Patent Publication Number: US-9408054-B2

Title: Method for obtaining location information for emergency services in wireless multimedia networks

Description:
PRIORITY INFORMATION 
     This invention is a continuation application of U.S. patent application Ser. No. 14/143,017, entitled “METHOD FOR OBTAINING LOCATION INFORMATION FOR EMERGENCY SERVICES IN WIRELESS MULTIMEDIA NETWORKS”, filed Dec. 30, 2013, which is a continuation of U.S. patent application Ser. No. 13/858,863, of the same title, filed Apr. 8, 2013, and now issued as U.S. Pat. No. 8,655,306, which is a continuation of U.S. patent application Ser. No. 13/528,138, of the same title, filed Jun. 20, 2012, and now issued as U.S. Pat. No. 8,417,214, which is a continuation of U.S. patent application Ser. No. 10/575,999, of the same title, filed Apr. 17, 2006, and now issued as U.S. Pat. No. 8,229,389, which is a National Stage Entry of application number PCT/IB04/03325, filed Oct. 11, 2004, and which is hereby incorporated by reference as though fully and completely set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to communications. Specifically, communication of an emergency request. 
     2. Description of the Prior Art 
     Communications networks are becoming ubiquitous. The lines that once differentiated voice networks, data networks and video networks are blurring. In addition, wireless networks and terrestrial networks such as circuit-switched networks and packet-switched networks are often integrated. 
     Currently there are substantial wireless networks in North America, Europe, Asia and other parts of the world. These wireless networks are often based on communications standards. For example, Second-Generation Wireless Network (2G) standards and Third-Generation Wireless Network (3G) standards are currently being deployed. Some of the more recent standards provide for multimedia traffic such as voice and data traffic across these networks. 
     Circuit-switched and packet-switched networks have also advanced to provide more capability and functionality such as multimedia functionality. In addition, standards based protocols such as H.323 and Session Initiation Protocol (SIP) are currently being deployed to integrate multimedia functionality across terrestrial networks, such as packet-switched networks. 
     Given the need for ubiquitous communications, methods have developed for providing multi-media capability across wireless, packet-switched and circuit-switched networks. In order to properly integrate the networks, the services offered in any aspect of the network must be properly managed in other parts of the network. Some services currently being offered in the circuit-switched and packet-switched network also need to be supported in the multimedia network. 
     One specific service that is currently offered in wireless networks is an emergency service. The emergency service enables the ability to obtain the location of a wireless end user device and provide that location to the emergency service provider. Thus, there is a need for a method and apparatus for obtaining location information for emergency services within a multimedia network. 
     SUMMARY OF THE INVENTION 
     A method and apparatus is presented that obtains wireless end-user location information for emergency services within a multimedia network. In one embodiment, end-user location information is obtained within a multimedia network at session initiation. In a second embodiment, end user location information is obtained within a multimedia network after session initiation. In order to accomplish the foregoing methods, in one embodiment of the present invention, an application server, such as a Location Application Server (LAS) is implemented in a multimedia network. In accordance with the teachings of the present invention, an interface (i.e., herein referred to as an MI interface) is defined to enable communication between the LAS and a Gateway Mobile Location Center (GMLC). 
     In accordance with the teaching of the present invention, a multimedia architecture is defined. In one embodiment, the multimedia architecture includes user equipment (UE), a Proxy-CSCF (P-CSCF), a Server-CSCF (S-CSCF), a LAS and a GMLC. Two methods of operating the multimedia architecture are defined. In one embodiment, location information is acquired at session initiation. In a second embodiment, location information is acquired after session initiation. 
     At session initiation, a UE sends an emergency request (e.g., INVITE) to a P-CSCF. The P-CSCF forwards the emergency request to a S-CSCF. On receipt of an emergency request (e.g., INVITE) the S-CSCF forwards the request to the LAS. The LAS sends a location request to the GMLC via an MI interface. The GMLC initiates a Mobile Terminating Location Request (MT-LR) procedure to determine the UE&#39;s location information. The location information is returned to the LAS and then to the S-CSCF. The S-CSCF includes the location information in the emergency request (e.g., INVITE) and communicates the emergency request (e.g., INVITE message) to an EC. 
     After session initiation, a UE sends an emergency request (e.g., INVITE) to a P-CSCF. The P-CSCF forwards the emergency request to a S-CSCF. On receipt of an emergency request (e.g., INVITE) the S-CSCF forwards the request to the LAS. The LAS sends a request for routing information to the GMLC via an MI interface. The GMLC sends an acknowledgement including routing information that will enable the EC to request the UE location at a later time (e.g. a routing key). At any time after receiving the request for routing information, the GMLC initiates a Mobile Terminating Location Request (MT-LR) procedure to determine the UE&#39;s location information. Upon receipt of the emergency request (e.g., INVITE message), the EC can request location information from the GMLC by using the routing information obtained in the emergency request (e.g., INVITE message). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  displays a wireless IP multimedia (IMS) network implementing the teachings of the present invention. 
         FIG. 2  displays a network implementing the method of acquiring location, information at session initiation. 
         FIG. 3  displays a message flow diagram depicting a method of acquiring location information at session initiation. 
         FIG. 4  displays a network implementing the method of acquiring location information after session initiation. 
         FIG. 5  displays a message flow diagram depicting a method of acquiring location information at session initiation. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. 
     In one embodiment of the present invention, a multimedia network is defined. The multimedia network includes a Location Application Server (LAS). In one embodiment, the LAS is an implementation of an Application Server specifically for location services. In accordance with the teachings of the present invention, a communication interface, referred to as an MI interface is defined between the LAS and a Gateway Mobile Location Center (GMLC). The MI interface enables communication between the LAS and the GMLC. As such, location information associated with User Equipment (UE) may be communicated to an Emergency Center (EC) using the multimedia network. In one embodiment the GMLC provides the functionality required to support location services and is positioned in a location services network. 
     The method and apparatus of the present invention are in compliance and may implement various features and concepts from 3GPP TS 23.002; 3GPP TS 23.060; 3GPP TS 23.228; 3GPP TS23.003; and 3GPP TS 23.271, which are each herein incorporated by reference. It should be appreciated that while specific references have been identified, the invention is not limited to the cited references. 
     A multimedia network architecture is defined. In one embodiment, the multimedia network architecture operates using the Session Initiation Protocol (SIP) as defined in Internet Engineering Task Force (IETF) RFC 3261 (June 2002), which is herein incorporated by reference. However, it should be appreciated that the multimedia network architecture may be implemented with a variety of competing technologies such as H.323 as defined in the International Telecommunications Union (ITU), version 7, approved Jul. 7, 2003. In one embodiment, the multimedia network architecture includes a Call Session Control Function (CSCF) and Application Server (AS). The CSC may be implemented as a Proxy-CSCF (P-CSCF) and/or a Server-CSCF (S-CSCF). The P-CSCF communicates information from the UE to the S-CSCF. The S-CSCF communicates with the EC and with the AS. 
     In accordance with the teachings of the present invention, a method and apparatus is implemented for obtaining a wireless end user&#39;s location information for emergency services within a multimedia network. A Location Application Server (LAS) is implemented in the multimedia network. In accordance with the teaching of the present invention, an MI interface is defined between the LAS and a GMLC to obtain the wireless end user&#39;s location information in the multimedia network. The MI interface enables communication between the LAS and GMLC. In one embodiment, multimedia protocols such as Session Initiation Protocol (SIP) and H.323 are implemented in the multimedia network to facilitate acquisition of the wireless end user&#39;s location information. In one embodiment, the location information is obtained at session initiation. In a second embodiment, the location information is obtained after session initiation. Each method may be initiated based on when the location information is requested. 
       FIG. 1  displays a communication network implemented in accordance with the teachings of the present invention. In  FIG. 1  User Equipment (LIE) is shown as  102 . In one embodiment, UE  102  is implemented to detect an emergency service request and to indicate the emergency service request to a network. The UE  102  communicates with access networks  101  as well as an multimedia network  105 . For example, the UE  102  communicates with a GSM Edge Radio Access Network (GERAN)  112  and a Universal Terrestrial Radio Access Network (UTRAN)  122 . In one embodiment, the GERAN  112 , and the UTRAN  122  are implemented as access subsystems to access a core network  103 . 
     The GERAN  112  communicates through core network  103  using a Second-Generation Message Switching Center (2G-MSC)  114  and/or a Second-Generation Serving GPRS Support Node (2G-SGSN) to a Gateway Mobile Location Center (GMLC)  120 . The UTRAN  122  communicates through core network  103  using a Third-Generation Serving GPRS Support Node (3G-SGSN)  124  and/or a MSC server  126  to the GMLC. 
     In accordance with the teachings of the present invention, the UE  102  is capable of communication with a multimedia network  105 . In one embodiment, the multimedia network  105  is implemented as an IP Multimedia Core Network Subsystem (IMS) network compliant with 3GPP TS 23.228 v6.5.0 (2004-03), which is herein incorporated by reference. In one embodiment of the present invention the IMS network  105  includes a Proxy CSCF (P-CSCF), Serving CSCF (S-CSCF) and Location Application Server (LAS)  116 . 
     In  FIG. 1 , the UE  102  communicates with a P-CSCF  104 , which communicates with a S-CSCF  106 . The S-CSCF  106  communicates with a Location Application Server (LAS)  116 . The LAS  116  communicates across an MI interface with a GMLC  120 . In one embodiment, the P-CSCF  104  functions as a proxy by accepting request, services the request and/or forwards the request for servicing. The P-CSCF  104  may function as a user agent terminating and independently generating transactions such as SIP transactions. In one embodiment, the S-CSCF  106  manages session states as necessary to support services operating in the network. In one embodiment, the LAS  116  receives emergency session establishment request from the S-CSCF  106 , sends location and routing information request to the GMLC  120  and on receipt of location and/or routing information, the LAS  116  forwards the location and/or routing information to the S-CSCF  106 . The S-CSCF  106  then forwards the location and/or routing information to the EC  108 . In the scenario where routing information is forwarded to the EC  108 , the EC  108  may the access the GMLC  120  to access the location information. 
       FIG. 2  displays a network implementing a method of obtaining location information at session initiation. A UE  202  communicates with a P-CSCF  204 . The P-CSCF  204  is capable of communication with an S-CSCF  206 . The S-CSCF  206  communicates with the EC  208  and the LAS  212 . In accordance with the teachings of the present invention, the LAS  212  is capable of communication with the GMLC  214  using a defined MI interface. The GMLC  214  is ultimately in communication with the serving nodes (MSC/SGSN/SMLC)  216 . 
     During operation, an INVITE request  203  is sent from the UE  202  to the P-CSCF  204 . The P-CSCF  204  detects that the user is initiating an emergency call and forwards the INVITE request  205  to a S-CSCF  206  in the same network  210 . In accordance with the teachings of the present invention, the S-CSCF  206  defects this is an emergency call and forwards the INVITE request  218  to the LAS  212 . A Location Request  220  is sent from the LAS  212  to a GMLC in the same network  214 . In one embodiment, the location request  220  may be an immediate location request or a deferred location request. 
     The GMLC  214  sends a Location Service (LCS) Mobile Terminal Location Request (MT-LR)  222  to the server nodes  216 . In one embodiment, the MT-LR procedures are implemented in accordance with the MT-LR procedures described in 3GPP TS 23.271 V6.7.0 (2004-03), which is herein incorporated by reference. The server nodes  216  communicate a response including the location information of the user to the GMLC  224  (as shown by the two-directional arrow  222 ). The GMLC  214  communicates a Location Response  326  including the location information of the user to the LAS  212 . The LAS  212  communicates an INVITE message  224  including the received location information of the user to the S-CSCF  206 . The S-CSCF  206  then forwards the INVITE message  207  including the location information of the user to the EC  208 . 
       FIG. 3  displays a message flow diagram depicting a method of acquiring location information at session initiation. The message flow diagram of  FIG. 3  depicts message flow between S-CSCF  300 , LAS  302 , GMLC  304  and EC  306 . During operation, a SIP INVITE request  310  is communicated from the S-CSCF  300  to the LAS  302 . The LAS  302  sends a location request  312  to the GMLC  304 . In one embodiment, the GMLC  304  is pre-configured and resides in the same network (e.g., home or visited network  308 ) as the LAS  302 . In one embodiment, the location request includes the type of location (e.g., current location), the UE&#39;s public identity and the required quality of set-vice (QoS), such as the accuracy, response time, etc. 
     Upon receipt of the Location Request  312 , the GMLC  304  initiates Mobile Terminating Location Request (MT-LR) procedures as shown by  314  to obtain the UE&#39;s location. In one embodiment, the MT-LR procedures are implemented in accordance with the MT-LR procedures described in 3GPP TS 23.271 V6.7.0 (2004-03). The GMLC  304  returns the location information to the LAS  302  in a Location Response  316 . The LAS  302  then includes the location information in a SIP INVITE request  318  to the S-CSCF  300 . A variety of packet formats and messages may be used to implement the foregoing methods. For example, the Internet Protocol or the GSM MAP protocol may be used. 
       FIG. 4  displays a network implementing the method of acquiring location information after session initiation. A UE  402  communicates with a P-CSCF  404 . The P-CSCF  404  is capable of communication with an S-CSCF  406 . The S-CSCF  406  may communicate with the EC  408  and the LAS  412 . In accordance with the teachings of the present invention, the LAS  412  is in communication with the GMLC  414  through an MI interface. The GMLC  414  is ultimately in communication with serving nodes (MSC/SGSN/SMLC)  416 . 
     During operation, an emergency INVITE request  403  is sent from the UE  402  to the P-CSCF  404 . The P-CSCF  404  detects that the user is initiating an emergency call and forwards the emergency INVITE request  405  to a S-CSCF  406  in the same network. The P-CSCF  404  and the S-CSCF  406  will detect the user initiating an emergency call. There are a variety of method for doing this for example, the user may initiate a “special” INVITE message e.g. a SOS INVITE request or an INVITE with a new SIP Emergency header. In the first case, the CSCF on receipt of an SOS INVITE detects it is an emergency request. In the latter case, the CSCF will need to look in all INVITE requests for the Emergency header. It should be appreciated that a variety of alternative methods may be implemented and still remain within the scope of the present invention. 
     The S-CSCF  406  detects this is an emergency call and forwards the emergency INVITE request  418  to the LAS  412 . A request for routing information  420  is sent from the LAS  412  to a GMLC  414  in the same network. The GMLC  414  sends an acknowledgement  426  to the LAS  412  with routing information and possibly the location information, if this can be obtained. The routing information enables the EC  408  to access the GMLC  414  in order to request the UE&#39;s  402  location information at a later time. The LAS  412  communicates an INVITE message  424  including the routing information and possibly the location information back to the S-CSCF  406 . The S-CSCF  406  then communicates an INVITE message  407  to the EC  408 . If the INVITE message does not contain the location information, then the EC  408  may then send a location request  428  to the GMLC  414 . 
     At any time after the GMLC  414  receives a request for routing information  420 , the GMLC  414  sends a Location Service (LCS) Mobile Terminal Location Request (MT-LR)  422  to the server nodes  416 . The server nodes  416  communicate a response to the GMLC  414  (as shown by the two-directional arrow  422 ). 
       FIG. 5  displays a message flow diagram depicting a method of acquiring location information after session initiation. The message flow diagram of  FIG. 5  depicts the message flow between S-CSCF  500 , LAS  502 , (GMLC  504  and EC  506 . During operation, The S-CSCF  500  sends a SIP INVITE request  510  to the LAS  502 . The LAS  502  sends a request for routing information  512  to a pre-configured GMLC  504  in the same network  508 . In one embodiment, the request for routing information  512  includes the type of location (e.g. current location), the UE&#39;s public identity and required QoS (e.g. accuracy, response time). 
     The GMLC  504  sends a request for routing information acknowledgement  514 , which includes routing information that will enable the EC  506  to request UE&#39;s (not shown in  FIG. 5 ) location information at a later Lime (e.g. a routing key) and may include the UE location (if already/previously obtained). At any time after the request for routing information  512  is received, the GMLC  504  initiates the Mobile Terminating Location Request (MT-LR) procedures  516  as described in 3GPP TS 23.271 V6.7.0 (2004-03) to obtain the UE&#39;s location. The LAS  502  includes the routing information and possibly the location information provided in the request for routing information acknowledgement  514  in a SIP INVITE request  518  to the S-CSCF  500 . The EC  506  requests location information  520  from the GMLC  504  upon receipt of the SIP INVITE that includes the routing information. A variety of packet formats and messages may be used to implement the foregoing methods. For example, the Internet Protocol or the GSM MAP protocol may be used. 
     While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. 
     It is, therefore, intended by the appended claims to cover any and all such applications, modifications, and embodiments within the scope of the present invention.