KR101859582B1 - System and method for continuing voice call in wireless communication system - Google Patents

Abstract

A step in which the MS sets the SRVCC support status to the MS capability and the MME / SSGN checks the SRVCC to GERAN / UTRAN capability and transmits an Attach / TAU / RAU accept message including the IMSVoPS indicator = 0 to the MS If the SRVCC to GERAN / TRAN capability received by the SGSN / MME is 1, the MME / SSGN checks the supported source RAT and target RAT. If the supported SRVCC source RAT and target RAT are supported by the mobile station, the IMSVoPS indicator = 1 Transmitting an Attach / TAU / RAU accept message including an IMSVoPS indicator = 0 to the AT; transmitting the ATACH / TAU / RAU accept message to the AT; And using the IMS voice call in the E-UTRAN.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a voice call service apparatus and method in a mobile communication system,

The present invention relates to an apparatus and method for continuously providing a voice call in a mobile communication system, and more particularly, it relates to an apparatus and method for continuous service of a voice call in a mobile communication system, in which an IP Multimedia Subsystem (IMS) voice call is used when Single Radio Voice Call Continuity And to a method and a device.

Currently, LTE and IMS (IP Multimedia Subsystem) are being introduced to provide voice calls in a packet switch network. However, the present LTE network is currently installed only in a limited area, and the coverage is limited. If the LTE network is out of the limited area, continuity of the voice call is not ensured. In order to solve this problem, it is a trend to provide voice call continuity through interworking with a CS network providing full coverage. At this time, a Single Radio Voice Call Continuity (SRVCC) function that provides voice call continuity with a single radio is provided so that the terminal does not need to connect all the radio providing the PS and the CS.

However, the current design focuses on the terminal providing the SRVCC regardless of the source RAT and the destination RAT, but some operators provide SRVCC only to some destination RATs in some source RATs, and others do not. It does not. For example, a provider of a GERAN network provides SRVCC to the E-UTRAN and GERAN networks, does not provide for the UTRAN network, and a provider that already provides IMS services in the UTRAN is a GERAN network from both the E-UTRAN and the UTRAN. SRVCC in the future. If there are other operators that offer SRVCC according to the combination of various source RAT and destination RAT, and when a roaming agreement is made between such operators, the operator can perform the SRVCC handover to the terminal whether it supports the terminal or not, You must decide whether you want to. This is an important consideration in the decision to ensure that the voice call continuity is ensured by using the IMS voice call only when SRVCC is supported.

In a system in which a voice call can be provided in a packet switch network by introducing LTE and an IP Multimedia Subsystem (IMS), the present invention can support a SRVCC source RAT and a destination RAT, If not, the VoIMS indicator is not transmitted to prevent the voice call from being dropped. The present invention establishes SRVCC information and transmits it to the SGSN / MME. The SGSN / MME determines the IMS VoPS indicator by analyzing the information of the terminal and notifies the terminal of the IMS VoPS indicator. That is, a terminal that needs to use a voice call can select a CS network in the above situation, thereby preventing a voice call from being disconnected using CS without using VoIMS when SRVCC is not supported.

A method for serving a voice call in a mobile communication system according to an exemplary embodiment of the present invention includes a step in which the MS sets and transmits an SRVCC support status to an MS capability and an MME / SSGN examines the SRVCC to GERAN / UTRAN capability, , And transmits an Attach / TAU / RAU accept message including IMSVoPS indicator = 0 to the UE. If the SRVCC to GERAN / TRAN capability received by the SGSN / MME is 1, the MME / SSGN verifies the source RAT and the target RAT. If the supporting SRVCC source RAT and the target RAT are also supported by the UE, an Attach / TAU / RAU accept including IMSVoPS indicator = 1 is transmitted to the UE. Otherwise, an Attach / TAU / RAU accept including IMSVoPS indicator = 0 is transmitted to the UE And receiving the ATACH / TAU / RAU accept message and using the IMSVoPS indicator in the E-UTRAN when the AT receives the ATACH / TAU / RAU accept message.

A method for providing a voice call in a mobile communication system according to an exemplary embodiment of the present invention includes a step in which a UE sets an additional SRVCC to the target RAT 2 bit in a form A or B to transmit to a MME / SSGN, / SSGN to the UE if the SRVCC to GERAN / UTRAN capability is 0; if the SRVCC to GERAN / UTRAN capability is 1, transmitting an Attach / TAU / RAU accept message including an IMSVoPS indicator = to the target RAT. If the terminal supports the SRVCC source RAT and the target RAT supported by the network, it sends an Attach / TAU / RAU accept with IMSVoPS indicator = 1 to the terminal. Otherwise, the Attach including the IMSVoPS indicator = TAU / RAU accept to the UE; and if the UE receives the Attach / TAU / RAU accept and the IMSVoPS indicator is 1, the UE uses the IMS voice call in the E-UTRAN.

A method for providing a voice call in a mobile communication system according to an exemplary embodiment of the present invention includes the steps of transmitting an MS capability to an SGSN and transmitting an MS capability and a UE capability to the MME, The MME and the SGSN transmit an Attach / RAU / TAU accept message with the IMSVoPS indicator set to 0, respectively, if the value of the SRVCC to GERAN / UTRAN capability is 0; If the UE supports the SRVCC source RAT and the target RAT supported by the network, the SGSN and the MME set the IMSVoPS indicator to 1 and transmit the SRVCC source RAT and the target RAT, respectively, if the GERAN / UTRAN capability is 1, Otherwise, the SGSN and the MME set an IMSVoPS indicator to '0'; transmitting the IMSVoPS indicator to the E-UTRAN when the IMSVoPS indicator is '1' It is characterized in constituted by any process.

In the voice call service method according to the embodiment of the present invention, LTE and IMS (IP Multimedia Subsystem) are introduced to provide a voice call in a packet switch network, When the source RAT and the destination RAT are not supported by the UE, the VoIMS indicator is not transmitted, thereby preventing the voice call from being interrupted. Therefore, a terminal that needs to use a voice call can select a CS network in the above situation, thereby preventing a voice call from being disconnected by using CS without using VoIMS when SRVCC is not supported.

1 is a diagram for explaining an operation in a case where a terminal supports E-UTRAN-> GERAN SRVCC in a mobile communication system and a network supports E-UTRAN-> UTRAN SRVCC;
2 is a flowchart illustrating an operation procedure of a terminal and an MME / SSGN according to the first embodiment of the present invention.
3 is a flowchart illustrating an operation procedure of a terminal and an MME / SSGN according to a second embodiment of the present invention.
4A and 4B are flowcharts showing operation procedures of the MS and the MME / SSGN according to the third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same configurations of the drawings denote the same reference numerals as possible whenever possible.

1 is a view for explaining an operation in a case where a terminal supports E-UTRAN-> GERAN SRVCC and a network supports E-UTRAN-> UTRAN SRVCC in a mobile communication system.

Referring to FIG. 1, in step 111, the UE informs whether the UTRAN / E-UTRAN to the GERAN / UTRAN SRVCC support the MS capability as shown in Table 1 below.

MS capability
SRVCC to GERAN / UTRAN capability
0 SRVCC from UTRAN HSPA or E-UTRAN to GERAN / UTRAN not supported
1 SRVCC to UTRAN HSPA or E-UTRAN to GERAN / UTRAN supported

As shown in Table 1, currently used indicators have no distinction between source RAT and destination RAT. However, it is assumed that the actual UE supports E-UTRAN -> GERAN. Then, the MME supporting the E-UTRAN -> UTRAN that received the MME interprets the UE support in step 113, and transmits the VOIMS support indicator in step 115. In step 117, the terminal initiates a voice call using VoIMS. In step 119, the terminal moves out of the E-UTRAN radio area and accesses the UTRAN radio area during a voice call. In this case, the eNB fails to trigger SRVCC Handover in steps 121 and 123, or fails to trigger the SRVCC handover, thereby causing the terminal's voice call to be disconnected.

In this case, if the network does not support the supported SRVCC source RAT and destination RAT, it should be solved by not transmitting the VoIMS indicator. That is, a terminal that needs to use a voice call should select the CS network, so that the CS is used without using VoIMS when the SRVCC is not supported, thereby preventing a situation where a voice call is disconnected.

The present invention proposes a method in which a terminal sets up SRVCC information and transmits it to the SGSN / MME, the SGSN / MME analyzes the information of the terminal, determines an IMSVoPS indicator and informs the terminal, and the terminal checks the VoIMS service do. Hereinafter, the first to third embodiments of the present invention will be described in detail. In the following description, the RAN node (eNB, RNC) in the (E-UTRAN / UTRAN / GERAN) will be used in the same meaning as the RAN node.

First Embodiment

The first embodiment of the present invention adds the MS capability bit and the extension bit to the MS capability to ensure the continuity of the voice call. When transmitting the Attach / TAU / RAU request to the MME / SGSN, the UE transmits the extended MS capability according to whether the SRVCC is supported from the E-UTRAN / UTRAN to the GERAN / UTRAN as shown in Table 2 below.

MS capability
SRVCC to GERAN / UTRAN capability
0 SRVCC from UTRAN HSPA or E-UTRAN to GERAN / UTRAN not supported
1 SRVCC to UTRAN HSPA or E-UTRAN to GERAN / UTRAN supported

Additional SRVCC capability
First bit 0 SRVCC E-UTRAN to GERAN not supported 1 supported
Second bit 0 SRVCC E-UTRAN to UTRAN not supported 1 supported
Third bit 0 SRVCC UTRAN to GERAN not supported 1 supported
Fourth bit 0 SRVCC UTRAN to UTRAN not supported 1 supported

If the UE does not support SRVCC in Table 2, the SRVCC to GERAN / UTRAN capability is set to 0. If SRVCC is supported, the SRVCC to GERAN / UTRAN capability is set to 1 and then the optional SRVCC 4 bit to specify source RAT and target RAT. The operation and response setting of the MME / SGSN receiving the MS capability as shown in Table 2 and the operation of the MS according to the response of the MME / SGSN proceed as shown in FIG.

2 is a flowchart illustrating an operation procedure of a terminal and an MME / SSGN according to the first embodiment of the present invention.

Referring to FIG. 2, in step 211 of FIG. 2, the MS sets the SRVCC support status to the MME / SGSN as shown in Table 2 (Attach / TAU / RAU request to GERAN / UTRAN capability, Additional SRVCC capability).

In step 213, the SGSN / MME receiving the MS capability checks the SRVCC to GERAN.UTRAN capability. In step 213, the SGSN / MME determines whether the SRVCC to GERAN / UTRAN capability value is 0. At this time, if the SRVCC to GERAN / UTRAN capability value is 0, it means that the UE does not support SRVCC. In this case, the SGSN / MME transmits an Attach / TAU / RAU accept message including the IMSVoPS indicator = 0 to the RAN node (eNB, RNC) with the SRVCC capability in step 215 UTRAN / UTRAN / GERAN in the UE context setup request. The SRVCC capability transmitted to the RAN node (eNB, RNC) at this time (E-UTRAN / UTRAN / GERAN) includes an additional SRVCC capability.

Then, the RAN node (eNB, RNC) of the E-UTRAN / UTRAN / GERAN stores the additional SRVCC capability transmitted from the MME / SGSN in step 217 as a UE context, and then uses the SRVCC handover to trigger the SRVCC handover. At this time, since the SRVCC capability is all 0, the SRVCC handover is not triggered. In step 219, the RAN node (E-UTRAN / UTRAN / GERAN) inserts an Attach / TAU / RAU accept message including an IMSVoPS indicator into an RRC message,

 If the SRVCC to GERAN.UTRAN capability value received by the SGSN / MME is 1 in step 213, this means that the terminal supports SRVCC. In this case, in step 221, the SGSN / MME confirms the additional SRVCC capability to identify the supported source RAT and the target RAT. If the terminal does not support the SRVCC source RAT and the target RAT supported by the network (eg, the E-UTRAN to GERAN is supported by the network but the E-UTRAN to GERAN is set to 0) UTRAN / GERAN) RAN node (eNB, RNC) to transmit an Attach / TAU / RAU accept message including IMSVoPS indicator = 0 to the UE in step 223 because the SRVCC can not be used To the UE context setup request.

 The RAN node (eNB, RNC) of the E-UTRAN / UTRAN / GERAN stores the additional SRVCC capability transmitted from the MME / SGSN in the context of the UE in step 225 and then uses the SRVCC handover to trigger the SRVCC handover. At this time, although the SRVCC capability is not all 0, the SRVCC handover is not triggered since the SRVCC supported by the network can not be used. In step 227, the RAN node (E-UTRAN / UTRAN / GERAN) inserts an Attach / TAU / RAU accept message including an IMSVoPS indicator into an RRC message and transmits the received message.

 However, if the UE supports the SRVCC source RAT and the target RAT supported by the network as a result of checking the additional SRVCC capability in step 221, the E-UTRAN to GERAN is supported and the E-UTRAN to GERAN is set to 1 UTRAN / GERAN) RAN node (eNB) in order to transmit an Attach / TAU / RAU accept message including IMSVoPS indicator = 1 to the UE in step 231 because the SRVCC can be used by the UE in the network , RNC) together with the SRVCC capability in the UE context setup request.

 The RAN node (eNB, RNC) of the E-UTRAN / UTRAN / GERAN stores the additional SRVCC capability transmitted from the MME / SGSN in step 233 in the context of the UE and then uses the SRVCC handover to trigger the SRVCC handover. In this case, since the terminal can use the SRVCC supported by the network, the RAN node can trigger SRVCC handover if necessary. In step 235, the RAN node (E-UTRAN / UTRAN / GERAN) inserts an Attach / TAU / RAU accept message including an IMSVoPS indicator into an RRC message,

Upon receiving the IMSVoPS indicator 0 in step 219 or step 227, the UE determines that the VoIMS can not be used and moves to 2G / 3G in step 229 so as to use the CSFB or use a voice call. However, upon receiving the IMSVoPS indicator 1 in step 235, the UE determines that VoIMS can be used. If the UE supports the IMS, it remains in the E-UTRAN in step 227 and uses the IMS-based voice call.

The first embodiment of the present invention as described above can be designed so as not to affect the terminal that does not use the SRVCC and to give an impact only by using the SRVCC. To this end, the first embodiment of the present invention adds 4 bits of additional information (additional SRVCC capability information). The 4 bits of the new information may be information as shown in Table 2 above.

In addition to the first embodiment of the present invention, the MME / SGSN may transmit the SRVCC capability to the RAN node only when the SRVCC capability is determined to be available (i.e., only when the VoIMS indicator = 1 is set). That is, in step 215 of FIG. 2, the message may be delivered only in step 223 without being delivered. (This is also applicable to the second and third embodiments described later)

In addition to the first embodiment of the present invention, when transmitting the SRVCC capability from the MME / SGSN to the RAN node, it is also possible to further transmit a bit indicating SRVCC availability. Then, when the context of the UE is exchanged between the RAN node and the RAN node for handover after handover, the target RAN node can determine the SRVCC handover after receiving the stored SRVCC capability from the MME / SGSN have. (This is also applicable to the second and third embodiments described later)

Second Embodiment

The second embodiment of the present invention adds the MS capability bit and the extension bit to the MS capability by ensuring the continuity of the voice call.

When transmitting an Attach / TAU / RAU request to the MME, the UE transmits an extended MS capability as shown in Table 2 according to whether SRVCC is supported from the E-UTRAN to the GERAN / UTRAN.

MS capability
SRVCC to GERAN / UTRAN capability
0 SRVCC from UTRAN HSPA or E-UTRAN to GERAN / UTRAN not supported
1 SRVCC to UTRAN HSPA or E-UTRAN to GERAN / UTRAN supported

Additional SRVCC to the target RAT 2 bit - Type A
0 SRVCC to GERAN supported
1 SRVCC to UTRAN supported
2 SRVCC to both GERAN and UTRAN

Additional SRVCC to the target RAT 2 bit - Type B
First bit 0 SRVCC to GERAN not supported, 1 supported
Second bit 0 SRVCC to UTRAN supported not supported, 1 supported

FIG. 3 is a flowchart illustrating an MS setup of MS capability and operation procedures of a network and a terminal according to a second embodiment of the present invention. Referring to FIG.

Referring to FIG. 3, in step 311, the UE sets the additional SRVCC to the target RAT 2 bit as a type A or a type B. FIG. Here, when setting the additional SRVCC to the target RAT 2 bit in the above mode A or B, the value is adjusted according to the current camping RAT. That is, when the camping RAT is the E-UTRAN and the Attach / TAU request is transmitted to the MME, the additional SRVCC to the target RAT 2 bit is set according to whether the E-UTRAN to GERAN and the E-UTRAN to UTRAN support SRVCC, camping When RAT is UTRAN and sends Attach / RAU request to SGSN, additional SRVCC to the target Rat 2bit is set according to UTRAN to GERAN and UTRAN to UTRAN support SRVCC. In step 313, the MS transmits the established MS capability to the MME / SSGN. At this time, if the camping RAT is E-UTRAN, the value set by the UE is transmitted to the MME through an Attach / TAU request. If the camping RAT is GERAN / UTRAN, the RACH is transmitted to the SGSN through an Attach / RAU request.

 In step 315, the MME / SGSN receiving the MS capability of the MS examines the SRVCC to GERAN / UTRAN capability. If the SRVCC to GERAN / UTRAN capability is 0, the MME / SGSN detects it in step 315. UTRAN / GERAN) RAN node (eNB) in order to transmit an Attach / TAU / RAU accept message including an IMSVoPS indicator = 0 to the UE in step 317 because the UE does not support SRVCC in this case. RNC) together with the SRVCC capability in the UE context setup request. The SRVCC capability transmitted to the RAN node (eNB, RNC) at this time (E-UTRAN / UTRAN / GERAN) includes an additional SRVCC capability.

In step 319, the RAN node (E-UTRAN / UTRAN / GERAN) stores the additional SRVCC capability transmitted from the MME / SGSN in the UE context and then uses the SRVCC handover to trigger the SRVCC handover. At this time, since the SRVCC capability is all 0, SRVCC handover is not triggered. In step 321, the RAN node (E-UTRAN / UTRAN / GERAN) inserts an Attach / TAU / RAU accept message including an IMSVoPS indicator into an RRC message and delivers the received message.

However, if the SRVCC to GERAN / UTRAN capability is 1 in step 315, the MME / SGSN checks the additional SRVCC to the target RAT in step 323. If the entity receiving the message is an MME, the additional SRVCC to the target RAT is interpreted as E-UTRAN to GERAN and / or UTRAN. If the entity receiving the message is an SGSN, the additional SRVCC to the target RAT To UTRAN to GERAN and / or UTRAN. If the UE does not support the SRVCC source RAT and the target RAT supported by the network as a result of the confirmation of the additional SRVCC to target RAT, the MME / SGSN can not use the Attach / TAU including the IMSVoPS indicator = 0 in step 325. Therefore, / RAU accept in the UE context setup request with the SRVCC capability to the RAN node (eNB, RNC) (E-UTRAN / UTRAN / GERAN) to transmit to the UE. The SRVCC capability transmitted to the RAN node (eNB, RNC) at this time (E-UTRAN / UTRAN / GERAN) includes an additional SRVCC capability.

In step 327, the RAN node (E-UTRAN / UTRAN / GERAN) of the E-UTRAN / UTRAN / GERAN stores the additional SRVCC capability transmitted from the MME / SGSN in the context of the UE and then uses it to trigger SRVCC handover. At this time, since the SRVCC capability is not 0 but the SRVCC capability is not available, the SRVCC handover is not triggered. In step 329, the RAN node (E-UTRAN / UTRAN / GERAN) sends an RACH message including an IMSVoPS indicator = 0 to the AT.

However, if the SRVCC to GERAN / UTRAN capability is 1, the SRVCC source RAT supporting the network and the SRVCC when the terminal supports the target RAT are available as a result of checking the additional SRVCC to the target RAT. UTRAN / GERAN) RAN node (eNB, RNC) to transmit an Attach / TAU / RAU accept message including IMSVoPS indicator = 1 to the UE in step 333, the MME / Setup request to send. At this time, the SRVCC capability transmitted to the E-UTRAN / UTRAN / GERAN RAN node (eNB, RNC) includes an additional SRVCC capability.

 In step 335, the RAN node (E-UTRAN / UTRAN / GERAN) of the E-UTRAN / UTRAN / GERAN stores the additional SRVCC capability transmitted from the MME / SGSN in the context of the UE. At this time, since the terminal can use SRVCC, the RAN node can trigger SRVCC handover as needed. In step 337, the RAN node (E-UTRAN / UTRAN / GERAN) transmits the RACH message including the IMSVoPS indicator = 1 to the UE.

Upon receiving the IMSVoPS indicator 0 in step 321 or step 329, the UE determines that the VoIMS can not be used. In step 331, the UE moves to 2G / 3G to use CSFB or use a voice call. However, upon receiving the IMSVoPS indicator 1 in step 337, the UE determines that VoIMS can be used. If the UE supports IMS in step 339, the UE remains in the E-UTRAN and uses an IMS-based voice call.

In the second embodiment of the present invention proceeding as described above, it is possible to design the SRVCC to have no impact on a terminal that does not use the SRVCC, and to design an SRVCC to impact only a single word. The terminal must dynamically modify the value according to the camping RAT.

Third Embodiment

The third embodiment of the present invention guarantees the continuity of a voice call using the extended MS capability bit and the UE capability bit.

The MS transmits the MS capability to the SGSN when the camping RAT is GERAN / UTRAN, and transmits the MS capability and the UE capability to the MME when the camping RAT is E-UTRAN. Therefore, the additional SRVCC capability is included in the MS capability when the source RAT is the UTRAN, and is included in the UE capability when the source RAT is the E-UTRAN. That is, when transmitting to SGSN, only MS capability is transmitted in the following form, and when transmitting to MME, both MS capability and UE capability are transmitted. Table 3 below shows extension of MS capability and UE capability according to the third embodiment of the present invention.

MS capability
SRVCC to GERAN / UTRAN capability
0 SRVCC from UTRAN HSPA or E-UTRAN to GERAN / UTRAN not supported
1 SRVCC to UTRAN HSPA or E-UTRAN to GERAN / UTRAN supported

Additional SRVCC to the target RAT 2-bit (From UTRAN) type - A
0 SRVCC to GERAN supported
1 SRVCC to UTRAN supported
2 SRVCC to GERAN and UTRAN supported

Additional SRVCC to the target RAT 2 bit (From UTRAN) type - B
First bit 0 SRVCC to GERAN not supported, 1 supported
Second bit 0 SRVCC to UTRAN supported not supported, 1 supported

UE capability
Additional SRVCC to the target RAT 2-bit (From E-UTRAN) type - A
0 SRVCC to GERAN supported
1 SRVCC to UTRAN supported
2 SRVCC to GERAN and UTRAN supported

Additional SRVCC to the target RAT 2-bit (From E-UTRAN) type - B
First bit 0 SRVCC to GERAN not supported, 1 supported
Second bit 0 SRVCC to UTRAN supported not supported, 1 supported

 4A and 4B are diagrams illustrating terminal setup of the MS capability and the UE capability and operation procedures of the network and the terminal according to Table 4, respectively.

Referring to FIGS. 4A and 4B, in step 411, the AT sets the additional SRVCC to the target RAT 2 bit according to the current camping RAT as a type A or a type B. FIG. At this time, if the Camping RAT is a GERAN / UTRAN and sends a message to the SGSN, the UE sets an additional SRVCC to the target RAT only in the MS capability and transmits it to the SSGN in step 413. When the UE sends a message to the MME because it is the E-UTRAN, the UE sets an additional SRVCC to the target RAT in the MS capability and sets additional SRVCC to the target RAT in the UE capability. In step 415, Lt; / RTI > That is, the MS transmits an MS capability to the SGSN and the MS capability and the UE capability to the MME.

In step 417 and step 425, the MME and the SGSN confirm the SRVCC to GERAN / UTRAN capability, respectively. If the value of the MME and the SGSN is 0, the MME and the SGSN in step 419 and 427, respectively, 0 to transmit the Attach / RAU / TAU accept message. At this time, SRVCC capability is also transmitted to the RAN node.

In step 421 and step 429, the RAN nodes store the SRVCC capability received from the MME / SGSN and use them to determine an SRVCC handover trigger. Since SRVCC handover is not supported here, SRVCC handover is not triggered. The RAN node transmits an Attach / TAU / RAU accept message received in steps 423 and 431 to an RRC message.

However, if the SRVCC to GERAN / UTRAN capability is 1 in step 417 or 425, the SGSN and the MME check the additional SRVCC to the target RAT in steps 433 and 441, respectively. In this case, if the entity receiving the message is an SGSN, the SGSN checks the additional SRVCC included in the MS capability in step 433. If the entity receiving the message is an MME, if the MME is the MME, it checks the additional SRVCC to the target RAT included in the UE capability in step 441. If the UE does not support the SRVCC source RAT and the target RAT that are supported by the network as a result of the confirmation of the additional SRVCC to target RAT, the SGSN and the MME transmit and set the IMS VoPS indicators to 0 in steps 435 and 443, respectively. At this time, SRVCC capability is also transmitted to the RAN node.

In step 437 and step 445, the RAN nodes store the SRVCC capability received from the MME / SGSN and determine the SRVCC handover trigger, respectively. Since SRVCC handover is not supported here, SRVCC handover is not triggered. The RAN nodes transmit the Attach / TAU / RAU accept message received in steps 439 and 447 to the RRC message, respectively.

However, in step 433, the SGSN checks the additional SRVCC to the target RAT included in the MS capability. In step 441, the MME also checks the additional SRVCC to the target RAT included in the UE capability. As a result, When the RAT and the target RAT are also supported by the UE, the SGSN and the MME set the IMS VoPS indicator to 1 in steps 451 and 457, respectively. At this time, SRVCC capability is also transmitted to the RAN node.

In step 453 and step 459, the RAN nodes store the SRVCC capability received from the MME / SGSN and determine the SRVCC handover trigger, respectively. Since it is supported here, SRVCC handover is triggered afterwards. In step 455 and step 461, the RACH receives the Attach / TAU / RAU accept message in the RRC message, and then transmits the RACH message to the UE.

In step 423, 431, 439, or 447, the UE receiving the IMSVoPS indicator 0 determines that the VoIMS can not be used. In step 449, the UE moves to 2G / 3G to use the CSFB or use a voice call . If it is determined in step 455 or step 461 that the UE receiving the IMSVoPS indicator 1 can use the VoIMS and if the UE supports the IMS in step 463, the UE remains in the E-UTRAN and uses the IMS-based voice call.

In the third embodiment of the present invention, it is possible to prevent the SGSN from dynamically changing the set value according to the camping RAT and transmitting the SGSN.

The embodiments of the present invention disclosed in the present specification and drawings are merely illustrative of specific embodiments of the present invention and are not intended to limit the scope of the present invention in order to facilitate understanding of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (12)

A method of transmitting and receiving signals in a terminal of a mobile communication system,
Transmitting, to the network control node, a first message including information indicating whether a single radio voice call continuity (SRVCC) support of the MS is available;
Receiving a second message including information indicating whether an IMS (IP multimedia subsystem) voice call service can be provided based on the first message; And
And performing an IMS voice call service related operation based on the second message. The method according to claim 1,
The step of performing the IMS voice call service-
And if the IMS voice call related service can not be provided to the terminal based on the second message, moving to another network. The method according to claim 1,
Information indicating whether or not the SRVCC support of the UE is available may include information indicating whether the source base station associated with the SRVCC and the target base station associated with the SRVCC are one of E-UTRAN, GERAN, and UTRAN, And information indicating whether the terminal can support SRVCC. A method for transmitting and receiving signals at a network control node of a mobile communication system,
The method comprising: receiving a first message including information indicating whether a single radio voice call continuity (SRVCC) support of the MS is available; And
And transmitting a second message including information indicating whether an IMS (IP multimedia subsystem) voice call service can be provided based on the first message to the terminal,
And an IMS voice call service related operation is performed in the AT based on the second message. 5. The method of claim 4,
And if the IMS voice call related service can not be provided to the MS based on the second message, the MS moves to another network. 5. The method of claim 4,
Information indicating whether or not the SRVCC support of the UE is available may include information indicating whether the source base station associated with the SRVCC and the target base station associated with the SRVCC are one of E-UTRAN, GERAN, and UTRAN, And information indicating whether the terminal can support SRVCC. A terminal of a mobile communication system,
A transmitting and receiving unit for transmitting and receiving signals; And
Receiving unit,
Transmitting a first message including information indicating whether a single radio voice call continuity (SRVCC) support of the MS is available to the network control node,
Receiving a second message including information indicating whether an IMS (IP multimedia subsystem) voice call service can be provided based on the first message,
And a controller for performing an IMS voice call service related operation based on the second message. 8. The method of claim 7,
The control unit
And if the IMS voice call related service can not be provided to the terminal based on the second message, the terminal moves to another network. 8. The method of claim 7,
Information indicating whether or not the SRVCC support of the UE is available may include information indicating whether the source base station associated with the SRVCC and the target base station associated with the SRVCC are one of E-UTRAN, GERAN, and UTRAN, And information indicating whether the terminal can support SRVCC. A network control node of a mobile communication system,
A transmitting and receiving unit for transmitting and receiving signals; And
Receiving unit,
Receiving a first message including information indicating whether the terminal can support a single radio voice call continuity (SRVCC) from the terminal,
And a controller for transmitting to the terminal a second message including information indicating whether an IMS (IP multimedia subsystem) voice call service can be provided based on the first message,
And an IMS voice call service related operation is performed in the AT based on the second message. 11. The method of claim 10,
And if the IMS voice call related service can not be provided to the MS based on the second message, the MS moves to another network. 11. The method of claim 10,
Information indicating whether or not the SRVCC support of the UE is available may include information indicating whether the source base station associated with the SRVCC and the target base station associated with the SRVCC are one of E-UTRAN, GERAN, and UTRAN, And information indicating whether the terminal can support SRVCC.

Images