KR20120072312A - Method for providing mobility of terminal and mobile telecommunication system for the same - Google Patents

Abstract

PURPOSE: A mobility providing method and mobile communication system therefor are provided to solve occupation problems of wireless resources according to unnecessary messages without generating a handover request message, an unnecessary measurement report message, and a handover preparation failure messages. CONSTITUTION: A terminal measures an access mode of a previous target micro base station in order to prevent a serving base station from requesting unnecessary handover(309). The target minimum base station confirms consonance the CSG ID(Closed Subscriber Group Identity) of a handover request message with the CSG ID of SIB 1(System Information Block type 1)(314). The target micro base station notifies the readiness for handover to a base station through an MME(Mobility Management Entity). The target minimum base station finally orders handover to the terminal(315~317).

Description

METHOD FOR PROVIDING MOBILITY OF TERMINAL AND MOBILE TELECOMMUNICATION SYSTEM FOR THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system. In particular, an increase in occupied radio resources and system load increase due to unnecessary message generation and processing procedures in case of a handover of an inaccessible terminal to a compact base station operating in a closed access mode or a hybrid mode. Will be solved.

Recently, due to the rapid development of communication, computer network, and semiconductor technology, various services using wireless communication networks are being provided, and demands of consumers are increasing day by day, and the global market for wireless internet services is exploding. It is a trend. Accordingly, a service provided by a mobile communication system using a wireless communication network is developing not only a voice service but also a multimedia communication service for transmitting various data.

Currently, wireless data services such as Code Division Multiple Access (CDMA) 2000, Evolution Data Only (EV-DO), Wideband CDMA (WCDMA), and Wireless Local Area Network (WLAN) are commercially available. Demand is constantly increasing, and according to this trend, a method of providing a mobile communication service by installing a micro base station indoors to access a mobile communication core network through an indoor broadband network has been proposed. In particular, in the next generation network system, in order to satisfy the demand for high data rate and to provide various services stably, a method of arranging multiple small multi-cells (femtocells) has been proposed as an alternative. The micro base station that manages such a femtocell is called an indoor base station or a femto base station. By reducing the size of the cell, the efficiency of the next-generation network system using a high frequency band can be improved, and the use of multiple small cells can be advantageous in terms of increasing the frequency reuse frequency. In addition, the present invention can improve the channel deterioration problem due to the attenuation of radio waves, which is caused when a single base station covers the entire cell area, and the inability to service shadow users. Has this advantage. Based on these advantages, a combination of the existing macro cell (cell area managed by an outdoor base station) (femto-cell) and femtocell (cell area managed by an ultra-small base station such as an indoor base station or a femto base station) This is emerging.

Long Term Evolution (LTE) is a network for realizing the requirements of high data rate, low-latency, and packet optimized radio access for access networks. It is designed to accommodate high-speed rich media while guaranteeing backward compatibility with existing 3GPP / non-3GPP access networks. LTE is an All-IP-based network that excludes existing circuit-switched based communications.It has enhanced the quality of service (OoS) management function to provide real-time services (eg, voice communications, video communications) and non- By providing differentiated QoS for real-time services (eg web browsing, store and forward data transmission), the efficiency of network resources is improved. In addition, the introduction of smart antenna technology (ie MIMO) has expanded the bandwidth for wireless communication.

The general LTE network structure includes a macro base station (eNB: enhanced Node B), a small base station (home-eNB), a mobility management entity (MME), and a self organizing & optimizing network (SON) server. Since the micro base station and the macro base station each have their own connectivity to the core network, the user equipment (UE) may communicate through either the micro base station or the macro base station for communication. The MME is an entity used to perform handover management and call processing of the terminal. The SON server is any server that functions to perform macro / miniature base station installation and optimization and to provide the basic parameters or data required for each base station. The functions of the MME and SON server can all be performed from one network management device.

The UE can interwork with other networks such as E-UTRAN (Evolved UTRAN), which is a wireless access network of LTE, as well as other networks such as UMTS Terrestrial Radio Access Network (UTRAN) / GSM / EDGE Radio Access Network (GERAN).

A base station (eNB) of a UE and an E-UTRAN communicate through a radio resource control (RRC) protocol, and a broadcasting message from the base station eNB to a cell area controlled by the base station is defined as an RRC message. The RRC message may include control messages coming down from the Non-Access Stratum (NAS) protocol, which are not transparently read within the E-UTRAN and are transparently delivered to the UE or the core network. A channel frequency unit assigned to one base station is represented by a frequency assignment (FA) (for example, 4FA for WCDMA), and an identifier for identifying a cell in a physical layer in one FA, for example, a PCI (Physical Cell) in an LTE network. Identity), PSC (Primary Scrambling Code) is used in WCDMA, and PN (Pseudo Noise) offset is used in CDMA. For example, 504 physical layer cell identifiers exist in 1FA in LTE network, and 512 physical layer cell identifiers exist in 1FA in WCDMA network.

In the LTE network, handover is performed based on UE measurement value, and the measurement report message of the UE is controlled by a parameter determined by the base station. The base station receiving the measurement report message determines which cell to hand over to. Specifically, the UE measurement value is based on a received power (RSRP / Reference Symbol Received Power) or a reception state (RSRQ / Reference Symbol Received Quality). As shown in FIG. 1, when a handover condition is satisfied within a time of {Hysteresis, timeToTrigger} set by a base station, a handover triggering event (HO triggering event) is generated. The measurement report message of the terminal may be generated during event triggering or periodically according to the configuration of the base station. When the handover triggering event occurs, the terminal sends a measurement report message to the base station and the base station performs a handover.

As described above, the handover is triggered based on the reception power and the reception state. In particular, when a terminal served by the current base station (serving base station) is handed over to an adjacent cell (macrocell or femtocell) in a mixed network of macrocells and femtocells, the handover is performed. A neighbor cell list (NCL) indicating how a cell is configured may include cells of different sizes (eg, macrocells, femtocells, etc.). The neighbor cell list includes FA information of the base station and a physical layer cell identifier (eg, PCI) of each FA. When determining a target base station to be handed over, a femtocell that allows access to only a specific terminal (subscriber) should be considered.

In fact, the macro base station having a large service area or the small base station for shadow area resolution does not have a high possibility of handover signaling message because the handover frequency is not very high and the handover area is relatively large. In addition, the impact on overall system performance is limited. However, in urban and commercial areas, where data service congestion is difficult to operate, cell designs are often performed in such a way that micro base stations are concentrated in specific areas, and handover frequency is very high even considering low-speed mobility. Frequent handover may occur, especially when a terminal (non-user, not home-user) who has limited access to a small base station operating in closed access mode or hybrid mode performs a handover procedure. There is a problem in that a system load is increased by generating a message and increasing occupying radio resources.

 3GPP TS 36.331 v920

An object of the present invention is to provide mobility that can solve the increase of occupied radio resources and system load due to unnecessary message generation and processing procedure when handover to a small base station operating in closed access mode or hybrid mode. A method and a mobile communication system therefor are provided.

According to an aspect of the present invention, it is possible to solve an increase in occupied radio resources and an increase in system load due to unnecessary message generation and processing procedures in a handover of an inaccessible terminal to a compact base station operating in a closed access mode or a hybrid mode. A method of providing mobility and a mobile communication system therefor are disclosed. According to the present invention, when the terminal checks the access mode of the target miniature base station for handover, and transmits the measurement report message for the handover to the serving base station, the terminal provides the access mode information of the target miniature base station. At this time, the access mode information is information indicating that the CSG identifier is present in the white list of the terminal and the target micro base station operates in the hybrid access mode.

In this case, if the CSG identifier does not exist in the white list of the terminal and the connection of the target micro-base station is impossible, the terminal does not transmit a measurement report message to the serving base station.

According to the present invention, unnecessary measurement report message, handover request message, handover preparation failure message, etc. are not generated through the preliminary connection mode check of the terminal, and thus the radio resource efficiency is solved by solving the radio resource occupancy caused by unnecessary message generation. There is an advantage that can be increased.

1 is a view showing a condition for generating a handover triggering event.
2 illustrates a configuration of an exemplary mobile communication network in which the present invention may be implemented.
3 is a flowchart illustrating a method of providing mobility according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions will not be described in detail if they obscure the subject matter of the present invention.

2 is a diagram illustrating a configuration of an exemplary mobile communication network in which the present invention can be implemented.

In one embodiment, the mobile communication network includes, for example, Global System for Mobile communication (GSM), 2G wireless communication network such as CDMA, LTE network, wireless Internet such as WiFi, Wireless Broadband Internet (WiBro) and World Interoperability for Microwave Access. Mobile communication networks (e.g., 3G mobile networks such as WCDMA or CDMA2000, 3.5G mobile networks such as High Speed Downlink Packet Access (HSDPA) or High Speed Uplink Packet Access (HSUPA)) 4G mobile communication network currently in service, etc.) and macro base station (macro-eNB), micro base station (Home-eNB), and any other mobile communication network including UEs as components, but are not limited thereto. no. Hereinafter, an evolved universal terrestrial radio access network (e-UTRAN), which is a wireless access network of LTE, will be described.

As shown in FIG. 2, the mobile communication network may be composed of one or more network cells, and different types of network cells may be mixed in the mobile communication network. The mobile communication network is a small base station (11-15, 21-23, 31-33) that manages a small network cell (hereinafter referred to as 'femtocell'), such as indoors, and a wide range of cells (hereinafter referred to as 'macrocell'). Macro base station (macro-eNB or eNB) (10, 20, 30), terminal (UE) 40, Self Organizing & Optimizing Networks (SON) server 50, MME (60), S-GW (Serving Gateway) 80 and P-GW (PDN Gateway) (90). The number of components shown in FIG. 2 is exemplary, and the number of components of the wireless communication network to which the present invention can be implemented is not limited to the number shown in the drawings.

The macro base stations 10, 20, and 30 may be used in, for example, LTE, WiFi, WiBro, WiMax, WCDMA, CDMA, UMTS, GSM networks, for example, cells having a radius of about 1 km. It may include a feature of the macro cell base station for managing, but is not limited thereto.

The small base stations 11-15, 21-23, 31-33 can be used, for example, in LTE networks, WiFi networks, WiBro networks, WiMax networks, WCDMA networks, CDMA networks, UMTS networks, GSM networks, and the like. It may include features of an indoor base station or a femto base station for managing a cell having a radius of about m to several tens of meters, but is not limited thereto.

The micro base stations 11 to 15, 21 to 23, 31 to 33 and the macro base stations 10, 20 and 30 may each independently have connectivity of the core network.

The UE 40 is used in 2G wireless communication networks such as GSM networks, CDMA networks, wireless Internet networks such as LTE networks, WiFi networks, mobile Internet networks such as WiBro networks and WiMax networks, or mobile communication networks supporting packet transmission. It may include features of the mobile terminal, but is not limited thereto.

The micro base station management server (network management apparatus) 70 is responsible for the configuration information and management of the micro base stations 11 to 15, 21 to 23, 31 to 33 and the macro base stations 10, 20 and 30. The management server 70 may perform both functions of the SON server 50 and the MME 60. The SON server 50 may include any server that functions to perform macro / miniature base station installation and optimization and to provide basic parameters or data required for each base station. The MME 60 may include any entity used to manage mobility of the terminal 40 and the like. In addition, each MME (61, 62) performs a function of the base station controller (BSC), and performs resource allocation, call control, handover control, voice and packet processing for the base station (Home-eNB, eNB) connected to it can do.

In one embodiment, one network management device 70 may perform both the functions of the SON server 50 and the MME 60, and the SON server 50 and the MME 60 may include one or more macro base stations ( 10, 20, 30 and one or more micro base stations 11 to 15, 21 to 23, 31 to 33 may be managed.

In the mobile communication network, a macro cell and a femto cell are assumed to be mixed, but the network cell may be configured only by the macro cell or the femto cell.

In operation, access to the macro base stations 10, 20, and 30 is normally allowed to all terminals, but access to the micro base stations 11 to 15, 21 to 23, 31 to 33 is restricted to specific terminals (subscribers). There is an operation function that can be done. This is called a connection mode or an operation mode, and the connection modes of the small base stations 11 to 15, 21 to 23, 31 to 33 are classified according to which terminal provides a service. That is, it is divided into a closed access mode (CSG closed mode), an open access mode (Open access mode or CSG open mode), hybrid access mode (Hybrid access mode). Referring to Table 1, the small base station is described as follows.

Closed access mode allows access only to specific subscribers, and is a CSG indicator (Closed Subscriber Group indicator), which is a home-eNB access mode delimiter that is installed in the home to accommodate subscribers and is transmitted through SIB 1 messages. Is set to 'true' and contains the CSG Identity. In addition, the open access mode allows any subscriber to access without access permission conditions, and can be installed at a railway station or airport to accommodate a subscriber, set the CSG indicator to 'Fault', and do not include a CSG identifier. Hybrid connection mode can also be seen as a compromise. The hybrid access mode is a base station accessible to anyone, and is installed in a shopping mall to accommodate a subscriber, set the CSG indicator to 'Fault', and include a CSG identifier. However, the difference from the open access mode is that the subscriber having the CSG identifier of the base station in the white list owned by the terminal 40 provides the service with high priority, and the subscriber having no CSG identifier of the base station in the white list Restricted services are provided with low priority.

The micro base station in the open / closed access mode is described in detail as follows. The small base stations 11 to 15, 21 to 23, 31 to 33 may broadcast system information block type 1 (SIB 1), which is system information, to a femtocell area managed by the base station (11 to 15, 21 to 23, 31 to 33). A CSG indicator indicating whether access is restricted is included. That is, SIB 1 is a message in which a base station (Home-eNB, eNB) broadcasts information about its own cell to all the terminals 40, and includes a Cell Global Identity (CGI) (the only cell delimiter in the network) and a CSG indicator ( A factor indicating that the base station is a small base station), a CSG identifier (an ID for a CSG), and the like.

When the small base stations 11 to 15, 21 to 23, 31 to 33 are operated in the closed access mode so that only a specific subscriber can access and receive the femtocells they manage, the small base stations 11 to 15, 21 to 23 , 31 to 33) set the CSG indicator in the SIB to a value of 'true' and inform the terminal in the cell that is broadcasting and managing. In addition, when operating in the open connection mode, the CSG indicator is set to a value of 'false' and then broadcast.

When the terminal 40 moves into the femtocell managed by the small base stations 11 to 15, 21 to 23, 31 to 33, after receiving the SIB 1 message from the small base station, the CSG indicator in the message has a value of 'true'. After confirming that, the terminal 40 can access the micro base station only when it is confirmed that the micro base station is included in a white list which is a list of the micro base stations accessible by the terminal 40. The white list is stored in the USIM of the terminal 40 or transmitted to the terminal 60 by the MME 60 in the Attatch / TAU update procedure.

For the micro base station operating in the closed access mode, only the user (home user) defined in the home user table managed by the micro base station can be connected to and provided with the micro base station.

In addition, for the micro base station operating in the open access mode, not only the user defined in the home user table but also a non-home user can access and provide services to the micro base station. A user may be given more preferential services than a non-home user. Specifically, the micro base stations 11 to 15, 21 to 23, 31 to 33 operated in the closed access mode are connected only to the terminal 40, for example, a terminal of a user registered as a micro base station service subscriber. Allow. The terminal 40 has a list of the smallest base stations called the white list, and can access only the smallest base stations belonging to the white list, and access to the smallest base stations is not allowed.

The terminal 40 may know whether access to the corresponding base station is restricted based on the CSG indicator of the SIB 1 broadcasted by the small base stations 11 to 15, 21 to 23, 31 to 33. In addition, as the identifier for identifying the small base station cell by the terminal 40, a physical layer cell identifier (PCI), which is a cell classification factor in the physical layer, and a global cell identifier, which is a unique cell discrimination factor in a wireless communication network, are identified. (GCI: Global Cell Identity).

If the mobile communication network is assumed to be an LTE network, the LTE network is interworked with an inter-RAT network (WiFi network, WiBro network, WiMax network, WCDMA network, CDMA network, UMTS network, GSM network, etc.). If one of the inter-RAT networks (for example, WiBro network) is the mobile communication network, it is also linked to other networks (LTE network, WiFI network, WiMax network, WCDMA network, CDMA network, UMTS network, GSM network, etc.). In the drawing, one network (for example, LTE network) and another network (WiFi network, WiBro network, WiMax network, WCDMA network, CDMA network, UMTS network, GSM network, etc.) are shown spaced apart from each other, but one network and the other network overlap. It is assumed that it is (Overlay).

The E-UTRAN, which is composed of LTE base stations (Home-eNB, eNB), has a flat structure based on IP and processes data traffic between the terminal 40 and the core network. The MME 60 is responsible for controlling the signals between them. The MME 60 is responsible for signal control between the base station (Home-eNB, eNB) and the S-GW (Serving Gateway) 80, and determines where to route the incoming data from the terminal 40. The S-GW 80 is responsible for an anchoring function for terminal movement between the base station (Home-eNB / eNB) and the base station (Home-eNB / eNB), between the 3GPP network and the E-UTRAN, and the P-GW ( An IP network is connected through a PDN (Packet Data Network) Gateway (PDN) 90.

MME (60) / S-GW (80) that is the core network equipment manages a plurality of base stations (Home-eNB, eNB), each base station (Home-eNB, eNB) is composed of a plurality of cells. The C-plane / U-plane is controlled between the base station (Home-eNB, eNB) and the MME 60 / S-GW 80 through the S1 interface, and the handover and SON functions between the base stations (Home-eNB / eNB) are controlled. Use the X2 interface for this.

Hereinafter, with reference to FIG. 3, a handover procedure to a home-eNB operating in a closed or hybrid access mode will be described.

The UE receives a white list from the MME 60 in an attach process or a tracking area update (TAU) process according to a change in a tracking area code (TAC) accompanying power on (301) (301). ). Alternatively, the white list may be directly added to the USIM of the UE.

The UE sets up a call to a general macro base station eNB (302).

The serving base station (eNB) transmits Report Proximity Config to the UE by using an RRC connection reconfiguration message (303). The Report Proximity Config indicates whether the UE is allowed to report a function to the serving base station eNB when the UE accesses the target small base station Home-eNB in its cell area.

Thereafter, when the UE UE approaches the target home-eNB, it reports that it is “Entering”, meaning that it has approached the Proximity indication including the corresponding frequency (304).

If the frequency of the target home-eNB in the Proximity indication reported by the UE is different from the current busy frequency, the serving base station eNB uses the RRC connection reconfiguration message to search for the inter-frequency. The measurement gap is allocated (305). In response to this, the UE measures the PCI of the target home-eNB and reports the PCI to the serving base station eNB through a measurement report message when the handover condition is satisfied (306). . Then, the serving base station eNB uses the RRC connection reconfiguration message to read the SIB and report specific information to the terminal UE in order to obtain information of the target small base station Home-eNB having the PCI reported by the terminal UE. The SI request is transmitted (307).

The UE (UE) obtains a CGI, a CSG indicator, a CSG identifier (CSG Identity), and the like through SIB 1 transmitted by the target miniature base station (Home-eNB). The measurement information message is transmitted to the serving base station eNB (310).

Typically, the measurement report message includes CGI, CSG Identity, and Member Indication information. Member Indication is set to member if the CSG ID in SIB1 exists in the UE's own white list. If not, Member Indication is not included in the message. However, when the CSG ID is present in the white list of the terminal, the serving base station eNB cannot accurately determine the access mode of the target micro base station Home-eNB. Because if the Member Indication is set to "member", the same applies to the closed access mode. Therefore, the serving base station (eNB) is closed only by the "member" information set in the Member Indication, and the target small base station (Home-eNB) is closed. It is not possible to tell whether it is operating in the type connection mode or the hybrid connection mode. The serving base station eNB, which does not know in advance the access mode of the target micro-NB, transmits a handover request message to the MME 60 based on a measurement report message. The over request message is transmitted by setting the connection mode to "hybrid" when the target micro base station (Home-eNB) is in the hybrid connection mode, and transmits without including the connection mode. However, from the standpoint of the serving base station eNB, which cannot accurately determine the access mode of the target small base station Home-eNB, the transmission mode of the target small base station Home-eNB is set to “hybrid”. Or it can not be transmitted without including the connection mode.

Then, the MME 60 compares the CSG identifier in the handover request message with the white list of the existing subscriber DB and determines whether the connection is possible. It is operated in the closed access mode, the connection is not possible), handover preparation failure (HO preparation failure) message is transmitted to the serving base station (eNB). When the home-eNB operates in the closed access mode, the UE which cannot be connected performs a handover procedure, thereby causing unnecessary messages (eg, a handover request message to the MME, a handover preparation failure message, etc.). Generated, causing the problem of increased occupied radio resources (increased system load).

Therefore, in the present invention, in order to prevent the serving base station eNB from requesting unnecessary handover, the UE UE checks the access mode of the target micro-NB in advance (309).

When the UE UE approaches the home-eNB operating in the closed access mode, if the CSG identifier ID of the target home-eNB is not in the white list of the UE, the UE ) Does not transmit the measurement report message unnecessarily to the serving base station (eNB) because it is impossible to access the small base station (Home-eNB).

As a result of the check, if the CSG identifier (ID) of the target small base station (Home-eNB) is in the white list of the terminal, the UE (UE) transmits a measurement report message to the small base station (Home-eNB) (310). However, at this time, the Member Indication of the measurement report message is not set to "member" by referring only to the case where the CSG ID exists in the white list of the terminal, but the target micro-base station (Home-eNB) is closed in the serving base station (eNB). Mode, so that the CSG ID is present and the target home-eNB is operating in hybrid access mode (ie, the CSG ID is present and the CSG indicator is' False), and sends the Member Indication of the measurement report message set to "member".

The serving base station (eNB) then intuitively recognizes that the target small base station (Home-eNB) operates in a hybrid connection mode by referring to the Member Indication (set to "member") of the measurement report message, and sets the connection mode to "hybrid ( hybrid) "and transmits a handover request message to the MME 60 (311). If the Member Indication of the measurement report message is not set to "member", the serving base station eNB does not transmit the handover request message to the MME 60.

Therefore, unnecessary messages (measurement report message, handover request message, and handover preparation failure message) do not occur during the handover procedure of the UE that is not accessible, thereby improving the efficiency of radio resources.

Since the connection mode of the handover request message is set to "hybrid", the MME 60 determines that the target home-eNB operates in the hybrid connection mode and determines the membership status. The membership status is set to "member" if the CSD ID exists in the white list of the existing subscriber DB, and set to "non-member" if the CSD ID in the handover request message does not exist in the white list of the existing subscriber DB. The message is directly transmitted to the small base station (Home-eNB) according to the presence of the small base station gateway (313-3) or transmitted to the target small base station (Home-eNB) through the small base station gateway (313-1,313-2).

The target micro-base station determines whether the CSG ID in the handover request message and the CSG ID in SIB 1 that it transmits match (314).

As a result of the check, if it does not match, a handover preparation failure message is transmitted to the MME 60, and if there is a membership state, it is reflected in the subscriber's priority.

The target small base station (home-eNB) notifies the base station (eNB) through the MME 60 (including the small base station gateway, if present) that the handover preparation is completed, and finally the terminal (UE) to the target small base station ( Home-eNB) to handover (315 ~ 317).

Although the method has been described through specific embodiments, the method may also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. 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, and the like, and may be implemented in the form of a carrier wave (for example, transmission over the Internet) . The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the above embodiments can be easily deduced by programmers of the present invention.

Although the present invention has been described in connection with some embodiments thereof, it should be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention as understood by those skilled in the art. something to do. It is also contemplated that such variations and modifications are within the scope of the claims appended hereto.

10,20,30: Macro base station 11-15, 21-23, 31-33: Micro base station
40: terminal (UE) 50: SON server
60: MME 70: management server
80: Serving Gateway (S-GW) 90: PDN Gateway (P-GW)

Claims (11)

As a method of providing mobility,
a) checking, by a terminal, a connection mode of a target micro base station for handover; And
b) when the terminal transmits a measurement report message for handover to a serving base station, providing access mode information of the target ultra-compact base station. The method of claim 1,
The measurement report message includes a Cell Global Identity (CGI) and a Closed Subscriber Group (CSG) identifier (CSG Identity) of the target miniature base station. The method of claim 2,
In the step b), if the CSG identifier is not present in the white list of the terminal and the connection of the target ultra-compact base station is impossible, the terminal further comprising the step of not transmitting the measurement report message to the serving base station, How to provide mobility. The method of claim 2,
And the target subminiature base station operates in a hybrid connected mode. The method of claim 4, wherein
The access mode information is information for informing that the CSG identifier is present in the white list of the terminal and that the target subminiature base station operates in a hybrid access mode. The method of claim 5,
If the target ultra-compact base station is operating in a hybrid access mode, the serving base station further sets the access mode to 'hybrid' and sends a handover request message to the mobility management entity (MME). As a mobile communication system,
And a terminal for checking the access mode of the target miniature base station for handover, and providing the access mode information of the target miniature base station when transmitting a measurement report message for handover to a serving base station. The method of claim 7, wherein
The measurement report message includes a Cell Global Identity (CGI) and a Closed Subscriber Group (CSG) identifier (CSG Identity) of the target ultra-compact base station. The method of claim 8,
The terminal does not transmit the measurement report message to the serving base station if the CSG identifier is not present in the white list of the terminal and the target micro base station is not accessible. The method of claim 8,
The target micro base station operates in a hybrid connection mode,
The access mode information is information indicating that the CSG identifier is present in the white list of the terminal and that the target micro base station operates in a hybrid access mode. The method of claim 10,
And a serving base station for transmitting a handover request message to a mobility management entity (MME) by setting the connection mode to 'hybrid' when the target micro base station operates in a hybrid access mode.

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