JP2008092599A - Method and system for dealing with emergency session to be subjected to network identification - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and system for establishing an emergency session in a communication system which is provided with at least one user equipment and one or more network entities both of which are involved in establishing the emergency session. <P>SOLUTION: When a user equipment initiates the session by transmitting a message that indicates an identifier of a called entity, for example, a call number or a logic name, to network entities, one of the network entities analyses the received identifier. When the network entity detects that the session to be initiated is an emergency session, information for notifying the user equipment that the session to be initiated is an emergency session is sent back to the user equipment. At that moment, the user equipment initiates execution of the emergency session. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention generally relates to the connection of emergency sessions, such as emergency calls.

  Emergency calls must be supported in an IP multimedia network (IMS). The UE (user equipment) can usually indicate that the session is an emergency session in an initial session setup (eg, a SIP INVITE message).

However, a situation arises where the initial session setup message is only sent with the normal number and there is no indication of an emergency. These conditions occur, for example, when a subscriber is roaming another IMS network.
It is important to identify the intended emergency session as soon as possible because the network and the UE need to take some special action to carry out the emergency session.

The present invention provides a method and system for allowing an emergency session to be established in a reliable manner.
The present invention provides a method and / or system as defined in the claims.
The present invention discloses means and functions of how the network can detect an emergency session, how it can be notified to the UE, and how this information will affect subsequent session setup.

The present invention provides, among other things, network identification of emergency sessions initiated by session initiation entities such as user equipment (UE) including mobile or fixed stations or terminals and the like.
Even if the user equipment cannot detect itself that the initiated session is an emergency session, it can be notified quickly and appropriate steps can be initiated to establish an emergency session.

  According to the first embodiment of the present invention, immediately after a control means such as the P-CSCF discovers that a session is an emergency session in order to ensure that the resource is at the transport level for emergency calls. A response is sent back to the UE. Upon receiving such a response, the UE performs the normal emergency session procedure defined in the 3GPP specification, for example. To perform a normal emergency session, for example, the UE obtains or queries location information and sends it in an “invite” message, while the UE activates an emergency PDP context for the session. .

The present invention can identify a session as an emergency session as soon as possible, so the network and the UE can perform special actions necessary for the emergency session as quickly as possible.
In another embodiment of the present invention, a control entity such as a P-CSCF does not immediately respond to the UE when it receives an “invite” message from the UE, and from an emergency center or intermediate network entity, For example, it waits to receive a message such as “183 Session Progress” and adds emergency information to the message.

Information about the emergency call is not delayed at all, and call establishment can continue in the conventional manner or in other ways as in the case of the “183 Session Progress” message.
Sending “invite” messages requires significant radio resources and it is not desirable to send a large number of “invite” messages. In practice, there is no delay in session establishment. This is because the UE has not yet started forming the secondary PDP context before the UE receives the SDP message. This means that instructions can be included with high priority for the user plane. If no emergency center is indicated, a default emergency center can be selected.

The present invention relates to a situation where a PDP context activation cannot or will not be performed first when starting a session for any reason, and a message such as an “invite” message is first transmitted from the UE to the CSCF.
Further details, features and advantages of the present invention will become apparent from the following description of specific embodiments with reference to the accompanying drawings.

The present invention discloses solutions to a number of problems as follows.
-The UE can activate the emergency PDP context after being notified about the characteristics of the session. This is important for giving high priority to the PDP context in GPRS (General Packet Radio Service) and RAN (Radio Access Network).
-The UE sends location information after being notified about the characteristics of the session (assuming that location information is not sent in each "invite" message). The location information is used to select the most suitable emergency center (EC).

  FIG. 1 shows a call origination element such as a mobile station (UE) 10, ie a session initiation element, a serving network element such as a serving GPRS support node (SGSN), and a call state control function (CSCF) or proxy call state control. 1 shows an embodiment of the invention with a network including further control elements such as a function (P-CSCF) 11. Still other network elements required to perform an IP multimedia session, eg, incoming elements, gateway nodes if necessary, subscriber information registers such as home location register (HLR), or home subscriber server ( HSS) and the like are also known to those skilled in the art and are therefore not illustrated or described in detail. In general, the MSC (Mobile Switching Center, not shown) returns a “call processing” message to the UE that includes a priority information field that also defines an EC (emergency center).

In all the embodiments described above or below, the UE1 is provided with a USIM (User Service Recognition Module).
The embodiments shown in FIGS. 1, 2 and 3 relate to emergency sessions that are network-identified.
A solution for guaranteeing resources to the transport level to perform an emergency call is to the UE 10 immediately after a control means such as a network entity, eg P-CSCF 11, discovers that the session is an emergency session. To return a response. When the UE 10 receives this response, that is, when the network notifies that the session to be started is an emergency session, the UE 10 performs a normal emergency session procedure as defined in the 3GPP specification, for example.

FIG. 1 shows the solution at a general level.
In step 1, the UE 10 sends a session start message, e.g. called entity identifier, e.g. A SIP (Session Initiation Protocol) “INVITE” message indicating the 164 number or LN (logic name) is transmitted to the P-CSCF 11.

In step 2, the P-CSCF 11 analyzes this number or LN. If it is detected that a normal session should be started, the normal connection procedure is continued. However, if the P-CSCF 11 finds that the call is an emergency call, steps 3 to 6 shown in FIG. 1 are executed.
In step 3, a response indicating that the session is an emergency session is transmitted to the UE 10.

In step 4, the UE 10 returns a confirmation message ACK to the P-CSCF 11.
In optional step 5, the UE 10 notifies the user that the session is an emergency session, for example by displaying an appropriate message on the display of the UE 10.

  Then, as shown in step 6, a normal emergency session is executed. Normal emergency session execution means that, for example, the UE 10 obtains location information, sends it in an “invite” message, and the UE 10 activates an emergency PDP context for the session.

  The response message in step 3 may be a new message or an existing SIP message, or other known messages may be used. The information in the response message may be a new parameter in the SIP protocol, but an existing parameter can also be used.

  FIG. 2 shows a solution where in step 3 the SIP 302 message “Moved Temporarily” is used as a response. The parameter value in the 302 message indicates that the session is an emergency session. The parameter is, for example, “Contact: sip: emergency@visited.cscf.com”. This value can be used for the SIP URI when sending a new “invite” message to the P-CSCF 11, for example, or the UE 10 can send a new “invite” message with an emergency session indication. It may occur. Another way is to use the “SIP NOTIFY” method.

Aside from the above description, the embodiment shown in FIG. 2 has the same structure and function as FIG.
FIG. 3 shows another embodiment of the present invention. In addition to the UE 10 and the P-CSCF 11, a serving CSCF (S-CSCF) 12 and an emergency center (EC) 13 are shown. The embodiment of FIG. 3 provides another function compared to the embodiment of FIGS.

  In order to achieve very fast session establishment, the P-CSCF 11 does not return a response to the UE 10 immediately after discovering that the session is an emergency session. Rather, continue session establishment and optionally, if possible, the P-CSCF 11 will respond to messages generated by this P-CSCF 11 to ensure high priority processing of the message. Add session instructions.

  Details of this procedure are shown in FIG. Considering the nature of an emergency session, it is highly desirable not to add an additional delay to session establishment in the case of an abnormal condition. By using the approach of FIG. 3, the transfer of another “invite” message over the air interface can be avoided, which is probably the largest and slowest message, and therefore very much Waste time.

The response message to the UE 10 (in SIP, the message “183 progress” is preferred) preferably includes an emergency session indication. This allows the emergency PDP context to be activated for the session.
When the location information for selecting the emergency center 13 does not exist in the S-CSCF 12 (or the server), the S-CSCF 12 (or the server) selects the emergency center 13 without the user location information. (Eg, select the default emergency center or select the nearest emergency center) or use some other technique, eg, select the emergency center based on the address of the P-CSCF 11 .

  As shown in FIG. 3, in step 1, the UE 10 starts session establishment and transmits a session setup message, for example, an “invite” message to the P-CSCF 11. The P-CSCF 11 analyzes the called party / entity number or logic name (LN) indicated in the session setup message and discovers that the call is an emergency call. The P-CSCF 11 adds an emergency session indication to the “invite” message (other elements may add this indication of the emergency session to the “invite” message).

In step 2, an “invite” message is forwarded to the S-CSCF 12.
In step 3, the S-CSCF 12 selects the emergency center (EC) 13 and forwards an “invite” message to the EC 13.
In step 4, the EC 13 returns a response such as SIP 183 “session progress” to the S-CSCF 12 in response to the “invite” request. The subset of media flows shown in steps 4 through 6 indicate that the message is sent back to the originating endpoint to propose an EC 13 to provide support or to request an emergency session.

In step 5, the S-CSCF 12 returns a response such as SIP 183 “session progress” to the P-CSCF 11.
In step 6, the P-CSCF 11 returns a response such as SIP 183 “session progress” to the UE 10. This response includes an emergency session indication. Therefore, the UE 10 can learn that this session is an emergency session and can take action accordingly.

The circles and ellipses shown in FIG. 3 mean “emergency call detection and emergency instruction addition capability”.
FIG. 4 shows a proposal for normal emergency session establishment when the UE has a USIM. Assume that the UE has activated the signaling PDP context to the GGSN at the visited PLMN.

The steps shown in FIG. 4 will be described in detail below with reference to the step numbers in FIG.
1. UE requests SAI (Service Area Recognition) from SGSN.
2. The SGSN sends a response message to the UE.
3. The UE sends a SIP “Invite” request including the initial SDP to the P-CSCF determined via the CSCF discovery mechanism. Information about the emergency call is sent in an “invite” message. The UE includes location information in an “invite” message.

4). The P-CSCF uses the information in the “Invite” message to detect that the call is an emergency call, for example by analyzing the requested number or name. The P-CSCF selects the S-CSCF at the visited network and forwards the SIP “Invite” request containing information about the emergency call to the S-CSCF.
5. The S-CSCF selects an appropriate EC using the location information. The S-CSCF forwards the request to the EC.

6). The destination media stream capability is returned via the signaling path.
7). The S-CSCF forwards a message containing the destination SDP capability to the P-CSCF.
8). The P-CSCF grants the resources necessary for this session.
9. The P-CSCF forwards the SDP message to the originating endpoint.
10. The UE determines the final set of media streams for this session and sends its final SDP to the P-CSCF.

11. The P-CSCF forwards the final SDP to the S-CSCF.
12 The S-CSCF forwards this message to the EC.
13. PDP context activation request. The UE activates the PDP context for the emergency session by sending a secondary PDP context activate request message to the SGSN. The UE indicates that the PDP context is used for the emergency session. For the PDP context, the allocation / retention priority must be immediately set to a high value.

14 If the SGSN confirms that the PDP context is for an emergency session, it can itself request location information from the SRNC and receive updated or more accurate location information about the UE. The SGSN then sends a location report to the Gateway Mobile Location Service Center (GMLC) defined in TS 23.271, and the EC can obtain this location information from the GMLC.
15. Radio access bearer configuration.

16. PDP context formation request.
17. PDP context formation response.
18. Accept PDP context activate.
19. The UE sends a “resource reservation successful” message to the terminating endpoint via the signaling path established by the “invite” message.
20. The P-CSCF forwards this message to the S-CSCF.

21. The S-CSCF forwards this message to the EC.
22. The resource is successfully reserved.
23. The EC sends information about the alarm to the S-CSCF.
24. The S-CSCF forwards the ringing message to the P-CSCF.
25. The P-CSCF forwards this message to the UE.

26. The EC answers the call and sends a final 200 OK message to the S-CSCF.
27. The S-CSCF forwards the final 200 OK message to the P-CSCF.
28. The P-CSCF indicates that the resources reserved for this session must be committed here.
29. The P-CSCF forwards the final 200 OK message to the UE.
30. The UE starts the media flow for this session.
31. The caller responds with a SIP ACK message to the 200-OK final response, which is sent to the P-CSCF.
32. The P-CSCF forwards the SIP ACK message to the S-CSCF.
33. The S-CSCF forwards the ACK message to the EC.

Although the present invention has been described in detail with reference to specific embodiments, the scope of protection of the present invention covers all changes, omissions, additions and modifications of the features disclosed herein.
The teachings of the present invention are preferably implemented in all IP networks, but can also be used in various other types of networks, namely IM, GPRS and UMTS domains.

1 shows a first embodiment of the method and system according to the invention. FIG. 3 shows a second embodiment of the method and system according to the invention. FIG. 4 shows a third embodiment of the method and system according to the invention. It is a figure which shows implementation of the emergency session process in a normal case.

Claims (32)

A method for establishing an emergency session in a communication system comprising at least one user equipment and one or more network entities involved in establishing an emergency session comprising:
When the user equipment initiates a session by sending a message indicating the identifier of the called entity to the network entity, one of the network entities analyzes the received identifier and the session to be initiated is When detecting that the session is an emergency session, information to notify the user device that the session to be started is an emergency session is transmitted to the user device.
A method with a stage.   Upon receiving the information sent to the user equipment to notify the user equipment that the session to be initiated is an emergency session, the user equipment comprises a further step of starting execution of an emergency session. The method of claim 1.   3. The method of claim 2, wherein performing the emergency session includes obtaining user equipment location information and transmitting the location information to one of the network entities.   4. The method according to claim 2 or 3, wherein the execution of the emergency session includes activating an emergency PDP context for the session.   The information returned to the user equipment is a message, preferably a SIP (Session Initiation Protocol) message, which includes a parameter indicating the address of the network entity to be addressed in order to establish an emergency session. The method in any one of.   6. The method according to claim 1, wherein the identifier of the called entity is a call number or a logic name of the called entity.   When the network entity detects that the session to be initiated is an emergency session, the emergency center is notified about the emergency session to be established, and the information is only received after receiving a response from the emergency center 7. A method as claimed in any preceding claim, wherein the method is returned to the user equipment and then an emergency session is established between the user equipment and an emergency center.   8. A method according to any of the preceding claims, wherein the network entity analyzing received identifiers is a call state control function (CSCF). A method for establishing an emergency session in a communication system comprising at least one user equipment and at least one call control network element involved in establishing an emergency session comprising:
When the user equipment initiates a session by sending a message indicating the identifier of the called entity to the call control network element, the call control network element analyzes and receives the received identifier When detecting that the session to be performed is an emergency session, information for notifying the user device that the session to be started is an emergency session is returned to the user device.
A method with a stage.   The method of claim 9, wherein the call control network element is a P-CSCF.   The method according to claim 9 or 10, further comprising the further step of resuming the session by sending a message including the information to the call control network element.   11. A method according to claim 9 or 10, comprising the further step of the user equipment starting a new session by sending a message containing the information to the call control network element.   13. A method according to claim 11 or 12, further comprising the further step of responsive to receipt of the information, the network initiating an emergency session. A method for establishing an emergency session in a communication system comprising at least one user equipment and at least one call control network element and an emergency center involved in establishing an emergency session comprising:
When the user equipment initiates a session by sending a message indicating the identifier of the called entity to the call control network element, the call control network element analyzes the received identifier;
Upon detecting that the session to be initiated is an emergency session, the network element sends information to the emergency center or sends the information to an intermediate network element for forwarding to the emergency center, and The information informs the emergency center that an emergency session should be established, and provides an indication of the emergency session to notify the user equipment that the session to be initiated is an emergency session. Return to user device,
A method with a stage.   The method of claim 14, wherein after receiving a response from the emergency center, an emergency session is established between the user equipment and the emergency center.   The method according to claim 14 or 15, wherein the call control network element is a P-CSCF. A communication system for establishing an emergency session comprising at least one user equipment and one or more network entities involved in establishing an emergency session comprising:
The user equipment initiates a session by sending a message indicating the identifier of the called entity to the network entity,
One of the network entities analyzes the received identifier;
Upon detecting that the session to be initiated is an emergency session, the analyzing network entity or another network entity informs the user device that the session to be initiated is an emergency session. A communication system configured to transmit to.   The system of claim 17, wherein the user equipment is configured to initiate execution of an emergency session upon receiving information that the session to be initiated is an emergency session.   19. The system of claim 18, wherein performing the emergency session includes obtaining location information of a user equipment and transmitting the location information to one of the network entities.   20. A system according to claim 18 or 19, wherein the execution of the emergency session comprises activating an emergency PDP context for the session.   21. The information returned to the user equipment is a message, preferably a SIP (Session Initiation Protocol) message, including a parameter indicating the address of the network entity to be addressed to establish an emergency session. A system according to any of the above.   The system according to any of claims 17 to 21, wherein the identifier of the called entity is a call number or a logic name of the called entity.   When the network entity detects that the session to be initiated is an emergency session, it notifies the emergency center about the emergency session to be established, and sends the information to the user equipment only after receiving a response from the emergency center. 23. A system according to any of claims 17 to 22, wherein an emergency session is established between said user equipment and an emergency center.   24. A system according to any of claims 17 to 23, wherein the network entity analyzing received identifiers is a call state control function (CSCF). A communication system for establishing an emergency session comprising at least one user equipment and at least one call control network element involved in establishing an emergency session comprising:
When the user equipment initiates a session by sending a message indicating the identifier of the called entity to the call control network element, the call control network element analyzes and receives the received identifier A communication system configured to return to the user device information for notifying the user device that the session to be started is an emergency session when detecting that the session to be performed is an emergency session.   26. The system of claim 25, wherein the call control network element is a P-CSCF.   27. A system according to claim 25 or 26, wherein the user equipment resumes the session by sending a message containing the information to the call control network element.   27. A system according to claim 25 or 26, wherein the user equipment initiates a new session by sending a message containing the information to the call control network element.   27. A system according to claim 25 or 26, wherein in response to receiving the information, the network initiates an emergency session. A communication system for establishing an emergency session comprising at least one user equipment and at least one call control network element involved in establishing an emergency session and an emergency center,
When the user equipment initiates a session by sending a message indicating the identifier of the called entity to the call control network element, the call control network element analyzes the received identifier;
If it detects that the session to be initiated is an emergency session, it sends information to the emergency center or sends it to an intermediate network element for forwarding to the emergency center, the information To the emergency center, and an indication of an emergency session is sent to the user equipment to notify the user equipment that the session to be started is an emergency session. A communication system configured as described above.   31. The system of claim 30, wherein an emergency session is established between the user equipment and an emergency center after receiving a response from the emergency center.   The system according to claim 31 or 32, wherein the call control network element is a P-CSCF.

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