KR20100060353A - System and method for providing circuit switched fallback function - Google Patents

Abstract

A system and method for providing a CS fallback function in an EPS network are disclosed. According to an embodiment, a system providing a circuit switched (CS) fallback function in an evolved packet system (EPS) network may initially support its CS fallback support in a response message for a configuration request of an eNodeB. A mobility management node (MME) for transmitting including an indicating indicator; And the base station (eNodeB) which broadcasts the indicator to a radio resource control (RRC) message to a mobile station (UE). The method through the system, at the initial operation, the mobility management node (MME) including the indicator indicating the CS fallback support capability in the response message to the base station (eNodeB) configuration request transmission; Broadcasting, by the eNodeB, the indicator in a Radio Resource Control (RRC) message to a mobile station (UE); And the UE attempting a Combined EPS / IMSI Attach or Combined TA / LA Update to the MME based on the indicator.

Description

SYSTEM AND METHOD FOR PROVIDING CIRCUIT SWITCHED FALLBACK FUNCTION}

The present invention relates to a system and method for providing a CS (Circuit Switched) Fallback function in an evolved mobile communication network, in particular, a 4G Evolved Packet System (EPS) defined by 3GPP.

3GPP's next-generation core network (EPS) is an ALL-IP-based system that supports a variety of access networks, including Long Term Evolution (LTE), High-Speed Packet Access (HSPA) / HSPA +, as well as non-3GPP networks.

In the 3GPP EPS system, CS fallback means that a user equipment (UE) serving in an LTE Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) cell region is a network resource of a CS (Circuit Switched) region, that is, MSC (Mobile). CS services (e.g., video services, short message services, SMS (LoCation Services), Unstructured Supplementary Service Data (USSD) using a Switching Center, Release 99) or an MSC server (Release 5 or later) )) Is a technology that provides.

CS Fallback function is used when CS service is not available through EPS network. For reference, EPS is an AIPN (All IP Network) type network and requires interworking with an IMS (IP Multimedia Subsystem) network to provide services such as voice or SMS. Therefore, if the EPS network does not support the IMS service or the IMS function cannot be used, the CS fallback function should be used. CS Fallback function must be provided in UE as well as network.

The EPS network defines the SGs interface between the Mobility Management Entity (MME) and the MSC Server, which provides mobility management for CS Fallback. The SGs interface provides the ability to send / receive incoming / outgoing SMS messages as well as mobility management messages for CS Fallback. Specifically, mobility management process such as Combined EPS / IMSI Attach process, Combined TA / LA Update process, Detach process for CS Fallback function, Paging process from MSC server to MME for CS Fallback service, and UE ( User equipment) or a process of delivering an SMS message to / from the UE is performed through the SGs interface.

However, if a UE with CS Fallback function attempts to combine EPS / IMSI Attach to an MME that does not support CS Fallback function in the EPS network, the UE fails and of course, regardless of the CS Fallback Capability of the MME. There is a problem of wasting system resources by continuously trying Combined EPS / IMSI Attach for a preset number of retransmissions. In addition, until now, an operation process between an MME and an MSC server for SMS CS fallback service in an EPS network is not defined. In addition, in transmitting an SMS message received at the UE to the MME through the SGs interface, the MSC server transmits a paging message to the MME unconditionally regardless of the state (Idle, Active) of the UE. This causes a problem that the incoming SMS processing procedure is complicated.

It is an object of the present invention to provide a system and method for providing a CS fallback function in an EPS network.

According to an aspect of the present invention, a system and method for providing a CS fallback function in an EPS network are disclosed. According to an embodiment, a system providing a circuit switched (CS) fallback function in an evolved packet system (EPS) network may initially support its CS fallback support in a response message for a configuration request of an eNodeB. A mobility management node (MME) for transmitting including an indicating indicator; And the base station (eNodeB) which broadcasts the indicator to a radio resource control (RRC) message to a mobile station (UE). The method through the system, at the initial operation, the mobility management node (MME) including the indicator indicating the CS fallback support capability in the response message to the base station (eNodeB) configuration request transmission; Broadcasting, by the eNodeB, the indicator in a Radio Resource Control (RRC) message to a mobile station (UE); And the UE attempting a Combined EPS / IMSI Attach or Combined TA / LA Update to the MME based on the indicator.

According to another embodiment, a system that provides an SMS CS (Circuit Switched) Fallback function in an Evolved Packet System (EPS) network is received using an interface protocol (S1AP) between an eNodeB and a mobility management node (MME). SMS CS of the MME that converts the outgoing SMS message into an interface (SGs) protocol (SGsAP) between the MME and the exchange (MSC) server, and converts the incoming SMS message received using the SGsAP into the S1AP. Fallback converter (FB converter); And an agent (FB agent) of the MSC server, which processes the incoming and outgoing SMS messages through the SGs interface, independently of the SMS message handling function through the Iu-CS interface.

According to another embodiment, a system providing an SMS CS (Circuit Switched) Fallback function in an Evolved Packet System (EPS) network may include an indicator indicating a state information of a mobile station (UE) with an interface with an exchange server (MSC). SGs) mobility management node (MME) for transmission in a protocol (SGsAP) message; And the MSC server that determines whether to send a paging message for SMS reception based on the indicator. The method via the system includes the steps of: transmitting, by a mobility management node (MME), an indicator indicating status information of a mobile terminal (UE) in an interface (SGs) protocol (SGsAP) message with an exchange (MSC) server; Determining, by the MSC server, whether to send a paging message for an SMS incoming based on the indicator; And sending, by the MSC server, an incoming SMS message to the MME without transmitting the paging message to the MME when the indicator is UE-activated.

According to the present invention, the CS Fallback capability of the MME is transmitted to the UE through the eNodeB, thereby enabling the UE to control the operation for the CS Fallback function, thereby preventing unnecessary system resource waste. In addition, the present invention facilitates the implementation of the SMS CS Fallback function by presenting a protocol stack structure for providing an SMS CS Fallback function, a system structure for the MME and an MSC server, and an operation process.

In addition, in the present invention, by transmitting the status information of the UE from the MME to the MSC server through the SGs interface, when the MSC server receives an incoming SMS message for the CS fallback function from the SMS-SC, the UE prior to performing the paging operation By knowing the state of the, it is possible to simplify the process of the incoming SMS message by not performing unnecessary paging if the UE is active (Active) state.

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 an EPS system to which the present invention is applied.

The UE 10 supports CS Fallback capability, as well as Combined EPS / IMSI Attach, Combined TA / LA Update, Detach function, and SMS message origination / reception function.

The Mobility Management Entity (MME) 20 provides CS Fallback capability as well as Combined EPS / IMSI Attach, Combined TA / LA Update, Detach, SMS message processing and the MSC server 30 from the UE 10. It supports SGs interface connection management.

The MSC or MSC server 30 manages the CS Fallback capability as well as the Combined EPS / IMSI Attach, Combined TA / LA Update, Detach, SMS message processing from the MME 20 and the SGs interface connection to the MME 20. Support the function.

UTRAN (UMTS Terrestrial Radio Access Network) / GERAN (GSM / EDGE Radio Access Network) is a radio in UMTS / GSM that is composed of a base station (Node-B or BTS), a radio network controller (RNC), and a base international controller (BSC). The access network, which is ATM based, is located between the UE 10 and a wireless core network to transmit data and control information.

E-UTRAN (Evolved UTRAN) is a wireless access network of LTE. It provides a paging request for CS fallback purposes, a function of delivering an SMS message to the UE 10, and a direct connection function to a target cell capable of CS service. Support.

In FIG. 1, "Uu" represents an air interface between the UTRAN and the UE 10, and "Iu-CS" is an interface between the radio communication core network and the UTRAN. "Um" represents the air interface between the GERAN and the UE 10, and "A" is the interface between the wireless communication core network and the GERAN. In addition, "LTE-Uu" represents an air interface between the E-UTRAN and the UE 10, "S1-MME" is an interface between the E-UTRAN and the MME 20, and "SGs" is the MME 20 And the interface between the MSC server 30.

The base station (eNodeB) of the UE 10 and the E-UTRAN communicate through an RRC protocol, and a broadcasting message from the base station eNodeB to the cell area controlled by the base station eNodeB is defined as an RRC message. The RRC message may include control messages coming down from the Non-Access Stratum (NAS) protocol. The control messages are transmitted transparently to the UE 10 or the core network without being read in the E-UTRAN.

S1AP is used in the S1-MME interface section between the eNodeB and the MME 20, and SGsAP (SGs Application Protocol) is used in the SGs interface section between the MME 20 and the MSC server 30. SGsAP is an application protocol used between the MME 20 and the MSC server 30 and supports the CS fallback function on the SGs interface.

The SGs interface is based on the Gs interface function between the SGSN and the MSC server in the 3G UMTS network. In the Gs interface section, Paging Co-ordination function is provided between CS (Circuit Switching) and PS (Packet Switching) through BSSAP + protocol message.

The control plane protocol structure of the SGs interface is shown in FIG. SCTP (Stream Control Transmission Protocol) is used as the message transmission protocol of the SGs interface, and SGsAP is used as the application protocol. SCTP is a standard technology defined by IETF, and SGsAP is a newly defined protocol for CS Fallback function in 3GPP.

For CS Fallback function in EPS network, mobility management process such as Combined EPS / IMSI Attach, Combined TA / LA Update, and Detach should be provided.

The combined EPS / IMSI Attach process for mobility management will be described with reference to FIG. 3.

The Combined EPS / IMSI Attach process is a procedure for attaching to the MSC server 30 in the CS area through the EPS network. Through this process, although the UE 10 is located in the E-UTRAN region, it is possible to manage the mobility of the UE 10 in the CS region through the SGs interface.

The UE 10 transmits an attach request message to the MME 20 (301). At this time, the Attach Type is set to 'Combined EPS / IMSI Attach'.

The Initial E-UTRAN Attach operation defined in 3GPP TS 23.401 is performed (302).

The MME 20 infers the address of the MSC server 30 from the current location information of the UE 10 when the Attach Type of the Attach Request message is 'Combined EPS / IMSI Attach' (303), and the MSC of the corresponding address. The SGs location update request is sent to the server 30 (304).

The MSC server 30 generates an SGs interface connection establishment and management function for the corresponding UE 10 (305). In addition, the MSC server 30 performs a location registration procedure in the CS area in association with the home subscriber server (HSS) 40 (306), and when the procedure is completed, the SGs location registration response to the MME 20 (Location Update). Accept) transmits a message (307).

The MME 20 notifies the Combined EPS / IMSI Attach success by sending an Attach Reply message to the UE 10 (308).

The detach process for mobility management will be described with reference to FIG. 4.

Detach process is a procedure for informing the UE Detach operation occurred in the EPS network to the MSC server 30 through the SGs interface. Due to this process, it is impossible to provide the CS Fallback function through the SGs interface in the MSC server 30. For reference, the detach process may be initiated at the UE 10 or may be initiated at the MME 20 or the HSS 40.

For example, if the terminal is deactivated (power off, etc.) or the USIM is removed from the UE, the UE 10 transmits a Detach request message to the MME 20 (401). At this time, the Detach Type is set to 'Combined EPS / IMSI Detach'.

Perform Detach operation defined in 3GPP TS 23.401 (402).

When the MME 20 transmits an SGs IMSI Detach Indication message to the MSC server 30 (403), the MSC server 30 sends a corresponding UE 10 generated during the attach process (see FIG. 3). Delete the SGs interface connection establishment and management function (404).

The MME 20 transmits an acknowledgment message for the Detach request to the UE 10 (405).

A combined TA / LA update process for mobility management will be described with reference to FIG. 5.

The Combined TA / LA Update process is a procedure for notifying the MSC server 30 of the TA (Tracking Area) Update operation occurring in the EPS network through the SGs interface. Due to this process, the MSC server 30 updates the location information of the UE 10 through the SGs interface. The update process is performed by the MME 20a to which the UE 10 newly connects.

When the TA information is changed, the UE 10 determines an update operation (501), and transmits a TA update request message to a new MME (MME) 20a (502). At this time, the Update Type is set to 'Combined EPS / IMSI Update'.

The TA update operation defined in 3GPP TS 23.401 is performed (503).

When the MME 20a sends an SGs Location Update Request message to the MSC server 30 (504), the MSC server 30, in conjunction with the HSS 40, updates the location registration update procedure in the CS area. In step 505, when the procedure is completed, the SGs location registration update response message is transmitted to the MME 20a (506).

The MME 20a informs the UE 10 of the Combined EPS / IMSI update success by sending an Acknowledgment (507) message to the TA update request (507).

The process of sending / receiving SMS messages is as follows.

FIG. 6 shows a procedure for delivering an SMS message sent from the UE 10 to the MSC server 30 through the SGs interface, and FIG. 7 shows a paging message transfer and response function and a paging response of the MSC server 30. The procedure for delivering the SMS message, which is received to the UE 10 later, to the MME 20 via the SGs interface is shown.

Looking at the originating SMS processing procedure with reference to Figure 6, the UE 10 performs the Combined EPS / IMSI Attach procedure (601).

In the idle mode, that is, when there is no NAS Signaling Connection between the UE 10 and the MME 20, the UE 10 transmits a service request message to the MME 20. (602). At this time, the MME 20 selectively performs authentication or operations defined by the MME 20. In the case of an active mode, i.e., if there is already a connection between the UE 10 and the MME 20, this procedure is omitted.

When the UE 10 transmits an outgoing SMS message (Uplink NAS Transport) to the MME 20 (603), the MME 20 transmits an outgoing SMS message to the MSC server 30 using the SGs interface Uplink Unitdata message. (604).

The MSC server 30 transmits an outgoing SMS message (Forward Short Message) to the InterWorking Mobile service Switching Center (SMS-IWMSC) 50 (605). At this time, a MAP (Mobile Application Part) protocol message is used between the MSC server 30 and the SMS-IWMSC 50. Thereafter, the SMS-IWMSC 50 forwards the outgoing SMS message to the SMS Service Center (SMS-SC) 60 (606). At this time, the MAP protocol message is used between the SMS-IWMSC 50 and the SMS-SC 60.

The SMS-SC 60 transmits an outgoing SMS response message to the SMS-IWMSC 50 (607), and the SMS-IWMSC 50 sends an outgoing SMS response message to the MSC server 30 ( 608). Thereafter, the MSC server 30 transmits an outgoing SMS response message to the MME 20 using the SGs interface Downlink Unitdata message (609), and the MME 20 sends an outgoing SMS response message to the UE 10 (Downlink NAS). Transport (610).

Looking at the incoming SMS processing procedure with reference to Figure 7 as follows. In FIG. 7, the SMS-GMSC (SMS Gateway Mobile Service Switching Center) performs the same function as the SMS-IWMSC 50. However, since SMS-IWMSC is involved in SMS transmission processing, and SMS-GC is only involved in SMS incoming processing, the same reference numerals are used.

SMS message reception through the SGs interface at the UE 10 is possible after the Combined EPS / IMSI Attach procedure 701 of FIG. 3 is performed.

SMS-SC 60 forwards the incoming SMS message to SMS-GMSC 50 (702). At this time, the MAP protocol message is used between the SMS-SC 60 and the SMS-GMSC 50.

The SMS-GMSC 50 requests Send Routing Info For Short Message to the HSS 40 for the incoming SMS message and receives a Send Routing Info For Short Message Ack message (703). At this time, a MAP protocol message is used between the SMS-GMSC 50 and the HSS 40.

When the SMS-GMSC 50 transmits an incoming SMS message to the address of the MSC server 30 obtained in step 703, the MSC server 30 paging the MME 20 through the SGs interface. In step 705, the message is transmitted.

In the idle mode, i.e., when there is no connection between the UE 10 and the MME 20, the MME 20 transmits a paging message to the eNodeB 70 (706), and the eNodeB 70 The paging message is transmitted to the UE 10 (707). At this time, the UE 10 transmits a service request message in response to the paging request to the MME 20 through the eNodeB 70 (708), and the MME 20 requests the service to the MSC server 30. Send a message (paging response message) (709). If the UE 10 is in an active mode, that is, if the UE 10 and the MME 20 are already connected, steps "706" to "709" are omitted.

The MSC server 30 transmits the incoming SMS message to the MME 20 to the MME 20 using the SGs interface Downlink Unitdata message (710), and the MME 20 sends the incoming SMS message to the UE 10 (Downlink NAS). Transport (transport) (711).

In this regard, the UE 10 forwards an incoming SMS response message (Uplink NAS Transport) to the MME 20 (712), and the MME 20 sends an incoming SMS response message to the MSC server 30 in an SGs interface Uplink Unitdata message. It transmits using (713). The MSC server 30 transmits an incoming SMS delivery message to the SMS-GMSC 50 (714), and the SMS-GMSC 50 transmits an incoming SMS response message to the SMS-SCSC 60. (715).

In the above, when the UE 10 having the CS fallback function attempts the Combined EPS / IMSI Attach to the MME 20 that does not support the CS Fallback function, the UE 10 fails as well as the MME 20. Regardless of CS Fallback Capability, it will continue to try Combined EPS / IMSI Attach for a preset number of retransmissions. In addition, in delivering the SMS message received at the UE 10 to the MME 20 through the SGs interface, the MSC server 30 may be configured to display paging (regardless of the state (idle mode, activation mode) of the UE 10. Paging) message is unconditionally transmitted to the MME 20. Therefore, there is a need for a method of delivering the CS Fallback capability of the MME 20 to the UE 10. In addition, for the incoming SMS CS fallback function, a method of transmitting the status information of the UE 10 through the SGs interface is required. In this case, the MSC server 30 may determine whether to transmit the paging message according to the state of the UE 10, and do not transmit the paging message in the activation mode.

First, a method of transmitting the CS Fallback capability of the MME 20 to the UE 10 (MME CS Fallback Capability Transmission Function) will be described.

The MME 20 delivers the CS Fallback Flag during the S1 Setup operation from the MME 20 to the eNodeB 70, and the eNodeB 70 broadcasts information of an RRC message to the UE 10 (SIB: System Information Block). CS Fallback flag information received from the MME 20 is transmitted to the. Accordingly, the UE 10 determines whether to combine Combined EPS / IMSI Attach or Combined TA / LA by CS Fallback flag information received from the eNodeB 70 as broadcasting information.

In detail, the MME 20 and the eNodeB 70 perform a capability negotiation process as shown in FIG. 8 during initial operation. This process is based on the S1 Application Protocol (S1AP, 3GPP TS 36.413), which is an application protocol between the MME 20 and the eNodeB 70. As shown in FIG. 8, the eNodeB 70 transmits a Tracking Area (TA) list through the S1 SETUP REQUEST message to the MME 20 (801), and the MME 20 sends the S1 SETUP REPONSE to the eNodeB 70. The MME capacity information is transmitted through the message (802). Particularly, in the present invention, by adding a CS Fallback Indicator indicating the CS Fallback capability to the S1 SETUP REPONSE message transmitted from the MME 20 to the eNodeB 70, each node connected to itself in the eNodeB 70 is connected. To manage the CS fallback capability of the MME (20). The CS Fallback Indicator is set to 'TRUE' when the MME 20 supports the CS Fallback function, that is, when providing the SGs interface, and sets it to 'FALSE' when it does not support the CS Fallback Indicator.

In addition, since the eNodeB 70 has a function of broadcasting system information (SIB) to a cell area controlled by the eNodeB 70, the CS Fallback is transmitted to a broadcasting message transmitted from the eNodeB 70 to the UEs 10 as shown in FIG. 10. The indicator is added to transmit information on the CS fallback capability of the MME 20 (1001), so that the UE 10 can know whether the CS fallback function of the MME 20 to be selected.

As shown in FIG. 11, when a broadcasting message is received from the eNodeB 70 (1101), the UE 10 checks whether a CS fallback indicator exists in the message (1102) and provides CS Fallback Indicator information (TRUE, FALSE). ) Is stored in memory (1103). In addition, the initial value of the CS Fallback Indicator when the UE 10 does not receive the broadcasting message is set to 'FALSE'. According to the CS fallback indicator information (TRUE, FALSE), the UE 10 sets the attachment type (Type) to 'Combined EPS / IMSI Attach' when the UE is attached (1201) (1203). Set to an initial value (1204).

Here, the message broadcast from the eNodeB 70 is provided by a Radio Resource Control (RRC) protocol, and the RRC System Information Block (SIB) message corresponding to the broadcast message is classified into various types according to its characteristics. In the present invention, the CS Fallback Indicator is included in the SIB type that will include Network Pre-Configuration information.

Meanwhile, in the present invention, the protocol stack structure for the SMS CS fallback service between the MME 20 and the MSC server 30 is newly defined as shown in FIG. 13. FIG. 13 defines a protocol stack between the UE 10, the MME 20, and the MSC server 30 for the SMS CS fallback function. In FIG. 13, "MAP" is a Mobile Application Part, and "SMR" is a Short Message Relay layer, and uses Short Message Relay Protocol (SM-RP) between SMR layers. In addition, "SMC" is a short message control layer, and uses the short message relay protocol (SM-CP) between the SMC layers.

SMS protocols SM-CP and SM-RP messages (S1AP message) are transmitted from the UE 10 to the MME 20 transparently through the eNodeB 70, the MME 20 for the outgoing SMS message The S1AP message is converted into an SGsAP message without any processing and transferred to the MSC server 30 through the SGs interface. When the SMS message is received through the SGs interface, the MSC server 30 processes the outgoing SMS message.

On the contrary, when the SMS message is received from the outside (for example, SMS-GMSC), the MSC server 30 generates the SMS protocols SM-CP and SM-RP messages and converts the SM-CP and SM-RP messages into SGsAP messages. It passes to the MME 20 through the SGs interface. The MME 20 includes the incoming SMS message delivered as the SGsAP message in the S1AP message without any processing and delivers it to the UE 10 through the S1-MME interface.

For SMS message processing, the MME 20 includes an SMS CS Fallback Converter (hereinafter referred to as an 'FB converter') 21 as shown in FIG. 14, and the MSC server 30 is shown in FIG. 15. The SMS CS Fallback Agent (hereinafter referred to as 'FB Agent') 31 is provided.

As shown in FIG. 14, the FB converter 21 of the MME 20 converts an S1AP message (outgoing SMS message) received from the S1AP processor 22 into an SGsAP SMS message and transmits the SGsAP SMS message to the SGsAP processor 23. At this time, the outgoing SMS data is transmitted transparently without any processing. In addition, the FB converter 21 converts the SGsAP message (incoming SMS message) from the SGsAP processing unit 23 into an S1AP message and transmits it to the S1AP processing unit 22. At this time, the incoming SMS message is transmitted transparently without any processing.

As shown in FIG. 15, the reason why the FB agent 31 is placed in the MSC server 30 is to prevent the existing SMS processing function of the MSC server 30 from being affected. For example, when a failure such as RESET or RESET RESOURCE occurs on the Iu-CS interface, the MSC server 30 cannot provide the SMS service regardless of the failure of the SGs interface. Thus, by placing the FB agent 31 separately from the existing SMS processing function of the MSC server 30, by separating the SMS processing functions provided through different interfaces (i.e., SGs and Iu-CS), a new function for the application. Addition and maintenance can be performed easily. The FB agent 31 is identical to the SMS processing function of the MSC server 30, except that it has only different interfaces (i.e., SGs and Iu-CS). The FB agent 31 performs SGsAP interworking, SM-CP processing, SM-RP processing, SMS service control (Subscription check, ODB (Operator Determined Barring) check, CAMEL (Customized Application for Mobile Enhanced Logic) interaction, etc.), MAP Perform protocol inter-working function.

Looking at the correlation between the existing SMS processing function and the FB agent 31 in the MSC server 30, SMS messages through the Iu-CS interface is processed by the Legacy SMS Function 32, CS Fallback SMS messages through the SGs interface Processing is performed by the FB agent 31. However, the SMS-MAP protocol function 33 for interworking with SMS-IWMSC / SMS-SC (outgoing SMS processing) or SMS-GMSC / SMS-SC (incoming SMS processing) can be implemented using Legacy SMS Function 32 and FB agent ( 31) has a shared structure.

Lastly, for the incoming SMS CS fallback function, a method of transmitting the status information of the UE 10 through the SGs interface will be described.

The MME 20 transfers UE status information (Idle or Active) to the MSC server 30 as shown in FIG. 16. When the MSC server 20 delivers the incoming SMS message to the MME 20, the MSC server 20 determines whether to transmit paging based on the UE status information. At this time, the MSC server 30 does not transmit a paging message to the SGs interface when the state of the UE 10 is active.

Specifically, when the MME 20 detects a state change of the UE 10, the MME 20 has an SGs interface configured. That is, in case of supporting the CS fallback service, a UE-state-indication message is transmitted to the MSC server 30 (1602). At this time, the UE status information value is set to "UE-ACTIVE" or "UE-IDLE".

The MSC server 30 stores the state information of the UE 10 included in the UE state information message received from the MME 20 (1603). This UE status value is used later to determine whether to send a paging message for SMS incoming. That is, when the incoming SMS message is received from the SMS-SC 60, the MSC server 30 checks the status information of the UE 10 and, in the case of 'UE-ACTIVE', transmits a paging message to the MME 20. Instead, it immediately sends the incoming SMS message to the MME 20. In addition, when the incoming SMS message is received from the SMS-SC 60, the MSC server 30 does not need to transmit the CS-Paging message to the SGSN when the UE state is 'UE-ACTIVE' and the Gs interface is activated. That is, since it is known at this point that the UE 10 is located in the E-UTRAN region, the MSC server 30 does not need to transmit an unresponsive CS-Paging message to the SGSN.

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.

1 is a view showing the configuration of an EPS system to which the present invention is applied.

2 is an explanatory diagram showing an SGs interface between an MME and an MSC server.

3 is a flowchart illustrating a Combined EPS / IMSI Attach procedure.

4 is a flow chart illustrating a Detach procedure.

5 is a flowchart illustrating a Combined TA / LA Update procedure.

6 is a flowchart illustrating an outgoing SMS processing procedure.

7 is a flowchart showing an incoming SMS processing procedure.

8 is a flowchart illustrating a message processing procedure between an MME and an eNodeB for a CS fallback service according to an embodiment of the present invention.

9 is an explanatory diagram illustrating a configuration response message for a CS fallback service according to an embodiment of the present invention.

10 is a flowchart illustrating a message processing procedure of an eNodeB for a CS fallback service according to an embodiment of the present invention.

11 is a flowchart illustrating a message receiving process of a terminal for a CS fallback service according to an embodiment of the present invention.

12 is a flowchart illustrating an operation process of a terminal for a CS fallback service according to an embodiment of the present invention.

13 is an explanatory diagram showing a protocol stack structure for an SMS CS fallback service according to an embodiment of the present invention.

14 illustrates an FB converter of an MME for an SMS CS fallback service according to an embodiment of the present invention.

15 illustrates an FB agent of an MSC server for an SMS CS fallback service according to an embodiment of the present invention.

16 is a flowchart illustrating a message processing procedure of an MME for an incoming SMS CS fallback service according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10: UE (User Equiment) 20: Mobility Management Entity (MME)

21: FB Converter 30: Mobile Switching Center (MSC) Server

31: FB Agent

Claims (13)

A system that provides a circuit switched (CS) fallback function in an Evolved Packet System (EPS) network, A mobility management node (MME) which transmits an indicator indicating its CS fallback support capability in a response message to a configuration request of an eNodeB during initial operation; And And the base station (eNodeB) for broadcasting the indicator in a radio resource control (RRC) message to a mobile terminal (UE). The method of claim 1, Based on the indicator, the system further comprises a mobile station (UE) to attempt a Combined EPS / IMSI Attach or Combined TA / LA Update to the MME. The method of claim 1, The response message is an S1 setup response message sent using an S1 application protocol between the MME and the eNodeB. The method of claim 1, The RRC message is a System Information Block (SIB) message transmitted using an RRC protocol. As a method of providing a circuit switched (CS) fallback function in an evolved packet system (EPS) network, In the initial operation, the mobility management node (MME) including the indicator indicating the CS fallback support capability in the response message for the configuration request of the base station (eNodeB) transmitting; Broadcasting, by the eNodeB, the indicator in a Radio Resource Control (RRC) message to a mobile station (UE); And The UE attempting a Combined EPS / IMSI Attach or Combined TA / LA Update to the MME based on the indicator. The method of claim 5, The response message is transmitted using the S1 application protocol between the MME and the eNodeB, The RRC message is a System Information Block (SIB) message transmitted using an RRC protocol. A system that provides SMS CS (Circuit Switched) Fallback function in an EPS (Evolved Packet System) network, Converts an outgoing SMS message received using an interface protocol (S1AP) between an eNodeB and a mobility management node (MME) into an interface (SGs) protocol (SGsAP) between the MME and an exchange (MSC) server, and transmits the An SMS CS Fallback converter (FB converter) of the MME for converting and receiving an incoming SMS message using SGsAP into the S1AP; And A system comprising an agent of the MSC server (FB agent) for processing incoming and outgoing SMS messages via the SGs interface, independent of the SMS message handling function via the Iu-CS interface. The method of claim 7, wherein The MSC server separates an SMS processing function provided through another interface to the server, processes an SMS message through the Iu-CS interface in a legacy SMS processor, and processes the CS Fallback SMS message through the SGs interface into the FB agent. Processed in, system. A system that provides SMS CS (Circuit Switched) Fallback function in an EPS (Evolved Packet System) network, A mobility management node (MME) for transmitting an indicator indicating status information of a mobile terminal (UE) in an interface (SGs) protocol (SGsAP) message with an exchange (MSC) server; And And a switching server (MSC) server that determines whether to send a paging message for an SMS incoming based on the indicator. 10. The method of claim 9, The MSC server does not send the paging message to the MME when the indicator is UE-activated, and sends an incoming SMS message to the MME. 11. The method according to claim 9 or 10, The MME has a SGs interface is set, to support the CS Fallback service. As a method for providing an SMS CS (Circuit Switched) Fallback function in an EPS (Evolved Packet System) network, Transmitting, by a mobility management node (MME), an indicator indicating status information of a mobile terminal (UE) in an interface (SGs) protocol (SGsAP) message with an exchange (MSC) server; Determining, by the MSC server, whether to send a paging message for an SMS incoming based on the indicator; And And sending, by the MSC server, an incoming SMS message to the MME without sending the paging message to the MME when the indicator is UE-activated. The method of claim 12, The MME, the SGs interface is set, to support the CS Fallback service.

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