KR20150084240A - Method and apparatus for handover processing of user equipment not being able to access to femto base station, and mobile telecommunication system for the same - Google Patents

Abstract

The present invention relates to an apparatus and a method for handover processing to reduce the interference during the handover. The apparatus for handover processing provides a source eNB to determine the availability of connectivity of user terminal on a target HeNB before sending a handover requesting message to Mobility Management Entity(MME), when the target HeNB is determined to connect, the source eNB sends the handover requesting message to MME, and the user terminal is determined to be not able to connect to the target HeNB or the frequency used are different or used by other base station, the service is provided through other base station, and when the user terminal is determined to be not able to connect to the target HeNB and the user moved to a location where the frequency of target HeNB is different or not in used, the wireless source distributed from the target HeNB is avoided and other wireless source is distributed to user terminal.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a handover processing method and apparatus for a terminal that can not be connected to a femto base station, and a mobile communication system for the handover processing method and apparatus. 2. Description of the Related Art [

The present invention relates to a handover processing method of a terminal that can not connect to a closed femto base station in a mobile communication system having a hierarchical structure, and a handover processing method and apparatus capable of reducing handover interference.

Recently, due to the rapid development of communication, computer network and semiconductor technology, not only various services using wireless communication networks have been provided, but the demand of users has been increasing day by day, and the global wireless Internet service market has been exploding Trend. Accordingly, a service provided by a mobile communication system using a wireless communication network is being developed not only as a voice service, but also as a multimedia communication service for transmitting various data.

Recently, with the increase of smart phones and the demand for data traffic, mobile operators are investing equipment and technology considering the system part and the influence to accommodate the increased data traffic in various ways.

Wireless data services of CDMA (Code Division Multiple Access) 2000, Evolution Data Only (EV-DO), Wideband CDMA (WCDMA), Wireless Local Area Network (WLAN) and Long Term Evolution (LTE) The demand for mobile phone use and mobile data is continuously increasing. In accordance with this trend, a method of providing a mobile communication service by installing an ultra-small base station in the indoor area so as to access a mobile communication core network through an indoor broadband network has been proposed. In particular, in a next generation network system, a method of arranging a plurality of small-sized multi-cells (femtocells) as an alternative to satisfy a demand for a high data rate and stably providing various services is suggested. An ultra-small 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 a next generation network system using a high frequency band can be increased. In addition, the use of a plurality of small-sized cells is advantageous in terms of increasing the frequency reuse frequency. In addition, it is possible to improve the problem of deterioration of the channel condition due to the radio wave attenuation which occurred when one base station covers the entire cell area and the problem of inability to service the users in the shadow area, This has the advantage. Based on these advantages, a method of combining a macro cell (a cell area managed by an outdoor base station) and a femtocell (a cell area managed by an ultra-small base station such as an indoor base station or a femto base station) Is emerging.

Long Term Evolution (LTE) is a network for realizing requirements of high data rate, low-latency, and packet optimized radio access for an access network , And is designed to accommodate high-speed rich media while ensuring backward compatibility with existing 3GPP / non-3GPP access networks. LTE is an All-IP-based network that excludes existing circuit-switched based communications and enhances quality of service (OoS) management functions to provide real-time services (eg, voice communications, video communications) By providing differentiated QoS for real-time services (eg, web browsing, Store and Forward data transfer), we have increased the efficiency of network resources. In addition, by introducing smart antenna technology (ie, MIMO), the bandwidth for wireless communications has been extended.

In the Evolved Packet Core (EPC) network, which is an LTE core network, eNodeB <-> MME (Mobility Management Entity), MME <-> S-GW (Serving Gateway), and S-GW < Data Network Gateway) to perform call processing for voice and data processing.

In a handover for moving a base station controlled by a user equipment (UE), if there is a user terminal that can not be connected in the base station (eNodeB) during handover, an unnecessary message is continuously generated from the corresponding user terminal, There is a problem that affects the load.

Korean Patent Publication No. 10-2010-0032605 (published on Mar. 26, 2010)

The present invention provides a handover processing method of a terminal that can not connect to a closed femto base station in a mobile communication system having a hierarchical structure, and a handover processing method and apparatus capable of reducing handover interference.

The handover processing method of the present invention is characterized in that a) a source eNB is connected to a target base station (target HeNB) before a handover request message is transmitted to an MME (Mobility Management Entity) B) if the source base station determines that the user terminal is connectable to the target micro-base station, transmitting the handover request message to the MME; and c) When a frequency different from a frequency used by the target micro-base station is used by the source base station or another base station in an area where the target micro-base station is not accessible and the user terminal moves, Receiving the service using the source base station or the other base station; d) When a base station user terminal is determined not to be connectable to the target micro base station and a frequency different from a frequency used by the target micro base station is not used by the source base station or the other base station in an area where the user terminal has moved And allocating another radio resource to the user terminal while avoiding radio resources allocated by the target micro base station.

In addition, the handover processing apparatus of the present invention may be configured such that, prior to transmission of a handover request message from a source eNB to a Mobility Management Entity (MME), the handover processing apparatus determines whether the user terminal can access the target ultra- And controlling the source base station to transmit the handover request message to the MME when it is determined that the user terminal can access the target micro base station, When it is determined that the terminal can not access the target micro-base station, if a frequency different from the frequency used by the target micro-base station is used by the source base station or another base station in the area where the user terminal moves, The source base station or the other base station And if a frequency different from the frequency used by the target micro-base station is not used by the source base station or the other base station in the region where the user terminal moves, And a control unit for avoiding radio resources and allocating other radio resources to the user terminals.

According to the present invention, a user terminal that can not connect to a target eNodeB during a handover does not generate an unnecessary message, thereby reducing system load and improving system performance.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a configuration of an exemplary mobile communication network in which the present invention can be implemented; Fig.
2 is a diagram showing an embodiment of an EPC network to which the present invention can be applied;
3 is a schematic view showing the configuration of an EPC network according to an embodiment of the present invention.
4 is a diagram illustrating a call processing procedure for handover in an EPC network according to an embodiment of the present invention.
5 is a configuration diagram of a handover processing apparatus 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.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a configuration of an exemplary mobile communication network in which the present invention can be implemented. Fig.

In one embodiment, the mobile communication network includes a wireless network such as a Global System for Mobile communication (GSM), a 2G wireless communication network such as CDMA, an LTE network, a wireless Internet such as WiFi, a Wireless Broadband Internet (WiBro), and a World Interoperability for Microwave Access (E.g., 3G mobile communication network such as WCDMA or CDMA2000, High Speed Downlink Packet Access (HSDPA) or 3.5G mobile communication network such as HSUPA (High Speed Uplink Packet Access), or the like (4G mobile communication network currently in service), a macro base station (macro eNodeB), a micro base station (Pico eNodeB, a Home-eNodeB) and a terminal (UE) But is not limited thereto. Hereinafter, an E-UTRAN (Evolved Universal Terrestrial Radio Access Network) as a radio access network of LTE will be mainly described.

As shown in FIG. 1, the mobile communication network may include one or more network cells, and may include a Heterogeneous Network (HET) environment in which different kinds of network cells may be mixed in a mobile communication network. The mobile communication network includes miniature base stations (Pico eNodeB, Home-eNodeB, relay, etc.) 11 to 15, 21 to 23, and the like, which manage small-sized network cells (e.g., 'small cells' such as picocells, femtocells, (MAC) eNodeBs 10, 20 and 30, a UE 40, and SON (Self Organizing) terminals 40 and 40 for managing a wide range of cells (eg, 'macro cells' (MSS) 60, an S-GW (Serving Gateway) 80, a P-GW (Packet Data Network) gateway 90 and an HSS Server 100). The number of each component shown in FIG. 1 is illustrative, and the number of each component of the mobile communication network in which the present invention can be implemented is not limited to the number shown in the drawings.

For example, the macro base stations 10, 20 and 30 can be used in an LTE network, a WiFi network, a WiBro network, a WiMax network, a WCDMA network, a CDMA network, a UMTS network, But is not limited to, the characteristics of the macro cell base station that manages the base station.

The micro base stations 11 to 15 and 21 to 23 and 31 to 33 may be used in an LTE network, a WiFi network, a WiBro network, a WiMax network, a WCDMA network, a CDMA network, a UMTS network, but is not limited to, the features of a pico base station, an indoor base station or a femto base station, or a relay that manages a cell having a radius of about m to several tens of meters.

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

The user equipment (UE) 40 may be a mobile Internet network such as a 2G wireless communication network such as a GSM network, a CDMA network, a wireless Internet network such as an LTE network and a WiFi network, a WiBro network and a WiMax network. But is not limited to, the characteristics of a mobile terminal used in a communication network.

The management server (O & M server) 70, which is a network management apparatus of the micro-base station, is responsible for configuration information and management of the micro base stations 11 to 15, 21 to 23, and 31 to 33 and the macro base stations 10, . The management server 70 can perform all the functions of the SON server 50, the MME 60, and the HSS 100. [ SON server 50 may include any server that performs macro / micro base station installation and optimization and functions to provide basic parameters or data necessary for each base station. The MME 60 may include any entity used to manage the mobility of the user terminal 40 and the like. In addition, the MME 60 performs a function of a base station controller (BSC) and performs resource allocation, call control, handover control, voice and packet processing control, and the like on a base station (pico eNodeB, HeNB, macro eNodeB, Can be performed. The HSS 100 is a kind of database for service / authentication of the subscriber.

In one embodiment, one management server 70 can perform all the functions of the SON server 50, the MME 60, and the HSS 100, and the SON server 50, the MME 60, The base station 100 can manage one or more macro base stations 10, 20 and 30 and one or more micro base stations 11 to 15, 21 to 23 and 31 to 33.

Although it is assumed that a macro cell, a pico cell, and a femtocell are mixed in the mobile communication network, the network cell may be composed of a macro cell, a pico cell, and a macro cell.

Specifically, the micro-base stations 11 to 15, 21 to 23, and 31 to 33 can broadcast a system information block (SIB), which is system information, to a femtocell area managed by itself. And a CSG indicator (Closed Subscriber Group indicator) indicating whether or not it is restricted. SIB is a message that a base station (HeNB, macro eNB) broadcasts information about its own cell to all the user terminals 40. The SIB includes a CGI (Cell Global Identity) (unique cell classification factor in the network), a CSG indication , A CSG ID (ID for a specific subscriber group), and the like.

Access to the macro base stations 10, 20 and 30 is normally permitted to all user terminals, but access to the micro base stations 11 to 15, 21 to 23, and 31 to 33 is performed by a specific user terminal (subscriber) And the like. The connection mode of the micro base stations 11 to 15, 21 to 23, and 31 to 33 may be classified as shown in Table 1 according to which user terminal is provided with service . That is, a closed connection mode, an open connection mode, and a hybrid connection mode. The closed access mode (closed access mode or CSG closed mode) permits access only to a specific subscriber in a home or the like. The CSG indication, which is the connection mode classification factors of the micro-base station transmitted through the SIB, is set to & ID &lt; / RTI &gt; An open access mode (open access mode or CSG open mode) is a mode in which any subscriber can access without a connection permission condition in a railway station, an airport, an inbuilding, etc., and the CSG indication is "False" And may not include the CSG ID. Hybrid access mode is a mode in which any subscriber can access in a public place such as a coffee shop or a shopping mall. The CSG indication may be set to "False" and may include a CSG ID. The hybrid connection mode differs from the open connection mode in that the CSG ID of the micro base station is added to the whitelist (White List) stored in the UE 40 (indicating the CSG ID list of the micro base station to which the UE 40 is connectable) The UE 40 can provide a service with a high priority to the UE 40. If the CSG ID of the base station does not exist in the whitelist stored in the UE 40, The service can be provided with a lower priority than that of the service.

Ultra-small base station access mode Open connection mode Closed connection mode Hybrid connection mode purpose Train station, airport, building inside home Coffee shop, shopping mall Notification from micro base station CSG indication = False
CSG identity: Not included CSG indication = True
CSG identity: included CSG indication = False
CSG identity: included

When 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.). (LTE network, WiFi network, WiMax network, WCDMA network, CDMA network, UMTS network, GSM network, etc.) when one of the inter-RAT networks . (WiFi network, WiMax network, WCDMA network, CDMA network, UMTS network, GSM network, etc.) are shown apart from each other in the drawing, it is assumed that it is overlaid.

When the micro base stations 11 to 15, 21 to 23 and 31 to 33 and / or the macro base stations 10, 20 and 30 are collectively referred to as a 'base station device', the base station device (eNB 25 in FIG. The E-UTRAN having an IP-based flat structure can process data traffic between the user terminal 40 and the core network. The signal control between them can be handled by the MME 60. The MME 60 is responsible for signal control between the base station device 25 and the S-GW 80 and can determine where to route incoming data from the user terminal 40. The S-GW 80 performs an anchor function between the base station device 25 and the base station device 25 to move a terminal between the 3GPP network and the E-UTRAN, . The MME 60 / S-GW 80, which is a core network equipment, manages a plurality of base station devices 25, and each base station device 25 can be composed of several cells. The C-plane / U-plane is controlled between the base station device 25 and the MME 60 / S-GW 80 through the S1 interface and the X2 interface is used for the handover between the base station devices 25 and the SON function. .

The setup of the network interface can be made by setting the S1 interface connecting with the MME 60 in the center of the system and the X2 interface being a network line for direct communication with the base station device 25 of other cells present on the current system have. The S1 interface can exchange OAM (Operation and Management) information to support the movement of the UE 40 by exchanging signals with the MME 60. [ Also, the X2 interface can exchange information for fast handover, load indicator information, and self-optimization information between the base station apparatuses 25.

Referring to FIG. 2, a configuration of an EPC (Evolved Packet Core) network to which the present invention can be applied will be described. A call processing procedure for handover in an EPC network will be described with reference to FIG.

2 is a diagram showing an embodiment of an EPC network to which the present invention can be applied.

The E-UTRAN is an LTE radio access network composed of a base station apparatus (eNB) 25, is IP-based, and is located between the UE 40 and a core network for transmitting data and control information. In addition, a paging request for a circuit switch (CS) fallback, a function for delivering an SMS message to the UE 40, and a direct connection to a target cell capable of a CS service can be supported.

2, "LTE-uu" denotes an air interface between the E-UTRAN and the UE 40, "S1-MME" denotes an interface between the E-UTRAN (base station device 25) and the MME 60, "S1-U" is an interface between the E-UTRAN (base station apparatus 25) and the S-GW 80. "S5 / S8" is an interface between the S- Lt; / RTI &gt; And "SGi" may be an interface between the P-GW 90 and the IP network.

The UE 40 and the eNB 25 of the E-UTRAN communicate via a Radio Resource Control (RRC) protocol, and the base station 25 transmits a broadcast message May be defined as an RRC message. The RRC message may include control messages from the Non-Access Stratum (NAS) protocol, which may be transparently transferred to the UE 40 or the core network without being read in the E-UTRAN.

The base station device 25 is an end point for the radio signal of the E-UTRAN and the control signal is interlocked with the MME 60 via the S1-MME interface and the data traffic is transmitted to the S-GW 80 via the S1- Can be interlocked. The S-GW 80 can perform a buffering function for anchor and downlink traffic for mobility in the E-UTRAN. The P-GW 90 is an external IP network connection point, and can perform IP allocation and billing for a mobile subscriber, and traffic control functions for user data.

Data traffic downloaded from the EPC network can be delivered through mapping between the SGi interface, the S5 / S8 interface, the S1-U interface, and the LTE-uu interface section.

The IP network provides an IMS (IP Multimedia Subsystem) service for the UE 40 in the EPC network, and includes Policy & Charging Rule Function (PCRF), IMS nodes (for example, Proxy Call Session Control Function (P-CSCF) (Interrogating Call Session Control Function (CSCF), Serving Call Session Control Function (S-CSCF), Application Function (AF)), and the like.

The UE 40 can send and receive a call control message for multimedia services using the Gm interface with the IMS nodes via an EPC bearer (provided by E-UTRAN / S-GW / P-GW).

The E-UTRAN 25 may provide a wireless communication function to the UE 40 and may perform a function of managing radio resources for this purpose.

The MME 60 may receive authentication information for authenticating the UE 40 from the HSS 100 and perform authentication of the UE 40. [ In addition, the MME 60 manages the mobility of the UE 40 and the base station apparatus 25 in the upper layer of the base station apparatus 25, and can perform a call control function such as bearer setup / release. In addition, the MME 60 can be directly connected to the IP network through the S-GW 80 and the P-GW 90. The call processing control signal of the base station apparatus 25 is transmitted to the S-GW 80 via the MME 60 and is transmitted to the P-GW 90 in response to the call processing control signal, Lt; / RTI &gt;

The S-GW 80 acts as a gateway between the 3GPP network and the E-UTRAN 25 and performs handover between the base station apparatus and the base station apparatus (inter-eNodeB) and between the 3GPP network and the 3GPP network (inter-3GPP) 40 to provide a mobility anchor function. The S-GW 80 can transmit to the P-GW 90 a job necessary for call processing in accordance with the control signal of the base station device 25. [

The P-GW 90 may allocate an IP address to the UE 40 and apply different QoS policies to the UE 40. [ In addition, the P-GW 90 acts as a gateway to a PDN (Packet Data Network), allowing the UE 40 to access a data network such as the Internet or the Internet to receive services.

The S-GW 80 and the P-GW 90 are separated and communicate with each other via the S5 / S8 interface. However, the S-GW 80 and the P-GW 90 may be implemented as a single gateway .

The HSS 100 may manage authentication information for authenticating the UE 40, location information of the UE 40, and the profile of the UE 40. [ The profile of the UE 40 may include QoS rating information (e.g., priority, maximum available bandwidth, etc.) for each service item to which each UE 40 subscribes. In one embodiment, the authentication information for authenticating the UE 40 and the profile of the UE 40 may be transferred from the HSS 100 to the MME 60 when the UE 40 connects to the network.

The PCRF (not shown) manages policies and rules for charging and allows the P-GW 90 and the S-GW 80 to provide appropriate QoS for the UE 40 and use Allows you to perform the billing function for the bearer.

The IMS node (not shown) is made up of nodes such as P-CSCF, I-CSCF, S-CSCF, and AF in detail and the UE 40 provides multimedia services such as VoIP give.

3 is a schematic view showing the configuration of an EPC network according to an embodiment of the present invention.

The MME 60 and the S-GW 80 are located in the EPC network 80. Each of the MME 60 and the S-GW 80 includes a plurality of macro base stations (eNB) 25a, a very small base station (HeNB) 25b and an ultra-small gateway (HeNB gateway) 25c connected to the micro-base station. The micro-base station 25c used in the home can minimize the influence of the MME 60 / S-GW 80 because the micro-gateway 25c can manage the MME 60 / S-GW 80 directly. 60) / S-GW (80).

Handover can be classified into two types according to EPC intervention. The handover preparation and execution between the source base station 25a and the target base station 25b are interrupted by the X2 handover and the EPC in which handover preparation and execution are performed between the source base station (Source eNB) and the target base station (Target eNB) And the S1 handover in which the handover is performed. Table 2 below shows a base station type supporting X2 handover. The macro base station (eNB) does not provide the X2 handover to the ultra-small base station (HeNB) supporting the closed connection mode and must perform the S1 handover.

Source base station target  Base station Reference Macro base station or all micro base stations Compact base station supporting open access mode Macro base station or all micro base stations Compact base station supporting hybrid connection mode Very small base station supporting hybrid connection mode or very small base station supporting closed connection mode Compact base station supporting closed connection mode The source base station and the target base station have the same CSG ID and a public land mobile network (PLMN), which is a unique identifier of a company providing a mobile communication service, and are applicable only when the user terminal is a subscriber of the CSG cell. All ultra-small base stations Macro base station

4 is a diagram illustrating a call processing procedure for handover in an EPC network according to an embodiment of the present invention.

4, the UE 40 periodically measures the PCI (Physical Cell Identity) of the micro-base station (HeNB), and if it satisfies a specific condition, reports the PCI to the source base station 25a through the Measurement Report message (S401). The source base station 25a reads the SIB of the corresponding micro-base station (HeNB) and reports specific information to the UE 40 in order to obtain information of the micro-base station (HeNB) having the PCI reported by the UE 40. The RRC Connection Reconfiguration message To request an SI Request (S402). All the small base stations (HeNBs) can periodically broadcast their system information (CGI, TAI: Tracking Area Indicator, CSG Indication, CSG ID, etc.) through the SIB (S403). The UE 40 reads information such as CGI, CSG Indication, and CSG ID through the SIB of the target micro base station 25b, and reports the corresponding information and the Member Indication to the source base station 25a via the Measurement Report message (S404 ). If the CSG ID of the target micro base station 25b is present in the whitelist of the UE 40, the Member Indication may be included in the Measurement Report. If the CSG ID does not exist in the whitelist of the UE 40, It can be set not to include in Report. The source base station 25a may perform a preliminary access check as follows (S405) so as not to request an unnecessary handover request (HO Required) message. Since the source base station 25a has already recognized the PCI information used by all the micro-base stations in its area, the preliminary access check can be used for handover to the closed-type micro base station. And the preliminary access check can be performed only when the target tiny base station 25b is a closed-type micro-base station.

When the source base station 25a includes the CSG ID and the member indication in the information received by the Measurement Report message, the corresponding UE 40 determines that the target base station 25b can access the target base station 25b and transmits an HO Required message to the MME 60. [ (S407). On the other hand, if the Measurement Report message includes the CSG ID and does not include the member indication, the UE 40 can determine that the target micro base station 25b can not be connected.

It is determined that the UE 40 is not connectable to the target micro base station 25b and a frequency different from the frequency used by the target micro base station 25b is transmitted to the source base station 25a or another base station 25b, (Not shown), the UE 40 releases the connection with the base station to which the UE 40 is provided and connects to the source base station 25a or another base station using another frequency (RRC Connection Release with redirection The UE 40 can be controlled to transit to another frequency so that the UE 40 can receive the service of the source base station 25a or the other base station using another frequency or through the handover, In order to reduce interference to the target micro base station 25b when there is no other frequency in the area where the UE 40 can not be connected to the micro base station 25b and the UE 40 moves A method of avoiding the radio resources allocated by the target micro base station 25b and allocating other radio resources to the user terminal 40 can be used (S406). Herein, the RRC Connection Release with redirection refers to a method in which the UE 40 receives information of a base station to which the UE 40 is to move and performs a call connection process to the base station from the beginning to move a base station to receive a service, A method of moving a base station to which a service is provided without performing a call connection process may be indicated.

If handover is possible, the source base station 25a may transmit an HO Required message to the MME 60 based on the Measurement Report message (S407). The MME 60 may compare the CSG ID with the whitelist of the existing subscriber database (DB) in the HO Required message to determine whether the connection is possible (S408). As a result of the determination, if the access is not possible, the HO Preparation Failure message is transmitted to the source base station 25a, and the membership status of the UE 40 can be determined in the following two cases.

- Member: The CSG ID in the HO Required message is present in the whitelist of the existing subscriber DB.

- Non-member: The CSG ID in the HO Required message does not exist in the whitelist of the existing subscriber DB.

The MME 60 can directly request an HO Request message to the target micro base station 25b if the micro gateway 25c does not exist according to the presence of the ultra small gateway 25c when the connection is possible, If the gateway 25c exists, it can be requested through the ultra-small gateway 25c (S409, S410).

The target micro base station 25b may check whether the CSG ID in the HO Request message matches the CSG ID in the SIB broadcasted by the target base station 25b in step S411. If the CSG ID does not match, the target micro base station 25b may transmit an HO Failure message to the MME 60. On the other hand, if the CSG ID in the HO Request message matches the CSG ID in the SIB to which it is broadcasted, the target micro-base station 25b notifies the source of the requested handover completion through the ultra-small gateway 25c and the MME 60 (S412, S413, S414), and finally instructs the UE 40 to perform handover to the target micro base station 25b (S413).

5 is a configuration diagram of a handover processing apparatus according to an embodiment of the present invention.

5, the handover processing apparatus 500 may include a preliminary connection determining unit 510, a control unit 520, a handover performing unit 530, and a radio resource allocating unit 540.

The preliminary connection determining unit 510 may determine whether the source base station 25a can access the target micro base station 25b before transmitting the handover request message to the MME 60. [ If the CSG ID and the Member Indication exist in the Measurement Report message transmitted from the UE 40 to the source base station 25a, the preliminary connection determining unit 510 determines that the corresponding UE 40 is the target micro BS 25b, And if the CSG ID exists in the Measurement Report message and the Member Indication does not exist, the UE 40 can determine that the target micro base station 25b can not be accessed.

The control unit 520 controls the handover performing unit 530 to transmit the HO Required message to the MME 60 when the preliminary connection determining unit 510 determines that the UE 40 can access the target micro BS 25b, The preliminary connection determination unit 510 determines that the UE 40 can not access the target micro base station 25b and the target micro base station 25b is used in the region where the UE 40 has moved The RRC connection release with redirection or handover may be performed so that the corresponding UE 40 can receive service using another base station when the source base station 25a or another base station uses a different frequency. On the other hand, if it is determined that the UE 40 is not connectable to the target micro base station 25b and a frequency different from the frequency used by the target micro base station 25b in the area where the UE 40 has moved is received by the source base station 25a If it is not being used by another base station, allocates another radio resource to the UE 40 by avoiding the radio resources allocated by the target micro base station 25b in order to reduce interference to the target micro base station 25b The radio resource assignment unit 540 can be controlled. As an example, a radio resource other than the radio resource currently used by the UE 40 may be a radio resource that does not conflict with the current time zone.

Under the control of the control unit 520, the handover performing unit 530 may transmit an HO Required message to the MME 60 when it is determined that the UE 40 can access the target micro base station 25b, Is not accessible to the target micro base station 25b and there is a frequency different from the frequency used by the target micro base station 25b in the area where the UE 40 has moved, Handover can be performed so as to make a transition.

The radio resource assignment unit 540 determines that the UE 40 can not access the target micro BS 25b under the control of the control unit 520 and determines that the target micro BS The UE 40 can allocate a radio resource other than the radio resources currently used by the target micro base station 25b to the UE 40 when the frequency that is different from the frequency is not used by another base station.

Although the method has been described through particular embodiments, the method may also be implemented as computer readable code 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, and the like, and may be implemented in the form of a carrier wave (for example, transmission over the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. 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.

11 to 15, 21 to 23, and 31 to 33: micro base stations 10, 20, and 30:
40: User terminal 50: SON server
60: MME 80: S-GW
90: P-GW 100: HSS
500: Handover processing device 510:
520: control unit 530: handover performing unit
540: Radio resource allocation unit

Claims (8)

A handover processing method comprising:
the method comprising the steps of: a) determining whether the source eNB is able to access the target base station (target HeNB) before the handover request message is transmitted to the MME (Mobility Management Entity)
b) if the source base station determines that the user terminal is connectable to the target micro-base station, transmitting the handover request message to the MME;
c) if a frequency different from a frequency used by the target micro-base station is used by the source base station or another base station in an area where the user terminal is determined to be unreachable to the target micro-base station, , Causing the user terminal to receive a service using the source base station or the other base station,
d) If the user terminal is determined to be unreachable to the target micro-base station and a frequency different from the frequency used by the target micro-base station is used by the source base station or the other base station in the area where the user terminal has moved , Allocating another radio resource to the user terminal by avoiding radio resources allocated by the target micro-base station
The handover processing method comprising: The method according to claim 1,
The step a)
If the Measurement Report message transmitted from the user terminal to the source base station includes a specific subscriber group identity (CSG ID) of a target base station and a member indication, the user terminal can access the target base station And determining that the user terminal is not reachable to the target micro-base station if the Measurement Report message includes the CSG ID and does not include the Member Indication. 3. The method of claim 2,
The step a)
If the CSG ID is present in a whitelist representing a CSG ID list of a micro base station to which the user terminal is connectable, the user terminal sets the Member Indicatoin to be included in the Measurement Report message, And if it is not present in the Measurement Report message, the Member Indicatoin is not included in the Measurement Report message. The method according to claim 1,
The step c)
(RRC) connection release with redirection or handover to the source base station or the other base station using the different frequency. And controlling the source base station or the other base station to use the service of the source base station or the other base station to be used. A handover processing apparatus comprising:
A preliminary connection judging unit for judging whether or not a user terminal is reachable to a target micro BS (target HeNB) before transmission of a handover request message from a source eNB to a Mobility Management Entity (MME)
If it is determined that the user terminal can access the target micro-base station, the source base station controls the source base station to transmit the handover request message to the MME, and the user terminal can not access the target micro base station If a frequency different from the frequency used by the target micro-base station is used by the source base station or another base station in the region where the user terminal moves, the user terminal uses the source base station or the other base station And if a frequency different from a frequency used by the target micro-base station is not used by the source base station or the other base station in an area where the user terminal has moved, And a control unit for controlling to allocate another radio resource to the user terminal
And a handover processing unit. 6. The method of claim 5,
Wherein,
If the Measurement Report message transmitted from the user terminal to the source base station includes a specific subscriber group identity (CSG ID) of a target base station and a member indication, the user terminal can access the target base station And determines that the user terminal can not access the target micro-base station if the Measurement Report message includes the CSG ID and does not include the Member Indication. The method according to claim 6,
The user terminal comprises:
The target micro base station sets the Measurement Indication message to include the Member Indication if the CSG ID is present in a whitelist indicating a CSG ID list of a micro base station to which the user terminal is connectable, And not to include the Member Indicatoin in the Measurement Report message if it is not present in the list. 6. The method of claim 5,
Wherein,
And controls the user terminal to receive the service of the source base station or the other base station using the different frequency through RRC Connection Release with redirection or handover.

Images