KR101539982B1 - Method for call processing in performing handover between heterogeneous networks in a mobile communication system, device therefor - Google Patents

Abstract

In the present invention, disclosed are a call processing method in performing a handover between heterogeneous networks in a mobile communication system and a device therefor. Specifically, according to the present invention, a packet data network gateway device comprises: a dedicated bearer support determining unit which, if a terminal having a call using a dedicated bearer which is set in a mobile communication system receives a dedicated bearer setting request message set in the terminal according to a handover between heterogeneous networks, determines whether the network which transmits a setting request message supports the dedicated bearer; a dedicated bearer managing unit which, if the network which transmits the setting request message does not support the dedicated bearer, deletes the dedicated bearer set in the terminal; and a call session processing unit which transmits a session termination request message to request a termination of a call session to an IP multimedia subsystem (IMS).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handover method for handover between heterogeneous networks in a mobile communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly, to a method and a device for processing a call when a terminal performs handover between heterogeneous networks during a call.

The mobile communication system has been developed to provide voice service while ensuring the user 's activity. The mobile communication system is gradually expanding not only to voice but also data service, and now it has developed to the extent of providing high-speed data service. However, since the spread of mobile devices causing high-capacity traffic is rapidly spreading, there is a shortage of resources. In order to accommodate the rapidly increasing wireless traffic and to provide higher quality service to the users, .

In the 3rd Generation Partnership Project (3GPP), as a part of efforts to optimize and improve the performance of mobile communication networks, research on Long Term Evolution / System Architecture Evolution (LTE / SAE) technology has been started. In the 3GPP LTE system, in an existing mobile communication system, the sub-domains of a circuit-switched (CS) for voice and a packet-switched (PS) for data are unified into one IP (Internet Protocol) domain, Traffic flows from a radio link connecting to a base station to a packet data network (PDN) connecting to a service entity all operate on an IP basis. The PDN refers to a network in which a server supporting a specific service (for example, an IMS server, etc.) is located.

Further, the 3GPP now complies with the requirement of IMT (International Mobile Telecommunication) -Advanced, which aims to support IP-based multimedia seamless service through data rate of 1Gbps at high speed and 100Mbps at low speed by supplementing LTE technology (MIMO), Coordinated Multi-Point Transmission and Reception (CoMP), eICIC (Multi-User Multiple Input Multiple Output), and so on. (Enhanced Inter-Cell Interference Coordination) technology.

Korean Registered Patent No. 10-0851593, registered on August 05, 2008 (name: apparatus and method for connecting to different types of manganese)

It is an object of the present invention to provide a method and apparatus for improving a call quality of a terminal during a handover between heterogeneous networks of a terminal in a mobile communication system.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to an aspect of the present invention, there is provided a packet data network gateway apparatus for supporting call processing in a mobile communication system, the apparatus comprising: A dedicated bearer support confirmation unit for determining whether the network that transmitted the setup request message supports the dedicated bearer, upon receiving a dedicated bearer setup request message set up in the terminal according to a handover to the network, A dedicated bearer management unit for deleting the dedicated bearer set in the terminal and a call session processing unit for sending a session end request message for requesting the end of the call session to the IP Multimedia Subsystem (IMS) when the network does not support the dedicated bearer do.

According to another aspect of the present invention, there is provided a method for supporting a call processing in a packet data network gateway apparatus in a mobile communication system, the method comprising the steps of: Determining whether the network that transmits the setup request message supports the dedicated bearer when the UE receives the dedicated bearer setup request message set up in the UE according to the handover to the heterogeneous network, If the dedicated bearer is not supported, deleting the dedicated bearer set in the terminal and transmitting a session end request message for requesting the end of the call session to the IP Multimedia Subsystem (IMS).

According to the embodiment of the present invention, when a call terminates due to a handover of a terminal in a mobile communication system to a heterogeneous network, the call quality of the counterpart terminal can be improved by forcibly terminating the call session.

The effects obtained in the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description .

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the technical features of the invention.
1 is a diagram showing a schematic structure of a mobile communication system to which the present invention can be applied.
FIG. 2 is a diagram for explaining a call processing method in a handover between heterogeneous networks during a call.
FIG. 3 is a diagram for explaining a call processing method in a handover between heterogeneous networks during a call according to an embodiment of the present invention.
FIG. 4 is a diagram for explaining a method of processing a call when handover between heterogeneous networks during a call according to an embodiment of the present invention.
5 is a diagram illustrating a configuration of a packet data network gateway device (PGW) according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details.

In some instances, well-known structures and devices may be omitted or may be shown in block diagram form, centering on the core functionality of each structure and device, to avoid obscuring the concepts of the present invention.

Throughout the specification, when an element is referred to as "comprising" or " including ", it is meant that the element does not exclude other elements, do. Also, the terms " part, "" module," and " module ", etc. in the specification mean a unit for processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software have. Also, the terms " a or ", "one "," the ", and the like are synonyms in the context of describing the invention (particularly in the context of the following claims) May be used in a sense including both singular and plural, unless the context clearly dictates otherwise.

The specific terminology used in the following description is provided to aid understanding of the present invention, and the use of such specific terminology may be changed into other forms without departing from the technical idea of the present invention.

Embodiments of the present invention provide a standard document related to at least one of a 3rd Generation Partnership Project (3GPP) system, a 3GPP Long Term Evolution (LTE) and an LTE-A system, 3GPP2, and Institute of Electrical and Electronics Engineers And the like. That is, the steps or portions of the embodiments of the present invention that are not described in order to clearly illustrate the technical idea of the present invention can be supported by the documents. In addition, all terms disclosed in this document may be described by the standard document.

The following techniques may be used in various wireless communication systems. For the sake of clarity, the 3GPP LTE and 3GPP LTE-A systems will be described below, but the technical idea of the present invention is not limited thereto.

In the present specification, a 'terminal' refers to a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), a subscriber station (SS), an advanced mobile station (AMS) Machine-type communication device, an M2M (machine-to-machine) device, a D2D device (device-to-device), and a station (STA).

Also, in this specification, a 'base station' has a meaning as a terminal node of a network that directly communicates with the terminal. The specific operation described herein as being performed by the base station may be performed by an upper node of the base station, as the case may be. That is, it is apparent that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A 'base station (BS)' may be replaced by a term such as a fixed station, a Node B, an eNode B (eNB), an access point (AP)

1 is a diagram showing a schematic structure of a mobile communication system to which the present invention can be applied.

3GPP has begun research on Long Term Evolution / System Architecture Evolution (LTE) technology as part of its efforts to optimize and improve performance. The SAE high-level reference model defined in 3GPP includes non-roaming cases and roaming cases of various scenarios.

In the 3GPP LTE system, in an existing mobile communication system, the sub-domains of a circuit-switched (CS) for voice and a packet-switched (PS) for data are unified into one IP (Internet Protocol) domain, Traffic flows from a radio link connecting to a base station to a packet data network (PDN) connecting to a service entity all operate on an IP basis. Here, the PDN refers to a network in which a server supporting a specific service (for example, an IMS server) is located.

The 3GPP LTE system, that is, the Evolved Packet System (EPS) is a wireless access network such as an Evolved Packet Core (EPC) which is an IP-based packet switched core network and an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) (RAN: Radio Access Network), and UMTS (Universal Mobile Telecommunications System) is an evolved network. 1 is a simplified reconstruction of the EPS.

EPC may be composed of various components (or entities). In FIG. 1, a Serving Gateway (SGW), a Packet Data Network Gateway (PDN GW) and a Mobility Management Device (MME) A Mobility Management Entity (HSS), a Home Subscriber Server (HSS), a Policy and Charging Rule Function (PCRF), a Serving General Packet Radio Service (SGSN) Supporting Node (SGSN) / RTI > An enhanced packet data gateway (ePDG), a subscriber profile repository (SPR), an online charging system (OCS) and an off-line charging system (OFCS), as well as the EPC component shown in FIG. : Offline Charging System).

The SGW is an element that functions as a boundary point between the radio access network (RAN) and the core network and functions to maintain a data path between the eNB (not shown) and the PDN GW. Also, when a terminal moves across an area served by an eNB, the SGW acts as a local mobility anchor point. That is, the packets can be routed through the SGW for mobility in the E-UTRAN. In addition, the SGW is also capable of handling mobility with other 3GPP networks (RANs defined prior to 3GPP Release-8, e.g., UTRAN or GERAN (Global System for Mobile Communication) / EDGE (Enhanced Data Rates for Global Evolution) In addition, the SGW may perform functions such as idle mode downlink packet buffering and lawful interception of the E-UTRAN.

The PDN GW (or P-GW, PGW) corresponds to the termination point of the data interface towards the packet data network. The PDN GW may include policy enforcement features such as policy enforcement features, packet filtering, charging support, lawful interception, UE IP allocation, packet screening, etc. Function can be performed. Further, mobility management with a 3GPP network and a non-3GPP network (e.g., an untrusted network such as an Interworking Wireless Local Area Network (I-WLAN), a Code Division Multiple Access (CDMA) network or a trusted network such as WiMax) It can serve as an anchor point for.

In the example of the network structure of FIG. 1, the SGW and the PDN GW are configured as separate gateways, but two gateways may be implemented according to the Single Gateway Configuration Option.

The MME is an element that performs signaling and control functions to support UE access to network connections, allocation, tracking, paging, roaming, and handover of network resources. The MME controls the control plane functions related to subscriber and session management. The MME manages a large number of eNBs and performs signaling for selection of conventional gateways for handover to other 2G / 3G networks. The MME also performs functions such as security procedures, terminal-to-network session handling, and idle terminal location management.

The Policy Control and Charging Rules Function (PCRF) is a node that performs policy decision to dynamically apply policies, quality of service (QoS) applied to the UE. Policy and Charging Control (PCC) rules generated in the PCRF are forwarded to the PDN GW.

The Home Subscriber Server (HSS) manages user subscription information (or subscription data or subscription records) and location information.

The SGSN handles all packet data such as the user's mobility management and authentication to another 3GPP network (e.g., GPRS network).

As described above, a terminal having an IP capability can access an IP service network (for example, IMS) provided by a provider (that is, an operator) via various entities in the EPC not only for 3GPP access, (IP Multimedia Subsystem), Packet-Switched Streaming (PSS), etc.).

1 illustrates various reference points (e.g., S1-U, S1-MME, etc.). In 3GPP system, a conceptual link connecting two functions existing in different functional entities of E-UTRAN and EPC is defined as a reference point.

In addition, as described above, in addition to the GTP (GPRS Tunneling Protocol) protocol that has been traditionally used in the existing 3GPP while supporting non-3GPP interworking, various protocols of the Internet Engineering Task Force (IETF) have been introduced. In particular, IETF protocols such as PMIPv6 (Proxy Mobile IPv6) and DSMIPv6 (Dual Stack Mobile IPv6) have been introduced in draft versions prior to the RFC (Request for Comments) of the IETF, and are now an important protocol for non-3GPP interworking in the SAE standard. Is used. Basically, GTP protocol is used for 3GPP inter-radio access technology handover, and IETF-based protocols are used on S3 interfaces for non-3GPP interworking. In particular, reference point S5, which is a reference point for providing user plane tunneling and tunnel management between SGW and P-GW, and S8 (not shown), which is a reference point used for roaming, And IETF-based protocols.

The following Table 1 illustrates the reference points shown in FIG. 1 and the protocol options available accordingly. In addition to the examples in Table 1, various reference points may exist depending on the network structure.

Reference point protocol Explanation S1-MME S1-AP The reference point for the control plane protocol between the E-UTRAN and the MME S1-U GTP-U Reference point between E-UTRAN and SGW for path switching between eNBs during handover and user plane tunneling per bearer S4 GTP A reference point between the MME and the SGSN that provides user and bearer information exchange for 3GPP access network mobility in an idle and / or active state. This reference point may be used in PLMN- or between PLMN- (e.g., in the case of a PLMN-to-PLMN handover) S6a Diameter Reference point for control plane protocol between HSS and MME S4 GTP A reference point between SGW and SGSN that provides the associated control and mobility support between GPRS core and SGW anchor functions. Also, if a direct tunnel is not established, it provides user plane tunneling. S5 GTP, PMIP A reference point that provides user plane tunneling and tunnel management between the SGW and the PDN GW. Used for UE mobility and for connection to the PDN GW where the SGW is not co-located for the required PDN connectivity, for SGW relocation S11 GTP-C Reference point for control plane protocol between MME and SGW Gx Diameter Reference point for control plane protocol between PCRF and P-GW SGi IP PDN Reference point between GW and PDN. Here, the PDN may be an operator external public or private PDN or an operator-in-PDN (e.g., IMS service)

The 3GPP LTE system described above is a data-only network based on All-IP, and high-quality voice service called VoLTE (Voice over LTE) is supported under such 3GPP LTE system environment. VoLTE was standardized by the Global System for Mobile Communications Association (GSMA) as a defined profile to ensure high quality and compatibility when using IMS, an IP telephony technology, in LTE systems. VoLTE transmits voice, text, video call, and multimedia contents in a SIP (Session Initiation Protocol) protocol, which is a standard VoIP (Voice over IP) protocol. The 3GPP LTE system is a data- Therefore, voice and text services are transmitted as data packets through the IMS architecture.

However, since the VoLTE service is a service that can be provided only within the 3GPP LTE system coverage, a radio access network (RAN) such as UTRAN or GERAN (hereinafter, referred to as " 3G network) coverage, the call is interrupted. In order to compensate for this, the Single Radio Voice Call Continuity (SRVCC) function, which does not interfere with the call even when the mobile terminal goes to the 3G network coverage during the VoLTE call in LTE coverage, has been commercialized.

In addition, when the call is disconnected, the subscriber's terminal that has moved to the 3G network coverage is immediately disconnected. However, since the subscriber within the coverage of the LTE system can not know that the call is disconnected, Experience. This will be described below with reference to FIG.

Hereinafter, the call processing exemplified in this specification may be omitted or simplified in order to explain the gist of the present invention, but the present invention is not limited thereto.

FIG. 2 is a diagram for explaining a call processing method in a handover between heterogeneous networks during a call.

The mobile communication system generates a PDN connection (PDN (Packet Date Network) connection (or an EPS session or an IP session) suitable for the purpose of packet data to be transmitted / received by the UE, and creates bearers in the PDN connection And transmits the packet. The EPS session has one or more EPS bearers, and the EPS bearer is divided into a default bearer and a dedicated bearer. A basic bearer is a minimum basic bearer of an EPS session for one PDN, and a dedicated bearer is created when a user uses a service that can not be provided with QoS (Quality of Service) as a set basic bearer. That is, the dedicated bearer is set to a QoS different from that of the basic bearer already set, and is combined with the basic bearer by LBI (Linked EPS Bearer Identity). The terminal can connect to a plurality of APNs (i.e., PDNs) and one basic bearer and one or more dedicated bearers can be set per APN.

In addition, the mobile communication system determines how to allocate network resources and control billing when EPS session is created / changed, and applies the session while maintaining the session. Specifically, when creating or modifying an EPS session, the PCRF determines the PCC rules for each SDF (Service Data Flow), and the PGW receives the PCC rules from the PCRF and applies them to the EPS bearer. The PCC rules can be determined based on the policy of the mobile communication provider and include policy rule name, service ID, SDF template, gate status, QoS (Quality of Service) A QoS class identifier (QCI), an allocation and retention priority (ARP), a guaranteed bit rate (GBR), a maximum bit rate (MBR)), .

In FIG. 2, it is assumed that the terminal A is connected to the terminal B and the E-UTRAN to perform a VoLTE voice call. The terminal A is connected to the IMS APN for the VoLTE service. The terminal A is connected to the base bearer (QCI = 5) applied to the SIP signaling connected to the IMS network and the user voice packet RTP (Real-time Transport Protocol) It is assumed that a dedicated bearer (QCI = 1) is set for transmission and reception. That is, in order to support VoLTE, one or more dedicated bearers other than the basic bearer must be set in the terminal.

Hereinafter, for convenience of description, an example of a 3G network in which a terminal is handed over will be described on the assumption of a UTRAN.

Referring to FIG. 2, the terminal A is connected to the terminal B and the E-UTRAN and moves to the 3G network area during VoLTE voice communication (S201). The source base station transmits, A, the source base station of the terminal A transmits a handover request message for requesting handover of the terminal A to the source MME of the terminal A (S203).

Upon receiving the handover request message, the source MME detects handover between heterogeneous wireless access systems through a handover request message, extracts a target SGSN based on the information included in the handover request message, and transmits the extracted target SGSN A Forward Relocation Request message is transmitted (S205). Thereafter, the target SGSN transmits a Forward Relocation Response message to the source MME in response to the transmission re-location request message (S207). The source MME having received the transmission re-location response message transmits a handover command message to the source base station (S209).

Thereafter, the target SGSN transmits a Forward Relocation Complete message to the source MME to notify that the handover of the terminal A is completed, and the source MME transmits a Forward Relocation Complete message in response to the transmission re- Forward Relocation Complete Acknowledgment) message to the target SGSN (S211).

As described above, when the terminal A completes the handover from the 3GPP LTE system to the 3G network, the VoLTE call of the terminal A is terminated at this point (S213).

The target SGSN of the terminal A transmits an Update PDP Context Request (PDP) message to the PGW of the terminal A to transmit two Packet Network Protocol Context Request (PDP) messages through the E-UTRAN to the two bearers (QCI = 5) and dedicated bearer (QCI = 1) to the PGW (S215).

Upon receiving the PDP context update request message from the SGSN, the PGW determines whether the network requesting the bearer setup is a network supporting dedicated bearers. If the network is not a network supporting dedicated bearers, the PGW is set in the A- Is deleted (S217). In this case, the network that does not support the dedicated bearer may correspond to the case where the network itself can not support the dedicated bearer, or may be a network that is configured not to support the dedicated bearer according to the policy of the mobile communication service provider.

In response to the PDP context update request message, the PGW transmits a PDP Context Update Response message (Update PDP Context Request) to the SGSN to delete the dedicated bearer set in the UE A through the E-UTRAN, (I.e., set) (S219).

Upon receiving the PDP context update response message from the PGW, the SGSN confirms that only the basic bearer is set up, and deletes the dedicated bearer set in the UE (S221).

On the other hand, since the terminal A is in a state in which the VoLTE call is ended but the call session is not terminated in the step S213, the terminal B does not terminate the call and the terminal B can not receive the RTP packet which is the user voice packet from the terminal A Occur). Thereafter, when the terminal B does not receive the RTP packet from the terminal A continuously for a preset time (for example, 10 seconds), the terminal B transmits a session with the terminal A to the IMS with a cause (NO RTP) (Step S223).

When the terminal B transmits a BYE message for terminating the session with the terminal A, the VoLTE call of the terminal B is terminated at this point (S225). If the terminal B does not know that the call is terminated and waits for the RTP packet from the terminal A for a predetermined time, the terminal B ends the session. As described above, there is a disadvantage that the counterpart terminal of the terminal moving to the 3G network area among the VoLTE conversations suffers inconvenience of terminating the call after silencing for a predetermined time.

Thereafter, the terminal B completes the call session end procedure by receiving the 200OK message as an acknowledgment of the BYE message from the IMS (S227).

In order to solve such a problem, in the present invention, any one of VoLTE calls in the PGW hands over to a heterogeneous network that does not support a VoLTE service (i.e., a heterogeneous network that does not support a dedicated bearer) , A message to terminate the session for the call is transmitted to the PCRF to suggest a method for removing the call session itself.

FIG. 3 is a diagram for explaining a call processing method in a handover between heterogeneous networks during a call according to an embodiment of the present invention.

In FIG. 3, it is assumed that the terminal A is connected to the terminal B and the E-UTRAN to perform a VoLTE voice call as in FIG. The terminal A is connected to the IMS APN for the VoLTE service. The terminal A is connected to the base bearer (QCI = 5) applied to the SIP signaling connected to the IMS network and the user voice packet RTP (Real-time Transport Protocol) It is assumed that a dedicated dedicated bearer (QCI = 1) is set.

Hereinafter, for convenience of explanation, it is assumed that a UTRAN is an example of a 3G network in which a UE is handed over. However, the UTRAN is not limited to the UTRAN. However, the UTRAN may not support dedicated bearers, The present invention can be applied to an access network.

3, the terminal A is connected to the terminal B and the E-UTRAN to move to the 3G network area during VoLTE voice communication (S301), and the source base station transmits, to the terminal B, A, the source base station of the terminal A transmits a handover request message for requesting handover of the terminal A to the source MME of the terminal A (S303).

Upon receiving the handover request message, the source MME detects handover between heterogeneous wireless access systems through a handover request message, extracts a target SGSN based on the information included in the handover request message, and transmits the extracted target SGSN A Forward Relocation Request message is transmitted (S305). Thereafter, the target SGSN transmits a Forward Relocation Response message to the source MME in response to the transmission re-positioning request message (S307). The source MME having received the transmission re-location response message transmits a handover command message to the source base station (S309).

Thereafter, the target SGSN transmits a Forward Relocation Complete message to the source MME to notify that the handover of the terminal A is completed, and the source MME transmits a Forward Relocation Complete message in response to the transmission re- Forward Relocation Complete Acknowledgment) message to the target SGSN (S311).

In this manner, when the terminal A completes the handover from the 3GPP LTE system to the 3G network, the VoLTE call of the terminal A is terminated at this point (S313).

The target SGSN of the UE A transmits an Update PDP Context Request (PDP) message to the PGW of the UE A, and transmits the PDP Context Request message to the UEs A through the E-UTRAN through two bearers (QCI = 5) and the dedicated bearer (QCI = 1) to the PGW (S315).

Upon receiving the PDP context update request message from the SGSN, the PGW determines whether the network requesting bearer setup is a network supporting dedicated bearers. If the network is not a network supporting dedicated bearers, The dedicated bearer is deleted (S317). In this case, the network that does not support the dedicated bearer may correspond to the case where the network itself can not support the dedicated bearer, or may be a network that is configured not to support the dedicated bearer according to the policy of the mobile communication service provider.

The PGW that deleted the dedicated bearer for the terminal A transmits a CCR (Credit Control Request) (or CCR-U (Credit Control Request Update)) message to the PCRF in order to terminate the call session of the terminal A (cause = 10) S319).

Upon receiving the CCR (or CCR-U) message from the PGW, the PCRF transmits an ABR (Abort Session Request) message for ending the call session to the IMS (S321). In response to the ABR message, And receives a response (Abort Session Answer) message (S323). In step S325, the MS transmits a Credit Control Answer / Response (CCA) message to the PGW in response to the CCR (or CCR-U) message.

Upon receiving the CCA (or CCA-U) message from the PCRF, the PGW transmits a PDP context update request message (Update PDP Context Request) to the SGSN in response to the PDP context update request message, And informs that only the basic bearer is set (S327).

Upon receiving the PDP context update response message from the PGW and confirming that only the basic bearer is set, the SGSN deletes the dedicated bearer set in the UE through the E-UTRAN (S329).

On the other hand, the IMS, which has received the session end request message for ending the call session from the PCRF, transmits a session end response message in step S323, and transmits a call termination request by the PCRF to the end of the call session by a cause (Abort Session by PCRF) BYE message to the terminal B (S331).

As described above, when the terminal B receives the BYE message from the IMS, the VoLTE call of the terminal B is terminated at this point (S333). In step S313, the terminal B may terminate the call at a time substantially equal to the time when the terminal A ends the call. Therefore, the inconvenience of terminating the call after the mute for a predetermined period of time has been resolved by the counterpart terminal that was in the call with the terminal that has moved to the 3G network area during the VoLTE call.

Thereafter, since the call is terminated, the terminal B deletes one dedicated bearer (QCI = 1) set in the terminal B, and the terminal B transmits a 200 OK message to the IMS in response to the BYE message. Is completed (S335).

FIG. 4 is a diagram for explaining a method of processing a call when handover between heterogeneous networks during a call according to an embodiment of the present invention.

Referring to FIG. 4, as described above, in order to support the VoLTE service, one or more dedicated bearers to be applied to one basic bearer applied to SIP signaling connected to an IMS network and a RTP packet, which is a user voice packet, Therefore, when any one of two or more UEs connected to the E-UTRAN and performing VoLTE communication moves to the 3G network area and performs handover between heterogeneous radio access systems, the PDN GW transmits the E And receives a setup request message of a dedicated bearer set in the terminal through the UTRAN (S401). At this time, the PDP context update request message may be used as the dedicated bearer setup request message.

The PDN GW checks whether the network that transmitted the setup request message of the dedicated bearer supports the dedicated bearer (S403). In this case, the network that does not support the dedicated bearer may correspond to the case where the network itself can not support the dedicated bearer, or may be a network that is configured not to support the dedicated bearer according to the policy of the mobile communication service provider.

As a result of the determination in step S403, if the network to which the UE handed over, i.e., the network that transmitted the setup request message of the dedicated bearer, is a network that does not support dedicated bearers, the PDN GW transmits, via the E-UTRAN, (S405).

Then, in step S407, the PDN GW transmits a call session end request message to the IMS in order to terminate the call between the handover-initiated terminal and the counterpart terminal in the VoLTE call. Here, the PDN GW may transmit a call session end request message directly to the IMS, but may transmit a call session end request message to the IMS through the PCRF. The PDN GW may use the CCR (or CCR-U) message (cause = 10) to send a call session end request message to the IMS through the PCRF. After receiving the CCR (or CCR-U) message (cause = 10) from the PDN GW, the PCRF sends a session end request (ABR) message to the IMS, and the IMS receiving the ABR message transmits a BYE message Thereby terminating the call of the counterpart terminal.

5 is a diagram illustrating a configuration of a packet data network gateway device (PGW) according to an embodiment of the present invention.

The configuration of the PGW 500 shown in FIG. 5 shows functional elements that are functionally separated, and any one or more configurations may be physically integrated with each other.

5, the PGW 500 according to an exemplary embodiment of the present invention may include a communication unit 510, a storage unit 520, and a control unit 530. The control unit 530 may include a dedicated bearer support confirmation unit 531, a dedicated bearer management unit 533, and a call session processing unit 535 for each function. The communication unit 510, the storage unit 520, and the control unit 530 of the PGW 500 may be mutually and functionally connected to perform the functions according to the present invention.

Describing each component more specifically, the communication unit 510 provides an interface for enabling communication with the SGW, the PCRF, and the IP service network (e.g., IMS). The communication unit 510 can send and receive a message using the SGW, the GTP, or the PMIP protocol through the S5 reference point, and can transmit and receive the message using the PCRF and the Diameter protocol through the Gx reference point. In addition, messages can be transmitted and received using the IP service network and the IP protocol through the SGi reference point. In particular, in the present invention, the communication unit 510 may receive a dedicated bearer setup request message (e.g., a PDP context update request message) from a 3G network node (e.g., SGSN) A dedicated bearer setup response message may be transmitted to the 3G network node. Also, the communication unit 510 can transmit a call session end request message to the IMS and receive a call session end response message from the IMS in response to the call session end request message. At this time, when transmitting / receiving a call session end request / response message to / from the IMS through the PCRF, a call session end is requested by the PCRF through the CCR (or CCR-U) message, and a response to the CCR (or CCR-U) And receive a response thereto via a CCA (CCA-U) message.

The storage unit 520 is a means for storing data and / or programs necessary for the operation of the PGW 500. [ In particular, in the present invention, the storage unit 520 may store information on the bearer set in the terminal.

The storage unit 520 may be inside or outside the control unit 530 and may be connected to the control unit 530 by various well-known means.

The control unit 530 controls the overall flow of the PGW 500 and controls the flow of signals for performing the functions of the communication unit 510 and the storage unit 520. Particularly, in the present invention, the control unit 530 implements the functions, processes and / or methods proposed in FIGS. 3 to 4 above.

Specifically, the dedicated bearer support confirmation unit 531 of the controller 530 checks whether the network that transmitted the setup request message of the dedicated bearer supports the dedicated bearer. In this case, the network that does not support the dedicated bearer may correspond to the case where the network itself can not support the dedicated bearer, or may be a network that is configured not to support the dedicated bearer according to the policy of the mobile communication service provider.

If the network to which the UE handed over the UE, i.e., the network that transmitted the setup request message of the dedicated bearer, does not support the dedicated bearer, the Dedicated Bearer Management Unit 533 transmits the Dedicated Bearer Lt; / RTI > At this time, when the network to which the UE has handed over, i.e., the network that transmitted the setup request message of the dedicated bearer supports the dedicated bearer, sets the dedicated bearer set in the UE through the E-UTRAN.

The call session processing unit 535 transmits a call session end request message to the IMS in order to terminate the call between the terminal that has performed the handover and the terminal that was in the VoLTE call. Here, the PDN GW may transmit a call session end request message directly to the IMS or may transmit a call session end request message to the IMS through the PCRF. The PDN GW may use the CCR (or CCR-U) message (cause = 10) to send a call session end request message to the IMS through the PCRF.

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In addition, in the case of an implementation by firmware or software, an embodiment of the present invention may be embodied in the form of a module, a procedure, a function, and the like for performing the functions or operations described above, Lt; / RTI > Here, the recording medium may include program commands, data files, data structures, and the like, alone or in combination. Program instructions to be recorded on a recording medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. For example, the recording medium may be an optical recording medium such as a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, a compact disk read only memory (CD-ROM), a digital video disk (DVD) Optical media such as a floppy disk and a hardware device specifically configured to store and execute program instructions such as ROM, RAM, flash memory and the like. Examples of program instructions may include machine language code such as those generated by a compiler, as well as high-level language code that may be executed by a computer using an interpreter or the like. Such hardware devices may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be apparent to those skilled in the art. Furthermore, although specific terms are used in this specification and the drawings, they are used in a generic sense only to facilitate the description of the invention and to facilitate understanding of the invention, and are not intended to limit the scope of the invention. Accordingly, the foregoing detailed description is to be considered in all respects illustrative and not restrictive. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

In addition, a device or terminal according to the present invention may be driven by instructions that cause one or more processors to perform the functions and processes described above. Such instructions may include, for example, interpreted instructions such as script commands, such as JavaScript or ECMAScript commands, or other instructions stored in executable code or computer readable media. Further, the apparatus according to the present invention may be implemented in a distributed manner across a network, such as a server farm, or may be implemented in a single computer device.

Further, a computer program (also known as a program, software, software application, script or code) that is embedded in the apparatus according to the present invention and which implements the method according to the present invention includes a compiled or interpreted language, a priori or procedural language , And may be deployed in any form including standalone programs or modules, components, subroutines, or other units suitable for use in a computer environment. A computer program does not necessarily correspond to a file in the file system. The program may be stored in a single file provided to the requested program, or in multiple interactive files (e.g., a file storing one or more modules, subprograms, or portions of code) (E.g., one or more scripts stored in a markup language document). A computer program may be deployed to run on multiple computers or on one computer, located on a single site or distributed across multiple sites and interconnected by a communications network.

Moreover, in describing the embodiments according to the present invention, operations are depicted in the drawings in a particular order, but it is to be understood that they should perform such operations in that particular order or sequential order shown in order to obtain the desired result, Should not be understood as being performed. In certain cases, multitasking and parallel processing may be advantageous. Also, the separation of the various system components of the above-described embodiments should not be understood as requiring such separation in all embodiments, and the described program components and systems will generally be integrated together into a single software product or packaged into multiple software products It should be understood.

Although the call processing method for handover between heterogeneous networks according to the present invention has been described with reference to an example applied to the 3GPP LTE / LTE-A system, it is also applicable to various wireless communication systems.

500: packet data network gateway device
510: communication unit 520:
530: Control section 531: Dedicated bearer support confirmation section
533 dedicated bearer management unit 535 call session processing unit

Claims (5)

1. A packet data network gateway apparatus for supporting call processing in a mobile communication system,
When a terminal in a call is handed over to a heterogeneous network using a dedicated bearer set in the mobile communication system and receives a dedicated bearer setup request message set in the terminal from a target network to which the terminal has moved, A dedicated bearer support confirmation unit for determining whether the target network supports the dedicated bearer;
A dedicated bearer management unit for deleting the dedicated bearer set in the terminal if the target network does not support the dedicated bearer; And
And a call session processor for transmitting a session end request message for requesting the end of the established call session to the IP Multimedia Subsystem (IMS) when the dedicated bearer is deleted from the dedicated bearer management unit, . The method according to claim 1,
Wherein the call session processing unit transmits the session end request message to the IMS through a Policy and Charging Rule Function (PCRF) device. The method according to claim 1,
Wherein the dedicated bearer setup request message is a PDP Context Update Request message. The method according to claim 1,
Wherein the dedicated bearer is applied to transmission and reception of a Real-time Transport Protocol (RTP) packet that is a user voice packet during the call. A method for supporting call processing in a packet data network gateway (GW) device in a mobile communication system,
Upon receiving a dedicated bearer setup request message set up in the terminal from a handover target network according to a handover to a heterogeneous network using a dedicated bearer established in the mobile communication system, Determining whether a dedicated bearer is supported;
If the target network does not support dedicated bearer, deleting the dedicated bearer set for the terminal; And
And transmitting a session termination request message to the IP Multimedia Subsystem (IMS) for requesting termination of the call session established through the dedicated bearer when the dedicated bearer is deleted.

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