ATIS 0500026-2014 Operational Impacts on Public Safety of ATIS-0700015 Implementation of 3GPP Common IMS Emergency Procedures for IMS Origination and ESInet Legacy Selective Router.pdf

1、 ATIS-0500026 ATIS Standard on - OPERATIONAL IMPACTS ON PUBLIC SAFETY OF ATIS-0700015, IMPLEMENTATION OF 3GPP COMMON IMS EMERGENCY PROCEDURES FOR IMS ORIGINATION AND ESINET/LEGACY SELECTIVE ROUTER TERMINATION As a leading technology and solutions development organization, ATIS brings together the to

2、p global ICT companies to advance the industrys most-pressing business priorities. Through ATIS committees and forums, nearly 200 companies address cloud services, device solutions, emergency services, M2M communications, cyber security, ehealth, network evolution, quality of service, billing suppor

3、t, operations, and more. These priorities follow a fast-track development lifecycle from design and innovation through solutions that include standards, specifications, requirements, business use cases, software toolkits, and interoperability testing. ATIS is accredited by the American National Stan

4、dards Institute (ANSI). ATIS is the North American Organizational Partner for the 3rd Generation Partnership Project (3GPP), a founding Partner of oneM2M, a member and major U.S. contributor to the International Telecommunication Union (ITU) Radio and Telecommunications sectors, and a member of the

5、Inter-American Telecommunication Commission (CITEL). For more information, visit . Notice of Disclaimer for example for mobile calls, the Common IMS Network may query location determination equipment via the LS. Once the Common IMS Network has obtained location, it must select the appropriate emerge

6、ncy services network to deliver the call. The LRF may use internal processes to access an integrated Routing Determination Function (RDF) to do this, or it may interrogate an external RDF. Using the routing information provided by the RDF, emergency calls may be delivered to either a NENA i3 ESInet

7、or a legacy emergency services network. 5 ESRPSelectiveRouterECRFALIi3 PSAPBCFAccessNetworkLegacy PSAPLeLeCSCommon IMS Network Emergency Services NetworkMGCFiciLRFIBCFPCSCFLS RDFSignalingQuery/ResponseECSCFFigure 6. 1 - Conceptual Architecture 6.1 Location Retrieval Function (LRF) Based upon a reque

8、st from the Emergency-Call Session Control Function (E-CSCF), the LRF retrieves location information for UEs from the LS (if necessary) and based on the location retrieved, obtains routing information for an emergency session from the RDF. The RDF provides routing information for an emergency sessio

9、n. The LRF returns this routing information to the E-CSCF which may route the call toward a PSAP behind a NENA i3 ESInet or legacy emergency services network. Once the call is delivered to the appropriate network, the LRF may be queried (via the Le interface in Figure 6.1) for initial location (and

10、updated location if the subscriber is mobile). 6.2 Location Server (LS) For certain types of emergency calls, the Common IMS Network will have to acquire the location of the UE. The type of call defines how the LS determines location. For example, if the call is from a mobile user, the LS may obtain

11、 location via location determination equipment. If the call is from a user with a fixed device, the LS may contain the provisioned location of the UE. 6.3 Routing Determination Function (RDF) Once the LRF has obtained the UE location (if necessary), it uses that location to query the RDF to get rout

12、ing instructions. Those routing instructions determine the destination and type of emergency services network that will receive the emergency call. The RDF returns those routing instructions to the LRF, which in turn returns them to the E-CSCF. 6.4 Media Gateway Control Function (MGCF)/Media Gateway

13、 (MGW) The MGCF/MGW converts the native signaling and media within the Common IMS network to that expected by the legacy emergency services network. 6 6.5 Proxy Call Session Control Function (P-CSCF) The P-CSCF is a routing proxy within the Common IMS network that routes the call from the access net

14、work toward the E-CSCF. The P-CSCF receives the emergency request from the UE, detects that it is an emergency call, and typically forwards it to the E-CSCF. 6.6 Emergency Call Session Control Function (E-CSCF) The E-CSCF is a routing proxy within the Common IMS network that routes the call from the

15、 P-CSCF toward the emergency services network. The E-CSCF receives routing instructions from the LRF which allows it to determine the appropriate emergency service network and route the call to either the MGCF for calls destined to the legacy emergency services network or the Interconnecting Border

16、Control Function (IBCF) for calls destined to a NENA i3 ESInet. 6.7 Interconnecting Border Control Function (IBCF) The IBCF within the Common IMS network delivers security and control for calls destined to the NENA i3 ESInet. 6.8 Legacy Emergency Services Network Figure 6.1 shows calls being deliver

17、ed to legacy E9-1-1 emergency services networks from the MGCF to the SR. The call is then routed to a legacy PSAP. The PSAP will query the regional Automatic Location Identification (ALI) which may subsequently query the LRF to obtain location and (potentially) a callback number. 6.9 NENA i3 ESInet

18、Figure 6.1 shows calls being delivered to NENA i3 networks from the IBCF to the Border Control Function (BCF) in the ESInet. The NENA i3 elements are defined within NENA 08-003. 7 Simplified Call Flows To understand the impacts of ATIS-0700015 on Public Safety, it is useful to discuss calls that Pub

19、lic Safety entities may receive. Four call flows are illustrated in this document. The first (Figure 7.1) depicts calls being delivered to a legacy emergency services network and that network having to query the Common IMS Network for location. The second (Figure 7.2) call flow shows calls being del

20、ivered to a legacy emergency services network and the PSAP querying the regional ALI (which contains the subscribers location). This flow assumes that the subscriber location is provisioned in the regional ALI and not within the Common IMS Network. The third (Figure 7.3) call flow shows calls being

21、delivered to a NENA i3 ESInet with the location of the subscriber in the call request (LbyV). The fourth (Figure 7.4) call flow shows calls being delivered to a NENA i3 ESInet with the location of the subscriber referenced by a Reference Identifier (RI). The Emergency Services Routing Proxy (ESRP) m

22、ust dereference this location for routing and the PSAP must dereference this location for dispatch. 7.1 Calls to Legacy Emergency Services Networks with Location Cached in the LRF Figure 7.1 illustrates a call to a Legacy emergency service network where the LRF caches the location and the PSAP must

23、query for it via the regional ALI system (which queries the LRF). This example is similar to existing 7 VoIP emergency calls where the location is contained within the VoIP Position Center (VPC) or a wireless call where the location is provided by a Mobile Positioning Center/Gateway Mobile Location

24、Center (MPC/GMLC). 1. The call is originated and enters the Common IMS Network. 2. The P-CSCF recognizes the call as an emergency call and forwards it to the E-CSCF. 3. The E-CSCF routes the call to the LRF to obtain location and to get routing information. 4. The LRF returns routing instructions to

25、 the E-CSCF and the E-CSCF forwards the call to the MGCF. 5. The MGCF routes the call to the PSAP via the SR. 6. The PSAP queries the ALI system for location and callback number. 7. The ALI system forwards the request to the LRF. The LRF returns the location and callback number to the ALI system, wh

26、ich forwards it to the PSAP. Figure 7. 1 - Calls to Legacy SR with Location Cached in the LRF 7.2 Calls to Legacy Emergency Services Networks with Location Provisioned in the Regional ALI System Figure 7.2 illustrates a call to a legacy emergency service network where the location is provisioned in

27、the regional ALI system and the PSAP must query the regional ALI system for it. This call is similar to an existing wireline call where the location is provisioned in the ALI. This call flow assumes that the ALI record has been provisioned in the regional ALI system using normal methods. 1. The call

28、 is originated and enters the Common IMS Network. 2. The P-CSCF recognizes the call as an emergency call and forwards it to the E-CSCF. 3. The E-CSCF routes the call to the LRF to obtain routing information. 4. The LRF returns routing instructions to the E-CSCF and the E-CSCF forwards the call to th

29、e MGCF. 5. The MGCF routes the call to the PSAP via the SR. 6. The PSAP queries the regional ALI system for location, and the regional ALI system returns the location to the PSAP. 8 Figure 7. 2 - Calls to Legacy SR with Location Provisioned in the Regional ALI System 7.3 Calls to a NENA i3 ESInet wi

30、th Subscriber Location Figure 7.3 shows a call to a NENA i3 ESInet where the subscribers location (i.e., LbyV) and callback number are delivered with the call request. 1. The call is originated and enters the Common IMS Network. 2. The P-CSCF recognizes the call as an emergency call and forwards it

31、to the E-CSCF. 3. The E-CSCF routes the call to the LRF to obtain location (if needed) and to get routing information. 4. The LRF returns routing instructions to the E-CSCF and the call is routed to the IBCF. 5. The IBCF routes the call to the ESRP in the ESInet via the BCF. 6. The subscribers locat

32、ion and callback number are passed in the call request. The NENA i3 ESInet uses normal routing techniques to deliver the call, with the subscribers location and callback number, to the PSAP. The ESRP interrogates the ECRF for routing instructions. 7. The ECRF returns the PSAP URI to the ESRP and the

33、 ESRP routes the call to the PSAP. Figure 7. 3 -Calls to a NENA i3 ESInet with Location by Value 9 7.4 Calls to a NENA i3 ESInet with Location Reference Identifier Figure 7.4 illustrates a call being delivered to a NENA i3 ESInet with a Location reference identifier (i.e., location-by-reference). Th

34、e ESInet will have to query the Common IMS Network for a routing location and the PSAP will have to query the Common IMS Network for a dispatch location. 1. The call is originated and enters the Common IMS Network. 2. The P-CSCF recognizes the call as an emergency call and forwards it to the E-CSCF.

35、 3. The E-CSCF routes the call to the LRF to obtain location (if needed) and to get routing information. 4. Since there is a chance to obtain a location update, the LRF creates a Reference Identifier (i.e. a location reference) and returns it to the E-CSCF. The call is routed to the IBCF. 5. The IBC

36、F routes the call to the ESRP in the ESInet via the BCF, passing the RI. 6. The ESRP in the NENA i3 ESInet “dereferences” the routing location by querying the LRF. 7. The ESRP uses that location to obtain routing instructions from the ECRF. 8. The ESRP then routes the call to the PSAP passing the RI

37、. 9. The PSAP “dereferences” the location using the RI to obtain initial location and may request location updates in the same manner. Figure 7. 4 - Calls to a NENA i3 ESInet with Location Reference Identifier 8 Operational Impacts to 9-1-1 Authorities and PSAPs ATIS-0700015 does not introduce any a

38、dditional network interfaces to the PSAP over what is specified in existing standards. Legacy PSAPs continue to receive calls via the SR and query for location and callback numbers via the regional ALI. NENA i3 PSAPs continue to receive calls via the ESRP. If the LbyR method is used, the PSAP may ha

39、ve to query (“dereference”) the LRF for location. This is the same interface for dereferencing location as defined in the NENA i3 08-003 specification. 8.1 Considerations for Legacy PSAPs ATIS-0700015 uses the same methodologies to deliver emergency calls from IMS-based originating networks that exi

40、st for emergency calls from legacy wireless and (i2/pre-i2) VoIP networks. Therefore, the PSAP or 9-1-1 Authority may have to work with the provider of the originating Common IMS Network so they can allocate and provision the RIs (used in this case as functionally equivalent to Emergency Services Ro

41、uting Keys (ESRKs), Emergency Services Routing Digits (ESRDs), and Emergency Services Query Keys (ESQKs) that may be provided by the originating IMS network in their SR databases/ALI systems. 8.2 Considerations for NENA i3 PSAPs ATIS-0700015 uses the same methodologies to deliver emergency calls fro

42、m an IMS-based originating network that have been defined for delivering calls from i3-compliant IP-based originating networks to NENA i3 PSAPs. If 10 a call is delivered to the NENA i3 ESInet with the caller location (LbyV) in the call request, the NENA i3 ESInet will use normal call routing and de

43、liver the call (with location and callback number) to the PSAP. The PSAP will then display the location but will not have the opportunity to request a location update since it is assumed the location is fixed. If there is an opportunity for the originating Common IMS Network to obtain updated locati

44、on for the caller, the originating IMS Common Network will create a RI (used in this case to represent LbyR). This RI will be passed to the i3 PSAP call handling equipment, which will query for an initial location. If necessary, the call taker will query for an updated location, or in some cases, th

45、e i3 call handling equipment may do it automatically for the initial rebid.68.3 Routing Wireless Calls Based upon Associated Location Section 8.2.1 in ATIS-0700015 describes the use of an Associated Location for routing wireless calls as follows (modified editorially for clarity here): ”An Associate

46、d Location is used in some wireless routing scenarios where the cell address or cell centroid cannot be used to route a call to the ESInet. The Associated Location (shown as the Routing Location in Figure 6 of ATIS-0700015) is selected by the LRF, will be used by the RDF and is returned by the LRF t

47、o an E-CSCF based upon its request for routing location (an LbyR scenario) and may be subsequently re-used by the ESInet to route the call to the appropriate PSAP. The Associated Location is used for routing only and is not presented to the PSAP.” How the Associated Location is established is beyond

48、 the scope of this standard. Additionally, Step 6 of Figure 8-3 states: “The LRF maps the cell ID received in the SIP INVITE message t o a routing location that is the Associated Location designated for the appropriate PSAP for that cell” The IMS-based originating network provider and the 9-1-1 Auth

49、ority must have a process such that the Associated Location can be agreed upon and related to specific cell site/sectors. The mappings between cell site/sectors and Associated Locations must then be provisioned in the LRF. The process between the IMS-based originating network provider and the 9-1-1 Authority must have the following steps: 1. The IMS-based originating network provider identifies the cell site/sector coverage for the region. 2. The 9-1-1 Authority provides PSAP boundaries for routing of wireless calls to the IMS-based originating network provider. 3. The IMS-based