CN101577882B - Emergency call realization system and method for IP multimedia subsystem - Google Patents

Abstract

The present invention discloses a system and method for implementing an emergency call for an IP multimedia subsystem, a location server and an emergency call session control function entity, wherein the above method includes: the first location server first responds to the emergency call initiated by the UE, and sends an emergency call to the second The second location server sends a routing query request message for obtaining the routing address of the PSAP, then obtains the routing address of the PSAP of the visited network from the response message of the routing query request message returned by the second location server, and sends the routing address of the PSAP to To the E-CSCF, the E-CSCF routes the emergency call to the PSAP of the visited network according to the routing address of the PSAP. Through the present invention, the emergency call initiated by the user roaming to the visited network can be sent to the emergency communication acceptance center of the visited network, and the purpose of providing emergency call service for the roaming user in the visited network is achieved.

Description

Emergency call implementation system and method for IP multimedia subsystem

technical field

The present invention relates to the communication field, and in particular, relates to an emergency call implementation system and method for an IP multimedia subsystem, an IP multimedia subsystem, a location server and an emergency call session control function entity.

Background technique

IP Multimedia Core Network Subsystem (IMS for short) is an IP-based network architecture proposed by the 3rd Generation Partnership Project (3GPP for short). IMS builds an open and flexible business environment, support multimedia applications, and provide users with rich multimedia services.

IMS is an IP-based telecommunications network architecture that has nothing to do with access technology, and can be a packet access network (for example, General Packet Radio Service (General Packet Radio Service, referred to as GPRS), Wireless Local Area Network (Wireless Local Area Network, referred to as WLAN) ), etc.), and can also provide services for mobile cellular networks (such as Global System for Mobile Communications (GSM for short), Universal Mobile Telecommunications System (UMTS for short), etc.).

Emergency call (Emergency Call) is a unique voice service function in the mobile communication system. Usually, as long as the user's mobile terminal is within the area covered by the mobile network, even if the terminal is not inserted into the Subscriber Identity Module (SIM) or set to restrict outgoing calls, the user can dial emergency numbers (such as 110, 119, 911, etc.) to initiate an emergency call. After the user initiates an emergency call, the emergency call will be transferred to the corresponding emergency call center, that is, the emergency communication acceptance center (Public Safety Answering Point, referred to as PSAP), for example, the emergency call will be transferred to the police station, fire brigade, emergency center etc., the emergency call center provides users with 24-hour emergency rescue services. In addition, the operation of the entire emergency call system can be completed by cooperation between telecom operators and emergency service agencies such as public security, fire protection, and hospitals.

Generally speaking, emergency calls are implemented in the circuit switched (Circuit Switch, referred to as CS) domain (also referred to as the circuit domain for short); The ) domain also starts to support the emergency call service, and implements the emergency call through IMS call signaling control on the PS domain. Generally, the emergency call service provided by the IMS domain may be referred to as IMS emergency call for short.

Fig. 1 shows a structural frame diagram of an IMS emergency call system in the related art. As shown in Figure 1, the IMS emergency call system includes the following functional units: user equipment (User Equipment, referred to as UE) 101, proxy call session control function (Proxy Call Session Control Function, referred to as P-CSCF) 102, service call session control Function (Serving Call Session Control Function, referred to as S-CSCF) 103, home subscriber server (Home Subscriber Server, referred to as HSS) 104, emergency call session control function (Emergency Call Session Control Function, referred to as E-CSCF) 105, A location retrieval function (Location Retrieval Function, LRF for short) 106 and an emergency communication acceptance center (Public Safety Answering Point, PSAP for short) 107 .

Among them, when making an emergency call, UE 101 sends the emergency call request to P-CSCF 102 through the Gm port, and P-CSCF 102 forwards the emergency call request to S-CSCF 103 through port Mw as an agent; S-CSCF 103 is UE 101 It belongs to the service entity of the network, and provides functions such as business logic and authority control for UE 101; HSS 104 saves user registration information and customized business information, and connects to S-CSCF 103 through port Cx; LRF 106 provides current information to the network The user's location information, the routing decision function (Routing Decision Function, referred to as RDF) embedded in LRF can decide the routing address of PSAP 107 according to the user's location information, LRF 106 is connected to PSAP 107 through port Le; PSAP 107 is used as an emergency call The service center is responsible for accepting emergency calls from users. E-CSCF 105 is a functional entity in the IMS domain, E-CSCF 105 and P-CSCF 102 are located in the same network (when the user roams, E-CSCF 105 and P-CSCF 102 are located in the visited network), between them Connected through the port Mw, the E-CSCF 105 is responsible for receiving the request for establishing an emergency session from the P-CSCF 102, and according to the location information provided by the user or obtaining the location information and routing information of the user from the LRF 106 through the port Mi, the emergency session The establishment request is sent to the PSAP 107 connected to the IP network through the Mm interface, or sent to the emergency communication acceptance center connected to the Public Switch Telephone Network (PSTN) through the Mi/Mg interface. In addition, the PSAP 107 can directly obtain user location information from the LRF 106, and contact the home network through the Mm/Mw interface to call back the user.

FIG. 2 is a signaling flow chart of a related art in which a user who has normally registered in the IMS domain roams to a visited network and initiates an emergency call in the visited network. As shown in Figure 2, the UE initiates an emergency call on the visited network, and the emergency call processing process includes the following steps:

Step 201, the UE registers with the S-CSCF of the home network;

Before the UE initiates an emergency call, it first needs to attach at the IP Carrier Access Network (IP-CAN for short). If the bearer network is an Evolved Packet System (EPS for short), it needs to be attached at the EPS bearer The network establishes an emergency bearer, and the Mobility Management Entity (MME) in the EPS system is responsible for mobility management and user authentication and other control plane functions; if the bearer network is GPRS, it is necessary to establish emergency Packet Data Protocol (PDP for short) context, Serving GPRS Support Node (SGSN for short) is responsible for control plane functions such as mobility management and user authentication;

Step 202, the UE initiates an emergency call request to the visited network, where the visited network is an IMS network;

Step 203: After receiving the call request initiated by the UE, the P-CSCF of the visited network judges whether the call request is an emergency call request: if it is not an emergency call request, process it according to the normal call process, and this process ends; otherwise, perform step 204 ;

Step 204, the P-CSCF sends the call request to the E-CSCF of the visited network according to the local policy; wherein, the address of the E-CSCF can be statically configured in the P-CSCF;

Step 205: After receiving the emergency call request, the E-CSCF sends a location retrieval message to the Location Retrieval Function (LRF for short), and the message includes the location information of the UE. After receiving the location acquisition message, the LRF obtains the routing address of the PSAP of the visited network on the LRF according to the location information of the UE contained in the message, and returns the address of the PSAP to the E-CSCF;

In step 206, the E-CSCF sends the emergency call to the PSAP of the visited network according to the routing address of the PSAP; if no corresponding PSAP address is found, the E-CSCF sends the emergency call to the default PSAP of the visited network; wherein, the PSAP can Set in CS domain, PS domain, or PSTN;

In step 207, the PSAP of the visited network confirms the call, and finally establishes an emergency session between the UE and the PSAP in the visited network.

From the above emergency call flow, it can be seen that the emergency call is a service implemented in the local network. After the UE roams to the visited network, it needs to establish a network bearer in the visited network, obtain the IP address assigned by the visited network, and then communicate with the visited network. The P-CSCF establishes contact, and then executes the subsequent emergency call procedure.

Currently, this solution is not well applicable in the following two scenarios.

Scenario 1, the visited network is configured with an IMS network but not configured with a packet network gateway of the IP bearer network (for example, a gateway GPRS Support Node (GGSN for short)), then the packet network gateway of the IP bearer network configured in the home network (eg, GGSN) will assign an IP address of the home network to the UE, so that the UE will initiate an IMS emergency call through the IMS network of the home network.

Fig. 3 is a signaling flow chart of the emergency call initiated by the UE in the scenario where the visited network is configured with an IMS network but not configured with a GGSN.

As shown in Figure 3, the following processing procedures are specifically included in this scenario:

From step 301 to step 304, the emergency call request initiated by the UE in the visited network is sent to the E-CSCF of the home network after the P-CSCF judges that the request is an emergency call;

In step 305, the E-CSCF searches the LRF of the home network for the routing address of the current PSAP according to the location information of the UE. Since the UE is visiting the network, the LRF has no relevant PSAP routing address and can only notify the PSAP address of the default configuration of the home network to E-CSCF;

Step 306a, the E-CSCF sends the emergency call to the default PSAP of the home network;

In step 307, an emergency session is established between the UE entering the visited network and the home PSAP center. Obviously, the emergency call initiated by the visited network is sent to the PSAP of the home network, and an emergency session is established with the PSAP emergency center of the home network, instead of the E-CSCF sending the emergency call to the PSAP of the visited network and realizing the communication between the UE and the PSAP in the visited network. Emergency conversation between (as shown in step 306b). Therefore, establishing an emergency call in the home network by the roaming user equipment does not conform to the principle that the emergency call service is provided locally.

Scenario 2: The visited network is not configured with an IMS network, but only with a PS network, such as a GPRS network or an EPS network. A location service center will also be configured in the GPRS network or EPS network. For example, a gateway mobile location center can be configured in the GPRS network (Gateway Mobile Location Center, referred to as GMLC), used to obtain the user's location information. In this scenario, the UE cannot use the IMS of the visited network to make an IMS emergency call, and can only control the IMS emergency call through the IMS network of the home network. Similar to Scenario 1, when the UE initiates an emergency call on the visited network, the emergency call initiated on the visited network can only be sent to the PSAP of the home network, which does not comply with the principle of providing local emergency calls.

It can be seen that in the above scenario, when the UE initiates an emergency call after roaming to the visited network, the IMS of the home network still controls the emergency call session, so that the emergency call request can only be sent to the emergency call center PSAP of the home network , but the emergency call session service cannot be implemented in the visited network, which violates the principle of providing emergency call services locally, and will cause emergency affairs to be unable to be processed in a timely manner in the visited place.

However, currently no effective solution has been proposed for the above-mentioned problem that the emergency call sent by the roaming user cannot be sent to the emergency communication acceptance center of the visited network.

Contents of the invention

The present invention is made in consideration of the above-mentioned problems, for this reason, the main purpose of the present invention is to provide a kind of emergency call realization system and method for IP multimedia subsystem, IMS system, location server and E-CSCF, in order to solve related In the technology, the emergency call sent by the roaming user cannot be sent to the emergency communication acceptance center of the roaming network.

According to one aspect of the present invention, a system for implementing an emergency call for an IP multimedia subsystem is provided, the system includes: a user equipment UE, a visited network, and a home network, wherein the UE is located in the visited network, and the home network is an IMS network, It includes: a first location server and an E-CSCF, and the visited network includes: a second location server and a tight PSAP.

The emergency call implementation system according to the present invention includes: the first location server is used to respond to the emergency call initiated by the UE, obtain the routing address of the PSAP of the visited network from the second location server, and return the obtained routing address of the PSAP to the home The E-CSCF of the network; the second location server is used to provide the routing address of the PSAP of the visited network to the first location server; the E-CSCF is used to route the emergency call to The PSAP.

According to still another aspect of the present invention, a location server is provided, and the location server is applied to an IMS system including an E-CSCF.

The location server provided according to the present invention includes: a requesting module, used to respond to the emergency call initiated by the UE, and request the routing address of the PSAP of the visited network from the location server of the visited network where the UE is located; The location server obtains the routing address of the PSAP of the visited network; the sending module is configured to send the routing address obtained by the obtaining module to the E-CSCF.

According to still another aspect of the present invention, an emergency call session control function entity is provided, and the emergency call session control function entity is applied to an IMS system including a location server.

The emergency call session control function entity provided according to the present invention includes: a first receiving module, configured to receive an emergency call from a UE; a first sending module, configured to send a location acquisition module to a location server after the first receiving module receives the emergency call request; a second receiving module, configured to receive the routing address of the PSAP of the visited network where the UE is located; a second sending module, configured to forward the emergency call to the PSAP according to the routing address of the PSAP of the visited network.

According to still another aspect of the present invention, an IMS system is provided.

The IMS system provided according to the present invention includes: E-CSCF, used to send a location acquisition request message to the location server when receiving an emergency call from the UE, and according to the routing address of the PSAP of the visited network where the UE is located returned by the location server , routing the emergency call to the above-mentioned PSAP; the location server is configured to request the location server of the visited network to obtain the routing address of the above-mentioned PSAP, and send the above-mentioned PSAP routing address obtained from the location server of the visited network to the above-mentioned E-CSCF.

According to another aspect of the present invention, a method for implementing an emergency call for IMS is provided, and the method is applied to a system including a UE, a visited network, and a home network, wherein the UE is located in the visited network, and the home network is an IMS network, including : a first location server and an E-CSCF, and the visited network includes: a second location server and a PSAP.

The emergency call implementation method for IMS according to the present invention includes: the first location server responds to the emergency call initiated by the UE, and sends to the second location server a route query request message for obtaining the routing address of the PSAP of the visited network; the first location server Obtain the routing address of the PSAP of the visited network from the response message of the routing query request message returned by the second location server; the first location server sends the routing address of the PSAP to the E-CSCF, and the E-CSCF sends the routing address of the PSAP according to the routing address of the PSAP Emergency calls are routed to this PSAP.

Through the above technical solution of the present invention, the location server of the home network can obtain the address of the emergency communication acceptance center of the visited network, so that the emergency call initiated by the user roaming to the visited network can be sent to the emergency communication acceptance center of the visited network, achieving The purpose of providing emergency call service for roaming users in the visited network.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

FIG. 1 is a structural block diagram of an IMS emergency call realization system according to related technologies;

FIG. 2 is a signaling flow chart for a user normally registered in an IMS domain to initiate an emergency call in a visited network according to the related art;

FIG. 3 is a signaling flow chart of UE initiating an emergency call when the visited network is configured with an IMS network but not configured with a GGSN according to related technologies;

4 is a structural block diagram of an emergency call implementation system for IMS according to an embodiment of the present invention;

FIG. 5 is a structural block diagram of a specific structural example of an emergency call implementation system for IMS according to an embodiment of the present invention;

FIG. 6 is a structural block diagram of a location server according to an embodiment of the present invention;

FIG. 7 is a structural block diagram of an E-CSCF according to an embodiment of the present invention;

FIG. 8 is a structural block diagram of an IMS system according to an embodiment of the present invention;

FIG. 9 is a flow chart of a method for implementing an emergency call for an IMS according to a method embodiment of the present invention;

Fig. 10 is a signaling flowchart of a processing example of the method for implementing an emergency call for IMS in practical application according to the method embodiment of the present invention.

Detailed ways

Functional Overview

As mentioned above, in view of the problem that the emergency call sent by the roaming user cannot be sent to the emergency communication acceptance center of the visited network, the present invention proposes an emergency call implementation system and method for the IP multimedia subsystem, an IMS system, and a location server and E-CSCF, in the technical solution provided by the embodiment of the present invention, the location server of the home network requests the location server of the visited network to obtain the routing address of the PSAP of the visited network, and according to the obtained routing address of the PSAP, roams to The emergency call initiated by the user of the visited network is sent to the PSAP of the visited network, so that the purpose of providing emergency call service for the roaming user in the visited network is achieved.

The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

System embodiment

In this embodiment, an emergency call implementing system for an IP multimedia subsystem is provided. The system is used for implementing a user equipment to a visited network (visited network deployment area may be referred to as Emergency call initiated by the place of visit).

In the visited network, regardless of whether the IMS network is deployed, a server related to location acquisition, such as a Gateway Mobile Location Center (GMLC for short), should be deployed in the visited network to provide user location information. Similarly, in the home IMS network, in addition to the GMLC, an additional LRF logic unit is deployed to obtain the location of the user, and a routing decision function (RoutingDecision Function, RDF for short) is embedded in the LRF to obtain the routing address of the PSAP.

In the present invention, in order to achieve that the emergency call initiated by the roaming user in the visited network can be routed to the PSAP of the visited network, preferably, in the general network deployment, functional units such as GMLC and LRF can be deployed together to form a physical entity , that is, the unit used for location service, hereinafter referred to as a location server (Location Service, referred to as LCS), and the LCS includes location service functions such as GMLC and LRF. The LCS has the ability to provide user location information and determine the PSAP routing address according to the user location information. The present invention will be described in detail below.

As shown in FIG. 4, the emergency call implementation system for IP multimedia subsystem according to this embodiment includes: UE, visited network 44, and home network 46 (the home network deployment area is called home), wherein the UE is located in the visited network 44. The home network 46 is an IMS network, including: the first LCS 402 and the E-CSCF 406, and the visited network 44 includes: the second LCS 404 and the PSAP 408,

The first LCS 402, located in the home network 46, is used to respond to the emergency call initiated by the UE, obtain the routing address of the PSAP 408 of the visited network 44 from the second LCS 404, and return the obtained routing address of the PSAP 408 to the home network 46 E-CSCF 406;

The second LCS 404, located in the visited network 44 and connected to the first LCS 402, is used to provide the routing address of the PSAP 408 of the visited network 44 to the first LCS 402;

The E-CSCF 406 is configured to route the emergency call to the PSAP 408 of the visited network 44 according to the acquired routing address of the PSAP 408 of the visited network 44.

The above servers and the processing procedures therebetween will be described in detail below.

Between the first LCS 402 and the second LCS 404, through the extended Lr interface or the newly added interface (the extended or newly added interface is named as the L(x) interface in this paper. The interface is named as another name), and, through the L(x) interface, the first LCS 402 can request the second LCS 404 to obtain the routing address of the PSAP 408 of the visited network 44, and receive the response from the second LCS 404 The routing address of the PSAP 408 visiting the network 44.

Before the first LCS 402 requests the second LCS 404 to obtain the routing address of the PSAP 408 of the visited network 44, the first LCS 402 needs to obtain the address of the second LCS 404.

In the specific implementation process, the first LCS 402 can first obtain the address of the second LCS 404, then send a routing query request message to the second LCS 404, and then carry the routing address of the PSAP 408 in the return response message by the second LCS 404, thereby Obtain the routing address of PSAP408.

Specifically, the first LCS 402 can obtain the address of the second LCS 404 in the following manner:

Obtain the address of the second LCS 404 according to the location information of the user equipment carried when the user equipment initiates an emergency call, wherein the address of the second LCS 404 is an address that is statically configured in advance or obtained through the home user server. Preferably, multiple addresses can be pre-configured A table of correspondence between LCS and location information, after obtaining the location information of the UE and/or the bearer network information of the visited network 44, the corresponding LCS can be found through the configured correspondence table. In addition, the first LCS 402 can further obtain the address of the second LCS 404 according to the bearer network information of the visited network 44 carried when the user initiates an emergency call.

In addition, the route query request message sent by the first LCS 402 to the second LCS 404 may be an extension of the location query message, or may be a newly added specific message. Wherein, the request identifier of the PSAP 408 routing address of the visited network 44 may be carried in the location query message and the specific message. The second LCS 404 can start routing address query according to the request identifier of the PSAP 408 routing address of the visited network 44.

The location query message and the specific message sent by the first LCS 402 to the second LCS 404 may further include location information of the user equipment. Optionally, the location query message and the specific message may further include emergency call service type information.

In this way, the second LCS 406 can obtain the routing address of the PSAP 408 of the visited network 44 according to the location information of the user equipment, or further according to the service type information of the emergency call.

Preferably, when the location information reported when the user initiates an emergency call is incomplete, or the location of the user changes frequently, the second LCS 406 can also search for the current location of the user equipment in the visited network 44 in response to a location query message or a specific message information, and obtain the routing address of the PSAP 408 of the visited network 44 according to the current location information of the searched user equipment.

Optionally, the second LCS 404 can store records related to this emergency call, including the location information of the user equipment, the address of the home network server, the routing information of the PSAP 408 of the visited network 44, etc., and assign an association for this emergency session record The location-associated code is ready for subsequent use. For example, the PSAP 408 can use the location-associated code to query the updated location information of the user.

The present invention will be described in detail below in conjunction with specific embodiments.

Fig. 5 shows a structural block diagram of an emergency call implementation system for an IP multimedia subsystem in practical application according to a system embodiment of the present invention. As shown in Figure 5, the main functional network elements configured on the home network side include at least: Proxy Call Session Control Function (P-CSCF for short) 502, Serving Call Session Control Function (Serving Call Session Control Function, P-CSCF for short) S-CSCF) 503, Home Subscriber Server (Home Subscriber Server, HSS for short) 504, Emergency Call Session Control Function (Emergency Call Session Control Function, E-CSCF for short) 505, First LCS (H-LCS) 506 , Home PSAP (H-PSAP) 507; the main functional network elements configured on the visited network side include at least: visited PSAP (V-PSAP) 509 and second LCS (V-LCS) 508, and UE 501 roams to the visited network at this time .

As shown in FIG. 5, both the visited network and the home network are deployed with LCSs, that is, a first LCS 506 and a second LCS 508, and a logical interface L(x) exists between the two LCSs. The L(x) interface may be an existing interface Lr for interconnection between the GMLCs of the visited network and the home network, or a newly defined interface. Through the L(x) interface, the location information of the user and the routing address of the PSAP serving the user can be transmitted between the home network and the visited network. In this way, when the user is roaming, through the first LCS 506 and the second LCS 508 as shown in Figure 5 and the interface L(x) provided by the present invention, it is possible to obtain the location information of the user and obtain the routing address of the PSAP of the visited network .

Specifically, in practical applications, based on the above emergency call implementation system, when the UE initiates an emergency call request to the home IMS network in the visited network, the first LCS finds the routing address of the second LCS according to the user's location information, bearer network information, etc., Then send a PSAP routing query request message to the second LCS; the second LCS searches for the corresponding PSAP routing address in the visited network according to the user's location information and returns it to the first LCS; the first LCS returns the PSAP routing address of the visited network to the home The E-CSCF of the network; the E-CSCF of the home network routes the emergency call request to the PSAP emergency center of the visited network according to the routing address of the PSAP.

Through the above technical solution, configure the first LCS and the second LCS on the home network side and the visited network side, communicate between the first LCS and the second LCS, and obtain the routing address of the PSAP of the visited network, so that Provide roaming users with local emergency call services based on the visited network.

In this embodiment, an LCS is provided, which is applied to an IMS system, and the IMS system also includes an E-CSCF.

FIG. 6 is a structural block diagram of an LCS according to an embodiment of the present invention. As shown in FIG. 6 , the LCS according to an embodiment of the present invention includes: a request module 62 , an acquisition module 64 and a sending module 66 . The above modules are further described below in conjunction with the accompanying drawings.

The request module 62 is configured to respond to the emergency call initiated by the UE, and request the routing address of the PSAP of the visited network from the LCR of the visited network where the UE is located;

The obtaining module 64 is connected to the requesting module 62, and is used to obtain the routing address of the PSAP of the visited network from the LCR of the visited network;

The sending module 66 is connected to the obtaining module 64, and is configured to send the routing address obtained by the obtaining module 64 to the E-CSCF in the IMS system.

In this embodiment, an E-CSCF is provided, which is applied to an IMS system, and the IMS system also includes an LCS.

FIG. 7 is a structural block diagram of an E-CSCF according to an embodiment of the present invention. As shown in FIG. 7 , the E-CSCF according to an embodiment of the present invention includes: a first receiving module 72, a first sending module 74, and a second receiving module 76 and the second sending module 78 . The above modules are further described below in conjunction with the accompanying drawings.

The first receiving module 72 is configured to receive an emergency call from the UE;

The first sending module 74 is connected to the first receiving module 72, and is configured to send a location acquisition request to the LCS of the IMS system after the first receiving module 72 receives the emergency call;

The second receiving module 76 is connected to the first sending module 74, and is used to receive the routing address of the PSAP of the visited network where the UE is located;

The second sending module 78 is connected to the second receiving module 76, and is configured to forward the emergency call to the PSAP according to the routing address of the PSAP of the visited network.

In this embodiment, an IMS system is provided. FIG. 8 is a structural block diagram of an IMS system according to an embodiment of the present invention. As shown in FIG. 8 , the IMS system according to an embodiment of the present invention includes: E-CSCF 82 and LCS 84. The above entities are further described below in conjunction with the accompanying drawings.

The E-CSCF 82 is configured to send a location acquisition request message to the LCS 84 when receiving an emergency call from the UE, and route the emergency call to the LCS 84 according to the routing address of the PSAP of the visited network where the UE is located PSAP;

The LCS 84 is connected to the E-CSCF 82 through the network, and is used to request the location server of the visited network to obtain the routing address of the PSAP, and send the routing address of the PSAP obtained from the location server of the visited network to the E-CSCF 82.

method embodiment

In this embodiment, a method for implementing an emergency call for an IP multimedia subsystem is provided, and the method is applied to a system including a UE, a visited network, and a home network, wherein the UE is located in the visited network, and the home network is an IMS network. It includes: the first LCS and the E-CSCF, and the visited network includes: the second LCS and the PSAP.

As shown in FIG. 9, the method for implementing an emergency call for an IP multimedia subsystem according to this embodiment includes: step S902, the first LCS responds to the emergency call initiated by the UE, and sends a routing query for obtaining the routing address of the PSAP to the second LCS request message; step S904, the first LCS obtains the routing address of the PSAP from the response message of the routing query request message returned by the second LCS; step S906, the first LCS sends the routing address of the PSAP to the E-CSCF, and the E-CSCF according to The routing address of the PSAP, which routes emergency calls to the PSAP.

It should be noted that, hereinafter, the first LCS also refers to the LCS on the home network side, and the second LCS also refers to the LCS on the visited network side.

The above processing procedure will be specifically described below.

The emergency call initiated by the user equipment roaming to the visited network, after the home network responds to the emergency call, before performing step S902, that is, before the first LCS requests to obtain the routing address of the PSAP of the visited network, the first LCS obtains the second The address of the LCS.

The first LCS may obtain the address of the second LCS in the following manner: the first LCS obtains the address of the second LCS according to the location information of the user equipment carried when the user equipment initiates an emergency call, or further according to the bearer network information of the visited network, wherein, The address of the second location server is statically configured in advance or obtained through the home subscriber server.

Step S902 is performed after the first LCS acquires the address of the second LCS, that is, the first LCS requests the second LCS to acquire the routing address of the PSAP of the visited network.

In step S902, the first LCS requests the second LCS to obtain the routing address of the PSAP of the visited network through a location query message or a newly added specific message, wherein the location query message and the specific message carry the location information of the user equipment, and The second location server obtains the routing address of the emergency communication acceptance center of the visited network according to the location information of the user equipment; or searches for the location information of the user equipment in the visited network in response to a location query message or a specific message, and based on the found location information of the user equipment Obtain the routing address of the emergency communication acceptance center of the visited network. In addition, the location query message and the specific message further carry type information of the emergency call.

After the second LCS obtains the routing address of the PSAP of the visited network, it sends the routing address of the PSAP to the first LCS. At this time, the first LCS performs step S906, that is, the first LCS returns the PSAP address of the visited network to the home network. (E-CSCF), the home network (E-CSCF) routes the emergency call request to the PSAP of the visited network according to the obtained routing address of the PSAP of the visited network, so that the UE can implement an emergency session with the emergency communication acceptance center of the visited network , thereby achieving the purpose of realizing an emergency conversation at the user's current location (visited place).

Through the above technical solution, the first LCS obtains the routing address of the PSAP of the visited network through the second LCS, and forwards the emergency call initiated by the user roaming to the visited network to the PSAP of the visited network, so that the visited network can provide roaming users with access-based Emergency call service local to the network.

The present invention will be described in detail below in conjunction with examples.

Fig. 10 shows the processing procedure of the method for implementing an emergency call for the IP multimedia subsystem in practical application according to the method embodiment of the present invention.

It should be noted that the LCS in FIG. 10 and in the following processing all include a location acquisition function (LRF) logic unit.

As shown in Figure 10, the concrete processing procedure that is used for the emergency call realization method of IP multimedia subsystem comprises:

Step 1002, the UE roams to the visited network, and initiates an IMS emergency call request in the visited network, and the call request is sent to the proxy call session control function (P-CSCF) of the home network;

After the UE roams to the visited network, it first needs to attach to the packet-switched (PS) bearer network of the visited network. During the attach process, the UE will obtain its location information in the visited network, including geographical location information (such as street address) and network location information (such as cell identity), etc.;

Step 1004: The P-CSCF of the home network judges that the received call request is an emergency call request, and sends the call request to the emergency call session control function (E-CSCF) of the home network for processing according to the local policy;

Step 1006: The E-CSCF of the home network initiates a location acquisition request message to the first LCS, and the message includes the emergency service type, UE location information, bearer network information, etc.; further, the first LCS according to the UE location information, bearer network information etc. to discover the second LCS. The address of the second LCS can be statically configured in the first LCS, or can be queried through a Home Subscriber Server (HSS).

Step 1008, the first LCS sends a request message for querying the PSAP routing address of the visited network to the second LCS through the L(x) interface;

Wherein, the location query message defined on the Lr interface can be extended in the query routing request message, and the location query message can carry a request identifier for requesting to obtain the PSAP routing address of the visited network; the second LCS detects that the request sent by the first LCS has This identification starts the PSAP routing address query process of the visited network;

In addition, it is also possible to newly define a routing query request message for routing information interaction;

The second LCS starts the routing decision-making function, and searches for the PSAP routing address of the visited network according to the location information of the UE. If the PSAP routing address of the visited network corresponds to the emergency service type, the specific address of the PSAP of the visited network can be determined according to the emergency service type. , if you call the fire alarm, you need to find the local emergency fire center;

Preferably, the second LCS can also query the visited network for the current location information of the UE according to the local policy. In this way, the location of the user changes after the user moves, or the UE location information obtained when the UE is attached is incomplete. In this case, the latest and complete UE location information of the UE is obtained, so that the second LCS can determine the routing address of the PSAP according to the latest location information of the UE, and return the updated location information of the UE to the first LCS in a response message, thereby The accuracy and completeness of UE location information are effectively guaranteed.

Optionally, the second LCS may save records related to this emergency session, for example, save information such as UE location information, the address of the first LCS, and the routing address of the PSAP of the visited network, and allocate a second emergency session record Location-associated code. When the PSAP has an emergency session with the UE, the PSAP may request the latest location information of the UE from the second LCS according to the location association code. In addition, saved emergency session records can be released after the emergency session ends.

Step 1010, the second LCS returns a routing query request response message to the first LCS, and returns the location information of the UE and the PSAP routing address of the visited network;

And, if the PSAP of the visited network is located in the IP network, then return the routing IP address of the PSAP of the visited network; if the PSAP of the visited network is in the CS network, then return the number of the circuit switched (CS) of the PSAP of the visited network;

Step 1012, the first LCS returns the location information of the UE and the PSAP routing address of the visited network to the E-CSCF of the home network;

Step 1014, the E-CSCF of the home network uses the PSAP address of the visited network to send an emergency call request to the PSAP of the visited network, which carries information such as the location information of the UE;

Step 1016, through the subsequent call establishment process, the UE located in the visited network establishes an emergency session with the PSAP of the visited network, and in the visited network, the PSAP can handle the emergency affairs of the user in a timely manner.

To sum up, with the help of the emergency call implementation system and method for IP multimedia subsystem provided by the present invention, when a user roaming to a visited network initiates an emergency call, the first LCS on the home network side and the visited The second LCS on the network side communicates, informs the first LCS on the home network side of the address of the PSAP on the visited network side, and the home network sends the emergency call to the PSAP on the visited network side, realizing roaming in the visited network. The user provides a local emergency call service.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (11)

1. A system for implementing an emergency call for an IP multimedia subsystem IMS, the system comprising: a user equipment UE, a visited network, and a home network, wherein the UE is located in the visited network, and the home network is an IMS network, Including: a first location server and an emergency call session control function entity E-CSCF, and the visited network includes: a second location server and an emergency communication acceptance center PSAP, characterized in that: The first location server is configured to respond to the emergency call initiated by the UE, obtain the routing address of the PSAP from the second location server, and return the obtained routing address of the PSAP to the E-CSCF ; The second location server is configured to provide the routing address of the PSAP to the first location server; The E-CSCF is configured to route the emergency call to the PSAP according to the acquired routing address of the PSAP. 2. The system according to claim 1, wherein the first location server obtains the routing address of the PSAP of the visited network from the second location server through a routing query request message. 3. The system according to claim 2, wherein the routing query request message carries a request identifier, which is used to instruct the second location server to query the routing address of the PSAP; Then the second location server is further configured to initiate a routing address query according to the request identifier. 4. The system according to claim 2, wherein the routing query request message carries the location information of the UE; Then the second location server is further configured to obtain the routing address of the PSAP of the visited network according to the location information. 5. A location server, applied to an IMS system including an E-CSCF, characterized in that, comprising: The requesting module is configured to, in response to the emergency call initiated by the UE, request the routing address of the PSAP of the visited network from the location server of the visited network where the UE is located; An obtaining module, configured to obtain the routing address of the PSAP of the visited network from the location server of the visited network; a sending module, configured to send the routing address obtained by the obtaining module to the E-CSCF, so that the E-CSCF routes the emergency call to the PSAP according to the obtained routing address of the PSAP . 6. An emergency call session control function entity, applied to an IMS system comprising a location server, characterized in that it comprises: a first receiving module, configured to receive an emergency call from the UE; A first sending module, configured to send a location acquisition request to the location server after the first receiving module receives the emergency call; The second receiving module is configured to receive the routing address of the PSAP of the visited network where the UE is located; The second sending module is configured to forward the emergency call to the PSAP according to the routing address. 7. A kind of IMS system, this system comprises: E-CSCF and location server, wherein, The E-CSCF is configured to send a location acquisition request message to the location server when receiving an emergency call from the UE, and according to the routing address of the PSAP of the visited network where the UE is located returned by the location server, routing the emergency call to the PSAP; The location server is configured to request the location server of the visited network to obtain the routing address of the PSAP, and send the routing address of the PSAP obtained from the location server of the visited network to the E-CSCF, So that the E-CSCF routes the emergency call to the PSAP according to the acquired routing address of the PSAP. 8. A method for implementing an emergency call for IMS, applied to a system including a UE, a visited network, and a home network, wherein the UE is located in the visited network, and the home network is an IMS network, comprising: a first location A server and an E-CSCF, the visited network includes: a second location server and a PSAP, wherein the method includes: The first location server responds to the emergency call initiated by the UE, and sends a routing query request message to the second location server to obtain the routing address of the PSAP; The first location server obtains the routing address of the PSAP from the response message of the routing query request message returned by the second location server; The first location server sends the routing address of the PSAP to the E-CSCF, and the E-CSCF routes the emergency call to the PSAP according to the routing address of the PSAP. 9. The method according to claim 8, wherein the routing query request message carries a request identifier, which is used to instruct the second location server to query the routing address of the PSAP; Before the first location server obtains the routing address of the PSAP from the response message of the routing query request message returned by the second location server, the method further includes: The second location server queries the location information of the UE according to the request identifier carried in the routing query request message, and obtains the routing address of the PSAP according to the location information; The second location server carries the acquired routing address in the response message and sends it to the first location server. 10. The method according to claim 8, wherein the routing query request message further carries the location information of the UE; Before the first location server obtains the routing address of the PSAP from the response message of the routing query request message returned by the second location server, the method further includes: The second location server obtains the routing address of the PSAP according to the location information carried in the routing query request message; The second location server carries the acquired routing address in the response message and sends it to the first location server. 11. The method according to any one of claims 8 to 10, wherein the route query request message is a location query message or a newly added specific message.

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