KR20090035361A - System and method for establishing poc session - Google Patents

Abstract

A system for establishing a PoC session and a method thereof are provided to guarantee the establishment of the PoC session by giving the priority higher than that of a general PoC session to the PoC session for crisis handling although the maximum number of simultaneous PoC sessions is exceeded. A PoC system comprises a PoC user terminal(200), a PoC XDMS(XML Document Management Server)(240), a common XDMS(230) and a PoC server(250). When transmitting a session invitation request message for the session establishing, an originatingn-side PoC(Push-to-talk Over Cellular) client(202) includes a crisis handling request perceiver in the message. The PoC server checks a preset PoC service setup of a desitnation-side PoC client which will deliver the session invitation request message. In case the PoC service setup is set as a state that a session cannot be established, the PoC server modifies the PoC service setup into a state that the request session can be established.

Description

System and Method for Establishing PoC Session

The present invention relates to a method of establishing a push-to-talk over cellular (PoC) session and a PoC system for implementing the same. Particularly, the present invention provides simultaneous multi-poC session support (SSS). The present invention relates to a method for guaranteeing establishment of a PoC session in consideration of crisis handling in a PoC system, and a PoC system for implementing the same.

Due to the revolutionary development of mobile communication and the expansion of communication networks, more expanded and various services and applications using mobile phones are provided. In addition, the needs of users are diversified, and beyond the simple call service, the service has been expanded to location services, multimedia services, push-to-talk (PTT) services, etc. In particular, PTT services are conventional radios or TRS (Trunked). It supports various additional functions such as instant messenger and status display as well as group call and voice call that were available in Radio System).

Currently, the establishment of standards for PoC (PTT over Cellular) service that uses this PTT concept through mobile communication network is actively discussed.Features of PoC service distinguished from existing mobile communication service One is that a user can belong to multiple sessions at the same time and can make calls while moving between sessions as needed, depending on the preference of the PoC user or the capability of the PoC terminal. In addition, the requirements for the simultaneous multi-session function, such as the requirement that the user can call and move multiple sessions using his PoC terminal in the simultaneous multi-session, define the mobile communication service. It is specified in the requirements of the Open Mobile Alliance (OMA).

In the PoC system supporting simultaneous multiple sessions, the PoC client sets the maximum number of simultaneous multiple sessions by a PoC user, and then simultaneously performs a multi-session session to the home PoC server, which is his PoC server, during PoC service. A new PoC session invitation request message may be received that exceeds the maximum number of. As such, if there is a session invitation that exceeds the maximum number of concurrent multiple sessions, the Home PoC server managing the PoC client may reject the received PoC session invitation, or the maximum number of concurrent multiple sessions is given to the PoC client. A message indicating that is exceeded may be transmitted to maintain and open a PoC session according to the user's decision of the PoC client. For example, if a PoC client user selects to release one of the existing PoC sessions, the PoC client may inform the PoC server to release one of the existing participating PoC sessions. In addition, if a PoC client user chooses to reject a new session and maintain an existing PoC session, the PoC server can be notified to the PoC server to inform the PoC client that invited the session to reject the session invitation and to maintain the existing PoC session. .

Next, referring to FIG. 1, when the maximum number of Simultaneous PoC Sessions exceeds the maximum number of Simultaneous PoC Sessions according to the related art, a process of controlling the establishment of simultaneous Multiple PoC sessions by the PoC server will be described. In FIG. 1, it is assumed that PoC server A and PoC client A are originating PoC networks, and PoC server B and PoC client B are receiving PoC networks. In addition, it is assumed that simultaneous PoC sessions are established and communicated between the PoC server B and the PoC client B.

First, in step 100, PoC client A forwards a session invitation request message to PoC server A (PF and CF) to establish a general PoC session. The session invitation request message is transmitted to the PoC server B, which is a home PoC server. At this time, the session invitation request message may be INVITE.

Thereafter, when the PoC server B receives the session invitation request message in step 102, the PoC server B checks the maximum number of simultaneous multi-sessions of the PoC client B to which the session invitation request message is delivered. Thereafter, in step 103, the PoC server B generates a session invitation rejection message when the maximum number of concurrent multi-sessions is exceeded when the session invitation request is received. To the PoC client A, the session initiator. In this case, the session invitation rejection message may be SIP 486 “Busy Here”, and the response message generated in this way may include a warning message indicating that there are a large number of concurrent PoC sessions, such as 104 Too many Simultaneous PoC Sessions. .

That is, even in a PoC system capable of simultaneously opening multiple PoC sessions, attempting to open a PoC session exceeding a predetermined maximum number of simultaneous multiple sessions fails to establish a corresponding session.

As described above, according to the conventional simultaneous multi-PoC session management method, a case may fail even when establishing a PoC session for handling a crisis situation. As a result, when the maximum number of simultaneous multiple sessions of each PoC client is reached, the establishment of PoC sessions to control the crisis cannot be guaranteed, and there is no separate method for differentiating the establishment of PoC sessions to handle the crisis. Did.

Accordingly, the present invention provides a method for guaranteeing the establishment of a session by giving priority to a PoC session for crisis processing over a general PoC session and a PoC system for implementing the same.

In addition, the present invention provides a method for ensuring the establishment of a PoC session for crisis management in simultaneous multi-PoC session management and a PoC system for implementing the same.

As described above, the present invention has an advantage in that it is possible to establish a PoC session specialized for a PoC session for crisis processing, in addition to establishing a general PoC session. In addition, even when the corresponding PoC client exceeds the maximum number of concurrent multi-PoC sessions available, there is an advantage in that a PoC session can be guaranteed when a PoC session is opened for crisis processing.

In order to achieve the above, the present invention is characterized by including a PoC client and a PoC server supporting at least one or more simultaneous multiple PoC sessions.

In addition, the present invention is characterized in that when the PoC client opens a new PoC session, the PoC client indicates a PoC session for crisis processing, and the PoC server authenticates whether the PoC client can handle the crisis.

In addition, the present invention, when setting the recipient of the PoC session invitation message for the crisis processing, a dynamic PoC group (Dynamic) that is created on the fly using pre-arranged PoC group or location information already stored PoC Group).

In addition, the present invention, in the PTT over Cellular (PoC) system for opening a session, the originating PoC client including a crisis processing request recognizer when transmitting a session invitation request message for opening a session and the session invitation request message; Upon reception, the preset PoC service setting of the receiving PoC client to which the received session invitation request message is delivered is inspected, and if the session is set to be incapable of establishing a session, the requested session can be established. It is characterized in that it comprises a PoC server for controlling to open a session corresponding to the session invitation request by modifying the PoC service settings to the state.

In addition, the present invention provides a method for opening a session for crisis processing in a PTT over Cellular (PoC) system, the PoC server including a crisis processing request recognizer when the originating PoC client sends a session invitation request message for opening a session Transmitting the received request message to the PoC server, inspecting a preset PoC service setting of a receiving PoC client to which the received session invitation request message is transmitted, and opening the test result session. Modifying the PoC service setting in a state in which the requested session can be established if the state is set to be impossible, and the PoC server establishes a session corresponding to the session invitation request according to the modified PoC service setting. Delivering a session invitation request message to the receiving PoC client to establish; It is characterized by.

Hereinafter, the present invention proposes a method for guaranteeing the establishment of a PoC session for handling an accident or a crisis situation by a PoC client performing an OMA PoC (PTT over Cellular) multimedia call service and a system for implementing the same. First, a PoC system to which the present invention is applied will be described with reference to FIGS. 2 to 4. In the following, an example of applying the present invention to a push-to-talk (PTT) system, in particular, to a PTT over Cellular (PoC) system that provides a PTT service using a cellular mobile communication network. In general, a PoC system uses a Session Initiation Protocol (SIP) protocol and a SIP extension protocol to deliver session participation information of a group call, and uses an XML Configuration Access Protocol (XCAP) protocol to obtain group information. The functions of the present invention described below can be implemented by the above-described protocols, and the basic structure of the present invention can be based on the PoC Rel.1 system. First, a general PoC system to which the present invention can be applied will be described.

2 is a conceptual diagram of a general PoC service system and related network structure.

As shown in FIG. 2, a general PoC system includes a PoC user equipment (UE) 200, a PoC XML Document Management Server (XDMS) 240, a common XDMS 230, and a PoC server 250. Can be configured. In addition, the PoC system may further include an aggregation proxy server 260. These components may be connected via an access network 210, a SIP / IP core network 220, and a remote PoC network 270.

Each of the above-described components will be described below.

The PoC terminal 200 may include a PoC client 202 and an XML Document Management Client (XDMC) 204.

The PoC client 202 is a service requester embedded in the PoC terminal 200 and resides in the PoC terminal 200 to perform network access for providing PoC service to a PoC service subscriber. In addition, the PoC service subscriber may receive the PoC service through the PoC terminal 200 in which the PoC client 202 is embedded. In the following description of the present invention, the term PoC client will be used as a generic term for a terminal having a PoC client and a PoC service subscriber. In addition, reference numerals of PoC clients will be omitted later unless otherwise specified.

The main function of the PoC client is to establish a PoC session, join an existing session that has been established, or terminate the established session at the PoC service subscriber, that is, a PoC user. In addition, the PoC client performs a function of creating and delivering a talk burst, a function of supporting instant personal alert, an authentication function when accessing a PoC service, and the like. The PoC client may be connected to the SIP / IP core network 220 which is a core network supporting SIP / IP multimedia through the access network 210.

The SIP / IP core network 220 is connected to the PoC server 250, the public XDMS 230, or the PoC XDMS 240 to provide PoC services. At this time, the PoC server 250 performs an overall PoC control function (Poling Control PoC Function) that maintains and manages a PoC session, or participates in a PoC that maintains a session for joining a PoC session established for one-to-one or multi-party calls. Participating PoC Function can be performed.

Meanwhile, the PoC service may be accompanied by a service for establishing a group session, such as a conference call. To this end, the OMA standard defines an XML Document Management (XDM) client 204, a public XDMS 230, and a PoC XDMS 240 for a group list service. 2 illustrates a common XDMS 230 that may be commonly used for PoC XDMS 240 and other service enablers used for PoC services. Information about the group and group members may be stored in the public XDMS 230 and the PoC XDMS 240 via the PoC client. The PoC client can know the information of the PoC clients that can be called through the list of individuals or groups received from the public XDMS 230 and the PoC XDMS 240. Meanwhile, creation, modification and management of groups and group members for the public XDMS 230 and the PoC XDMS 240 may be made through a communication network trusted by a PoC service provider such as the Internet or an intranet. Detailed description of the protocol and specific contents of XML document management such as creating, modifying, and removing a group list will be omitted.

In addition, when the proxy server 260 receives a group list related request from the XDMC 204 for the group service, the aggregation proxy server 260 routes the same to each public XDMS 230 and the PoC XDMS 240 according to a preset rule.

Next, the PoC server 250 will be described.

3 is a schematic structural diagram of a PoC server to which the present invention is applied. In the functional aspect, the PoC server is a Controlling PoC Function (hereinafter referred to as CF) for maintaining and managing a PoC session as a whole and a participating PoC Function (hereinafter referred to as 'PF') for maintaining maintenance between each session. It can be divided into. As shown in FIG. 3, PoC Client A 202-A is connected to PF A, PoC Client B 202-B is connected to PF B, and each of PF A and PF B is in charge of session maintenance. do. In addition, the CF is connected to each of the PFs to maintain the overall PoC session.

Then, the characteristics of each function of the PoC server will be described with reference to Tables 1 and 2 below.

Controlling PoC Function (CF) Provides centralized PoC session handling Provides the centralized Media distribution Provides the centralized Talk Burst Arbitration functionality including talker identification Provides SIP session handling, such as SIP session origination, termination, etc Provides policy enforcement for participation in group sessions Provides the participants information Collects and provides centralized media quality information Provides centralized charging reports May Provide transcoding between different codecs Support Talk Burst Control Protocol Negotiation

As shown in <Table 1>, CF plays a role of managing PoC session as a whole among PoC server's functions. In particular, CF accepts floor request, which is the right of PoC clients to speak, and sets the order to speak. The talk burst requested by any PoC client is distributed to all other PoC clients participating in the group call, and provides information on the PoC client participating in the group call.

PF manages sessions associated with CF and each PoC client in PoC sessions, as shown in Table 2 below. In particular, PF plays a role of relaying when PoC client requests a voice or grants voice to PoC client in CF. do. PF also plays a role of media relay between CF and PoC clients, transcoding if different codecs are used between them, and in the case of concurrent sessions when talking in one session. In addition, it plays a role of filtering one according to PoC user's choice.

Participating PoC Function (PF) Provides PoC session handling May provide the Media relay function between PoC Client and Controlling PoC server May provide user media adaptation procedures May provide the Talk Burst control message relay function PoC Client and Controlling PoC server Provides SIP session handling, such as SIP session origination, termination , etc, on behalf of the represented PoC Client Provides policy enforcement for incoming PoC session (eg access control, incoming PoC session barring, availablity status, etc) May collect and provide media quality information Provides the participant charging reports May provide filtering of the media streams in the case of simultaneous sessions May provide transcoding between different codecs May support Talk Burst Control Protocol Negotiation Stores the current Answer Mode and Incoming PoC Session Barring preferences of the PoC Client

4 is a diagram schematically illustrating a Controlling PoC Function block and a Participating PoC Function block of a PoC server.

Referring to FIG. 4, each PoC clients 102-A through 102-D establish a PoC session by accessing the CF 300 through the PFs 310-A through 310-D. Thereafter, the media for the corresponding speech of the PoC client granted the speaking right from the CF 300 is delivered to each PoC clients. At this time, the PoC client granted the right to speak may make an appropriate speech only after confirming the information of the PoC clients participating in the group session.

First, the following describes a procedure for establishing a PoC multimedia session in a PoC system having the above-described features.

The transmitting PoC client sends a multimedia message (which may include various formats of audio, video, text, etc.) using the SIP protocol to request call processing. In response to the call processing request, the receiving client takes various response procedures according to the response mode setting in the corresponding PoC server and the existence of a presession. The call processing procedure for the PoC call will be described by exemplifying the procedures of the same sender network and the receiver network.

The sending PoC client sends a SIP INVITE request including the SIP address information of the receiving PoC client to which it wants to communicate to the corresponding SIP / IP core network. In this case, the SIP INVITE message may further include elements such as PoC address information of a transmitting PoC client, required media parameters, and characteristic value information indicating that the PoC service is a PoC service. Here, the "required media parameter" may include a number of characteristic values such as an encoding method, a rate, a payload type, and the like regarding audio and video when the required session is multimedia.

SIP INVITE messages are routed to a participating PoC server via a corresponding IMS server in the IMS network, i.e., P-CSPF and S-CSPF, via a route query from a Dynamic Host Configuration Protocol (DHCP) server or a Domain Name Server (DNS) server. Is passed on. In a general call request, the participating PoC server to which the PoC client is connected can be implemented separately from the controlling PoC server that manages the talk burst of the session being established, so the SIP INVITE request sent to the PF can be configured to support the SIP / IP core network of the network. It is passed to the controlling PoC server CF via.

Meanwhile, the PoC session control network including the CF transmits a SIP INVITE request message to the receiving network, and then receives a response message of the receiving network. The SIP message answered from the receiving network may be a 1xx provisional response message, a 2xx successful response message, or an error response message such as 4xx to 6xx, depending on the settings of the receiving Poc client and the PF. Can be. In the auto-answer mode, a SIP 183 'session progress' signal may be received as a response message, through which the connection between the PoC server and the client may proceed in the IMS network of the call requester. The call permission signal of the receiving PoC client is returned in SIP 183 'session progress' or SIP 200 'OK' response, and is transmitted to the PoC client via the PoC server of CF and PF. When the CF receives a 200 OK response or a 183 session progress signal from the receiving PoC server, the CF determines that the PoC call is connected and transmits a floor granted signal to the transmitting PoC client, which gives talk burst voice. According to the above response, that is, 200 OK or 183 session progress, the granting of the burst burst authority may be divided into 'confirmed' or 'unconfirmed'. In the present invention, the CF needs a buffering function when receiving an 'unconfirmed' response.

On the other hand, after receiving the response signal for the SIP INVITE request signal, the transmitting PoC client receives the floor granted signal for transmitting the talk burst transmission grant signal (for example, a ring back tone) through the RTCP protocol. The floor granted signal is generated in the CF having the talk burst arbitration authority and transmitted to the PoC client through the PF managing the corresponding PoC client. In this case, the floor granted signal may be transmitted without passing through a SIP / IP core network such as IMS since the floor granted signal uses a bearer path. After confirming the ring back tone, the PoC client transmits the media (eg, voice) stream using the Real-time Transport Protocol (RTP) protocol.

5A and 5B illustrate an example of a process for guaranteeing establishment of a PoC session including a crisis processing request so as to open a PoC session for crisis handling in a PoC system according to the present invention. In FIG. 5A and FIG. 5B, it is assumed that PoC server A is a server performing both PF and CF roles, and PoC server B and PoC server C are servers performing PF roles. In addition, it is assumed that a PoC client B and a PoC client C participate in a general PoC session controlled by the PoC server A, and an ongoing session exists. Here, it may include both the case where the PoC clients B and C participate in the same PoC session and the case where the PoC clients B and C participate in the different PoC sessions. In addition, in the embodiments of FIGS. 5A and 5B, PoC User A, the owner of PoC Client A, reports a crisis situation to an opponent who has witnessed, is near, or is involved in, and handles the crisis situation. It is assumed that this is a case for informing that a call must be established by establishing a PoC session for the call.

First, in step 501 PoC client A transmits a session invitation request message for establishing a PoC session for crisis processing to PoC server A (PF and CF). In this case, the session invitation request message may be transmitted as an INVITE message, and includes a crisis processing request recognizer, which is a recognizer for notifying that a call must be established by performing a PoC session since it is a crisis situation. In addition, the format of the session invitation request message according to the present invention may be illustrated as shown in FIG. 6. 6 is an embodiment of a SIP session invitation request message format for delivering a crisis processing request recognizer indicating a PoC session establishment request for crisis processing according to the present invention.

Referring to FIG. 6, the INVITE message includes URI list information included in an ad hoc group session and 'application / sdp' representing a parameter of a media. At this time, the PoC client initiating the session invites a PoC session including a crisis processing request identifier by setting the field value for the 'crisis' parameter to '1' in the format parameter section of the 'MBCP' application media that sets the voice management protocol. The request message (INVITE message) can be delivered to the PoC server. Meanwhile, the conference management PoC server CF may deliver a PoC session invitation request message including a crisis processing request recognizer to the receiving PoC server PF and the PoC client using the same media format parameter as shown in FIG. 6. In addition, the conference management PoC server CF receives a response message from each receiving PoC server PF to determine whether to establish a PoC session for crisis processing, and delivers the response message to the PoC client corresponding to the session initiator. Can be. At this time, the response message may be delivered as a 200 OK message. If the field value of the 'crisis' parameter is set to '1' in the same manner as the crisis processing request identifier included in the PoC session invitation request message, The establishment of a PoC session for processing can be seen as negotiated. In addition, if the field value of the 'crisis' parameter is set to '0' in the response message, it may be considered that the establishment of a PoC session for crisis processing is not negotiated.

In step 502, the PoC server A authenticates whether the PoC client A that has transmitted the received session invitation request message is a PoC client capable of a Crisis Handling request. If it is an authenticated PoC client, it checks the recipient list. In this case, the authentication PoC client may preset and store a PoC client for a specific authentication, such as a government agency such as a fire station or a police station. In addition, the recipient list may be a list of predefined groups such as a Pre-arranged PoC Group, or a combination of users corresponding to the location information requested by PoC Client A, a requester for opening a session. Improvise a Dynamic PoC Group. It can also be an emergency contact network created and stored by PoC Client A for use in a crisis. If the PoC client A wants to open a PoC session for crisis processing to users corresponding to the specific location information, the PoC client A may include the location information to be requested in the session invitation request message transmitted in step 501.

When the PoC server A completes the authentication and the recipient list check in step 502, the session invitation request message is transmitted to the receiving PoC server, which is a PoC server of the receiving PoC client corresponding to the recipient list in steps 503 and 510, respectively. . 5A and 5B, it is assumed that the receiving PoC client included in the receiver list is a PoC client B and a PoC client C. In addition, in the embodiments of FIGS. 5A and 5B, the PoC server B does not support the simultaneous multiple PoC sessions in the PoC server B. However, the maximum number of concurrent multiple PoC sessions has been reached. Assume that PoC session establishment is set to be restricted. In addition, it is assumed that PoC service setting of PoC client C in Poc server C is set such that incoming PoC session barring is set to active to deny entry of a new PoC session invitation.

Under the above assumption, when the PoC server B in charge of the PoC client B receives the new session invitation request message in step 503, the PoC service setting is checked in step 504. Since the PoC service setting of the PoC client B cannot assume any more PoC session establishment as described above, the PoC service setting of the PoC client B is changed to control the establishment of the PoC session for crisis processing.

According to an embodiment of the present invention, if the PoC service is set to limit the opening of a new PoC session because the maximum number of simultaneous multi PoC sessions is reached because the simultaneous multiple PoC sessions are not supported, or the maximum number of simultaneous multiple PoC sessions is already set, the PoC may be changed. There are two ways to open a session. In addition, which one of the following two methods should be set in advance.

The first method is to change the configuration so that PoC server B increases the maximum number of simultaneous multiple PoC sessions previously set according to user preferences to accept a new PoC session for crisis processing received in step 503. .

As a second method, the PoC server B overrides the configuration by forcibly releasing one of the existing PoC sessions as in step 505 and then opening a new PoC session for crisis handling. There is this. If the PoC service configuration is changed in the second method, the session to be forcibly released must be determined. As such, the criteria for determining a session to be forcibly released may be a session participation time, frequency of session use, priority for each session according to user setting, session response mode, and the like. For example, a session corresponding to the latest session participation time, a session with the lowest frequency of session use, and a session with the lowest priority may be a forced release session. In addition, it may be determined that the session having the session response mode set to the manual response mode has a lower priority than the session set to the automatic response mode.

In the embodiments of FIGS. 5A and 5B, it is assumed that the PoC client B is configured to change the PoC service configuration using the second method.

Then, the PoC server B determines the session to be released according to the session decision criteria to force release of the PoC session in progress, and then, in step 505, the PoC server B releases a forced PoC session force release message for forced termination. At this time, the PoC session force release message may be transmitted as a BYE message.

Thereafter, when the PoC server B receives the final reception response message (OK response) from the PoC client B, the corresponding PoC session is released, so that the maximum number of simultaneous multiple PoC sessions that the PoC client B can join is less than one. Therefore, in step 507, the PoC server B may transmit a PoC session invitation request message for crisis processing to the PoC client B. In step 508, when the PoC client B transmits a final received response message (OK response) to the PoC server B, PoC server B delivers the final received response message to PoC server A (CF) in step 509. If it is assumed in the embodiments of FIGS. 5A and 5B that the PoC service configuration of the PoC client B is set to change the PoC service configuration using the first method, in step 504, the PoC server B performs simultaneous multiple sessions of the PoC client B. Modify the setting to increase the maximum number by 1. As such, since the maximum number of simultaneous multiple sessions is increased, the PoC server B does not perform steps 505 and 506, and performs steps 507 to 509.

In operation 510, the PoC server C PF receiving the PoC session invitation request message for crisis processing checks the PoC service setting of the PoC client C. Since the PoC service setting of PoC Client C is set to Incoming PoC Session Barring set to active, the PoC server C is set to deny entry of a new PoC session invitation. The bearing service setting is modified to inactive to release the blocking of the PoC session invitation request message in step 510, and the PoC session invitation request message is delivered to the PoC client C in step 512.

If the PoC client C sends the final reception response message in step 513, the PoC server C forwards the final reception response message to the PoC server A in step 514.

The PoC server A delivers a final response message indicating that the PoC session establishment for crisis processing is completed to the PoC client A, the PoC session establisher, in step 515. In addition, in step 516, the PoC server A transmits a talk right grant message for granting a talk right to the PoC client A who is the session establisher. At this time, the transmitted talk right grant message may be transmitted as a media burst granted message.

Subsequently, when a PoC session for crisis processing is established, PoC client A may transmit media in step 517, and PoC server A manages each home PoC server managing a participant list of the corresponding PoC session in steps 518 and 520. Deliver the received media to B and PoC server C. Then, the Home PoC Server B delivers the media to the PoC Client B in step 520, and the Home PoC Server C delivers the media to the PoC Client C in step 521.

Meanwhile, in the embodiments of FIGS. 5A and 5B, the PoC server A receives a response message from all receiving clients, and then transmits a final response message to the PoC client A. However, in another embodiment, in step 515, the final response message indicating the completion of the session establishment may be transmitted after receiving the final response message for accepting the session participation from one of the receiving clients. For example, after the PoC server A receives the response message from the PoC client in step 509, it is also possible to transmit the final response message even if the response message from the PoC client C is not received. That is, the final response message transmission in step 515 may be after receiving a final response message for accepting session participation from some or all of the corresponding PoC session participation clients according to the settings of the PoC user or the settings of the PoC service provider.

As described above, the present invention may define a parameter called 'crisis' in the SDP extension, which may indicate that the PoC thin line is established for crisis processing, and the PoC client and the PoC server may use a subscriber authentication procedure and corresponding parameters. Negotiate opening a PoC session for dealing with the crisis. In addition, the present invention is the maximum number of Simultaneous PoC Sessions (maximum number of Simultaneous PoC Sessions) or session priority, usage frequency, usage time, response mode, etc. set in the Home PoC server of participating clients invited to the corresponding PoC session. Examine the conditions of the system to establish a PoC session for dealing with the crisis.

As described above, when the PoC server checks the PoC service setting of the corresponding PoC client when the PoC server requests to open a PoC session, it is determined that the session cannot be established. In order to open a session, the PoC service configuration is modified to open a session. At this time, in the embodiment of the present invention, the PoC service setting is configured to set the maximum number of simultaneous multi-sessions and the receiving session blocking service as an example, but there may be various settings for opening a session.

1 is a signal flow diagram illustrating a process in which a PoC server controls the establishment of a PoC session when the maximum number of simultaneous multiple PoC sessions is exceeded when a PoC session is established according to the prior art;

2 is a configuration diagram of a PoC service system to which an embodiment of the present invention is applied;

3 is a functional block diagram of a general PoC server;

4 is a view for explaining a Controlling PoC Function block and a Participating PoC Function block of a PoC server;

5A and 5B are signal flow diagrams illustrating a process of guaranteeing establishment of a PoC session in consideration of emergency handling when establishing a PoC session according to an embodiment of the present invention;

FIG. 6 is an exemplary diagram illustrating a SIP session invitation request message format including an indicator indicating that a PoC session establishment request is made for emergency handling according to an embodiment of the present invention. FIG.

Claims (17)

In the PoC (PTT over Cellular) system for opening a session, An originating PoC client which includes a crisis processing request recognizer when transmitting a session invitation request message for opening a session; When the session invitation request message is received, the preset PoC service setting of the receiving PoC client to which the received session invitation request message is delivered is inspected, and if the session is set to be unable to open a session, the requested And a PoC server for controlling to open a session corresponding to the session invitation request by modifying a PoC service setting in a state in which a session can be established. The method of claim 1, wherein the PoC server, And upon receiving the session invitation request message including the crisis processing request recognizer, verifying whether the originating PoC client is a client capable of requesting a session invitation for crisis processing. The method of claim 1, wherein the PoC server, If the PoC service setting of the receiving PoC client has a maximum of one session or the maximum number of simultaneous multiple PoC sessions has already been reached, and a new PoC session is set to be restricted, the session cannot be established. And modifying the PoC service setting according to a preset Poc session setting changing method to control to open a session corresponding to the session invitation request. The method of claim 3, wherein One of a method of increasing the maximum number of the preset simultaneous multiple PoC sessions and a method of forcibly releasing one of the ongoing PoC sessions according to a preset forced release session determination condition is stored in the PoC server in advance. Session establishment system. The method of claim 4, wherein the forced release session determination condition, And a forced release session determination condition based on at least one of a session participation time, session usage frequency, session priority, and session response mode according to a user setting. The method of claim 3 or 4, wherein the PoC server, And a session invitation request message including a crisis processing request recognizer in the session invitation request message when delivering the received session invitation request message to the receiving PoC client. The method of claim 6, And a receiving side PoC client which transmits a response message indicating whether to participate in the requested session to the PoC server when receiving the session invitation request message including the crisis processing request recognizer. The method of claim 7, wherein the PoC server, And after receiving a response message from all receiving side PoC clients with respect to the received session invitation request message, sending a final response message indicating completion of session establishment to the calling side PoC client. The method of claim 7, wherein the PoC server, In response to the received session invitation request message, one of the receiving PoC clients of the receiving PoC client receives a final response message for accepting the session participation for crisis processing, and then sends a final response message indicating the completion of the session. Session establishment system, characterized in that for transmitting to. In the method for establishing a session for crisis handling in a PTT over Cellular (PoC) system, Sending the PoC server to the PoC server by including the crisis processing request identifier when the originating PoC client transmits the session invitation request message to open a session; When the PoC server receives the session invitation request message, inspecting a preset PoC service setting of a receiving PoC client to which the received session invitation request message is transmitted; Modifying a PoC service setting in a state in which the requested session can be established when the session is set to be incapable of establishing a session; And transmitting, by the PoC server, a session invitation request message to the receiving PoC client to open a session corresponding to the session invitation request according to the modified PoC service setting. 11. The method of claim 10, wherein the PoC service setting checking step comprises: when the PoC server receives the session invitation request message, authenticating whether the originating PoC client is a client capable of requesting a session invitation for crisis processing; And checking a preset PoC service setting of a receiving PoC client to which the received session invitation request message is transmitted when the calling PoC client is authenticated after performing the authentication process. The method of claim 10, wherein the modifying of the PoC service setting comprises: setting the PoC service setting to limit the establishment of a new PoC session because the PoC service setting has at most one session or has reached the maximum number of simultaneous multiple PoC sessions. If it is set to a state that can not be set, the session establishment method, characterized in that the process of modifying the PoC service settings according to the preset method of changing the Poc session settings. The method of claim 12, wherein And a method of increasing the maximum number of simultaneous multiple PoC sessions previously set and forcibly releasing one of the ongoing PoC sessions according to a preset forced release session determination condition. The method of claim 13, wherein the forced release session determination condition, And a forced release session determination condition based on at least one of a session participation time, session use frequency, session priority, and session response mode according to a user setting. The method of claim 10, And when the receiving PoC client receives the session invitation request message including the crisis processing request recognizer, transmitting a response message indicating whether to participate in the requested session to the PoC server. The method of claim 15, And after the PoC server receives a response message from all receiving side PoC clients with respect to the received session invitation request message, transmitting a final response message indicating completion of session establishment to the calling side PoC client. How to open a session. The method of claim 15, The PoC server receives a final response message indicating completion of session establishment after receiving a final response message for accepting a session participation for crisis processing from one receiving PoC client of all receiving PoC clients with respect to the received session invitation request message. Session establishment method, characterized in that the transmission to the originating PoC client.

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