KR101148036B1 - Method and system for handover to WLAN network from LTE network - Google Patents

Abstract

Disclosed are a handover method and a system between an LTE network and a WLAN network. In the handover method between the LTE network and the wireless LAN network to support continuity for an IP-based voice communication call, when a handover request for the user terminal 201 is received via the LTE network, a new bearer is received from the ITE network. Allocate a handover command to the user terminal, and when the handover is completed, the new IP is allocated from the target wireless LAN network, the location is registered through the IMS network, and the session is updated to renew the session. Can be corrected.

Description

Handover method between LTE network and WLAN network and system therefor {Method and system for handover to WLAN network from LTE network}

The present invention relates to a mobile communication system, and more particularly, to a method and apparatus for signaling to enable an IP-based voice communication service from a 3GPP network to a non-3GPP network.

Since Korea's first PC-to-PC Internet phone was provided free of charge in January 2000, by the end of 2003, about 200,000 Internet phone subscribers had grown into a niche market with differentiated rates and services.

Recently, researches are being actively conducted on wired / wireless integration and standardization technologies related to IP Multimedia Core Network Subsystem (IMS) of 3GPP standards. Recently, the issue of interworking with non-3GPP networks has been actively discussed.

However, the current standard has a problem in that it cannot guarantee the continuity of IP-based voice communication services between 3GPP networks and non-3GPP networks.

The present invention is to provide a method and apparatus for signaling to enable the IP-based communication call service provided by the IMS from the 3GPP network to the non-3GPP network.

The present invention also provides a call processing method and apparatus capable of handover from an LTE network to a WLAN network.

Accordingly, the present invention can extend the coverage of the IP-based VoIP service.

According to an aspect of the present invention, a system for performing handover from a 3GPP network to a non-3GPP network for guaranteeing service continuity for an IP-based voice communication call is provided.

According to an embodiment, a packet data gateway (PDG) of a WLAN network for allocating a new IP and a new bearer according to a handover request including existing network access information from a Long Term Evolution (LTE) network; A mobility management entity (MME) of the LET network that transmits a handover command including the new bearer information when a response including new bearer information according to the new bearer allocation is received from the packet data gateway; A call session control device of an IMS network for transmitting a session connection request including new bearer information from the user terminal 201 through the new IP according to the handover completion of the user terminal 201 according to the handover command; And an application server releasing an existing bearer according to the session connection request, storing the new bearer information, and ensuring a service continuity for an IP-based voice communication call through a session update. A system may be provided for performing this.

According to another aspect of the present invention, a method for performing a handover from a 3GPP network to a non-3GPP network to ensure service continuity for an IP-based voice communication call is provided.

According to an embodiment, in a handover method between an LTE network and a WLAN network to support continuity for an IP-based voice communication call, (a) a handover request to the user terminal 201 via an LTE network is performed. If received, the packet data gateway of the WLAN network assigns a new bearer; (b) When the mobility management device of the LTE network receives a response including new bearer information according to a new bearer allocation, a handover command including the new bearer information is received through the enhanced Node B (eNB). 201); (c) when the handover complete message is received from the user terminal 201 according to the handover command, the packet data gateway assigning a new IP for the user terminal 201; (d) A call session control apparatus of an IMS network requests and updates a location update for the user terminal 201 using the new bearer information from the user terminal 201 through the new IP, and updates the new bearer information. Transmitting a session connection request according to; And (e) the application server of the IMS network releasing the existing bearer according to the session connection request, and setting up a new bearer using the new bearer information. Can be.

By providing a handover method and a system between the LTE network and the wireless LAN network according to an embodiment of the present invention, it is possible to signal to enable the IP-based communication call service provided by the IMS from the 3GPP network to the non-3GPP network.

In addition, the present invention can be reliably handover from the LTE network to the WLAN network can provide continuity for IP-based services.

1 is a block diagram schematically illustrating a system for providing an IP-based communication call to a long term evolution network and a wireless LAN network through an IMS network according to the present embodiment;
2 is a flowchart illustrating a process of registering a location to receive an IP-based communication call service in an LTE network.
3 is a flowchart illustrating a process of registering a location in an IMS network after registering a location through an LTE network to receive an IP-based communication call service.
4 is a flowchart illustrating a handover procedure from an LTE network to a wireless LAN network according to the present embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In this specification, for providing an IP-based communication call (eg, voice communication, VoIP) to an LTE network and / or a WLAN (WLAN) network based on IMS service continuity (ie, through a service of IMS). Let's explain.

[Description of Fig. 1]

1 is a block diagram schematically illustrating a system for providing an IP-based communication call to a long-term evolution network and a wireless LAN network through an IMS network according to the present embodiment.

FIG. 1 illustrates VoIP (Voice Over IP) in an environment in which a wireless LAN (WLAN, hereinafter referred to collectively as WLAN) and Long Term Evolution (LTE: collectively referred to as LTE) coexist. The system structure for the traffic service is schematically shown.

Referring to FIG. 1, the wireless LAN network 101 includes an access gateway (WAG: hereinafter called WAG) 110 and a packet data gateway (PDG: hereinafter referred to as PDG). And an AAA server (Authentication, Authorization, Accounting) 120.

The WAG 110 provides a function of routing data transmitted and received with the access network to provide the 3GPP PS-based service to the user terminal 201. In addition, the WAG 110 performs various security functions, including packet filtering.

The PDG 115 performs authentication and authorization verification for the subscriber, and provides IPsec tunneling with the user terminal 201 to protect user traffic. In addition, the PDG 115 performs an IP allocation and charging function for the user terminal 201.

In addition, the PDG 115 supports call processing to enable handover processing with the LTE network 102 described below. This will be described in more detail with reference to the accompanying drawings below.

The AAA server 120 is responsible for the WLAN network access processing of the user terminal 201 and authentication, authorization, and fee calculation functions for providing a service to the user terminal 201.

The LTE network 102 supports mobility between various radio access technologies (that is, mobility between heterogeneous networks) based on the 3GPP system based on IP. That is, the LTE network 102 includes an eNB 125, a serving gateway (S-GW: Serving Gateway, hereinafter referred to as S-GW), and a packet data network gateway (PDN GW: PDN). And a mobility management device (MME: Mobility Management Entity, hereinafter referred to as MME).

The eNB 125 is similar in function to the NodeB and RNC of the UMTS system. That is, the eNB 125 manages radio resources of the LTE network 102 and is in charge of functions for radio bearer control, radio admission control, and dynamic resource allocation (ie, scheduling).

Since this is obvious to those skilled in the art, a separate description thereof will be omitted.

The S-GW 130 is an anchor point for mobility management in the 3GPP network.

The PDN GW 135 is an anchor point for mobility management between 3GPP networks and non-3GPP networks. Although FIG. 1 illustrates the S-GW 130 and the PDN GW 135 separately, the S-GW 130 and the PDN GW 135 may be implemented as one gateway environment according to an implementation method.

In addition, the PDN GW 135 performs a function of supporting signaling and traffic processing in handover processing between a 3GPP network and a non-3GPP network.

Referring to FIG. 1, the PDN GW 135 is responsible for signaling and traffic processing with the PDG 115 of the WLAN 101.

The MME 140 is a functional device directly connected to the LTE RAN using the S1 interface and performs a function of distributing a paging message to the eNB.

In addition, the MME 140 performs a function of supporting signal processing with heterogeneous networks during handover. This will be described in more detail with reference to the accompanying drawings below.

The IMS network is a communication network based on a communication network standard proposed by the 3rd generation partnership project (3GPP). The IMS network provides an IP (Internet protocol) -based communication service and mainly uses a SIP (session initiation protocol) signaling protocol. The IMS network can be used as a secondary network of a mobile communication network such as WCDMA.

As shown in FIG. 1, the IMS network 103 includes a call session control device (CSCF) 145, a home subscriber server (HSS) hereinafter. And an application server 155).

The CSCF 145 performs a function related to call processing in the IMS network. The CSCF 145 is composed of an Interrogate-CSCF (I-CSCF), a Proxy-CSCF (P-CSCF), and a Serving-CSCF (S-CSCF). I-CSCF provides routing information so that call request messages are delivered to the appropriate server within the IMS domain. The P-CSCF is a point where the user terminal 201 meets when accessing the IMS domain through the access network. The P-CSCF forwards a SIP registration request from the user terminal 201 to the I-CSCF. The S-CSCF establishes a call session and plays a role in receiving and processing a Session Initiation Protocol (SIP) message transmitted from the user terminal 201.

HSS 150 is a user information database that supports IMS entities performing session control. The HSS 150 stores user related subscription information related to multimedia session control, that is, user location information, security information for authentication and permission of the user, and user profile information including a service subscribed to by the user.

The application server 155 collects and manages network information registered for voice communication in an IP-based LTE network and a WLAN network.

[Description of Fig. 2]

2 is a flowchart illustrating a process of registering a location to receive an IP-based communication call service in an LTE network.

In operation 210, the user terminal 201 transmits an attach request message to the eNB 125. The user terminal 201 may transmit information including an RRC parameter including information on the selected network and the MME identifier in the location registration request message. Since the RRC parameter is obvious to those skilled in the art, a separate description will be omitted.

In step 212, the eNB 125 analyzes the RRC parameter included in the location request message received from the user terminal 201, selects an MME to transmit the location registration request message, and then selects the corresponding location registration request message. To send.

If the information on the user terminal 201 does not exist in the MME, the MME 140 receiving the location registration request message receives the subscriber identification information corresponding to the user terminal 201 for authentication of the user terminal 201. request. To this end, the MME 140 transmits an identity request message to the user terminal 201. Subsequently, the user terminal 201 transmits an identity response message including a subscriber identification number to the MME 140 in response to an identity request message (step 214).

In operation 216, the user terminal 201 performs an authentication and security procedure with the MME 140 and / or the HSS 150. Here, the user terminal 201 performs an authentication procedure with the MME 140 and / or the HSS 150 by EPS AKA. In addition, the MME 140 may perform a procedure for setting security with the user terminal 201 using a NAS algorithm.

When the authentication and security setting procedure is completed, a check procedure for identifying the device of the user terminal 201 is performed in steps 218 to 220.

More specifically, the MME 140 transmits an identity request message to the user terminal 201 to obtain an identification type of the user terminal 201. Subsequently, the user terminal 201 transmits an identity response message including a mobile identity to the MME 140.

Subsequently, the MME 140 transmits a mobile device identification check message (ME Identity check) including a mobile device identifier and a subscriber identification number to an equipment identity register (EIR). The EIR 202 may send a response message (ME Identity check ack) to the MME 140.

If the encryption option transmission flag is set in the attach request message from the user terminal 201, the MME 140 transmits an encrypted option transmission request message to the user terminal 201 in step 222. Receive Here, the encrypted option may be one or more of PCO and APN.

Subsequently, in step 224, the MME 140 transmits an update location request message to the HSS 150, and receives a response message (Update Location Ack) from the HSS 150. The location update request message may include information on one or more of MME identification information, subscriber identification information, mobile device identification information, MME capacity and update type.

When the location update to the HSS 150 is completed, the MME 140 selects the S-GW 130 in step 226 and assigns the EPS bearer identifier to the user terminal 201 for basic bearer allocation. Subsequently, the MME 140 transmits a create session request message to the selected S-GW 130. The session creation request message may include a PDN GW address, basic EPS bearer quality information, and EPS bearer identifier. The session creation request message may further include various information related to the session described in 3GPP TS 23.401.

In step 228, the S-GW 130 creates a new entry in the EPS bearer table corresponding to the session creation request message, and transmits a create session request message to the PDN GW 135. The S-GW 130 may transmit the session creation request message to the PDN GW 135 using the PDN GW address included in the session creation request message received from the MME 140.

In step 230, the PDN GW 135 creates a new entry in the EPS bearer context table, generates identification information for charging, and transmits a create session response message to the S-GW 130. The PDN GW 135 may route between the S-GW 130 and the packet data network in accordance with this new entry creation.

In step 232, the S-GW 130 transmits a create session response message to the MME 140.

In step 234, the MME 140 generates a location registration accept message and sends it to the eNB 125. The MME 140 may include an initial context setup request in the MME control message and transmit it to the eNB 125.

Upon receipt of the location registration grant message, in step 236 the eNB 125 sends an RRC connection reconfiguration message to the user terminal 201 including the EPS radio bearer identification. Here, the eNB 125 may transmit a location registration approval message to the user terminal 201 together.

In operation 238, the user terminal 201 transmits an RRC connection reconfiguration complete message to the eNB 125.

Accordingly, the eNB 125 transmits an initial context response message to the MME 140 (step 240).

Upon receiving the initial context response message, in step 242, the MME 140 sends a Modify bearer request message to the S-GW 130. Here, the bearer modification request message includes an EPS bearer identifier, an eNB address, a handover indication, and the like.

If the handover indication is included in the bearer modification request message, the S-GW 130 transmits a bearer modification request message to the PDN GW 135 in step 244. Through this, packet tunneling from a non-3GPP IP access system to a 3GPP access system can be performed quickly.

The PDN GW 135 receiving the bearer modification request message in step 246 transmits a bearer modification response message (Modify bearer response) to the S-GW 130, and the S-GW 130 sends a bearer modification response message (Modify bearer). response) to the MME 140 (step 248).

After receiving the bearer modify response message (Modify bearer response), in step 250, the MME 140 notifies request including an access point name (APN) and a PDN GW identifier for mobility for non-3GPP access. To the HSS 150. Accordingly, the HSS 150 maps and stores the APN and PDN GW identifiers according to the notification request message, and transmits a Notify response message to the MME 140.

Referring to FIG. 2, the process of registering a location by the user terminal 201 through the LTE network has been described. In order to receive an IP-based voice communication call (eg, VoIP) service through the LTE network, the user terminal 201 needs to register a location including information on the LTE network in the IMS network. This will be described below with reference to FIG. 3.

[Description of Fig. 3]

3 is a flowchart illustrating a process of registering a location in an IMS network after registering a location through an LTE network to receive an IP-based communication call service.

Hereinafter, in the process of the user terminal 201 finally registers information on a network (LTE network) to which the user terminal 201 currently accesses through the IMS network for access through the LTE network as described above with reference to FIG. 2. This will be explained.

In step 310, the user terminal 201 generates a location registration request message (register) for location registration with respect to the user terminal 201 in order to receive an IP-based voice communication call service through the LTE network. To send.

Here, the location registration request message may include information about the user terminal 201 and information about a network to which the user terminal 201 is connected.

In step 315, the P-CSCF 146 views the subscriber's domain according to the location registration request message and transmits a location registration request message (register) to the corresponding I-CSCF (147).

In operation 320, the I-CSCF 147 is assigned an S-CSCF 148 to register the user terminal 201 by querying the HSS 150. That is, the I-CSCF 147 transmits a user authorization request (UAR) message for the request of the S-CSCF 148 to register the user terminal 201 to the HSS 150, and sends the S from the corresponding HSS 150. Receive a response message (UAA: user authorization answer) including CSCF information.

Subsequently, in step 325, the I-CSCF 147 transmits a location registration request message to the assigned S-CSCF 148.

In operation 330, the S-CSCF 148 queries the HSS 150 to request and obtain authentication information necessary for authentication of the user terminal 201.

In more detail, the S-CSCF 148 transmits a multimedia authentication request (MAR) required for authentication of the user terminal 201 to the HSS 150. Accordingly, the HSS 150 transmits information necessary for authentication, such as an authentication vector, to the S-CSCF 148 by including in a multimedia authentication answer (MAA).

After acquiring authentication information required for authentication, in step 335, the S-CSCF 148 transmits authentication information required for authentication to the user terminal 201 (401 unauthorized). Here, the authentication information may include the aforementioned authentication vector.

In step 340, the user terminal 201 authenticates according to a predetermined algorithm using an authentication vector included in the authentication information, and then requests a location registration to the I-CSCF 147 through the P-SCSF 145 including the authentication result. Resend the message (register).

In step 345, the I-CSCF 147 is assigned an S-CSCF 148 to register the user terminal 201.

In operation 350, the I-CSCF 147 transmits a location registration request message including an authentication result value to the assigned S-CSCF 148.

In step 355, the S-CSCF 148 performs authentication on the user terminal 201 using the authentication result value included in the location registration request message, and registers the user terminal 201 when the authentication succeeds.

In step 360, the S-CSCF 148 obtains a service profile corresponding to the user terminal 201 from the HSS 150.

In operation 365, the S-CSCF 148 informs the user terminal 201 that location registration and authentication have succeeded (that is, the S-CSCF 148 sends an I-CSCF 147 an authentication success message 200 OK). And to the user terminal 201 through the P-CSCF 146).

Subsequently, in step 370, the S-CSCF 148 transmits a location registration request message including network connection information about a network to which the user terminal 201 is connected, to the application server 155.

Finally, in step 375, the application server 155 stores network access information corresponding to the user terminal 201 in the application server 155, and then transmits a success message 200 OK to the S-CSCF 148.

Accordingly, the user terminal 201 may be provided with an IP-based communication call service provided by the IMS through the LTE network.

 [Description of Fig. 4]

4 is a flowchart illustrating a handover procedure from an LTE network to a wireless LAN network according to the present embodiment. Hereinafter, a procedure of handover to a wireless LAN network while the user terminal 201 uses an IP-based communication service through the LTE network will be described.

In operation 410, the first user terminal 401 transmits a measurement report for handover to the eNB 125. For example, the first user terminal 401 may transmit a measurement report on the information on the network currently being accessed to the eNB 125 on a predetermined periodic basis.

Accordingly, the eNB 125 analyzes the received measurement report to determine whether the first user terminal 401 is out of coverage of the currently connected network (that is, the LTE network) to determine whether to handover to the target WLAN network. You can decide.

Hereinafter, it will be described on the assumption that the first user terminal 401 enters the coverage of the WLAN network out of the coverage of the connected LTE network.

In step 415, the eNB 125 generates a handover request message (Handover required) and transmits to the MME (140). Here, the handover request message may include identification information for accessing the target network to perform the handover (hereinafter, referred to as target network identification information), handover indication information, and the like.

Receiving the handover request message, the MME 140 performs a reassignment transmission request message (Forward) to perform a negotiation process for configuring traffic in an existing LTE network in a target network (for example, WLAN) environment. A relocation request is generated and sent to the target PDG 115 (step 420). The MME 140 may transmit traffic information about the session of the existing LTE network to the target PDG 115 through the reassignment transmission request message.

Accordingly, in step 425, the PDG 115 sets up a WLAN network environment according to the reassignment transmission request message and transmits a forward relocation response message to the MME 140. Here, the reassignment transmission response message includes information about the target network.

That is, the PDG 115 may allocate a new bearer and transmit a reassignment transmission response message including information on the allocated new bearer (hereinafter referred to as new bearer information) to the MME 140. The new bearer information (ie, information on the target network) may be included in the target to source transparent container defined in 3GPP TS 29.280 and transmitted to the MME 140.

When the reassignment transmission response message is received, in step 430, the MME 140 transmits a handover command message including the new bearer information to the eNB 125, and the eNB 125 sends the corresponding handover command message to the first user. Transmit to terminal 401 (step 435).

The first user terminal 401 changes the access network from the cell of the existing LTE network to the cell of the target WLAN using the new bearer information according to the handover command message.

In operation 440, the first user terminal 401 generates a handover complete message to the target WLAN and transmits the message to the MME 140.

Accordingly, in steps 445 to 450, the MME 140 transmits a forward relocation complete notify message to the PDG 115 of the target WLAN network, and forwards a response message from the PDG 115. ack).

In response to the completion of the handover of the first user terminal 401 to the WLAN, in step 455, the PDG 115 sends a bearer modification request message (Modify Bearer Request) to inform the existing network of the PDN of the existing network. Send to GW 135.

In operation 460, the PDN GW 135 transmits a bearer modification response message (Modify Bearer response) according to the bearer modification request message to the PDG 115.

Accordingly, a path update procedure is performed between the first user terminal 401 and the second user terminal 402 that is in the IP-based voice communication call.

Subsequently, in step 465, the first user terminal 401 is assigned a new IP from the handed over WLAN. Since a method of accessing a WLAN and assigning an IP is a general matter, the subject matter of the present embodiment may be obscured, and thus a detailed description thereof will be omitted.

After receiving the new IP, in step 470, the first user terminal 401 registers for location update to the CSCF 145 of the IMS network through the new IP in order to receive service continuity for the IP-based voice communication call. Do this. Since this is the same as already described with reference to FIG. 3, the location registration procedure will be omitted.

When the location registration process to the IMS network through the new IP is completed, in step 475 the first user terminal 401 transmits a session connection request message (INVITE) to the CSCF 145 to inform the movement of the existing session. . Here, the session connection request message may include new bearer information.

After receiving the session connection request message, the CSCF 145 forwards the session connection request message to the application server 155 in step 480.

Accordingly, in step 485, the application server 155 releases the existing bearer for the existing LTE network, and stores the new bearer information.

In operation 490, the application server 155 transmits an update message to the CSCF 145 to inform the second user terminal 201 of the path update according to the new bearer.

Accordingly, the CSCF 145 transmits an update message to the second user terminal 402 in step 495.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

101: WLAN network
110: WAG
115: PDG
120: AAA
102: LTE network
125: eNB
130: S-GW
135: PDN GW
140: MME
103: IMS network
145: CSCF
150: HSS
155: AS

Claims (13)

A system for performing handover between an LTE network and a wireless LAN network to support continuity for an IP-based voice communication call,
A Packet Data Gateway (PDG) of a WLAN network for allocating a new IP and a new bearer for a user terminal according to a handover request including existing network access information from an LTE (Long Term Evolution) network;
A mobility management entity (MME) of the LTE network for transmitting a handover command including new bearer information according to a response corresponding to a new bearer allocation;
In response to the handover completion of the user terminal according to the handover command, updating a location registration for the user terminal using the new bearer information through a new IP, and attempting to establish a session using the new bearer information. Call session control device of an IMS network; And
Between the LTE network and the WLAN network including an application server that stores the new bearer information and establishes a session update with another connected terminal according to an attempt to establish a session using the new bearer information to ensure continuity for an IP-based voice communication call. System to perform handover of the system.
The method according to claim 1,
The LTE network further includes an enhanced Node B (eNB) of the LTE network that determines whether the user terminal is handed over according to the measurement report from the user terminal and requests the handover for the user terminal to the mobility management device. A system for performing handover between a WLAN network.
The method according to claim 1,
The user terminal performs a handover between the LTE network and the wireless LAN network to send a handover complete message to the packet data gateway when the handover is completed.
The method of claim 3,
The packet data gateway performs a handover between the LTE network and the WLAN network informing of a bearer change to the mobility management device of the LTE network according to the reception of the handover complete message of the user terminal.
The method of claim 4, wherein
Further comprising a packet data network gateway of the LTE network for routing the call between the LTE network and the IMS network,
And the packet data gateway notifies the bearer change, and then performs handover between the LTE network and the wireless LAN network to notify the packet data network gateway of a route change according to the new bearer information to the LTE network.
The method according to claim 1,
The user terminal receives the handover command through an enhanced Node B (eNB) of the LTE network, performs the handover to the WLAN network using the new bearer information, and performs the new IP according to the handover completion. A system for performing handover between an LTE network and a wireless LAN network for updating location registration in an IMS network.
The method according to claim 1,
The other terminal is a system for performing a handover between the user terminal and the LTE network and a wireless LAN network which is a terminal receiving an IP-based voice communication service provided by the IMS network.
In a handover method between an LTE network and a wireless LAN network to support continuity for an IP-based voice communication call,
(a) if the packet data gateway of the WLAN network receives a handover request for the user terminal via the LTE network, allocating a new bearer;
(b) When the mobility management apparatus of the LTE network receives a response including new bearer information according to a new bearer allocation, a handover command including the new bearer information is sent to the user terminal through an enhanced Node B (eNB). Transmitting;
(c) when the handover complete message is received from the user terminal according to the handover command, the packet data gateway assigning a new IP for the user terminal;
(d) A call session control apparatus of an IMS network receives and updates a location update request for the user terminal from the user terminal using the new bearer information through the new IP, and updates a session connection request according to the new bearer information. Transmitting; And
(e) an application server of an IMS network releasing an existing bearer according to the session connection request, and setting up a new bearer using the new bearer information.
The method of claim 8,
The method of the handover between the LTE network and the wireless LAN network further comprises the step of transmitting the session update request to the other terminal after the new bearer is set by the application server.
10. The method of claim 9,
The other terminal is a handover method between the user terminal and the LTE network and a wireless LAN network that is a terminal receiving an IP-based voice communication service
The method of claim 8,
Before step (a) above,
Receiving, by the eNB, an LTE network measurement report from the user terminal; And
The eNB further comprises the step of determining whether or not the user terminal handover according to the measurement report.
The method of claim 8,
Before step (c),
Performing, by the user terminal, handover to the WLAN network using the new bearer information according to the handover command; And
And transmitting, by the user terminal, the handover complete message to the packet data gateway as the handover is completed.
The method of claim 12,
Transmitting, by the packet data gateway, a bearer change upon handover completion to the mobility management device of the LTE network according to the reception of the handover complete message; And
And transmitting, by the packet data gateway, a route change according to the new bearer information to a packet data network gateway of the LTE network.

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