KR20150072081A - Method and apparatus for processing of handover - Google Patents

Abstract

The present invention relates to a handover processing method and a device thereof. The present invention is used by user equipment (UE) in an evolved packet core network (EPC) to perform a handover operation in a section where an X2 connection to an evolved universal terrestrial radio access network (E-UTRAN), mobility management entity (MME), or serving gateway (S-GW) is not established or permitted. According to the present invention, the handover processing device performs an S1 handover operation by using an S1 interface when an X2 interface between a serving base station and a target base station is not available for the handover operation of the UE, and determines the occurrence of an X2 handover operation using the X2 interface from the target base station to a second target base station after the S1 handover operation is completed and before a tracking area update (TAU) process for registering the current location of the UE is completed. When the X2 handover operation is performed, the handover processing device postpones the TAU process, allocates a globally unique temporary identifier (GUTI) for the UE as a new member identification number, and transmits the GUTI to the second target base station.

Description

[0001] METHOD AND APPARATUS FOR PROCESSING OF HANDOVER [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly to a mobile communication system in which a user equipment (UE) in an EPC (Evolved Packet Core) network transmits an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), a Mobility Management Entity (MME) To a handover processing method and apparatus for smoothly performing a handover in an interval in which there is no or no X2 connection between a Serving Gateway (Serving Gateway).

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, EV-DO (Evolution Data Only), WCDMA (Wideband CDMA), and WLAN (Wireless Local Area Network) have been commercialized. Recently, There has been a proposal for providing a mobile communication service by installing an ultra-small base station indoors or outdoors to access a mobile communication core network through an indoor broadband network. 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 the EPC network, a control message such as call setup and release is recognized as an IP packet and transmitted to the P-GW or received from the P-GW and transmitted to the user equipment (UE). In this process, when a user terminal moves during a call, the call processing service can be seamlessly provided using the handover technique. However, if a user terminal moves to a new area and a handover occurs while a user terminal moves during a call and registers in a new area, there is a problem that call processing is disconnected.

Korean Patent Publication No. 10-2013-0083505 (published on July 23, 2013)

The present invention relates to a method for establishing an X2 connection between a Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a Mobility Management Entity (MME) or an S-GW (Serving Gateway) in a user terminal (UE) A handover processing method and apparatus for smoothly performing a handover in a non-existent or unacceptable section are provided.

A handover processing method of the present invention includes the steps of: a) performing S1 handover performed using an S1 interface when a handover of a user terminal can not be performed using an X2 interface between a serving base station and a target base station; b) performing a handover from the target BS to the second target BS using the X2 interface during a period before completion of the TAU (Tracking Area Update) procedure for registering the current location of the UE after the completion of the S1 handover; Determining whether a handover has occurred; And c) if the X2 handover occurs during the period before the completion of the TAU procedure after the completion of the S1 handover, pending the TAU procedure and transmitting a Globally Unique Temporary (GUTI) Identifier to the second target base station.

In addition, when the handover processing apparatus of the present invention can not perform a handover using the X2 interface between the serving base station and the target base station, after the S1 handover is performed using the S1 interface, a TAU (Tracking Area Update) A TAU processing unit for registering the current position of the user terminal through the TAU processing unit; If an X2 handover for performing a handover using the X2 interface occurs from the target BS to the second target BS after the S1 handover is completed and before the completion of the TAU procedure, A GUTI allocation unit for allocating a Globally Unique Temporary Identifier (GUTI); Determining whether the X2 handover has occurred during a period before completion of the TAU procedure after completion of the S1 handover, and if the X2 handover has occurred after completing the TAU procedure after completion of the S1 handover, And to transmit the allocated GUTI to the second target BS.

According to the present invention, when a new handover occurs during the handover, call processing such as mutual authentication of the MME and the MN, integrity and encryption algorithm delivery process, location registration, and bearer setup process is omitted, And the call processing is not interrupted, so that a high quality service can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a configuration of a mobile communication network according to an embodiment of the present invention; Fig.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]
3 is a diagram illustrating a call processing procedure for packet and voice service support in an EPC network according to an embodiment of the present invention.
4 is a diagram illustrating an S1 handover procedure according to an embodiment of the present invention.
FIG. 5 is an exemplary diagram illustrating an X2 handover procedure according to an embodiment of the present invention; FIG.
6 is an exemplary view showing a configuration of a handover processing apparatus according to an embodiment of the present invention.
7 is a flowchart illustrating a procedure of a handover processing method 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.

1 is a diagram illustrating a configuration of a mobile communication network according to an embodiment of the present invention.

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 (For example, 3G mobile communication network such as WCDMA or CDMA2000, High Speed Downlink Packet Access (HSDPA) or 3.5G mobile communication network such as High Speed Uplink Packet Access (HSUPA), or the like) A 4G mobile communication network currently in service, and any other mobile communication network including a macro base station (macro eNodeB), a micro base station (Pico eNodeB, Home eNodeB), and a user terminal (UE: User Equipment) However, the present invention 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, (Macro eNodeBs) 10, 20 and 30 for managing a wide range of cells (e.g., 'macro cells'), a user equipment (UE) 40, A SON (Self Organizing / Optimizing Networks) server 50, an MME (Mobility Management Entity) 60, an S-GW (Serving Gateway) 80, a P-GW (Packet Data Network) And a Home Subscriber Server (HSS) 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 terminal 40 may be a mobile Internet network such as a GSM network, a 2G wireless communication network such as a CDMA network, a wireless Internet network such as an LTE network and a WiFi network, a WiBro network, and a WiMax network, But are not limited to, the characteristics of the terminal.

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, and the like on the base stations (pico eNodeB, home eNodeB, macro eNodeB, Control and so on. 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.

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 (e.g., WiBro network) is the mobile communication network. (WiFi network, WiMax network, WCDMA network, CDMA network, UMTS network, GSM network, etc.) are shown apart from one another 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 Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) is an IP-based flat structure and handles data traffic between the user terminal 40 and the core network. The signal control between them is performed by the MME 60. The MME 60 takes charge of signal control between the base station device 25 and the S-GW 80 and determines where to route incoming data from the user terminal 40. [ The S-GW 80 is responsible for an anchor function between the base station device 25 and the base station device 25 for movement of a user terminal between the 3GPP network and the E-UTRAN, Connect to the network. 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 is composed of a plurality of cells. The S1 interface is used between the base station apparatus 25 and the MME 60 / S-GW 80 and the X2 interface is used for handover and SON functions between the base station apparatus 25 and the MME 60 /

The setup of the network interface is accomplished by setting up the S1 interface connecting with the MME 60 at the center of the system and the X2 interface, which is a network line for direct communication with the base station device 25 of other cells present on the current system. The S1 interface exchanges operation and management (OAM) information to support the movement of the user terminal 40 by exchanging signals with the MME 60. [ In addition, the X2 interface exchanges signals for fast handover, load indicator information, and information for self-optimization among 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 process for supporting packet and voice services in an EPC network will be described with reference to FIG.

2 is a diagram illustrating an exemplary configuration of an EPC network according to an embodiment of the present invention.

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 wireless communication core network to transmit data and control information. In addition, when a terminal using the LTE system moves to an existing 2G / 3G mobile communication network using a voice service, a paging request for a circuit switch (Fallback) to receive voice service, an SMS message to the UE 40 ) And a direct connection to a target cell capable of a CS service.

2, "LTE-Uu" denotes an air interface between the E-UTRAN (base station apparatus 25) and the UE 40, S5 / S8 "is an interface between the S-GW 80 and the E-UTRAN (base station device 25) and the S- GW 90. [0033] FIG. And "SGi" is 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 a broadcasting message to the cell area controlled by the eNB 25 RRC message. The RRC message may include control messages from the Non-Access Stratum (NAS) protocol, which are transparently transmitted to the UE 40 or the core network without being read in the E-UTRAN.

The eNB 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 interworked with the S-GW 80 via the S1- do. The S-GW 80 performs 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 performs IP allocation and billing for a mobile subscriber and traffic control functions for user data.

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.

UE 40 sends and receives a call control message for multimedia services using IMS nodes and the Gm interface through an EPC bearer (provided by E-UTRAN / S-GW / P-GW).

The E-UTRAN 25 provides a radio communication function to the UE 40 and performs a function of managing radio resources for the radio communication function.

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 diagram illustrating call processing procedures for packet and voice service support in an EPC network according to an embodiment of the present invention.

When the UE 40 requests the MME 60 to perform call processing through the E-UTRAN, the MME 60 receives the subscriber information for the UE 40 from the HSS 100. The bearer for packet transmission is established by the S-PW 80 / P-GW 90 by constructing various information necessary for the call processing, and the UE 40 responds.

Specifically, in order to receive the packet service and the voice service, the UE 40 first transmits a call setup request message to the radio section (S301).

The eNB 25 of the E-UTRAN forwards the call processing request message received from the UE 40 to the MME 60 (S302), and the MME 60 transmits the call processing request message The HSS 100 requests information for preparation of call setup with the UE 40 and receives information for preparation of call setup from the HSS 100 in step S303. The MME 60 selects one of the plurality of S-GWs 80 / P-GWs 90 using the information received from the HSS 100 and requests a bearer setup. When the bearer setup is completed (S304), a packet service and a voice service for the UE 40 are possible. At this time, upon completion of the bearer setup with the S-GW 80 / P-GW 90, the MME 60 transmits a completion message (attach complete) for the attach request of the UE 40 to the user And informs that the resource allocation for the network has been granted and assigned in the network.

Handover can be classified into two types according to EPC intervention. The handover preparation and execution between the source eNB 25a and the target eNB 25b are performed between the source eNB 25a and the target eNB 25b through the X2 handover and the EPC in which handover preparation and execution are performed between the source eNB 25a and the target eNB 25b without EPC intervention And handover.

4 is a diagram illustrating an S1 handover procedure according to an embodiment of the present invention.

The S1 handover is a handover method performed using the S1 interface. It is an interface between the E-UTRAN (eNB) and the EPC (the MME 60 in the case of a control message and the S-GW 80 in the case of a user packet) Even if there is no connection using the X2 interface between the source eNB 25a and the target eNB 25b or a connection using the X2 interface is allowed to be used for the handover Or a handover preparation operation is failed between a serving cell indicating an area in which the serving base station 25a can provide a service and a target cell indicating an area in which the target base station 25b can provide the service The S1 handover can be performed. When the S1 handover is performed, the serving base station 25a can communicate with the target base station 25b through the MME 60 for handover control. The handover procedure can be divided into three stages. Step 3 of the handover may be divided into a handover preparation step, a handover execution step, and a handover completion step. In step S401, the serving base station 25b periodically transmits / receives a signal to / from the UE 40 in the handover preparation step, determines a S1 handover, and transmits a Handover Required message for a handover request to the MME 60. The MME 60 may transmit a handover request message to the target base station 25b and request handover execution (S402). The target base station 25b may prepare a variety of handovers for establishing a bearer to prepare a packet to be delivered by the UE 40 (S403). In addition, the MME 60 informs the MME 60 of information on the established bearer, and can create a bearer tunnel (S404). The MME 60 transmits a handover command for handover to the serving base station 25a to the UE 40 and notifies the UE 40 of the handover start (Step S405). When the S1 handover process is completed in step S406, the MME 60 registers the current location of the UE 40 through a Tracking Area Update (TAU) procedure and notifies the UE 40 of a new subscriber identification number (GUTI) Unique Temporary Identifier) to the Target eNB 25b (S407). Thereby enabling the UE 40 to provide seamless service while moving.

5 is a view illustrating an X2 handover procedure according to an embodiment of the present invention.

The X2 interface can perform an X2 handover when there is an X2 connection between a serving base station (Source eNB 25a) to which a serving cell belongs as an eNB interface and a target base station (Target eNB 25b) to which a target cell belongs. When the X2 handover is performed, the serving base station 25a and the target base station 25b can communicate with each other for handover control without involvement of the MME 60. [ Similarly to the S1 handover, the X2 handover may consist of a handover preparation step, a handover execution step, and a handover completion step. However, unlike the S1 handover, the X2 handover does not perform the role in the handover preparation step (S501) and the handover execution step (S502). When the handover execution step is completed, the target base station 25b transmits a Path Switch Request message to the MME 60 to inform the UE 40 that the cell to be served is changed (S503), and requests the path change of the existing EPS bearer . The MME 60 may forward the Path Switch Request message to the S-GW / P-GW 80, 90 to modify the existing bearer information (S504). The target base station 25b may receive the bearer information modification result from the MME 60 in step S505 and request the serving base station 25a to delete the existing bearer information in step S506.

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

6, the handover processing apparatus 600 may include a TAU processing unit 610, a control unit 620, and a GUTI allocating unit 630. [ In an embodiment, the handover processing apparatus 600 may include the MME 60, but the handover processing apparatus 600 may be provided separately from the MME 60.

If the handover can not be performed between the serving base station and the target base station using the X2 interface, the TAU processor 610 transmits the current location of the UE 40 via the TAU procedure after the S1 handover, which is performed using the S1 interface, Can be registered.

After completion of the S1 handover, the controller 620 determines whether or not X2 handover for performing a handover using the X2 interface has occurred from the target BS to the second target BS before completion of the TAU procedure. When the X2 handover occurs before the completion of the procedure, the TAU processor 610 is controlled to suspend the TAU procedure performed by the TAU processor 610 and control the GUTI allocator 630 to transmit a new GUTI To the second target base station. In one embodiment, the control unit 620 may receive a fact that an X2 handover has occurred through the Path Switch Request message from the second target BS, and the controller 620 transmits a newly allocated GUTI to the target BS May be included in the TAU Accept message transmitted from the MME 60 to the second target base station.

The GUTI allocator 630 may control the UE 40 to allocate a new GUTI to the second target BS when an X2 handover occurs before completion of the TAU procedure after the completion of the S1 handover. In one embodiment, a new GUTI may be assigned in response to a request from the UE 40 when the UE 40 moves to an area not registered in the network.

7 is a flowchart illustrating a procedure of a handover processing method according to an embodiment of the present invention. Although FIG. 7 shows the S1 handover in which the MME 60 is changed, the S1 handover may be performed without changing the MME 60.

As shown in FIG. 7, the MME 60 in the EPC network is an object that handles handover in an area where the UE 40 moves. If the X2 interface does not exist, the handover can be performed through the S1 interface. The S1 handover is performed for the target eNB 25b (Target eNB 25b) to be moved through the Handover Required message of the serving base station (Source eNB 25a) And informs the source MME 60a which is in charge of the serving base station 25a to prepare for handover (S701). Thus, the source MME 60a prepares for handover and can transmit information for handover call processing to the target base station 25b. If the S1 handover is completed in step S702, the target base station 25b notifies the target MME 60b that the UE 40 has successfully completed the handover to the target base station 25b through the Handover Notify message (S703). When the S1 handover is completed, a TAU (Tracking Area Update) procedure is performed. Through the TAU procedure, the target base station 25b can inform the target MME 60b that the TA area has been moved (S704). If the X2 handover occurs before the TAU procedure is completed, the target BS 25b may send a Handover Request message to the new target BS (second target BS) 25c to request the X2 handover S705), the second target base station 25c may respond with a Handover Request Ack message (S706). When receiving the Handover Request Ack message, the target base station 25b includes information on the PDCP-SN (Packet Data Convergence Protocol Serial Number), the HFN (Hyper Frame Number) receiver, and the status of the transmitter to the second target base station 25c Lt; RTI ID = 0.0 &gt; (S707). &Lt; / RTI &gt; PDCP-SN and HFN are defined in 3GPP (3rd Generation Partnership Project) TS 36.423 standard. If the target MME 60b receives the fact that the X2 handover has occurred through the Path Switch Request message from the second target base station 25c in step S708, the target MME 60b temporarily pauses the TAU procedure, Lt; / RTI &gt; In the Path Switch Request message processing process, when the UE 40 moves to a TA area not registered in the network, it may request the MME 60 to newly allocate a GUTI. The target MME 60b can transmit the Path Switch Request Ack message to the second target BS 25c when the Path Switch Request message is processed (S708), and transmits the Path Switch Request Ack message to the second target BS 25c, TAU Accept message (S710). At this time, the target MME 60b may transmit the newly allocated GUTI in the Path Switch Request message process to the second target BS 25c in step S710. Through the above procedure, the call processing such as the mutual authentication of the target MME 60b and the manganese, the integrity and encryption algorithm delivery process, the location registration, and the bearer establishment process can be omitted, thereby improving the call quality, Since the processing is not interrupted, the user can receive continuous service.

  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
600: handover processing device 610: TAU processing section
620: control unit 630: GUTI allocation unit

Claims (6)

A handover processing method comprising:
a) performing S1 handover performed using the S1 interface when the handover of the user terminal can not be performed using the X2 interface between the serving base station and the target base station;
b) performing a handover from the target BS to the second target BS using the X2 interface during a period before completion of the TAU (Tracking Area Update) procedure for registering the current location of the UE after the completion of the S1 handover; Determining whether a handover has occurred; And
c) if the X2 handover occurs during the period before the completion of the TAU procedure after the completion of the S1 handover, pending the TAU procedure and transmitting a Globally Unique Temporary Identifier (GUTI) ) To the second target base station. The method according to claim 1,
The GUTI comprises:
In a TAU Accept message transmitted from an MME (Mobility Management Entity) in charge of the target BS to the second target BS. Handover processing method. The method of claim 1, wherein
The step b)
And the MME having jurisdiction over the target BS receives from the second target BS the fact that the X2 handover has occurred through the Path Switch Request message. A handover processing apparatus comprising:
If the handover can not be performed between the serving base station and the target base station using the X2 interface, the current location of the user terminal is registered through the TAU (Tracking Area Update) procedure after the S1 handover performed using the S1 interface is completed A TAU processing section;
If an X2 handover for performing a handover using the X2 interface occurs from the target BS to the second target BS after the S1 handover is completed and before the completion of the TAU procedure, A GUTI allocation unit for allocating a Globally Unique Temporary Identifier (GUTI); And
Determining whether or not the X2 handover has occurred during the period before completion of the TAU procedure after completion of the S1 handover, and performing the TAU procedure if the X2 handover occurs before completion of the TAU procedure after completion of the S1 handover And for transmitting the allocated GUTI to the second target base station. 5. The method of claim 4,
The GUTI comprises:
In a TAU Accept message transmitted from an MME (Mobility Management Entity) in charge of the target BS to the second target BS. 5. The method of claim 4,
Wherein,
And receives a notification that the X2 handover has occurred through the Path Switch Request message from the second target BS.

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