KR20120069207A - Method of operating user equipment in wireless communication system, user equipment using and home enodeb - Google Patents

Abstract

PURPOSE: A terminal operating method in a wireless communication system, a terminal, and a home evolved-nodeb(HeNB) are provided to reduce interference applied to the terminal when a macro base station and the HeNB uses identical wireless resources. CONSTITUTION: A radio frequency(RF) unit(111) transmits and receives radio signals. A processor(113) is in connection with the RF unit and a memory(112). The RF unit receives the system information of a neighboring cell. The memory stores a closed subscriber group(CSG) white list. If CSG identification included in the system information is existed in the CSG white list, the processor transmits a measurement report to a base station.

Description

Method of operation of a terminal in a wireless communication system, a terminal and a home base station {METHOD OF OPERATING USER EQUIPMENT IN WIRELESS COMMUNICATION SYSTEM, USER EQUIPMENT USING AND HOME ENODEB}

The present invention relates to wireless communication, and more particularly, to an operation method of a terminal for controlling inter-cell interference in a wireless communication system and an apparatus to apply the method.

The 3rd Generation Partnership Project (3GPP) long term evolution (LTE), an enhancement of Universal Mobile Telecommunications System (UMTS), is introduced as 3GPP release 8. 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in downlink and single carrier-frequency division multiple access (SC-FDMA) in uplink. Recently, a discussion on 3GPP LTE-Advanced (LTE-A), an evolution of 3GPP LTE, is underway.

In the evolution of wireless communication technology, heterogeneous networks (“heterogeneous networks”) are emerging.

Heterogeneous networks are used together with a macro cell, a micro cell (eg, a femto cell, a pico cell, etc.). A micro cell is a system that covers an area smaller than a radius of an existing mobile communication service when compared to a macro cell.

In such a heterogeneous network, a user terminal existing in any one of a macro cell and a micro cell may cause inter-cell interference in which signal interference is caused by a signal generated from another cell. For example, when a home eNB (HeNB) that provides a service of a micro cell provides a closed subscriber group (CSG) function, when a user terminal does not smoothly handover when entering the micro cell. The user terminal continues to communicate with the macro base station of the macro cell to interfere with the user terminal in the micro cell. In addition, the user terminal communicating with the macro base station is also interfered by the home base station in the micro cell.

An object of the present invention is to provide a method and apparatus for solving an interference problem between a macro base station and a home base station in a heterogeneous network.

In a wireless communication system according to an aspect of the present invention, an operation method of a terminal includes: receiving system information of an adjacent cell; Determining whether a plurality of closed subscriber group (CSG) IDs included in the system information exist in a CSG white list; And transmitting a measurement report to a base station when at least one of the plurality of CSG IDs is present in the CSG white list, wherein the plurality of CSG IDs exist in a macro cell provided by the base station. A unique CSG ID having a value unique to each of the home base stations, and a common CSG ID having at least two home base stations of the plurality of home base stations having a common value, wherein the measurement report includes the CSG ID; And a CSG ID value existing in the CSG white list.

The neighbor cell may be an area where a home base station existing in the macro cell provides a service.

The method includes receiving a first RRC connection reset message from the base station; Transmitting a first RRC connection reset complete message to the base station; And transmitting a physical cell identifier (PCI) of the neighbor cell to the base station, wherein the first RRC connection reestablishment message may be a message requesting PCI of the neighbor cell.

The method also includes receiving a second RRC connection reestablishment message from the base station; And transmitting a second RRC connection reset complete message to the base station, wherein the second RRC connection reset message may be a message requesting reporting of system information of the neighbor cell.

The system information may include a system information block (SIB) and a master information block (MIB) of the neighbor cell. The SIB may include the unique CSG ID and the common CSG ID. The system information may be broadcast from the home base station of the neighbor cell.

Terminal according to another aspect of the present invention is a radio frequency (RF) unit for transmitting and receiving radio signals; Memory; And a processor coupled to the RF unit and the memory, wherein the RF unit receives system information of an adjacent cell, the memory stores a CSG white list, and the processor includes a plurality of CSGs included in the system information. closed subscriber group) determines whether an ID exists in the CSG white list, and if at least one of the plurality of CSG IDs is present in the CSG white list, transmits a measurement report to a base station, wherein the plurality of CSG IDs The base station includes a unique CSG ID having a value unique to each of a plurality of home base stations existing in a macro cell providing a service, and a common CSG ID having at least two home base stations of the plurality of home base stations in common. The measurement report may include a CSG ID value existing in the CSG white list among the plurality of CSG IDs. Characterized in that.

Home base station according to another aspect of the present invention is a radio frequency (RF) unit for transmitting and receiving radio signals; Memory; And a processor coupled to the RF unit and the memory, wherein the RF unit transmits system information, the processor generates the system information, and the system information includes a plurality of closed subscriber group (CSG) IDs. The plurality of CSG IDs may include a unique CSG ID having a value unique to each home base station and a common CSG ID having at least two home base stations in common.

According to the present invention, the UE receives the macro base station and the home base station providing the CSG function coexist, that is, the macro base station and the home base station providing the CSG function use the same radio resource (for example, the same frequency). Interference can be reduced. That is, the handover between the macro base station and the home base station providing the CSG function can be made smoothly, thereby solving the interference problem received by the terminal.

1 is a block diagram illustrating a wireless communication system.
2 is a block diagram illustrating a functional split between an E-UTRAN and an EPC.
FIG. 3A shows the X2 user plane interface X2-U, and FIG. 3B shows the X2 control plane interface X2-CP.
4 shows an example in which a micro cell exists in a macro cell.
5 shows a connection method between a macro base station and a HeNB according to an embodiment of the present invention.
6 shows an X2 inbound handover procedure.
7 illustrates an ANR process of a macro base station according to an embodiment of the present invention.
8 shows a measurement report transmission process of a terminal according to an embodiment of the present invention.
9 shows an S1 connection between a macro base station and a home base station.
10 and 11 illustrate an S1 inbound handover procedure between a macro base station and a home base station according to an embodiment of the present invention.
12 is a block diagram showing the configuration of a HeNB and a terminal according to an embodiment of the present invention.

1 is a block diagram illustrating a wireless communication system. This may be a network structure of 3GPP LTE / LTE-A. The E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) includes a base station 20 (BS) that provides a control plane and a user plane to a user equipment (UE) 10. do.

The terminal 10 may be fixed or mobile and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), and a wireless device. .

The base station 20 refers to a fixed station communicating with the terminal 10, and may be referred to by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and the like.

One or more cells may exist in one base station 20. In this case, the cell refers to an area where the base station 20 can provide a service, that is, an area covered by the base station 20.

The base station 20 is connected to the Evolved Packet Core (EPC) through the S1 interface. More specifically, it is connected to a Mobility Management Entity (MME) through an S1 control plane interface (hereinafter referred to as S1-MME), and an S-GW (serving gateway) through an S1 user plane interface (hereafter referred to as S1-U). Connected. The S1 interface supports a many-to-many-relation between base station 20 and MME / S-GW 30.

An interface for transmitting user traffic or control traffic may be used between the base stations 20. For example, the base stations 20 may be connected to each other through an X2 interface. The X2 interface includes a user plane interface (X2-U) and a control plane interface (X2-CP).

2 is a block diagram illustrating a functional split between an E-UTRAN and an EPC. The hatched box represents the radio protocol layer and the white box represents the functional entity of the control plane. Describe the function of each functional entity.

The base station performs the following functions.

(1) Radio resource management such as radio bearer control, radio admission control, connection mobility control, and dynamic resource allocation to a terminal ; RRM) function. (2) Internet Protocol (IP) header compression and encryption of user data streams. (3) Routing of user plane data to S-GW. (4) Scheduling and sending of paging messages. (5) Scheduling and transmission of broadcast information. (6) Set up measurements and measurement reports for mobility and scheduling.

The MME performs the following functions.

(1) Non-Access Stratum (NAS) signaling. (2) NAS signaling security. (3) idle mode UE Reachability, (4) tracking area list management. (5) Roaming Functions (6) Authentication.

S-GW performs the following functions.

(1) mobility anchoring. (2) lawful interception.

P-GW (P-Gateway) performs the following functions.

(1) Terminal IP (Internet Protocol) allocation. (2) packet filtering.

Among the radio protocol layers, a physical layer (PHY) provides an information transfer service to a higher layer by using a physical channel. The physical layer is connected to a medium access control (MAC) layer, which is a higher layer, through a transport channel. Data travels between the MAC and physical layers over the transport channel. Transport channels are classified according to how and with what characteristics data is transmitted over the air interface. Data moves between physical layers, that is, between physical layers of a transmitter and a receiver. In the physical layer, a physical control channel may be used. Functions of the MAC layer include mapping between logical channels and transport channels and multiplexing / demultiplexing into transport blocks provided as physical channels on transport channels of MAC service data units (SDUs) belonging to the logical channels.

The MAC layer provides a service to a Radio Link Control (RLC) layer through a logical channel. The logical channel may be divided into a control channel for transmitting control region information and a traffic channel for delivering user region information.

Functions of the RLC layer include concatenation, segmentation, and reassembly of RLC SDUs.

Functions of the Packet Data Convergence Protocol (PDCP) layer in the user plane include delivery of user data, header compression, and ciphering. Functions of the PDCP layer in the user plane include the transfer of control plane data and encryption / integrity protection.

The RRC (Radio Resource Control) layer is defined only in the control plane. The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of radio bearers.

The radio bearer (RB) refers to a logical path provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, PDCP layer) for data transmission between the terminal and the network. The establishment of the RB means a process of defining characteristics of a radio protocol layer and a channel to provide a specific service, and setting each specific parameter and operation method.

FIG. 3A shows the X2 user plane interface X2-U, and FIG. 3B shows the X2 control plane interface X2-CP.

X2-U provides for the delivery of user plane protocol data units (PDUs). The protocol stack of X2-U consists of a physical layer, a data link layer, an Internet protocol (IP), a user datagram protocol (UDP), and a GPRS Tunnelling Protocol (GTP-U). The protocol stack of X2-U is the same as the S1 user plane protocol stack.

The protocol stack of X2-CP consists of a physical layer, a data link layer, IP, and a stream control transmission protocol (SCTP). X2-AP means X2 application protocol.

Hereinafter, a method of reducing interference that may occur when a base station having different sizes of service areas coexist with each other will be described. First, the terms are defined for clarity.

Hereinafter, a macro base station (referred to as a macro eNB, or simply eNB) means a general large base station installed at a fixed location as a base station used for mobile communication. The area where the macro base station provides a service is called a macro cell. The macro cell may be used in the same sense as the macro base station.

A home base station (HeNB) refers to a base station having a smaller service area than a macro base station, and may also be referred to as another term such as a pico base station or a femto base station. The home base station may be mainly installed in the home, but is not limited thereto. The area where the home base station provides a service is called a micro cell for convenience (the micro cell may be used in the same sense as the home base station). The micro cell may exist in the macro cell and may exist in plural in one macro cell. Home base stations can be used in communication shadow areas that are not covered by macro base stations alone, or in areas where data service demands are high, so-called hot zones.

Such a home base station can operate in various modes. For example, a home base station can operate in an open mode, a closed subscriber group mode (CSG mode), and a hybrid mode. The open mode is an operation mode that allows access to both the terminal registered and the unregistered terminal in the home base station, and the closed user group mode distinguishes between the terminal registered in the home base station and the unregistered terminal and accesses only the registered terminal. Allowed mode of operation. In the terminal view, when the home base station operates in the CSG mode, the home base station can communicate with the home base station only when it is registered as a member of the home base station (ie, registered). If not, it is not possible to communicate with the home base station. The mixed mode is an operation mode in which an open mode and a CSG mode are mixed. Hereinafter, it is assumed that the home base station operates in the CSG mode, and it is assumed that it is not allowed to change the operation mode during the operation. That is, if the interference is more than a certain level during the operation of the home base station, the operation mode is changed, such as changing from the CSG mode to the mixed mode.

According to the conventional 3GPP standard, the HeNB operating in the CSG mode broadcasts CSG identification (ID) as system information. HeNB has one CSG ID. That is, the HeNB has a unique identifier with respect to the CSG, which is called a CSG ID (which may be called a unique CSG ID). The UE may have a list of CSG IDs of HeNBs to which the UE belongs, which is called a CSG white list. For example, the CSG white list may be stored in a subscriber identity module (SIM) card of the terminal. The CSG white list may be changed by the request of the terminal or the command of the network.

The HeNB delivers the CSG ID of the CSG supported by the UE through system information so that only the member terminals of the corresponding CSG are connected. When the UE finds a CSG cell, it can check which CSG the CSG cell supports by reading the CSG ID included in the system information. The terminal reading the CSG ID is regarded as a cell that can access the CSG cell only when the UE is a member of the CSG cell, that is, when the CSG ID of the CSG cell is included in its CSG white list.

4 shows an example in which a micro cell exists in a macro cell.

Referring to FIG. 4, a plurality of HeNBs exist in a macro cell covered by a macro base station, and a plurality of micro cells provided by each HeNB exist. As described above, the HeNB operates in the CSG mode, and in consideration of this characteristic, each micro cell may be referred to as a CSG cell.

The terminal may enter the CSG cell while communicating with the macro base station. In this case, if the CSG cell is a CSG cell to which the UE subscribes, handover is normally performed and there is no problem related to interference. However, if the CSG cell is a CSG cell to which the terminal does not subscribe, the terminal continues to communicate with the macro base station, and as a result, the terminal interferes with other terminals communicating with the CSG cell, and itself is also interfered with. Hereinafter, a method and apparatus for solving this problem will be described.

5 shows a connection method between a macro base station and a HeNB according to an embodiment of the present invention.

Referring to FIG. 5, the HeNB may be connected to the MME / S-GW through a home base station gateway (HeNB GW). In this case, the S1 interface or the X2 interface may be used between the HeNB and the home base station gateway, and the S1 interface may be used between the home base station gateway and the MME / S-GW.

An X2 interface may be used between the macro base station eNB and the HeNB. In this case, as shown in FIG. 5 (a), the HeNB may be connected to the macro base station through the home base station gateway using the X2 interface, and without passing through the home base station gateway using the X2 interface as shown in FIG. 5 (b). It may also be directly connected to the macro base station.

Although the conventional macro base station and the home base station do not use the X2 interface, the present invention may perform handover between the macro base station and the home base station through the X2 inbound handover (described later) using the X2 interface. That is, using the connection method as shown in FIG. 5 (a) or (b), X2 inbound handover can be used between the macro base station and the HeNB. For example, when the UE communicates with the macro base station and moves into the CSG cell of the HeNB, X2 inbound handover may be performed.

6 shows an X2 inbound handover procedure.

Referring to FIG. 6, the source base station transmits an RRC connection reset message (first RRC connection reset message) to the terminal (S610). The source base station may request the report of the physical cell ID (PCI) of the neighbor cell through the RRC connection reconfiguration message. The PCI may be any one of a predetermined number of IDs. For example, the PCI may be any one of 504 IDs. The terminal transmits an RRC connection reconfiguration complete message to the source base station (S620). The terminal monitors a signal transmitted from an adjacent cell.

The terminal acquires the PCI of the neighbor cell by using the synchronization channel signal of the neighbor cell and transmits the PCI to the source base station through a measurement report message. The neighbor cell which acquired PCI is called a target cell below, and the home base station of the target cell is called a target HeNB. The synchronization channel may be, for example, a broadcast control channel (BCCH), and the synchronization channel signal may be a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). PSS and SSS are signals transmitted in downlink of neighbor cell to help cell search. By detecting the PSS, PCI and slot synchronization can be obtained. When the SSS is detected, the length of the cyclic prefix (CP), the physical layer cell group ID, and frame synchronization can be obtained.

The source base station transmits an RRC connection reestablishment message (second RRC connection reestablishment message) again, and requests a system information block (SIB) and a master information block (MIB) of the target cell through the RRC connection reestablishment message. SIB constitutes system information, each containing a set of functionally-related parameters. The SIB Type 1 message (SystemInformationBlocktype1 message) of the SIB includes information related to whether the user terminal can access the corresponding cell. The SIB Type 1 message has information about scheduling in the time domain of the remaining SIBs.

Among the SIBs, the MIB is transmitted on the PBCH and consists of a limited number of the most frequently transmitted parameters necessary for initial access to the cell. For example, the MIB may include information on downlink cell bandwidth, information on a physical HARQ indication channel (PHICH) configuration of a cell, a system frame number (SFN) of a system, and the like. The RRC connection reconfiguration message may include gap information. The gap information takes into account the time taken by the UE to decode the SIB and MIB of the target cell.

The terminal responds to the source base station RRC connection reconfiguration complete message, and obtains the MIB, SIB information of the target cell.

The terminal performs a primary access control procedure through the MIB and SIB information of the target cell (S630). The primary access control procedure is a procedure for determining whether the CSG ID of the target cell exists in the CSG white list in the terminal.

If the CSG ID of the target cell exists in the CSG white list, the terminal transmits a measurement report message including the CSG ID and the CSG member status information of the target cell to the source base station (S640).

The source base station determines whether to handover (S650), and transmits a handover request message to the target HeNB (S660). The handover request message includes a CSG ID, which is called a target CSG ID.

The target HeNB determines whether the target CSG ID matches the broadcast CSG ID (S670), and if it matches, transmits a handover request ACK to the source base station (S680).

The source base station again transmits an RRC connection reconfiguration message including mobility control information to the terminal (S690), and transmits a status transfer message to the target HeNB (S700). The status transfer message may be for conveying PDCP status information.

The terminal transmits an RRC connection reconfiguration message to the target HeNB (S710). The target HeNB sends a path switch request message to the MME (S720), the MME requests a bearer change to the S-GW (S730), and receives a bearer response change message from the S-GW again (S740), and the MME switches the path. The request ACK is transmitted to the target HeNB (S750).

S1 inbound handover performs two access control processes (primary access control in the terminal and secondary access control in the MME), whereas the above-described X2 inbound handover differs in that the terminal performs only the primary access control process.

The following table shows an SIB Type 1 message of a HeNB according to an embodiment of the present invention.

Referring to Table 1, the SIB Type 1 message broadcast by the HeNB according to the present invention includes a CSG ID commonly used by a plurality of HeNBs in addition to the existing SIB Type 1 message. That is, the system information broadcast by the HeNB may include a plurality of CSG IDs. For example, as shown in Table 1, a new parameter 'csg-Identity-common' may be defined in the SIB Type 1 message. This parameter is called a common CSG ID for convenience.

That is, the conventional HeNB has one CSG ID, but the HeNB according to the present invention has a common CSG ID together with the existing CSG ID. The CSG ID of each HeNB is uniquely set, but a common CSG ID may have a plurality of HeNBs having the same value. For example, there may be three HeNBs in the macro cell, such as HeNB # 1, HeNB # 2, HeNB # 3. In this case, the CSG ID of HeNB # 1 may be 3 and the common CSG ID may be 0. The CSG ID of HeNB # 2 may be 4 and the common CSG ID may be 0. In addition, the CSG ID of HeNB # 3 may be 7, and the common CSG ID may be 0.

In addition, the terminal according to the present invention is configured to store not only the CSG ID of the HeNB but also the common CSG ID in the CSG white list. The terminal may store the CSG ID and the common CSG ID in the SIM card.

7 illustrates an ANR process of a macro base station according to an embodiment of the present invention.

Automatic neighbor relation (ANR) is a function for the base station to identify a useful neighbor base station using the terminal. The base station may request the terminal to report the PCI, ECGI (evolved cell global identifier) of the neighbor base station from the broadcast information of the neighbor base station. ECGI is an ID uniquely given to a cell. Unlike PCI, ECGI has a unique value in every cell. The base station may manage information on the neighbor base station in the form of a neighbor relation table (NRT). When the base station finds a new neighbor base station, it adds it to the NRT and removes it from the NRT when it is determined that it is no longer the neighbor base station.

In FIG. 7, it is assumed that the terminal supports the CSG function and is set to CSG ID = 10 and common CSG ID = 0 in the CSG white list stored in the SIM card. And, it is assumed that the HeNB of the micro cell B has CSG ID = 7, common CSG ID = 0, PCI = 5, and ECGI = 19. The macro base station may request the terminal to report the measurement report for the neighboring cell, and the terminal receiving the request reports the measurement report including the PCI value (ie, 5) for the cell to the macro base station when the neighboring cell is found. (Step 1).

The macro base station requests the terminal to report the ECGI value for the cell with PCI = 5 (step 2).

The UE acquires the ECGI, CSG ID, and common CSG ID of the neighboring cell through the MIB and SIB broadcasted through the BCCH of the HeNB of the neighboring cell (micro cell B) (step 3). The terminal compares the CSG ID and the common CSG ID of the neighbor cell with the CSG ID and the common CSG ID stored in their CSG white list, and checks whether there is matching information.

If at least one of the neighbor cell's CSG ID and the common CSG ID matches the CSG ID and the common CSG ID stored in the CSG white list of the UE, the UE is a macro base station with the CSG ID or the common CSG ID. Send (step 4).

When the CSG related ID of the neighbor cell transmitted by the UE is the common CSG ID, the macro base station performs an S1 inbound handover process or an X2 inbound handover process. If the CSG related ID of the neighbor cell transmitted by the UE is a unique CSG ID, S1 inbound handover or X2 inbound handover may be performed as in the prior art. In the X2 inbound handover process, the HeNB checks whether the target CSG ID included in the handover request message transmitted by the macro base station matches the CSG ID broadcasted by the HeNB itself or the common CSG ID and matches the terminal to the terminal. Take over the communication with the user.

8 shows a measurement report transmission process of a terminal according to an embodiment of the present invention.

Referring to FIG. 8, the terminal receives an RRC connection reconfiguration message from a source base station (S810). After transmitting the RRC connection reset complete message to the source base station (S820), the UE monitors whether there is a signal of a specific level or more transmitted from the neighboring cells (S830).

If there is a signal of a certain level or more, the terminal acquires the PCI of the neighbor cell using the synchronization channel signal of the neighbor cell (S840), and transmits the PCI to the source base station through a measurement report message (S850). The neighbor cell which acquired PCI is called a target cell, and the home base station of the target cell is called a target HeNB.

The terminal receives the RRC connection reconfiguration message from the source base station again (S860). At this time, the source base station requests a system information block (SIB) and a master information block (MIB) of the target cell through an RRC connection reconfiguration message.

The terminal responds to the source base station RRC connection reconfiguration complete message (S870), and obtains the MIB, SIB information of the target cell (S880).

The terminal performs a primary access control procedure through the MIB and SIB information of the target cell (S890). That is, the terminal determines whether the CSG ID of the target cell exists in the CSG white list in the terminal.

If the CSG ID (unique CSG ID or common CSG ID) of the target cell exists in the CSG white list, the terminal transmits a measurement report message including the CSG ID and CSG member status information of the target cell to the source base station. (S900). If the CSG ID (unique CSG ID or common CSG ID) of the target cell does not exist in the CSG white list of the UE, information indicating that the member is not in the CSG member state is transmitted (S910).

According to the present invention, a plurality of micro cells in a macro cell may have a common CSG ID. That is, each HeNB may have a common CSG ID having a common value along with a unique CSG ID. As in the related art, when each HeNB has only a unique CSG ID, a handover may not be performed frequently when a specific UE enters a micro cell. In this case, the terminal continues to communicate with the macro base station, resulting in interference with the terminal communicating with the HeNB. In addition, the terminal communicating with the macro base station also receives interference from the HeNB, communication quality is reduced.

In contrast, according to the present invention, a plurality of HeNBs may have a common CSG ID and the common CSG ID may have the same value. Therefore, when the terminal enters the micro cell, the probability of handover is increased. As a result, since the terminal does not continuously communicate with the macro base station, interference to the terminal in the micro cell can be reduced.

9 shows an S1 connection between a macro base station and a home base station.

Referring to FIG. 9, the macro base station eNB may be connected to the MME / S-GW through the S1 interface, and the MME / S-GW and the home base station gateway HeHe GW may also be connected through the S1 interface. The HeNB GW and the home base station HeNB may be connected through the S1 interface. The home base station according to the present invention may use the X2 inbound handover method through the X2 interface described above, but may also be S1 inbound handover from the macro base station through the S1 interface as in the prior art. However, there is a slight difference in S1 inbound handover through the S1 interface.

10 and 11 illustrate an S1 inbound handover procedure between a macro base station and a home base station according to an embodiment of the present invention.

First, a conventional S1 inbound handover process will be described. Referring to FIG. 10, a terminal (CSG UE) exchanges an RRC connection reset message and an RRC connection reset complete message with a macro base station (source eNB) and performs a primary access control process. The terminal transmits an RRC measurement report to the macro base station, and may include target CSG ID and CSG member status information. The macro base station transmits a message (Handover Required) indicating that handover is required to the MME after determining whether to handover. At this time, the transmission may include the target CSG ID. After performing the access control process, the MME transmits a handover request message to a target base station (target CSG HeNB). The home base station determines whether the target CSG ID included in the handover request message is the same as the CSG ID broadcasted by the home base station, thereby determining whether to allow access. Thereafter, the home base station transmits a handover request ACK to the MME. The MME creates an Indirect Data Forwarding Tunnel Request with the S-GW, and the S-GW generates an Indirect Data Forwarding Tunnel Response. The MME sends a handover command to the macro base station. The macro base station transmits an RRC connection reconfiguration message including mobility control information to the terminal. The terminal is separated from the old cell (macro cell) and performs synchronization with the new cell (micro cell). The macro base station forwards the buffered packet to the home base station. In addition, the macro base station transmits the status information of the macro base station to the MME, the MME transfers the MME status information to the home base station. The home base station receives the buffered packet from the macro base station. The terminal transmits an RRC connection reconfiguration message to the home base station, and the home base station notifies the handover to the MME. The MME sends a bearer request to the S-GW, and the S-GW transmits a bearer response to the MME after switching the downlink path. The MME transmits a terminal context release command to the macro base station, and the macro base station transmits a terminal context release completion message to the MME. The MME deletes the indirect data forwarding tunnel request to the S-GW, and the S-GW sends an indirect data forwarding tunnel response to the MME. Which protocol layer each process is performed is shown in FIGS. 10 and 11.

According to the present invention, there is a difference from the conventional method in the above-described S1 inbound handover process. That is, when the macro base station transmits a 'Handover Required' message to the MME, the conventional base station transmits the unique CSG ID of the home base station to the target CSG ID, but according to the present invention, the unique CSG ID and the common CSG ID of the home base station are according to the present invention. Any one of can be transmitted. The MME transmits a handover request message to the home base station by performing an access control procedure as well as a case where the target CSG ID is a unique CSG ID and a common CSG ID.

The home base station determines whether the target CSG ID received from the MME is the same as the unique CSG ID or the common CSG ID broadcasted by the home base station. The home base station transmits a “Handover Request ACK” to the MME when the broadcasted unique CSG ID or common CSG ID and the target CSG ID are the same. Otherwise, the conventional S1 inbound handover procedure may be used in the same manner.

That is, according to the present invention, there is a difference in considering not only the unique CSG ID of the home base station but also the common CSG ID during the access control of the MME and the access control of the home base station.

12 is a block diagram showing the configuration of a HeNB and a terminal according to an embodiment of the present invention.

Referring to FIG. 12, the HeNB 110 includes an RF unit 111, a memory 112, and a processor 113. The RF unit 111 is a unit that transmits and receives a radio signal and may include an antenna and a power amplifier. The memory 112 is a storage device for driving program storage of the HeNB 110, buffering of radio signals, and the like. The processor 113 is a control processing apparatus connected to the RF unit 111 and the memory 112 to operate the HeNB 110. The processor 113 performs the function of the HeNB described above. For example, the processor 113 may receive the handover request signal of the macro base station, determine the validity of the CSG ID or the common CSG ID, and transmit the handover request ACK signal. In addition, the processor 113 may broadcast a unique CSG ID unique to the home base station and a common CSG ID having a value common to at least two or more home base stations through the BCCH. The processor 113 may generate and transmit a signal based on a protocol of an S1 interface or an X2 interface. The processor 113 may be in charge of a modem function and an L2 / L3 function.

The terminal 120 includes an RF unit 121, a memory 122, and a processor 123. The RF unit 121 is a unit that transmits and receives a radio signal and may include an antenna and a power amplifier. The memory 122 is a device that stores a driving program, a radio signal, a CSG white list, and the like of the terminal 120. The memory 122 may be configured as a SIM card. The processor 123 is a control processing apparatus connected to the RF unit 121 and the memory 122 to operate the terminal 120. The processor 123 performs the functions of the above-described terminal. For example, the processor 123 determines whether a plurality of CSG IDs included in the system information transmitted by the home base station of the neighboring cell exist in the CSG white list, and at least one of the plurality of CSG IDs is included in the CSG white list. If present, the measurement report can be sent to the macro base station.

In the above-described exemplary system, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (17)

In the method of operation of a terminal in a wireless communication system,
Receiving system information of an adjacent cell;
Determining whether a plurality of closed subscriber group (CSG) IDs included in the system information exist in a CSG white list; And
If at least one of the plurality of CSG IDs is present in the CSG white list, transmitting a measurement report to a base station;
The plurality of CSG IDs have values common to a unique CSG ID having a value unique to each of a plurality of home base stations existing in a macro cell to which the base station provides a service, and at least two or more home base stations among the plurality of home base stations. And a CSG ID value present in the CSG white list among the plurality of CSG IDs. The method of claim 1, wherein the neighbor cell is an area where a home base station existing in the macro cell provides a service. The method of claim 1,
Receiving a first RRC connection reestablishment (radio resource control) message from the base station;
Transmitting a first RRC connection reset complete message to the base station;
Further comprising transmitting a physical cell identifier (PCI) of the neighbor cell to the base station,
The first RRC connection reestablishment message is a message for requesting PCI of the neighbor cell. The method of claim 3, wherein
Receiving a second RRC connection reestablishment message from the base station; And
Further comprising the step of transmitting a second RRC connection reset complete message to the base station,
The second RRC connection reestablishment message is a message for requesting reporting of system information of the neighbor cell. The method of claim 1,
The system information includes a system information block (SIB) and a master information block (MIB) of the neighbor cell. 6. The method of claim 5, wherein the SIB comprises the unique CSG ID and the common CSG ID. 2. The method of claim 1, wherein the system information is broadcast from a home base station of the neighbor cell. A radio frequency (RF) unit for transmitting and receiving a radio signal;
Memory; And
A processor connected to the RF unit and the memory,
The RF unit receives the system information of the neighbor cell,
The memory stores a CSG white list,
The processor determines whether a plurality of closed subscriber group (CSG) IDs included in the system information exist in the CSG white list, and when at least one of the plurality of CSG IDs exists in the CSG white list, the base station Send measurement reports to
The plurality of CSG IDs have values common to a unique CSG ID having a value unique to each of a plurality of home base stations existing in a macro cell to which the base station provides a service, and at least two or more home base stations among the plurality of home base stations. Branch has a common CSG ID,
And the measurement report includes a CSG ID value present in the CSG white list among the plurality of CSG IDs. The terminal of claim 8, wherein the neighbor cell is an area where a home base station existing in the macro cell provides a service. The method of claim 8,
The processor receives a first RRC connection reset message from the base station, sends a first RRC connection reset complete message to the base station, and transmits a physical cell identifier (PCI) of the neighbor cell to the base station. Wherein the first RRC connection reconfiguration message is a message for requesting PCI of the neighbor cell. 11. The method of claim 10,
The processor receives a second RRC connection reestablishment message from the base station, and transmits a second RRC connection reestablishment complete message to the base station, wherein the second RRC connection reestablishment message is a message requesting reporting of system information of the neighbor cell. Terminal characterized in that the. The method of claim 8,
The system information terminal comprises a system information block (SIB) and a master information block (MIB) of the neighbor cell. The terminal of claim 12, wherein the SIB includes the unique CSG ID and the common CSG ID. The terminal of claim 8, wherein the system information is broadcasted from a home base station of the neighbor cell. The terminal of claim 8, wherein the memory is a subscriber identity module (SIM) card of the terminal. A radio frequency (RF) unit for transmitting and receiving a radio signal;
Memory; And
A processor connected to the RF unit and the memory,
The RF unit transmits system information,
The processor generates the system information, the system information includes a plurality of closed subscriber group (CSG) ID,
The plurality of CSG IDs include a unique CSG ID having a value unique to each home base station and a common CSG ID having at least two home base stations in common. 17. The home base station according to claim 16, wherein the system information is broadcast.

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