and inform the final handover target base station to the indoor serving base station via the MOB_HO-IND message (1711).

If the terminal 11 receives the MOB_BSHO-REQ message from the indoor serving base station (1708), the terminal 11 recognizes that handover to the base station candidate groups that it has searched for is impossible and the indoor serving base station is not available. The neighbor base stations are searched using the information of the alternate neighbor base stations included in the transmitted MOB_BSHO-REQ message (1710), and finally the handover target base station is determined to inform the final handover target base station through the MOB_HO-IND message (1711). .

When the initial process of handover execution ends, the terminal 11 performs a network reentry procedure. That is, since the terminal 11 can no longer transmit or receive packets through the indoor serving base station from the time when the MOB_HO-IND message is transmitted. After moving to a new network, the procedure for acquiring transmission parameters and reentering the network (Ranging process, basic capability negotiation process, terminal authentication and key exchange process, registration process, connection establishment process, IP) Address assignment process, etc.] (1712 ~ 1720). However, if the target base station receives the information of the terminal 11 regarding the performance capability and authentication from the indoor serving base station, the terminal 11 may shorten the handover process by omitting the corresponding process during the network entry process.

That is, when the initial handover execution process ends, the terminal 11 performs a network reentry procedure. Accordingly, when the UE 11 receives Fast_Ranging_IE from the target base station (1712), transmits an RNG-REQ message to the target base station (1713), receives an RNG-RSP response message (1714), and fast ranging operations. Will complete.

Thereafter, the terminal 11 transmits the SBC-REQ message to the target base station (1715), receives the SBC-RSP message from the target base station in response (1716), and goes through a basic capability negotiation process. The terminal 11 transmits a PKM-REQ message to the target base station (1717), receives a PKM-RSP message from the target base station (1718) in response thereto, and performs a terminal authentication and key exchange process. Finally, the terminal 11 transmits the REG-REQ message to the target base station (1719), receives a REG-RSP message from the target base station in response to the registration (Registration) process (connection establishment process, IP address allocation process), and network re-entry process to complete the entire handover process.

As such, when the network entry process is successfully completed, the terminal 11 may receive a service from the target base station.

Now, with reference to FIG. 18, when the terminal 11 starts handover, the handover control process in the indoor serving base station will be described.

The indoor serving base station transmits a MOB_NBR-ADV message including neighbor BS information to the terminal 11 (1801), and requests a scanning interval and an iteration from the terminal 11. When the MOB_SCN-REQ message is received (1802), a scanning interval and an iteration are allocated to transmit the MOB_SCN-RSP message to the terminal 11 (1803).

Then, the indoor serving base station is a MOB_MSHO-REQ message containing the CINR value of the neighbor base stations (the candidate base stations including the target base station) recommended by the terminal 11 (that is, the terminal is a search result of the target base stations And the like) (1804), the terminal 11 recommends the handover of the terminal 11 to the candidate base station (the target base station is included) recommended by the terminal 11 through the backbone network (1805). When a response is received from the recommended target base stations (a candidate base station including the target base station) (1806), based on the response, the indoor serving base station selects a target base station that can be recommended again (1807), and backbone The exchange of messages using the network confirms the handover to the selected recommended target base station (1808).

If there is even one target base station capable of handover by the terminal 11 (1809), the indoor serving base station transmits a MOB_BSHO-RSP message in response to the MOB_MSHO-REQ message transmitted by the terminal 11. The list of recommended target base stations is transmitted to the terminal 11 in step 1811. However, when there is no target base station to which the terminal 11 can handover (1809), the indoor serving base station transmits the MOB_NBR transmitted by itself in response to the MOB_MSHO-REQ message transmitted by the terminal 11. In operation 1810, a MOB_BSHO-REQ message including information on alternative neighboring base stations not included in the ADV message is transmitted to the terminal 11.

Subsequently, the indoor serving base station receives the MOB_HO-IND message from the terminal 11 as the terminal 11 determines the target base station, and finally receives a notification of handover (1812). Resource Retain Time After the connection with the terminal 11 is disconnected (1813).

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

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 can be used for an integrated portable Internet system composed of indoor / outdoor base stations.

1 is a configuration example of a typical outdoor portable Internet (WiBro) network,

2 is an explanatory diagram showing a handover control process in a portable Internet network composed of an indoor / outdoor base station;

3 is a flowchart illustrating a handover control process in the outdoor WiBro network of FIG. 1;

4 is an explanatory diagram showing the format of a MOB_NBR-ADV message in FIG. 3;

FIG. 5 is a flowchart illustrating a handover control process in the portable Internet terminal MS when the portable Internet terminal MS starts handover in FIG.

FIG. 6 is a flowchart illustrating a handover control process in a serving base station (BS) when the portable Internet terminal (MS) starts handover in FIG.

FIG. 7 is a flowchart illustrating a handover control process in a portable Internet terminal MS when the serving base station BS starts handover in FIG.

8 is a flowchart illustrating a handover control process in a serving base station (BS) when the serving base station (BS) starts the handover in FIG.

9 is an exemplary configuration diagram of an indoor / outdoor portable Internet (WiBro) network to which the present invention is applied;

10 and 11 are explanatory diagrams showing a handover control process in an inner cell region according to an embodiment of the present invention;

12 to 15 are explanatory diagrams showing a handover control process in a cell outer region according to an embodiment of the present invention;

16A and 16B are flowcharts of an embodiment of a handover control method according to the present invention;

17 is a flowchart illustrating a handover control process in a portable Internet terminal MS when the portable Internet terminal MS starts handover according to the present invention;

18 is a flowchart illustrating a handover control process in a serving base station (BS) when the portable Internet terminal (MS) starts handover according to the present invention.

* Explanation of symbols for the main parts of the drawings

11: Mobile Internet Terminal (MS) 12: Outdoor Base Station (BS)

13: indoor base station (Inner_BS)

Claims (32)

A method for constructing a handover message in a wireless communication system including an indoor base station and an outdoor base station, The cell area provided by the outdoor base station is divided into an interior or an exterior according to the location where the indoor base station is disposed, and the indoor base station in the cell area of the outdoor base station is configured according to the configuration of the indoor base station. Dividing into a content base station or a group constituent indoor base station; And Constructing, by the indoor serving base station, a neighboring base station information related message for handover based on the arrangement information and configuration information of the indoor base station; How to configure a handover message comprising a. The method of claim 1, The indoor base station, And a hierarchical structure of an ID of the outdoor base station configured as a superset. The method of claim 2, The indoor base station, A single component indoor base station located in an inner region of a cell area of one outdoor base station or a group composed indoor base station, and a single configured indoor base station located in an outer region where the cell areas of the plurality of outdoor base stations overlap Or a group configuration indoor base station, wherein the outdoor base station and the hierarchical ID are configured. The method of claim 3, The placement information of the indoor base station is And the indoor base station is information indicating whether the cell areas of the plurality of outdoor base stations exist in an overlapped area. The method of claim 3, Configuration information of the indoor base station, And information indicating whether the indoor base station independently operates in a single operation or in a group. The method of claim 3, The indoor serving base station, In the case of a single component indoor base station located in the inner region of the cell area of the one outdoor base station, And broadcasting only the information of the one outdoor base station in the neighbor base station information related message or not transmitting the neighbor base station information related message. The method of claim 3, The indoor serving base station, In the case of an indoor base station located in the inner region of the cell area of the one outdoor base station, Broadcast only the information of another indoor base station and one outdoor base station in the group to which it belongs, in the neighbor base station information related message, or broadcast only the information of the other indoor base station in the neighbor base station information related message. Method for constructing a handover message, characterized in that. The method of claim 3, The indoor serving base station, In the case where the cell area of the plurality of outdoor base stations is located in an overlapping outer region and is a single component indoor base station, And broadcasting only the information of the plurality of outdoor base stations in the neighbor base station information related message or not transmitting the neighbor base station information related message. The method of claim 3, The indoor serving base station, In the case where the cell area of the plurality of outdoor base stations is located in an overlapping outer region and is a group-organized indoor base station, Broadcast only the information of another indoor base station and the plurality of outdoor base stations in the group to which the mobile station belongs to the neighbor base station information related message, or broadcast only the information of the other indoor base station in the neighbor base station information related message. Method for constructing a handover message, characterized in that. The method according to any one of claims 6 to 9, The indoor serving base station, In response to a handover request of a terminal, a handover candidate base station is asked whether a handover is possible through a backbone network, and if a target base station capable of handover exists, a handover response message is transmitted to the terminal, and the handover is performed. And a handover request message containing information of alternative neighbor target base stations to the terminal when there is no target base station available. The method according to any one of claims 6 to 9, The indoor serving base station, Method for constructing a handover message, characterized in that for transmitting a message related to the neighbor base station information at the request of the terminal. The method of claim 11, The terminal, When the indoor serving base station does not include outdoor base station information in the neighbor base station related message or transmits the neighbor base station related message, the neighbor base station related message including the outdoor base station information for proceeding a pre-scanning process is sent. And requesting the indoor serving base station. In the handover control method at the base station, Storing, by the outdoor base station, connection information with the terminal when the terminal performs the first handover from the outdoor base station to the indoor serving base station; When the terminal searches for the outdoor base station and requests a handover from the indoor serving base station to the outdoor base station when the second handover is required, the handover is requested to the indoor serving base station including the search result of the outdoor base station. Transmitting, by the indoor serving base station, the confirmation result of the handover candidate base station to the terminal; And As the terminal selects a handover target base station, the outdoor base station selected as the handover target base station to ensure handover of the terminal by using the connection information; Handover control method in a base station comprising a. The method of claim 13, The indoor serving base station, A method for controlling handover in a base station, comprising: broadcasting a message related to neighboring base station information for handover based on configuration information and configuration information of an indoor base station. The method of claim 14, The indoor serving base station, In the case of a single component indoor base station located in an inner region of a cell area of one outdoor base station, And transmitting only the information of the one outdoor base station in the neighbor base station information related message or not transmitting the neighbor base station information related message. The method of claim 14, The indoor serving base station, In the case where the cell area of the plurality of outdoor base stations is located in an overlapping outer region and is a single component indoor base station, And transmitting only the information of the plurality of outdoor base stations in the neighbor base station information related message or not transmitting the neighbor base station information related message. The method according to any one of claims 13 to 16, The terminal, Store the information on the outdoor base station during the first handover, search for the outdoor base station using information stored in the outdoor base station when the second handover is performed, and select the outdoor base station as a handover candidate base station. Handover control method in the base station, characterized in that. The method of claim 17, The outdoor base station, Storing connection information with the terminal during the first handover, and skipping a message exchange process for authentication and registration required in the handover process by using the connection information previously stored during the second handover; Handover control method at the base station. In the handover control method at the base station, When the terminal performs the first handover from the outdoor base station to the indoor serving base station, the indoor serving base station constructs a message related to neighbor base station information for handover based on the configuration information and configuration information of the indoor base station and broadcasts it. Making; The terminal searches for the outdoor base station and the indoor base station based on previously stored information of the outdoor base station and 'information of the same group of indoor base stations acquired through the neighbor base station information related message'. When the indoor serving base station requests a handover to the indoor serving base station, including a result of the base station search when the second handover is needed from the indoor serving base station, the indoor serving base station receives the confirmation result of the handover candidate base station. Transmitting to the terminal; And As the terminal selects a handover target base station, the indoor serving base station performing the second handover to the selected handover target base station; Handover control method in a base station comprising a. The method of claim 19, The indoor serving base station, In the case of an indoor base station located in the inner region of the cell area of one outdoor base station, And broadcast only the information of the indoor base station and the one outdoor base station in the neighbor base station information related message or broadcast only the information of the indoor base station in the neighbor base station information related message. Handover Control Method in. The method of claim 19, The indoor serving base station, In the case where the cell area of the plurality of outdoor base stations is located in an overlapping outer region and is a group-organized indoor base station, And broadcast only the information of the indoor base station and the plurality of outdoor base stations in the neighbor base station information related message, or broadcast only the information of the indoor base station in the neighbor base station information related message. Handover Control Method in. The method according to any one of claims 13 to 16 and 19 to 21, The indoor serving base station, In response to a handover request of the terminal, the handover candidate base station is asked whether a handover is possible through a backbone network, and if a handover target base station capable of handover exists, a handover response message is transmitted to the terminal. And transmitting a handover request message containing information of an alternate neighbor target base station to the terminal when the handover target base station does not exist. The method according to any one of claims 14 to 16 and 19 to 21, The indoor serving base station, The handover control method in the base station, characterized in that for transmitting the neighbor base station information related message at the request of the terminal. 24. The method of claim 23, The terminal, When the indoor serving base station does not include outdoor base station information in the neighbor base station related message or transmits the neighbor base station related message, the neighbor base station related message including the outdoor base station information for proceeding a pre-scanning process is sent. And requesting the indoor serving base station. In the handover control method in the terminal, After the terminal performs the first handover from the outdoor base station to the indoor serving base station, storing information about the previously connected outdoor base station; Performing, by the terminal, searching for an outdoor base station based on information about the outdoor base station previously stored; When the terminal needs a second handover from the indoor serving base station to the outdoor base station, requesting a handover to the indoor serving base station including a search result of the outdoor base station, and handing over from the indoor serving base station. Receiving a confirmation result of the candidate base station; And Selecting, by the terminal, a handover target base station and performing a handover to the outdoor base station Handover control method in a terminal comprising a. The method of claim 25, The outdoor base station, Storing connection information with the terminal during the first handover, and skipping a message exchange process for authentication and registration required in the handover process by using the connection information previously stored during the second handover; Handover control method in the terminal. In the handover control method in the terminal, After the mobile station performs the first handover from the outdoor base station to the indoor serving base station, the terminal stores information about the previously connected outdoor base station and stores the configuration information and configuration information of the indoor base station from the indoor serving base station. Receiving a message related to neighbor base station information for handover based on the base; Searching, by the terminal, the outdoor base station and the indoor base station based on previously stored information about the outdoor base station and 'information of the same group of indoor base stations acquired through the neighbor base station information related message'; When the terminal needs a second handover from the indoor serving base station to the other indoor base station, requesting a handover to the indoor serving base station including a result of the base station search, and a handover candidate from the indoor serving base station. Receiving a confirmation result of the base station; And Selecting, by the terminal, a handover target base station and performing the second handover to the selected handover target base station; Handover control method in a terminal comprising a. delete delete delete delete delete

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