KR20130022812A - Handover method and apparatus for accuracy and performance enhancement in handover to smallcell - Google Patents

Abstract

PURPOSE: A method for improving the performance and the accuracy of handover to a small cell and a device thereof are provided to search for a femto-cell matched with a PSC(Primary Scrambling Code) of candidate target cells transmitted during handover based on a surrounding cell information table. CONSTITUTION: A table composing unit(141) stores a cell information table composing a PSC of surrounding cells corresponding to each femto base station in a database. A femto-cell search unit(143) receives the PSC of surrounding candidate cells measured and reported by a terminal through a network when handover is requested. The femto-cell search unit refers to the database to search for a corresponding femto base station including the PSC matched with the surrounding candidate cells. The femto-cell search unit responds to the identifier of the searched femto base station to permit the handover of the terminal. [Reference numerals] (141) Table composing unit; (142) Database; (143) Femto-cell search unit; (AA) Femto base station

Description

HANDOVER METHOD AND APPARATUS FOR ACCURACY AND PERFORMANCE ENHANCEMENT IN HANDOVER TO SMALLCELL}

The present invention relates to a method and apparatus for handover to a small cell, and more particularly, to a handover method and apparatus for improving accuracy and performance in handover from a macro cell to a small cell.

The small cell is installed inside / outside the macro cell area providing the mobile communication service to provide data offloading or coverage extension function. Can be. The small cell may include a femtocell, a picocell, and a microcell. Particularly, among the small cells, the femto base station is a 3GPP LTE (Home NodeB) in a 3GPP UMTS (Universal Mobile Telecommunications System). In Term Evolution, it is defined as HeNB (home evolved NodeB).

As shown in FIG. 1, a macro cell base station connects communication of a mobile terminal under the control of a controller (RNC) interworking with a core network (CN), and a femto base station operates at a small size / low power level and thus has a femtocell area of a smaller range than a macro cell area. It can be installed in indoor and outdoor hotspot areas, such as homes and offices to cover the space. A femto base station is a small cellular base station connected to a broadband router, and includes a mobile communication network, a circuit network, and the Internet under the control of a femto gateway (G / W) and an HMS (H (e) NB management system) for managing femto base stations. In conjunction with the core network (CN), not only 2G but also 3G voice and data communication is possible.

Currently, a mobile terminal uses primary scrambling code (PSC) information of a target base station for handover in a macro cell. However, femto base stations often use femtocell dedicated PSCs, and only a few (eg, eight) femtocell dedicated PSCs are reused in duplicate. Therefore, when the mobile terminal handovers to the femtocell, an ambiguity occurs in the classification of the target femtocell base station through the PSC, thus making it difficult to perform an accurate handover. Therefore, if this ambiguity is not resolved, resource allocation should be made to a large number of femtocells having the same PSC as the target femtocell connected to one femto gateway (G / W) when the UE attempts handover to the femtocell. Therefore, there is a problem that resource waste occurs.

Accordingly, the present invention is to solve the above-described problems, an object of the present invention, by configuring the neighbor cell information table based on the base station identification information (PSC) for each femto base station in advance, the terminal is based on this hand By searching for femtocells that best match the base station identification information (PSC) of candidate target cells to be transmitted when over, the handover is allowed, and thus the femtocell is performed to accurately perform the handover from the current location of the terminal to the most appropriate target femtocell. To provide a handover method and apparatus of the present invention.

First, to summarize the features of the present invention, according to an aspect of the present invention for achieving the object of the present invention, a handover method for handover to a femto cell, a plurality of peripherals that the femto base station searches for and transmits Receiving base station identification information of a cell and storing a cell information table including base station identification information of a plurality of neighboring cells corresponding to each femto base station in a database; And base station identification information of a plurality of neighbor candidate cells measured and reported by the terminal when a handover request is received through a network, and best matched with base station identification information of the plurality of neighbor candidate cells by referring to the database. And searching for a corresponding femto base station having a response to the network of an identifier of the femto base station found to allow handover of the terminal.

The base station identification information may be primary scrambling code (PSC) information used for cell search.

The base station identification information of the plurality of neighboring cells may consist of identification information of macro base stations, identification information of femto base stations, or identification information of one or more macro base stations and one or more femto base stations.

The base station identification information of the plurality of neighbor cells may include base station identification information for a predetermined number of base stations having the largest signal strength among the received signals received by the femto base station from the base stations of the plurality of neighbor cells.

In the storing in the database, the cell information table may be configured by matching base station identification information of the plurality of neighbor cells with its cell ID transmitted from the femto base station and base station identification information.

Storing the base station identification information of the plurality of neighboring cells in the database in the cell information table arranged in the order of the signal strength, and storing the base station identification information of the plurality of neighboring cells with the base station that best matches the base station identification information of the plurality of neighboring candidate cells. If there are a plurality of femto base stations having the base station identification information, the identifier information of the corresponding femto base station with the best matching order may be responded to the network.

The identifier information of the femto base station may be a cell ID of the femto base station in addition to the PSC.

Further, according to another aspect of the present invention, a femtocell management server that supports handover to a femtocell receives base station identification information of a plurality of neighbor cells that a femto base station searches for and transmits, and a plurality of corresponding femto base stations A table constructing unit configured to store a cell information table including base station identification information of a neighboring cell in a database; And base station identification information of a plurality of neighbor candidate cells measured and reported by the terminal when a handover request is received through a network, and best matched with base station identification information of the plurality of neighbor candidate cells by referring to the database. And a femtocell search unit for searching for a corresponding femto base station having a response to the network with an identifier of the femto base station found for handover permission of the terminal.

According to the method and apparatus for handover to a small cell according to the present invention, even if a large number of femtocells are connected to one femto gateway (G / W), the terminal attempts handover without ambiguity about the classification of femtocells. Handover can be performed accurately to a target femtocell that best matches the base station identification information (PSC) of candidate target cells to be transmitted, and prevents resource waste due to resource allocation attempts to a large number of femtocells. can do.

1 is a diagram illustrating a service environment of a general macro cell and femtocell.
2 is a diagram illustrating a communication network system according to an embodiment of the present invention.
3 is a view for explaining a femto management server according to an embodiment of the present invention.
4 is a flowchart illustrating an operation of a communication network system according to an embodiment of the present invention.
5 is a diagram illustrating a cell information table managed by a femto management server according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

2 is a diagram illustrating a communication network system 100 according to an embodiment of the present invention.

Referring to FIG. 2, a communication network system 100 according to an embodiment of the present invention may include a core network (CN) 110, an internet 111, and a control station (RNC: radio network controller) 120. ), Under the control of the femto gateway 130, the femto management server (HMS) 140, the mobile terminal 160, the femto base station 170, and the control station 120, each macrocell region 121 ˜ 127 is controlled. Covering macro base stations (e) NB.

Here, the mobile terminal 160 may be a smartphone, but is not limited thereto, and a notebook PC, a desktop PC, a Palm Personal Computer, or the like that can communicate through the core network 110 or a cellular phone may be a cellular phone. phone (PCS phone), Personal Communications Services phone (PCS phone), synchronous / asynchronous IMT-2000 (International Mobile Telecommunication-2000) capable of wireless communication, personal digital assistant (PDA), WAP phone: It can be a wireless application protocol phone, mobile play-station, other portable multimedia player (PMP) and portable or mobile terminal, and can be used for home or business that can communicate with other electronic devices through the other core network 110. It may include various electronic devices or devices throughout society.

The core network 110 is a network of a mobile communication provider including a mobile communication network such as WCDMA, WiFi, WiBro, and wired and wireless Internet. The control station 120 connected between the macro base stations ((e) NB) and the core network 110 has a function of Radio Resource Management (RRM) according to scheduling of radio resources in cooperation with the core network 110. And a handover function for supporting mobility between cells, and the like, to support the mobile terminal 160 to perform 2G and 3G voice and data communication through the macro base stations (e) NB.

The macro base stations 121 to 127 and the femto base station 170 respectively cover a macro base station and an H (e) NB () that cover communication of a macrocell region corresponding to (e) NB ((evolved) NodeB) defined in 3GPP. It may be a femto base station covering communication of the femtocell area corresponding to a home (evolved) NodeB). The femto base station 170 operates at a very small / low power level to cover a femtocell area of a much smaller range than the macro cell area, so that the macro base station (e) NB may cover homes, offices, etc. It can be installed in a number of indoor and outdoor hot spots, connected to the femto gateway 130 managing the femto base station 170, under the control of the femto gateway 130 and femto management server (HMS) 140 Interworking with the core network 110 based on the Internet Protocol (IP) through the Internet 111 enables communication of voice and data of 3G as well as 2G with other mobile terminals in a macrocell area or a femtocell area.

In particular, in the present invention, after the femto base station 170 is installed, the femto management server (HMS) 140 transmits base station identification information (eg, 5 PSCs) of a plurality of neighbor cells that initially search for and transmit neighbor cells. Received through the gateway 130, the femto management server (HMS) 140 is a database (see FIG. 5) of the cell information table (see FIG. By storing in advance in 142 of 3, when the mobile terminal 160 receives base station identification information (eg, 5 PSCs) of a plurality of neighboring candidate cells measured and reported upon handover request through the networks 110 and 111. The femto management server (HMS) 140 searches for a corresponding femto base station having base station identification information that best matches the base station identification information of the plurality of neighbor candidate cells by referring to the database 142 of the mobile terminal 160. Corresponding Detected to Allow Handover By responding to the network (111, 112) the identifier of the femto base station (e.g., femto cell ID), the mobile terminal 160 can be handed in (hand-in) correctly.

Accordingly, in the present invention, even if a large number of femto base stations 170 are connected to one femto gateway 130, the mobile terminal 160 is handed over from the macro cell to the femtocell without ambiguity about the classification of the femto cell. The handover to the target femto base station that best matches the base station identification information (eg, PSC) of candidate target cells transmitted at the time can be made accurately, and the resource according to an attempt to allocate resources to a large number of femto cells It is possible to prevent waste.

To this end, the femto management server 140 according to an embodiment of the present invention may include a table configuration unit 141, a database 142, and a femtocell search unit 143 as shown in FIG. 3.

First, briefly, the table configuration unit 141, after the femto base station 170 is installed, the base station identification information (e.g., 5 PSCs) of the plurality of neighbor cells for initially searching for and transmitting neighbor cells is transmitted to the femto gateway ( Received through 130, the cell information table (see FIG. 5) constituting base station identification information of a plurality of neighboring cells corresponding to each femto base station 170 is stored in advance in the database 142. In the cell information table of the database 142 (see FIG. 5), the base station identification information (eg, for a plurality of neighboring cells) regarding the cell ID and base station identification information (eg, PSC) transmitted by each femto base station 170 is provided. 5 PSCs) are stored in correspondence, wherein base station identification information (eg, 5 PSCs) of a plurality of neighbor cells may be formed of identification information (eg, 5 PSCs) of macro base stations, or identification of femto base stations. Information (eg, five PSCs) may be formed, or identification information (eg, five PSCs) of a predetermined number of base stations including identification information of one or more macro base stations and one or more femto base stations.

When the femtocell search unit 143 receives base station identification information (eg, 5 PSCs) of a plurality of neighboring candidate cells that are measured and reported when the mobile terminal 160 requests a handover, through the networks 110 and 111, Identifier of the corresponding femto base station retrieved to allow handover of the mobile terminal 160 by searching for the corresponding femto base station having base station identification information that best matches the base station identification information of the plurality of neighbor candidate cells with reference to the database 142. By responding (eg, femto cell ID) to the networks 111 and 112, the mobile terminal 160 supports hand-in with the corresponding femto base station.

Hereinafter, referring to the flowchart of FIG. 4, in the communication network system 100 according to an embodiment of the present invention, a process of handover of the mobile terminal 160 from the macro cell to the femtocell through the femto management server 140 is performed. Explain in more detail.

First, when the femto base station 170 is installed in the macro cell region, each femto base station 170 searches (searches) neighbor cell information (S110). The femto base station 170 performs a signal based on received signal code power (RSCP), energy per chip over interface noise (ECCI), etc. in a received signal received from the base stations of the neighbor cell in the process of searching for neighbor cell information. Receiving base station identification information for a predetermined number of base stations (eg, five) having the largest signal strength by receiving the strength, for example, receiving primary scrambling code (PSC) information used for synchronization during cell search. Can be extracted from the signal. As such, the five PSC information extracted by each femto base station 170 may be for the femto base stations with a large signal strength, or may be for macro base stations with a large signal strength, or five PSCs. The information may consist of a mixture of for femto base stations and for macro base stations.

When each femto base station 170 searches for five pieces of PSC information as described above, together with its own cell ID and base station identification information (PSC information), the five pieces of PSC information for the neighboring cells searched are included in a predetermined message. Transmission to the femto gateway 130 (five PSC information may be included in the message in the order of the signal size), and the femto gateway 130 transmits it to the femto management server (HMS) 140 (S111).

As such, through the femto gateway 130, the table configuration unit of the femto management server (HMS) 140 for receiving the five PSC information of the neighbor cell with the cell ID and PSC information of the installed femto base station 170 141 configures five pieces of PSC information of neighbor cells corresponding to the cell ID and the PSC information of each femto base station 170, and stores and manages the corresponding cell information table (see FIG. 5) in the database 142 in advance. (S120).

As described above, in the cell information table (refer to FIG. 5) of the database 142, five PSC informations of corresponding neighbor cells are stored corresponding to the cell ID and the PSC information of each femto base station 170. All five PSC information for the neighboring cell may be made of PSC information for macro base stations, or may be made of PSC information for femto base stations, and may be a mixture of PSC information of one or more macro base stations and one or more femto base stations. It may be.

Thereafter, the mobile terminal 160 generates a measurement report message Me_REP for the handover request to the femtocell, and transmits the measurement report message to the serving macro base station (e) NB, and the macro base station (e) NB. This may be delivered to the core network (CN) 110 (S130). The mobile terminal 160 determines the signal strength based on RSCP, EcIo, etc. from the received signals received from the base stations of the neighboring cell (peripheral target target cell) to determine the maximum number of signal strengths (for example, five). Base station identification information for the base stations of, for example, PSC information used for synchronization during cell search can be extracted from the received signal, the PSC for the serving macro base station ((e) NB) in communication Also, the measurement report message (Mea_REP) including the PSC of the serving macro base station ((e) NB) and five PSC information of neighboring candidate cells searched as described above (five PSC information in order of signal size). May be included in the message) to be transmitted to the core network (CN) 110 via the serving macro base station (e) NB. Here, the five PSC information for the neighbor candidate cell transmitted by the mobile terminal 160 through the measurement report message Mea_REP may also be for the femto base stations, in addition to the macro base stations, or The five PSC information for the neighbor candidate cell may consist of a mixture of for femto base stations and for macro base stations.

Accordingly, the core network (CN) 110 confirms the handover to the femtocell according to the measurement report message Me_REP (S131), and the PSC of the serving macro base station ((e) NB) received from the mobile terminal 160. And a handover request message including five PSC information about neighboring candidate cells to the femto gateway 130 through the Internet 111, and the femto gateway 130 sends it to the femto management server (HMS) 140. It transmits (S132).

As described above, the femtocell search unit 143 of the femto management server (HMS) 140 that receives the handover request message from the core network (CN) 110 through the femto gateway 130, refers to the database 142. As described above, a corresponding femto base station that best matches five pieces of PSC information of neighboring candidate cells received through the handover request message is searched for (S140).

For example, five pieces of PSC information (PSC # 1 to PSC # 5) for neighboring candidate cells transmitted from the mobile terminal 160 correspond to cell regions 121, 123, 125, 126, and 127 of FIG. 2. In the case of the PSC information, the femtocell search unit 143 searches the database 142 for the femto base station that most matches the five PSC information (PSC # 1 to PSC # 5) of the neighbor candidate cells.

For example, five PSC information (PSC # 1 to PSC # 5) of neighboring candidate cells are stored in the database 142 in advance in the cell ID of the femto base station 170 and five corresponding to the neighboring cells corresponding to the PSC information. If the PSC information (PSC # 1 ~ PSC # 5) is completely matched, the femtocell search unit 143 selects the corresponding femto base station 170 having five PSC information for the corresponding completely matched neighbor cell, and does not match completely If not, select the femto base station that most matches.

For example, the femtocell search unit 143 is not completely matched as described above, but if only four match, for example, the PSC corresponding to the cell areas, 121, 122, 123, 126, 127 of FIG. The femto base station having the information may be selected as the best matched femto base station.

As described above, the femtocell search unit 143 searches for the corresponding femto base station that is best matched in step S140, and selects the best matched femto base station by giving priority to the case where all five PSC informations match with each other. If not, the matched numbers are sequentially selected in order of 4, 3, 2, and 1 to select the best matched femto base station.

In addition, there may be a plurality of femto base stations having the same number of matching PSC information as described above. In this case, the femtocell search unit 143 may select the most suitable femto base station among them. For example, the table configuration unit 141 may store five pieces of PSC information (PSC # 1 to PSC # 5) of neighbor cells corresponding to the cell ID and the PSC information of the femto base station 170 in the database 142. It is possible to configure a cell information table arranged in the same order of signal strength (femto base station 170 can refer to the message included in the order of the signal size in step S111), and accordingly the femtocell search unit 143 compares the PSC Among femto base stations having the same number of information, a corresponding femto base station with the best signal strength order may be selected.

In addition, the femtocell search unit 143 searches for a corresponding femto base station that best matches, and then a mobile terminal requesting handover by referring to a database, for a non-CSG member, that is, a terminal registered in advance. The handover may be rejected after confirming that the member is not a member of the CSG scheme supporting the handover to the femtocell.

As such, when the femtocell searcher 143 selects the corresponding femto base station that is best matched in step S140, the femtocell searcher 143 responds to the femto gateway 130 with an identifier (eg, femtocell ID) of the femtocell base station. In operation S141, the femto gateway 130 transmits a message (H / O_RSP) for allowing handover together with other necessary information (eg, PSC of the serving macro base station ((e) NB)). It may be transmitted to the core network (CN) 110 through (S150).

At this time, the femto gateway 130 performs a resource allocation process with the femto base station in advance so that the mobile terminal 160 can hand over to the corresponding femto base station selected by the femtocell search unit 143. It is possible to make a wait for the handover of the 160 (S142), the core network (CN) (110) via the control station 120 through the serving macro base station (e) NB through the mobile terminal 160 When the message to allow handover is transmitted (S151), the mobile terminal 160 performs a handover process with the corresponding femto base station so that the user can receive the service from the femto base station due to the hand. S160).

In the communication network system 100 according to an embodiment of the present invention as described above, even if a large number of femtocells are connected to one femto gateway 130 for handover to a femtocell, the ambiguity of the distinction between femtocells (ambiguity) ), The handover to the target femtocell that best matches the base station identification information (PSC) of the candidate target cells transmitted by the terminal 160 at the time of handover can be made accurately, and the resources of many femtocells Resource waste due to allocation attempts can be prevented.

The functions used in the femto gateway, the femto management server, and the method according to the embodiment of the present invention described above can be implemented as computer readable codes on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, a hard disk, a removable storage device, And the like. In addition, it is understood that the computer readable recording medium can be distributed over network coupled computer systems and stored and executed in the form of computer readable code in a distributed fashion.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

Femto gateway (130)
Femto management server (140)
Table Organizer (141)
Database (142)
Femtocell Searcher (143)

Claims (7)

In the handover method for the handover to the femtocell,
Receiving base station identification information of a plurality of neighboring cells searched and transmitted by the femto base station, and storing a cell information table including base station identification information of the plurality of neighboring cells corresponding to each femto base station in a database; And
The mobile station receives base station identification information of a plurality of neighboring candidate cells measured and reported upon handover request through a network, and obtains base station identification information that best matches base station identification information of the plurality of neighboring candidate cells with reference to the database. And searching for a corresponding femto base station having an identifier of the femto base station retrieved to allow handover of the terminal to the network. The method of claim 1,
The base station identification information is a primary scrambling code (PSC) information used for cell search. The method of claim 1,
The base station identification information of the plurality of neighboring cells is formed of identification information of macro base stations, identification information of femto base stations, or handover method, characterized in that consisting of identification information of one or more macro base station and one or more femto base station. . The method of claim 1,
The base station identification information of the plurality of neighboring cells is characterized in that the femto base station is a base station identification information for a predetermined number of base stations having the largest signal strength among the received signals received from the base stations of the plurality of neighboring cells Over way. The method of claim 1,
In the storing in the database, the cell information table is configured by matching the cell ID transmitted from the femto base station with the base station identification information of the plurality of neighbor cells to the base station identification information. . 5. The method of claim 4,
Storing the cell information table in which the base station identification information of the plurality of neighbor cells is arranged in the order of the signal strength in the database,
If there are a plurality of femto base stations having base station identification information for the base stations that best match the base station identification information of the plurality of neighboring candidate cells in the database, the identifier information of the corresponding femto base station whose order is best matched is determined. Handover method characterized in that the response to the network. A femto management server supporting handover to a femto cell,
A table configuration unit configured to receive base station identification information of a plurality of neighboring cells searched and transmitted by the femto base station, and to store a cell information table including base station identification information of the plurality of neighboring cells corresponding to each femto base station in a database; And
The mobile station receives base station identification information of a plurality of neighboring candidate cells measured and reported upon handover request through a network, and obtains base station identification information that best matches base station identification information of the plurality of neighboring candidate cells with reference to the database. A femtocell search unit that searches for a corresponding femto base station having an identifier of the femto base station found to allow handover of the terminal to the network.
A femto management server comprising a.

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