KR101617448B1 - Method for performing transfer of collaborative session control in wireless communcation system based on ip multimedia subsystem - Google Patents

Abstract

A method of moving a collaborative session control between terminals is performed in an IMS (IP Multimedia Subsystem) based network system. The method comprising the steps of: sending a subscription message requesting notification of information about the other terminal to an IMS network element, receiving a subscription acceptance message, which is a response to the subscription message, from the IMS network element, Receiving from the IMS network element a notification message including information on the cooperative session control, performing a movement procedure of the cooperative session control to the selected terminal when the terminal to move cooperative session control is selected from among the at least one other terminal .

Inter UE Transfer (IUT), Inter-Port Migration, Media Flow, Collaborative Session Control, Service Control, IP Multimedia Subsystem (IMS), S-CSCF, SCC AS

Description

[0001] METHOD FOR PERFORMING TRANSFER OF COLLABORATIVE SESSION CONTROL IN WIRELESS COMMUNICATION SYSTEM [0002] BASED ON IP MULTIMEDIA SUBSYSTEM [0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IMS (IP Multimedia Subsystem) based system, and more particularly, to a method of performing movement of Collaborative Session Control.

The IMS (IP Multimedia Subsystem) is attracting attention as a core communication system for providing new services in IP (Internet Protocol) based next generation communication environment. IMS is a set of nodes that provides various multimedia services in the environment of mobile communication network and performs call control, and integrates IP network and mobile communication environment. Accordingly, the IMS facilitates the interoperability between the user terminal and the IP network, thereby making it possible to provide an IP-based multimedia service using the user terminal. The IMS stores and manages the control layer and data for managing connectivity layer, call and session routing, billing, and file protocol for connection with IMS, And an application layer that creates a service.

IMS can support various contents types including voice, multimedia data, and text by interworking with the existing telephone network PSTN and the Internet. The IP-based multimedia service provided by IMS can roughly be classified into a messaging service, a voice service, and a video service. The messaging service includes a Short Messaging Service (SMS), a Multimedia Messaging Service (MMS), an E-mail service, a SIM-to-IM (SIP for Instant Messaging and Presence Leveraging Extensions- And Instant Messaging and Presence Service (IMPS). The voice service includes a voice over IP (VoIP) service, a push-to-talk over cellular (PoC) service, and the video service includes a video-over IP (Video-over IP) service.

These existing services have a proprietary protocol silo for transmitting each message. That is, the services transmit messages using a transmission protocol unique to each service. The transmission protocols currently used in the respective services are summarized in Table 1.

Type of service Transport protocol SMS Call Signaling Protocol MMS Wireless Session Protocol (WSP) or Hyper Text Transfer Protocol (HTTP) E-mail Internet Engineering Taskforce Team (IETF) Lemonade Internet Messaging Access Protocol (IMAP), Data Synchronization (DS) SIMPLE-IM SIP (Session Initiation Protocol) / SIMPLE and Message Session Relay Protocol (MSRP) IMPS WSP or HTTP VoIP SIP / Real-time Transport Protocol (RTP) PoC SIP / RTP Video_oIP SIP / RTP

Referring to Table 1, the IMS uses a Session Initiation Protocol (SIP), which is a signaling protocol that can be used for IP-based multimedia services. SIP is an application layer call control protocol for creating, modifying, and terminating an IP-based multimedia service session between a user terminal and an entity having an IP address between a user terminal and a user terminal .

In an IMS system, a plurality of terminals can generate a Collaborative Session, in which case one terminal can control the media flow on the other terminal, and the other terminals only transmit and receive media flows. The UE providing the service control in the cooperative session is referred to as a Controller UE, and the controlled UEs providing the media flow in the cooperative session are referred to as Controlled UEs. The service control on the media flow that constitutes a cooperative session is called collaborative session control, which may be simply referred to as a service control. In addition, it is possible to move a media flow or cooperative session control for a terminal to another terminal, or remove a media flow or a cooperative session control created in another terminal. This function is widely used for inter UE transfer. Hereinafter referred to as IUT).

In performing the movement of the cooperative session control between the terminals, the state or performance information of the corresponding terminal is notified to the terminal requesting the notification whenever the status or performance of the other terminal is changed. However, depending on the situation, there may be a terminal that can not perform the movement of the cooperative session control among the other terminals.

In this case, the control terminal does not know which terminal can perform the movement of the cooperative session control. Therefore, the control terminal attempts to move the cooperative session control to the UE that can not perform cooperative session control movement, resulting in a signaling overhead due to the failure of the cooperative session control movement. Therefore, there is a need for a method for efficiently performing coordinated session control movement.

SUMMARY OF THE INVENTION The present invention provides a cooperative session control method and a cooperative session control method that can eliminate movement of cooperative session control by determining whether cooperative session control can be performed through status or performance information about other terminals And a method for performing the movement of the object.

According to an aspect of the present invention, there is provided a method of moving a Collaborative Session Control (IMS) performed between terminals in an IMS (IP Multimedia Subsystem) based network system. The method comprising the steps of: sending a subscription message requesting notification of information about the other terminal to an IMS network element, receiving a subscription acceptance message, which is a response to the subscription message, from the IMS network element, Receiving from the IMS network element a notification message including information on the cooperative session control, performing a movement procedure of the cooperative session control to the selected terminal when the terminal to move cooperative session control is selected from among the at least one other terminal .

According to another aspect of the present invention, there is provided a method for moving a cooperative session control between terminals performed in an IMS network in an IMS-based network system. The method includes receiving a control message including a service control flag indicating whether the control terminal can perform a role or not, from the other terminal, a notification message including the service control flag indicating that the other terminal is registered in the IMS network And transmitting a cooperative session control move request message for requesting movement of the cooperative session control to the other terminal when the service control flag of the other terminal indicates that the role of the control terminal can be performed, And transmitting a cooperative session control move completion message to the mobile station indicating that the movement of the cooperative session control is completed.

According to the present invention, the terminal can set flags related to inter-terminal movement of collaborative session control and register it in the IMS network including flag values set. Thus, it is possible to efficiently acquire status or performance information of other terminals required for movement of the cooperative session control. This reduces the signaling overhead associated with the failure of coordinated session control movement. In addition, the IMS network notifies the other terminals of the creation or modification of the control terminal, and the other terminal can directly acquire the cooperative session control from the control terminal using this information.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals designate like elements throughout the specification.

1 shows an IMS-based wireless communication system.

Referring to FIG. 1, an IMS-based wireless communication system includes a user equipment (UE) 10, a mobile communication network 20, and an IMS network 30.

The terminal 10 is a device for communicating with network nodes and / or other terminals constituting an IMS network through a radio access network (RAN) such as Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN). The name of the terminal 10 is not particularly limited. For example, the terminal 10 may be a mobile station (MS), a user terminal (UT), a user equipment (UE), a mobile equipment (ME), a subscriber station SS, a wireless device or a wireless station, or the like. Such a terminal 10 may be a general but fixed device having mobility. Examples of the terminal 10 having mobility include a notebook computer, a PDA, a smart phone, and a multimedia device. Examples of the terminal 10 having stability include a PC, a TV, a fixed display device, and the like. The terminal 10 may have a unique ID and an IP address (IP Addr). The ID may be a Public User ID in the form of a SIP URI (Uniform Resource Identifier) or a TEL URI. The components of the terminal 10 are described in more detail in Fig.

2 is a block diagram showing elements of a terminal;

2, a terminal 10 includes a processor 11, a memory 12, an RF unit 13, a display unit 14, a user interface unit , 15). The processor 11 implements various procedures of the layers of the air interface protocol. The generation and transmission of registration messages for registration with the IMS network described below and the generation and transmission of messages associated with cooperative session control movement can be implemented through the processor 11. [ The memory 12 is connected to the processor 11 to store a terminal drive system, an application, and general files. The display unit 14 displays various pieces of information of the terminal and can use well known elements such as a liquid crystal display (LCD) and an organic light emitting diode (OLED). The user interface unit 15 may be a combination of well-known user interfaces such as a keypad or a touch screen. The RF unit 13 is connected to the processor to transmit and / or receive a radio signal.

Referring again to FIG. 1, the mobile communication network 20 routes an SIP message so that a call can be established between the terminal 10 and the IMS network 30. The mobile communication network 20 is composed of a radio access network 22 and a PS network 24 (Packet Switched Network).

The IMS network 30 includes a Serving-Call Session Control Function (S-CSCF) 34 for actually processing various sessions in the network, A Proxy-Call Session Control Function (P-CSCF) 32 for delivering a SIP message received from the terminal 10 to the S-CSCF and an application server SCC AS (Service Centralization and Continuity Application Server, 36).

The terminal 10 performs a registration procedure to inform the IMS network 30 of information related to its current location in order to start a session for media flow transmission / reception with a remote UE 50 , These registration procedures involve P-SCSF, S-CSCF and SCC AS in IMS network elements. Hereinafter, the process of registering the terminal in the IMS network will be described in detail.

3 is a flowchart illustrating a registration procedure in which a terminal registers in an IMS network.

Referring to FIG. 3, a plurality of terminals UE-A1 and UE-A2 sequentially register with the IMS network. Here, the IMS network in which a plurality of terminals are registered may refer to a home network. If the terminal resides in a visited network, the IMS network is registered in the home network through the external network. UE-A1 and UE-A2 may be associated terminals belonging to one user domain and registered by the same ID. Or UE-A1 and UE-A2 may be independent terminals belonging to different user IDs. In FIG. 3, UE-A1 and UE-A2 are referred to as related terminals belonging to the domain of user A for convenience. However, it is needless to say that UE-A1 and UE-A2 may be separate and independent terminals. Also, although only two terminals are shown in FIG. 3, a larger number of associated terminals can be registered in the IMS network. The IMS network element may be a P-CSCF, an S-CSCF, or an SCC AS, which is a physical or logical entity involved in the registration process of the terminal with the IMS network.

First, the UE-A1 transmits a register message to the IMS network element (S100). The registration message includes the registration information of the UE-A1 as the SIP message or the state or capability information of the UE-A1. The status or performance information may include information on whether or not the terminal is registered, information on the types of media supported by the terminal, codec related information, configuration related information such as the size of the screen, and information related to the wireless access network to which the terminal is currently connected.

In addition, the status or performance information of the UE can be acquired from the UE in the IMS network using the OPTIONS message in addition to the registration message. In addition, the status or performance information of the terminal can be acquired from the database when there is a database for managing the status or performance information. If UE-A1 is present in the foreign network, the registration message may be forwarded to the S-CSCF via the P-CSCF not shown in the figure.

The IMS network element registers UE-A1 and transmits a registration confirmation message to the UE-A1 (S101). The UE-A1 transmits a Subscribe Message to the IMS network element (S102). When the status or performance information of another terminal is changed, when the specific terminal desires to receive the notification service related thereto, the specific terminal must request the subscription to the information change notification service to the IMS network element. The message used at this time is a Subscribe Message. The subscription message may also be referred to as an information notification subscription request message. The IMS network element transmits a subscription acceptance message to the UE-A 1 indicating that the subscription has been successfully performed (S 103).

Next, UE-A2 registers with the IMS network element (S104, S105). The registration procedure is the same as the registration procedure by UE-A1. When UE-A2 registers with the IMS network element, this fact is notified to UE-A1 (S106), and the message used at this time is called a Notification Message. The UE-A 1 receiving the notification message transmits a notification confirmation message informing the acknowledgment of the notification message to the IMS network element (S 107). This notification message is also transmitted when UE-A2 moves to another radio access network. For example, when the UE-A2 moves and the connected radio access network is changed (S108), a new registration message including the changed radio access network information is transmitted to the IMS network element (S109). As a result, the changed location of UE-A2 is registered in the IMS network. In step S111, the IMS network element transmits a registration acknowledgment message to the UE-A 2, and transmits a new notification message informing the UE-A 2 of the change of the state information of the UE-A 2 to the UE-A 1. In addition, the UE-A 1 receiving the notification message may transmit a notification confirmation message to the IMS network element informing the acknowledgment of the notification message (S 112).

In this way, the terminal registers in the IMS network and uses information about the state or performance of the other terminal, thereby moving the media flow and / or the collaborative session control between different terminals. transferred or removed. Such inter-terminal movement of the media flow and / or cooperative session control is called IUT (Inter UE Transfer). The information related to the execution of the IUT may be included in the registration message or may be a separate control message. On the other hand, the IUT presumes that a plurality of terminals exist. Hereinafter, a plurality of terminals supporting the IUT may belong to the domain of the same user or may belong to each of the users different from each other independently.

4 is a diagram showing a state in which a media flow or service control moves.

Referring to FIG. 4, UE-1 performs communication with a remote UE or a relative application server (hereinafter, referred to as a counterpart UE) through an IMS network. Here, a voice media flow and a video media flow are provided between the UE-1 and the counterpart UE. The UE-1 has the service control authority for the voice media flow and the video media flow. The media flow or service control by the IUT is mobile between UE-1 and UE-2. Suppose that only the service control and voice media flows are moved from UE-1 to UE-2 by the IUT. Then, there is still a video media flow session between the UE-1 and the counterpart UE, and a voice media flow session is newly started between the UE-2 and the counterpart UE. On the other hand, the UE-2 has service control regarding the video media flow and the voice media flow.

A plurality of sessions generated by the IUT are referred to as collaborative sessions. Meanwhile, a terminal providing a service control regarding a media flow constituting a cooperative session is referred to as a Controller UE, and a terminal for which transmission and reception of a media flow is controlled by a control terminal is referred to as a controlled terminal (Controllee UE) . The service control for the cooperative session provided by the control terminal is also referred to as a collaborative session control.

5 and 6 are flowcharts illustrating a procedure in which a service control related to a media flow between terminals is moved.

5 and 6, it is assumed that UE-A1, UE-A2, and UE-A3 capable of IUT exist and are all registered in the IMS network according to the registration procedure described in FIG. On the other hand, the UE-A1 is a UE subscribed to the information change notification service to receive notifications of status or performance information of other UEs, and if the status or performance of another UE changes, the IMS network can notify UE- do. Therefore, the session initiation procedure by the UE-A1 will be described.

The UE-A1 transmits a session initiation request message to the S-CSCF (S200). At this time, the media to be provided through the session are audio media and visual media. Based on the subscriber information of the user A, a session initiation request procedure is performed between the S-CSCF and the SCC AS (S201). When the S-CSCF forwards the session initiation request message to the remote UE (S202), the counterpart UE transmits a session initiation acceptance message to the S-CSCF (S203). The Session Initiation Accept message is also referred to as a 200 OK message as an SIP message. After the session initiation acceptance procedure is performed between the S-CSCF and the SCC AS (S204), the S-CSCF transmits a session initiation acceptance message to the UE-A1 (S205). Hereinafter, a procedure corresponding to steps S200 to S205 is referred to as a session initiation procedure.

The media flow of voice and video is transmitted and received between the UE-A1 and the counterpart UE using the session described above (S206), and the service control authority of the current voice and video media flows is allocated to the UE-A1 (S207).

UE-A1 decides to move the service control regarding the voice and video media flow to UE-A2 (S208). Since UE-A1 is a terminal, it can be said that user A, which is substantially a user of UE-A1, determines whether or not service control regarding voice and video media flows is shifted. The UE-A1 determines whether there is a service control move instruction of the user A, and determines the movement of the service control if there is a move instruction. Of course, if a certain condition is satisfied, the UE-A1 may arbitrarily move the service control regardless of the user A's intention. When the movement of the service control is determined, a movement procedure of the service control is performed. The following steps S209 to S216 are an example of the procedure of movement of the service control.

The UE-A1 transmits a service control movement request message to the S-CSCF (S209), and the S-CSCF again transmits a service control movement request message to the SCC AS (S210). When the SCC AS sends a service control move request message to the S-CSCF (S211), the S-CSCF transmits the service control move request message to the UE-A2 (S212). If the UE-A2 transmits a service control move acceptance message to the S-CSCF (S213), the S-CSCF forwards the service control move accept message to the SCC AS (S214). When the SCC AS receives a service control move acceptance message from the UE-A2, the SCC AS transmits a service control movement complete message to the S-CSCF (S215), and the S-CSCF transmits it to the UE-A1 (S216). Thereby, the UE-A2 has the service control right regarding the cooperative session composed of the voice and video media flows (S217).

As a result of the movement of the service control, a cooperative session is created in which the UE-A1 and the UE-A2 participate, while the voice and video media flow is still provided by the UE-A1. The service control for the cooperative session composed of the voice and video media flows is handled by the UE-A2. That is, the UE-A1 is the controlled terminal and the UE-A2 is the controlling terminal.

In some cases, when some terminals can not perform the role of the control terminal, that is, there is a case where the cooperative session control can not be moved between the terminals. For example, assume that UE-A2 can not be a control terminal in the circumstances. In this case, the UE-A1 or the IMS network can not move the cooperative session control to the UE-A2. It is possible to attempt an unnecessary process to move the cooperative session control to UE-A2, which can not provide cooperative session control, although the cooperative session control can not be moved to UE-A2 anyway. This failure occurs because the terminal UE-A1 can not know to which terminal the current cooperative session control can be moved or not.

In order to solve this problem, a service control flag is used as a control message for efficiently performing inter-terminal movement of the cooperative session control. The service control flag is an indicator for instructing the controller to enable or disable the cooperative session control between the terminals. The fact that the UE can move the cooperative session control means that the UE can perform the role of the control terminal and that the cooperative session control can not be moved means that the UE can perform the role of the control terminal . For example, if the service control flag for the terminal is an indicator of 1 bit, it indicates that cooperative session control can be moved to the terminal (that is, the role of the control terminal can be performed) if the service control flag is 0, 1 indicates that it is impossible to move the cooperative session control to the UE (i.e., the role of the control terminal can not be performed).

As an example, let the service control flag for UE-A2 be one. When the UE-A2 registers with the IMS network element, the IMS network element notifies UE-A1, which is the control terminal, of the registration status of the UE-A2 or the status or performance information of the UE-A2 including that the service control flag is one. As a result, the UE-A 1 can not perform the role of the control terminal of the UE-A 2, and thus does not attempt to move the cooperative session control to the UE-A 2.

As another example, let us say that the service control flag for UE-A2 is zero. When the UE-A2 registers with the IMS network element, the IMS network element transmits a notification message containing the registration information of the UE-A2 including the service control flag or the status or performance information of the UE-A2 to the control terminal UE-A1 do. The status or performance information of the terminal includes information on whether or not the terminal is registered, information on the type of the media supported by the terminal, codec related information, configuration related information such as the size of the screen, and information related to the wireless access network to which the terminal is currently connected. Upon receiving the notification message, the UE-A 1 can recognize that the UE-A 2 is registered in the IMS network and can consider the UE-A 2 as a moving target of cooperative session control. In this manner, the UE-A1 can refer to the service control flag to prevent unnecessary cooperative session control move attempts. Of course, this is only an example, and the bits indicated by bit information 0 or 1 may be reversed, and the number of bits used may be variable.

The service control flag may be included in the registration message or in a separate SIP message for indicating movement of the cooperative session control. Hereinafter, for convenience, the service control flag is assumed to be included in the registration message.

7 is a flowchart illustrating a method of transmitting a service control flag according to an exemplary embodiment of the present invention. This is the case where, in the transmission of the service control flag, the IMS network element that transmits the notification message is the S-CSCF.

Referring to FIG. 7, the UE-A 1, the UE-A 2 and the UE-A 3 sequentially register in the IMS network. First, the UE-A1 transmits a registration message including a service control flag to the S-CSCF to register in the IMS network (S300). At this time, the service control flag indicates that the service control can be moved (controller enable). The S-CSCF may store the service control flags of UE-A1. When the UE-A1 is registered, the S-CSCF transmits a registration confirmation message to the UE-A1 (S301). The UE-A1 transmits a subscription message to the S-CSCF in order to be notified of the change of status or performance information of the other UE (S302), and the S-CSCF transmits a subscription acceptance message to the UE-A1 (S303).

Next, the UE-A2 performs the registration process (S304, S305). At this time, the S-CSCF can store the service control flag of the UE-A 2. The S-CSCF sends a notification message to the UE-A1 indicating that the UE-A2 capable of moving the cooperative session control is registered in the IMS network, because the service control flag related to the UE-A2 indicates that the service control can be moved (S306). In response, the UE-A1 transmits a notification confirmation message to the S-CSCF indicating that the notification has been confirmed (S307). Finally, the UE-A3 performs the registration process (S308, S309). However, unlike UE-A1 and UE-A2, the service control flag for UE-A3 indicates that the service control can not be moved (Controller disable). Accordingly, the S-CSCF transmits a notification message to the UE-A 1 notifying that the UE-A 3, which is unable to move the cooperative session control, is registered in the IMS network (S 310). In response to this, the UE-A1 transmits a notification confirmation message to the S-CSCF indicating that the notification has been confirmed (S311)

In FIG. 7, the cause of triggering the transmission of the notification message of the S-CSCF is limited to the registration of the terminal. However, the present invention can be applied to all cases in which the status or performance information of the terminal is changed, for example, when the terminal is unregistered, the wireless access network is changed, or the performance information of the terminal is changed . Also, as described above, UE-A1, UE-A2, and UE-A3 may be associated terminals belonging to the same user A's domain, or may be independent terminals.

8 is a flowchart illustrating a method of transmitting a service control flag according to another example of the present invention. This is the case in the transmission of the service control flag, when the IMS network element transmitting the notification message is the SCC AS.

Referring to FIG. 8, the UE-A 1, the UE-A 2 and the UE-A 3 sequentially perform registration to the IMS network. First, the UE-A1 transmits a registration message including a service control flag to the S-CSCF to register in the IMS network (S400). At this time, the service control flag indicates that the service can be moved (controller enable). When the UE-A1 is registered, the S-CSCF transmits a registration confirmation message to the UE-A1 (S401). In connection with the registration of the UE-A1, the S-CSCF forwards the registration message received from the UE-A1 to the SCC AS (S402) and receives the registration confirmation message from the SCC AS (S403). The SCC AS can store the service control flags of UE-A2.

The UE-A1 transmits a subscription message to the S-CSCF in order to be notified of the change of status or performance information of the other UE (S404), and the S-CSCF forwards it to the SCC AS (S405). The SCC AS transmits a join acceptance message to the S-CSCF (S406), and the S-CSCF transmits the join accept message to the UE-A1 (S407).

Next, the UE-A2 performs the registration process (S408 to S411). Since the service control flag for UE-A 2 indicates that service control can be moved, the SCC AS sends a notification message to UE-A 1 indicating that the UE-A 2 capable of moving the cooperative session control is registered in the IMS network (S 412) . The UE-A1 transmits a notification confirmation message to the SCC AS indicating that the notification message has been confirmed (S413).

Finally, the UE-A3 performs a registration process (S414 to S417). However, unlike UE-A1 and UE-A2, the service control flag for UE-A3 indicates that the service control can not be moved (Controller disable). Accordingly, the SCC-AS transmits a notification message to the UE-A 1 notifying that the UE-A 3 that is unable to move the cooperative session control is registered in the IMS network (S 418). In response, the UE-A1 transmits a notification confirmation message to the S-CSCF indicating that the notification has been confirmed (S419).

9 and 10 are flowcharts illustrating a method of moving a service control regarding a media flow according to an exemplary embodiment of the present invention. This is a case where the IMS network element that transmits the notification message in the transmission of the service control flag is the S-CSCF, and the process of moving the service control regarding the media flow between the terminals will be described.

Referring to FIGS. 9 and 10, the UE-A1 transmits a registration message including a service control flag to the S-CSCF to register in the IMS network (S500). At this time, the service control flag indicates that the cooperative session control is enabled (Controller enable). The S-CSCF may store the service control flags of UE-A1. When the UE-A1 is registered, the S-CSCF transmits a registration confirmation message to the UE-A1 (S501). The UE-A1 sends a subscription message to the S-CSCF (S502) in order to be notified of the registration of the other terminal or the change of the status or performance information of the other terminal (S502), and the S- (S503). On the other hand, a session initiation procedure is performed according to a session initiation request of the UE-A1 (S504 to S509). The session initiation procedure is performed by the same procedure as steps S200 to S205 in Fig. Thereafter, the video and audio media flows are transmitted between the UE-A1 and the counterpart UE (S510), and the service control rights of the video and audio media flows are allocated to the UE-A1 (S511).

Next, the UE-A2 performs the registration process (S512, S513). The service control flag for UE-A2 indicates the disablement of the cooperative session control (Controller disable). The S-CSCF sends a notification message containing information about the UE-A2 to the UE-A1 (S514), and the UE-A1 sends a notification confirmation message to the S-CSCF (S515). The information about UE-A2 includes the registration fact of UE-A2 or the status or performance information of UE-A2. The state or performance information of the UE-A 2 may include information on registration of the UE-A 2, information related to configuration such as the type of the media supported by the UE-A 2 and codec related information, the size of the screen, And includes information related to the accessed wireless access network. The UE-A 1 does not attempt to move the cooperative session control to the UE-A 2 because it knows that the UE-A 2 can not act as a control terminal.

Finally, the UE-A3 performs the registration process (S516, S517). The service control flag for UE-A3 indicates the availability of cooperative session control. The S-CSCF sends a notification message to the UE-A1 informing that the UE-A3 capable of movement of the cooperative session control is registered in the IMS network (S518). In response, the UE-A1 transmits a notification confirmation message to the S-CSCF indicating that the notification has been confirmed (S519).

The UEs currently registered in the IMS network are UE-A1, UE-A2, and UE-A3, and the non-mobile terminal of cooperative session control is UE-A2. Thus, cooperative session control can not be moved between UE-A1 and UE-A2, and cooperative session control can move between UE-A1 and UE-A3. Thus, UE-A1 may consider the movement of cooperative session control to UE-A3.

In the case where the UE-A1 wants to move the cooperative session control of the UE-A1 to another UE, the UE-A1 transmits the service control flag information of the UE to the other UE, based on the service control flag information included in the notification message received from the S- (S520). The UE that can move the service control is UE-A3. If there is an instruction to move the service control from the user to the UE-A3, the UE-A1 performs a cooperative session control movement procedure to the UE-A3 (S521 to S528). The cooperative session control moving procedure is the same as steps S209 to S216 in Fig. The resultant voice and video media flows of the service control are transmitted and received between the UE-A1 and the counterpart UE, and the service control authority for the cooperative session composed of the voice and video media flows is held by the UE-A3 (S529).

11 and 12 are flowcharts illustrating a method of moving a service control regarding a media flow according to another example of the present invention. This is different from FIG. 9 and FIG. 10 only in the case where the IMS network element that is the subject of transmitting the notification message is the SCC AS, and the remaining procedures are the same, and anyone skilled in the art can easily understand the procedure.

The present invention may be implemented in hardware, software, or a combination thereof. (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microprocessor, and the like, which are designed to perform the above- , Other electronic units, or a combination thereof. In software implementation, it may be implemented as a module that performs the above-described functions. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, it is intended that the present invention covers all embodiments falling within the scope of the following claims, rather than being limited to the above-described embodiments.

1 shows an IMS-based wireless communication system.

2 is a block diagram showing elements of a terminal;

3 is a flowchart illustrating a registration procedure in which a terminal registers in an IMS network.

FIG. 4 is a diagram showing a state in which a service control related to a media flow or a media flow moves.

5 and 6 are flowcharts illustrating a procedure in which a service control related to a media flow between terminals is moved.

7 is a flowchart illustrating a method of transmitting a service control flag according to an exemplary embodiment of the present invention.

8 is a flowchart illustrating a method of transmitting a service control flag according to another example of the present invention.

9 and 10 are flowcharts illustrating a method of moving a service control regarding a media flow according to an exemplary embodiment of the present invention.

11 and 12 are flowcharts illustrating a method of moving a service control regarding a media flow according to another example of the present invention.

Claims (10)

A method for performing Inter UE Transfer between Collaborative Sessions, the method comprising: Transmitting, by the terminal, a subscription message to the network element requesting notification of information about at least one or more other terminals; Receiving, from the network element, a subscription acceptance message, which is a response to the subscription message; Wherein the terminal includes information about at least one or more other terminals and information about an ability to indicate whether the one or more other terminals can be a controller terminal capable of controlling the cooperative session Receiving a notification message from the network element; Receiving a control right for the cooperative session based on the information about the capability of the one or more other terminals and selecting a terminal that can become a controller terminal; And And performing a control-only transfer procedure for the cooperative session to the selected terminal regardless of the movement of the cooperative session. The method according to claim 1, Wherein the network element is a Serving-Call Session Control Function (S-CSCF) of an IMS (IP Multimedia Subsystem) network of a UE. The method according to claim 1, Wherein the network element is a service centralization and continuity application server (SCC AS), an application server supporting session continuity of a media flow. The method according to claim 1, Wherein the subscription message and the subscription accept message are session initiation protocol (SIP) messages, which are signaling protocols that can be used for IP-based multimedia services. The method according to claim 1, Wherein the at least one or more other terminals belong to the same user. The method according to claim 1, Wherein the at least one or more other terminals belong to different users. The method according to claim 1, Wherein the information about the capabilities of the at least one or more other terminals includes the registration status or performance information of the one or more other terminals. 8. The method of claim 7, Wherein the status or performance information comprises a Service Control Flag indicating the enable or disable of control of the cooperative session. 9. The method of claim 8, The status or performance information includes configuration related information including information on whether or not the other terminal is registered, type of media supported by the other terminal, codec related information, screen size, ≪ / RTI > wherein the cooperative session information includes related information. The method according to claim 1, Wherein the terminal is a controlled terminal controlled by the other terminal after transferring the control right to the cooperative session to the selected terminal.

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