Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/02—Services making use of location information
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/90—Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/02—Services making use of location information
  • H04W4/029—Location-based management or tracking services
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/50—Connection management for emergency connections
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W40/00—Communication routing or communication path finding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W8/00—Network data management
  • H04W8/26—Network addressing or numbering for mobility support
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation

Definitions

• the present invention relates generally to methods and systems providing telephony communications through packet-switched communication networks.
• Particular aspects of the invention relate to location-based services in Internet Protocol (IP) based packet switched mobile communication networks, a method of making location-based services available to network subscribers when roaming between or within such communication networks, and the support and routing of emergency calls in such communication networks.
• IP Internet Protocol
• IP networks because the Internet Protocol is the most commonly used primary protocol.
• Many modem wireless networks utilize a combination of telephony equipment (such as conventional cellular phones) and packet switched equipment (usually network traffic routing equipment) compliant with one or more IP telephony standards such as, for example, the International Telecommunications Union (ITU) H.323 standard or the Internet Engineering Task Force (IETF) Session Initiation Protocol (SIP) specification, RFC 2543.
• ITU International Telecommunications Union
• IETF Internet Engineering Task Force
• SIP Session Initiation Protocol
• MIPT Mobile IP Telephony
• the Mobile IP Protocol to enable mobility.
• an IPT subscriber with General Packet Radio Service (GPRS) access in the visited network (see 3G TS 23.060, Stage 2, version 3.3.0), uses voice call services in their home network, so the subscriber is registered in a call control entity (such as a call state control function (CSCF)) in the home network.
• a call control entity such as a call state control function (CSCF)
• CSCF call state control function
• an emergency call setup request when received by a call control entity in a 2 nd generation cellular network, it selects a Public Safety Access Point (PSAP) to route the call to based on the Cell ID or the location information provided during the call setup.
• PSAP Public Safety Access Point
• this method cannot always be performed in 3 rd generation mobile IP networks based on the UMTS standard, since the Cell ID or location information may not always be available to a call control entity due to the way the emergency calls are setup. Therefore, there needs to be a method to support the selection of the PSAP in 3rd generation mobile IP networks based on the UMTS standard.
• the present invention addresses the disadvantages of MIPT networks discussed above. It broadly relates to systems and methods of providing, initiating, accessing, utilizing or managing location-based services and/or emergency calls in a 3 r generation Mobile IP Telephony network.
• One application of the invention relates to a service in which a subscriber visiting a network other than their own network uses their mobile terminal to make an emergency call.
• the emergency call is connected to a CSCF which then forwards the emergency call to a PSAP without authentication or billing and the approximate geographic location of the subscriber is transferred to the CSCF or to the PSAP at the same time that the emergency call is connected.
• the example embodiments of the invention offer a selection mechanism which provides controlled access to the CSCF of a local network so that an emergency call can be easily set up.
• a Gateway GPRS Service Node GGSN
• CSCF Call State Control Function
• An emergency call setup request is sent to the Call State Control Function (CSCF).
• the emergency call setup request includes the Service Area Identification (SAI) of GPRS.
• SAI Service Area Identification
• PSAP Public Safety Answering Point
• the approximate geographic location of the subscriber is transferred to the CSCF or to the PSAP at the same time that the emergency call is connected. It thus becomes possible to make an emergency call without a Subscriber Identification Module (SIM) and without any charges.
• SIM Subscriber Identification Module
• the access network in the example embodiments is able to control the PDP contexts which are used for emergency calls so that they can't be misused or that they are not subject to fraud.
• Fig. 1 is a block diagram showing parts of the architecture of an example embodiment 3 rd generation Mobile IP Telephony network.
• Fig. 2 is an expanded block diagram of an example 3 rd generation IP network additionally showing connections to other networks.
• Fig. 3 is a simplified block diagram depicting an example of location service entities and components of a 3 rd generation Mobile IP Telephony network according to example embodiments of the invention.
• Fig. 4 is a general signaling diagram of an example embodiment of the invention in which an emergency call is made by a subscriber with a Subscriber Identification Module (SIM).
• SIM Subscriber Identification Module
• Fig. 5 is a general signaling diagram of an example embodiment of the invention in which an emergency call is made by a subscriber without a Subscriber Identification Module (SIM).
• SIM Subscriber Identification Module
• Fig. 6 is a signaling diagram of example embodiment of the invention in which the location information for an emergency call is obtained during the call.
• Fig. 7 is a signaling diagram of another example embodiment of the invention in which the location information for an emergency call is obtained during the call.
• Fig. 8 is a signaling diagram of an example embodiment of the invention in which the location estimate is obtained before PDP Context Activation acceptance.
• Fig. 9 is a signaling diagram of an example embodiment of the invention in which the location estimate is provided to the mobile terminal.
• Fig. 10 is a signaling diagram of an example embodiment of the invention in which the SGSN knows the current Service Area Identification when it receives the Activate PDP Context Request.
• Fig. 11 is a signaling diagram of an example embodiment of the invention in which the mobile terminal originates the positioning method.
• Fig. 1 is a block diagram of a typical 3 ⁇ d generation Mobile IP Telephony network based on the UMTS standard.
• the detailed technical specifications for a UMTS network have been published by the 3 rd Generation Partnership Project in Release 1999 (www.3gpp.org ' ).
• the blocks in Fig. 1 represent different functionalities and do not necessarily correspond to different discrete network elements or equipment.
• the location services are supported by elements throughout the network. Some services are embedded in conventional network elements, such as the Radio Network (Controller (RNC), Mobile Services Switching Center (MSSC) and Service GPRS Support Node (SGSN).
• RNC Radio Network
• MSSC Mobile Services Switching Center
• SGSN Service GPRS Support Node
• some new network elements and interfaces are provided to support location services.
• LMU Location Measurement Unit
• BSS Base Station Subsystems
• Idle Slot Forward Link - Time Difference of Arrival ISFL-TDOA
• OTD Observed Time Difference Of Arrival - Idle Period Downlink
• LMU 301 primarily measures the Real Time Differences (RTD), Absolute Time Difference (ATD), or any other kind of radio interface timing of the signals transmitted by the base stations.
• RTD Real Time Differences
• ATD Absolute Time Difference
• the assistance measurements obtained by the LMU 301 are generic status information and can be used by more than one positioning method.
• the measurements may consist of location measurements specific to one mobile used to compute the location of that mobile or assistance measurements specific to all mobiles in a certain geographic area.
• LMU 301 All location, timing difference and assistance measurements obtained by LMU 301 are supplied to a particular Serving RNC 102 (SRNC) associated with the base station having the functionality of LMU 301. Instructions concerning the timing, the nature and any periodicity of those measurements are either provided by the SRNC 102 or are pre-administered in the base station.
• SRNC Serving RNC 102
• the LMU is a separate element from the GSM network. The communication between the GSM network and LMU is done through the GSM air interface.
• the LMU functionality is integrated into the base station, preferably without technical restrictions, at least when an Idle Slot Forward Link - Time Difference of Arrival (ISFL-TDOA) method or an Observed Time Difference Of Arrival - Idle Period Downlink (OTDOA-IPDL) method is used.
• ISFL-TDOA Idle Slot Forward Link - Time Difference of Arrival
• OTDOA-IPDL Observed Time Difference Of Arrival - Idle Period Downlink
• the Mobile Terminal (MT) 100 may be involved in various levels in the positioning procedures depending on the positioning method employed.
• the role of MT 100 is closely related to the positioning approach used in the system.
• the functionality of MT 100 may or may not encompass location calculation.
• it can initiate a location service by making a request to the network for positioning (network assisted positioning). If it supports the use of Idle Slot Downlink (IS-DL) sets, then it also performs the following functions:
• Each Node-B is able to shut down transmission during the idle period. This function can be predefined in Node B or can be controlled by the corresponding RNC 102. Each Node-B also can handle the functionality of LMU 301 including the functionality of the Positioning Signal Measurement Function (PSMF) and Location System Operation Function (LSOF). Thus, it is responsible for gathering uplink/downlink radio signal measurements for calculation of a mobile's position. It is also involved in overall operating of location services in the network.
• PSMF Positioning Signal Measurement Function
• LSOF Location System Operation Function
• the SRNC 102 in the Universal Terrestrial Radio Access Network (UTRAN) 103 contains functionality required to support location services and procedures between LMU 301 and location service entities in one Public Land Mobile Network (PLMN). It preferably controls the TDOA IS-DL procedures periodically or according to predetermined parameters, handles each Node-B's power ceasing period and performs the Location System Operation Function (LSOF), Positioning Radio Coordination Function (PRCF), Position Calculation Function (PCF), and Positioning Radio Resource Management (PRRM) entities.
• LSOF Location System Operation Function
• PRCF Positioning Radio Coordination Function
• PCF Position Calculation Function
• PRRM Positioning Radio Resource Management
• SRNC 102 also calculates the final location estimate and accuracy.
• the SRNC 102 controls each LMU 301 of a number of LMUs for the purpose of obtaining radio interface measurements to locate or help locate MT 100 in the area that it serves.
• the SRNC 102 is administered with capabilities and types of measurements produced by each of its LMUs.
• the location measurements returned by an LMU 301 to an SRNC 102 have a generic status and can be used for more than one positioning method (including Time of Arrival (TOA)).
• TOA Time of Arrival
• Iur interface supports inter-RNC soft handovers, including location services.
• Iur supports the functionality of the positioning entities in RNCs, including PCF, PRRM, Positioning Signal Measurement Function (PSMF) and LSOF.
• PSMF Positioning Signal Measurement Function
• LSOF LSOF
• Iur supports the relocation mechanisms to transfer the PCF, PRRM, PSMF and LSOF functionality from SRNC to Drift RNC (DRNC) in order for DRNCs to be able to handle the responsibility of SRNC in location service processes.
• DRNC Drift RNC
• UTRAN 103 is involved in the handling of various positioning procedures and RAN level overall controlling of location services. It controls an Idle Slot Downlink (IS-DL) method and manages overall coordination and scheduling of resources required to perform positioning of the mobile.
• IS-DL Idle Slot Downlink
• 103 calculates the final location estimate and accuracy and controls a number of LMU/Node B 101-1 to 101-n for the purpose of obtaining radio interface measurements to locate or help locate mobile terminal 100 in the serving area.
• UTRAN 103 provides Cell-ID and timing related data to 3G-MSC 104. According to the example embodiment of the invention described below, it may instead provide a Service Area Identification (SAI) code to 3G-MSC 104.
• SAI Service Area Identification
• 3G-MSC 104 is similar to the MSC in a GSM network, but the functionality of the Serving Mobile Location Center (SMLC) (element 302 in Fig. 3) may be integrated into SRNC 102.
• SMLC Serving Mobile Location Center
• the functions of 3G-MSC 104 are billing, coordination, location requests, authorizations of mobile terminals and managing call-related and non-call related positioning requests and operations for location services.
• UTRAN 103 since 3G-SGSN 105 has independent mobility management, UTRAN 103 instead generally provides a Cell-ID to SGSN 105. In the example embodiment of the invention described below, UTRAN 103 may instead provide SAI to SGSN 105.
• the location services parameters are included in the lu interface between RNCs 102 and 3G-MSC 104 and 3G-SGSN 105.
• 3G-SGSN 105 is similar to MSC 104.
• the functions of SGSN 105 are charging, coordination, authorizations of mobile terminals and managing positioning requests and operations of the location services as far as the packet switch accesses are concerned.
• each RNC 102 calculates the position of each mobile terminal 100 when a mobile-based positioning is applied by gathering uplink/downlink.(UL/DL) radio signal measurements. Then RNC 102 sends the location information to the UE or to SGSN. If the SGSN 105 receives the location information, it sends the location information to CSCF (element 304 in Fig. 3), to the PSAP (element 305 in Fig. 3), or to GMLC 106.
• the lu interface transforms coordinate estimates of Mobile Terminal 100 over Radio Access Network Application Part (RANAP) protocol from each RNC 102 to 3G-MSC 104 and SGSN 105 and Mobile Terminal 100 positioning related NAS messages, including paging, authentication, etc. messages over RANAP protocol.
• the interface also maps the location service Quality of Service (QoS) attributes and handles states information between UTRAN 103 and 3G-MSC 104.
• QoS Quality of Service
• Mobile Terminal 100 In a situation where Mobile Terminal 100 is connected to an external server via IP, the server might want to locate Mobile Terminal 100. If Mobile Terminal 100 is using dynamic IP addressing, the address has to be translated to an understandable address or the location request has to be otherwise processed.
• the external server could request the GGSN (element 303 in Fig. 3) to provide the identity behind the given dynamic IP address.
• the GGSN 303 can map the dynamic IP address to a MS-ISDN number, which is used by the external server to locate Mobile Terminal 100 via normal positioning methods. Alternatively, an IP port number can be reserved for allocation request use in Mobile Terminal 100.
• the external application can then use the dynamic IP address and known (standardized) port number to deliver a positioning request to Mobile Terminal I 00. Mobile Terminal I 00 then requests its own position via normal positioning procedures, and delivers the result to the external terminal.
• GMLC Gateway Mobile Location Center
• LCS Location Service
• PSAP 305 Location Service
• GMLC 106 receives and handles service requests for location information for an indicated mobile terminal 100 from external LCS clients, activates the location systems, if needed, and returns the result to the LCS client.
• GMLC 106 may request routing information from HLR 107 or SGSN 104. After performing registration authorization, it sends a positioning request to and receives final location estimates from 3G-MSC 105 and SGSN 104.
• Home Location Register 107 contains location services subscription data and routing information concerning subscriber calls. HLR 107 is accessible from GMLC 106 via a Mobile Application Part (MAP) interface.
• PSAP 305 is preferably a conventional PSAP and may be connected to GMLC 106 via the PSTN.
• the external LCS client(s) 108 may be any sort of service application offered by a service provider or content provider. LCS Client(s) 108 is closely related to the variety of available services. Sometime Mobile Terminal 100 or a service application in Mobile Terminal 100 is the client. In addition to changes in the main interfaces (i.e., Uu, lub, Iur and lu) of the network, there are also some interfaces defined to support location services.
• the Le interface provides the reference point for transforming information transferred between GMLC 106 and PSAP 305 and other external LCS clients 108. This information includes the positioning request and the final result of the positioning process.
• the Lh interface passes routing information from HLR 107 to GMLC 106 and supports any mobility management related database in HLR 107. It can also be used by GMLC 106 to request the address of a visited MSC or SGSN for a particular Mobile Terminal 100 whose location has been requested. It is preferably a type of MAP interface and may be implemented over a SS7 signaling network or possibly over IP protocol (MAP over IP).
• the Lg interface allows 3G-MSC 105 to access GMLC 106 (Home PLMN or Visited PLMN). The interface transforms subscriber information needed, for example, for authorization and positioning access routing.
• GMLC 106 can be used by GMLC 106 to convey a location request to the MSC or SGSN currently serving a particular Mobile Terminal 100 whose location was requested or by an MSC or SGSN to return location results to GMLC 106.
• It is preferably a type of MAP interface and may be implemented over a SS7 signaling network or possibly over IP protocol (MAP over IP).
• MAP over IP IP protocol
• the Lg' interface allows SGSN 104 to access GMLC 106 (Home PLMN or Visited PLMN). It may be identical to the Lg interface, but is labeled differently in Fig.1 to show that it may also be different.
• the interface transforms subscriber information needed, for example, for authorization and positioning access routing.
• MAP interface It is preferably a type of MAP interface and may be implemented over a SS7 signaling network or possibly over IP protocol (MAP over IP).
• MAP over IP IP protocol
• the MAP interfaces are as similar as possible to the MAP interfaces defined for location services in the GSM network. Because there is no Serving MLC (SMLC) in UMTS, the MAP interface between SMLC and VMSC is not needed. The locations services for GSM do not yet include GPRS, so the GPRS part of the UMTS network is added to the MAP signaling. It is feasible to use the same MAP interface between GMLC 106 and 3G-SGSN 105, and between GMLC 106 and 3G-MSC 104.
• SMLC Serving MLC
• Fig. 2 is an additional block diagram showing connections to other networks and, in particular, the Gateway GPRS Support Node (GGSN) 108 and Call State Control Function (CSCF) 109.
• GGSN Gateway GPRS Support Node
• CSCF Call State Control Function
• Fig. 3 is a simplified block diagrams showing the connections between network element functionalities and, in particular, the Gateway GPRS Support Node (GGSN) 303 and Call State Control Function (CSCF) 304. There is also shown in Fig. 3, the Public Safety Answering Point (PSAP) 305 to which emergency calls are connected through CSCF 304 according to the example method embodiments described below.
• GGSN Gateway GPRS Support Node
• CSCF Call State Control Function
• GGSN 303 and CSCF 304 are instrumental in implementing the example mechanisms illustrated in Figs. 4-11 for reliably transferring emergency calls to an appropriate PSAP without abuse or fraud.
• GGSN 303 and CSCF 304 are elements located in a network in which a subscriber is visiting. They utilize a signaling PDP context supported in 3rd generation MIPT networks.
• a signaling PDP context supported in 3rd generation MIPT networks Although not shown in Figs. 1-3 for the sake of clarity, it should be understood that there may be a plurality of different CSCFs and connected PSAPS.
• each CSCF 304 maintains a database of the connected PSAPs (or equivalent capability) which includes a correspondence between the PSAPs for each Service Area Identification (SAI) code it may receive for an emergency call such as in one of the example method embodiments described below.
• SAI Service Area Identification
• a CSCF receives an SAI code in an emergency call setup request, it connects the emergency call to a PSAP based, at least in part, on the correspondence between the SAI code and the PSAPs stored in the database.
• the selection of an appropriate PSAP by CSCF may ultimately be effected by other factors in addition to the SAI code. For example, load balancing or other procedures may effect the selection of a PSAP in order to attempt to ensure that the emergency call can be promptly answered at the PSAP to which it is connected.
• PDP packet data protocol
• GPRS General Packet Radio Service
• MT Mobile Terminal
• TFT traffic flow template
• Each PDP context can be selectively and independently activated, modified and deactivated.
• the activation state of a PDP context indicates whether or not data transfer is enabled for a corresponding PDP address and TFT. If all PDP contexts associated with the same PDP address are inactive or deactivated, then all data transfer for that PDP address is disabled. All PDP contexts of a subscriber are associated with the same Mobility Management (MM) context for the International Mobile Subscriber Identity (IMSI) of that subscriber.
• MM Mobility Management
• IMSI International Mobile Subscriber Identity
• the invention is not dependent on any particular positioning method and can be used generically with any standardized or proprietary positioning method.
• the positioning methods and network location services capabilities used in the example embodiments of the invention for supporting and routing an emergency call to a PSAP are the same positioning methods and network location services capabilities used for other location services clients.
• a number of different method embodiments, differing primarily in their positioning process, are described below with reference to the architecture of the network shown in Figs. 1 and 3. These method embodiments are merely non-limiting illustrative examples and the network is merely a non-limiting illustrative example of a network in which the method embodiments may be practiced. Of course, there may be other method embodiments and other networks in which the methods may be carried out.
• Fig. 4 shows the application of the PDP context activation procedure of the UMTS network in a example embodiment of the invention where a subscriber has a Subscriber Identification Module (SIM).
• Mobile Terminal 100 initiates a PDP context activation.
• the Activate PDP Context Request sent to SGSN 105 in step 1 includes a number of parameters. These parameters include a PDP address and an Access Point Name (APN).
• the PDP address is used to indicate whether a static PDP or dynamic PDP address is required.
• the APN is conventionally a logical name referring to the GGSN to be used.
• the GGSN is a gateway to connected external networks. In this example embodiments of the invention, the APN is instead used to indicate that the service required is an emergency call.
• SGSN 105 selects a suitable GGSN 303 according to the APN and sends a Create PDP Context Request message to the selected GGSN 303.
• GGSN 303 decides whether to accept or reject the request. If it accepts the request, GGSN 303 sets a traffic flow template (TFT) to allow only emergency call related traffic to be transferred on the PDP context. For example, a separate IP address or port number may be used for normal calls and for emergency calls, and GGSN 303 can set the TFT according to the information on the IP address or the port number.
• TFT traffic flow template
• GGSN 303 modifies its PDP context table and returns a Create PDP Context Response message to SGSN 105 in step 3. It includes the address of a suitable CSCF 304 in the Create PDP Context Response. Preferably, the address of CSCF 304 is sent in the Protocol Configuration Options parameter, but it can also be sent in another parameter or as a new parameter.
• SGSN 105 copies it to an Activate PDP Context Accept message relayed to MT 100 in step 4.
• MT 100 must contact the CSCF 304 specified in step 4.
• MT 100 may send location information to CSCF 304 in step 5. If for some reason the address of CSCF 304 is not sent to MT 100, then the GGSN 303 may need to change the destination IP address in the call setup message in order to use a local CSCF for the emergency call. This is shown as step 5 in Fig. 4.
• a secondary PDP context with correspondingly different Quality of Service (QoS) may be needed. If needed, MT 100 initiates a secondary PDP context activation.
• QoS Quality of Service
• the call setup request sent in step 5 of Fig. 4 includes the Service Area Identification (SAI) of MT 100.
• SAI Service Area Identification
• the Service Area Identification is used to uniquely identify an area consisting of one or more cells belonging to the same location area and to indicate the location of MT 100.
• CSCF 304 uses the SAI code, at least in part, to select an appropriate PSAP to which to connect the emergency call.
• GPRS General Packet Radio Service
• Fig. 5 The example embodiment in Fig. 5 is substantially the same as that set forth above with respect to Fig. 4 except that it is carried out for a subscriber without a Subscriber Identification Module (SIM).
• SIM Subscriber Identification Module
• the UE sends an Activate Anonymous Access (AA) PDP Context Request.
• AA Activate Anonymous Access
• FIG. 6 Another example embodiment, in which a location calculation is triggered by the emergency call, is illustrated in Fig. 6.
• the embodiment in Fig. 6 takes advantage of the PDP Context available in UMTS networks.
• it may use the APN parameter of the Activate PDP Context Request to indicate that the call is to be serviced as an emergency call as indicated at step 2.
• MT 100 sends an SM Service Request message before sending the Activate PDP Context Request as indicated at step 1.
• the SM Service Request message is sent to establish a secure signaling connection.
• a key feature of the example embodiment in Fig. 6 is that SGSN 303 sends a Location Reporting Control message to the RNC 102 in response to the emergency call.
• the SGSN 303 can initiate the location reporting procedure at step 3 immediately upon receiving the SM Service Request message where the parameter Service Type indicates an emergency call, or a request to activate a PDP context (the Activate PDP Context Request, the Activate Secondary PDP Context Request, or the Activate AA PDP Context Request) where the parameter APN indicates an emergency call.
• This feature has the advantage that location services are quickly performed for emergency calls, but are not unnecessarily performed for other types of calls.
• the RNC 102 is responsible for calculating the location information for MT 100 at step 4.
• the location of MT 100 is reported to the SGSN 303 in step 5 and relayed to GMLC 106 at step 6.
• An acknowledgement of the location report is sent back to SGSN 105 at step 7 and then the location information is transferred to a PSAP selected by CSCF 304 either on request or independently at step 8.
• Fig. 7 illustrates an example method embodiment similar to that of Fig. 6 except that the Mobile Terminal 100 (referred to as "UE" in Figs. 7-11) does not send a SM Service Request before sending the Activate PDP Context Request in step 1.
• SGSN 303 sends a location reporting control message (step 2), as soon as it receives the PDP context activation procedure (step 1), to request the Service Area ID from the Radio Access Network (UTRAN in the example network of Figs. 1 and 2) and to start the positioning procedure (step 4'). This may, but need not, be done by sending two separate location reporting control messages to request the Service Area ID and to start positioning according to the current RANAP specification (3G TS 25.413).
• PSDI PS Domain Identifier
• identifier may be, for example, a MS IP Address, PTMSI or MSISDN.
• SGSN 303 also assigns a PS Domain Identifier to the emergency call that is used to identify (e.g. route to) both the emergency services provider and the switch in the VPLNTN currently serving the emergency caller, and possibly the emergency caller, for the duration of the call.
• the RAN 103 While carrying out positioning, the RAN 103 returns the Service Area ID to SGSN 303 (step 3).
• SGSN 105 sends a Create PDP Context Request to GGSN 203 as described above with respect to Fig. 3 (step 4).
• GGSN 303 accepts the request, modifies its PDP context table and returns a Create PDP Context Response message (including the address of suitable CSCF) to SGSN 105 (step 5).
• SGSN copies the CSCF address within an Activate PDP Context Accept message relayed to MT 100 along with the Service Area ID and the PSDI telephone number assigned to the emergency call (step 6).
• RAN 103 When positioning is completed, RAN 103 returns a location estimate within a Location Report message to SGSN 105 (step 6'). SGSN 105 forwards a Subscriber Location Report (which includes the location estimate, an identifier (IMSI or IP address) and the PSDI) to GMLC 106 (step 7'). Preferably, the location estimate is associated with a time stamp which, together, mark the "initial location" of MT 100. After the PDP context has been activated, MT 100 sends a Invite message (containing the Service Area ID, the identifier and the PSSDI) to CSCF 304 (step 7).
• a Subscriber Location Report which includes the location estimate, an identifier (IMSI or IP address) and the PSDI
• GMLC 106 Preferably, the location estimate is associated with a time stamp which, together, mark the "initial location" of MT 100.
• MT 100 After the PDP context has been activated, MT 100 sends a Invite message (containing
• CSCF 304 selects a suitable PSAP (preferably using a database of PSAPs and their correspondence to Service Area IDs) and sends a setup message (containing the PSDI) to PSAP 305 (Figs. 7-11 refer to the PSAP as an EC (emergency center) rather than PSAP) (steps 8 & 9).
• the selected PSAP sends a LCS Service Request to obtain the initial location to GMLC 106 and GMLC 106 sends a LCS Service Response containing the initial location (steps 10 & 11).
• the emergency call is identified in the request and the response by its PSDI.
• the selected PSAP may request and receive updates on the current location of mobile terminal 100 using normal Mobile Terminated Location Requests (MT-LR) defined in 3G TS 23.171 v3.0.0 (Release 1999).
• Fig. 8 illustrates a method similar to that in Fig. 7 except that the positioning procedure is finalized, and a location estimate is obtained, before PDP Context Activation acceptance.
• Steps 1-4 are the same as the method in Fig. 7. However,- the SGSN 105 receives the Location Report (step 5'), containing the location estimate, from RAN 103 before GGSN 303 returns a Create PDP Context Response message to SGSN 105 (step 6).
• SGSN 105 includes the location estimate within the Activate PDP Context Accept message relayed to MT 100 along with the Service Area ID, PSDI and CSCF address (step 7).
• MT 100 includes the location estimate (along with the Service Area ID, identifier, and PSDI) in the Invite message sent to CSCF 304 (step 8).
• CSCF 304 includes the location estimate in the setup message sent to PSAP 305 (instead of the PSDI). This eliminates the need for the two steps for PSAP 305 to request and receive the initial location from GMLC 106 (steps 10 & 11 in Fig. 7) when the emergency call is connected.
• the selected PSAP may continue to request and receive updates on the current location of MT 100 in the same manner as in the example embodiment of Fig. 7 (steps 11-13).
• Fig. 9 illustrates a method embodiment similar to that of Figs. 7 and 8, except that RAN 103 provides the location estimate to MT 100 instead of making a Location Report to SGSN 105.
• Steps 1-6 in the embodiment of Fig. 9 are the same as steps 1-6 in the embodiment of Fig. 7.
• MT 100 must receive the location estimate from 103 in some manner, perhaps, but not necessarily, by using Radio Resource Control (RRC) messages.
• RRC Radio Resource Control
• the manner in which the location estimate is reported by RAN 103 may be predetermined or it may be controlled, for example in the Location Reporting Control message sent by SGSN 105 to RAN 103 in step 2.
• the positioning procedure should be finished before the Activate PDP Context Accept message is received by MT 100 in step 6. If it is not, then MT 100 delays the Invite message until the location estimate is received from RAN 103. Once the location estimate is received, MT 100 sends an Invite message (containing Service Area ID, the location estimate and the identifier) to CSCF 304 (steps 7). The remainder of the steps in the example embodiment of Fig. 9 (steps 8-12) are the same as steps 9-13 in Fig. 17.
• Fig. 10 illustrates an example embodiment similar to that of Fig. 7 except that SGSN 105 already knows the current Service Area ID when it receives the Activate PDP Context Request in step 1.
• SGSN 105 need not request the Service Area ID from RAN 103 and RAN 103 need not return the Service Area ID as in steps 2 and 3 of Fig. 4.
• the remainder of the steps in the embodiment of Fig. 10 are the same as the remainder of the steps in Fig. 7.
• the example embodiment illustrated in Fig. 11 differs significantly from the other example embodiments insofar as MT 100 itself originates the positioning method (step 2') as soon as the Activate PDP Context Request is sent to SGSN 105 (step 1). It can either perform its own MT based positioning calculation or request that a positioning method be performed using Mobile Originated Location Requests (MO-LR) procedures.
• the example embodiment in Fig. 10 thus avoids the need for the Location Reporting Control message from SGSN 105 or the Location Report from RAN 103. It also simplifies the Activate PDP Context Accept message sent from SGSN 105 since it only needs to include the address of the CSCF (step 4).
• the Invite message sent from MT 100 to CSCF 304 need only contain the location estimate and the Service Area ID (step 6).
• the service areas have to be coordinated between MT 100 and SGSN 105 in order to ensure that the Service Area ID provided by MT 100 is consistent with the Service Area ID expected by SGSN 105 and CSCF 304.
• the remainder of the steps in the example embodiment of Fig. 11 are the same as steps 9-13 in Fig. 9.
• Figs. 7-11 show a variety of methods, each with their own advantages and disadvantages.
• the emergency call can be connected without regards to delays in the positioning procedure because the initial location is delivered by GMLC 106 upon request from PSAP 305 after the emergency call is connected.
• the MT 100 must have a Subscriber Identification Module (SIM) in order to interface with CSCF 304.
• SIM Subscriber Identification Module
• the SAI could be made available directly to the mobile terminal by the RAN instead of, or in addition to, the SGSN within a PDP context acceptance message.
• RNC 102 could make SAI directly available by broadcast and/or point to point RRC messages. It is intended by the following claims to claim all such modifications and variations.

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