| ECRIT | R. Gellens |
| Internet-Draft | Core Technology Consulting |
| Intended status: Standards Track | B. Rosen |
| Expires: July 23, 2017 | NeuStar, Inc. |
| H. Tschofenig | |
| Individual | |
| January 19, 2017 |
Next-Generation Vehicle-Initiated Emergency Calls
draft-ietf-ecrit-car-crash-22.txt
This document describes how to use IP-based emergency services mechanisms to support the next generation of emergency calls placed by vehicles (automatically in the event of a crash or serious incident, or manually invoked by a vehicle occupant) and conveying vehicle, sensor, and location data related to the crash or incident. Such calls are often referred to as "Automatic Crash Notification" (ACN), or "Advanced Automatic Crash Notification" (AACN), even in the case of manual trigger. The "Advanced" qualifier refers to the ability to carry a richer set of data.
This document also registers a MIME media type and Emergency Call Additional Data Block for the vehicle, sensor, and location data (often referred to as "crash data" even though there is not necessarily a crash) and a SIP INFO package to enable carrying this and related data in SIP INFO requests. An external specification for the data format, contents, and structure are referenced in this document.
This document reuses the technical aspects of next-generation pan-European eCall (a mandated and standardized system for emergency calls by in-vehicle systems within Europe and other regions). However, this document specifies use of a different set of vehicle (crash) data, specifically, the Vehicle Emergency Data Set (VEDS) rather than the eCall Minimum Set of Data (MSD). This document is an extension of the IETF eCall document, with the primary differences being that this document makes the MSD data set optional and VEDS mandatory, and adds attribute values to the metadata/control object to permit greater functionality. This document registers a new SIP INFO package (identical to that registered for eCall but with the addition of the VEDS MIME type). This document also describes legacy (circuit-switched) ACN systems and their migration to next-generation emergency calling, to provide background information and context.
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Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
This document re-uses terminology defined in Section 3 of [RFC5012].
Additionally, we use the following abbreviations:
| Term | Expansion |
|---|---|
| 3GPP | 3rd Generation Partnership Project |
| AACN | Advanced Automatic Crash Notification |
| ACN | Automatic Crash Notification |
| APCO | Association of Public-Safety Communications Officials |
| EENA | European Emergency Number Association |
| ESInet | Emergency Services IP network |
| GNSS | Global Navigation Satellite System (which includes various systems such as the Global Positioning System or GPS) |
| IVS | In-Vehicle System |
| MNO | Mobile Network Operator |
| MSD | eCall Minimum Set of Data |
| NENA | National Emergency Number Association |
| NG | Next-Generation |
| POTS | Plain Old Telephone Service (normal, circuit-switched voice calls) |
| PSAP | Public Safety Answering Point |
| TSP | Telematics Service Provider |
| VEDS | Vehicle Emergency Data Set |
Because the endpoints of a Next-Generation ACN call are a PSAP and an IVS or TSP, to avoid receptively writing "IVS or TSP", the term "IVS" is used to represent either an IVS or TSP when discussing signaling behavior (e.g., sending VEDS data, sending a SIP INVITE request, receiving a SIP INFO request, etc.).
Emergency calls made by in-vehicle systems (e.g., automatically in the event of a crash or serious incident or manually by a vehicle occupant) assist in significantly reducing road deaths and injuries by allowing emergency services to respond quickly and appropriately to the specifics of the incident, often with better location accuracy.
Drivers often have a poor location awareness, especially outside of major cities, at night and when away from home (especially abroad). In the most crucial cases, the victim(s) might not be able to call because they have been injured or trapped.
For more than two decades, some vehicles have been equipped with telematics systems which, among other features, place an emergency call automatically in the event of a crash or manually in response to an emergency call button. Such systems generally have on-board location determination systems that make use of satellite-based positioning technology, inertial sensors, gyroscopes, etc., which can provide an accurate position for the vehicle. Such built-in systems can take advantage of the benefits of being integrated into a vehicle, such as more power capacity, ability to have larger or specialized antenna, ability to be engineered to avoid or minimise degradation by vehicle glass coatings, interference from other vehicle systems, etc. Thus, the PSAP can be provided with a good estimate of where the vehicle is during an emergency. Vehicle manufacturers are increasingly adopting such systems, both for the safety benefits and for the additional features and services they enable (e.g., remote engine diagnostics, remote door unlock, stolen vehicle tracking and disabling, etc.).
The general term for such systems is Automatic Crash Notification (ACN) or "Advanced Automatic Crash Notification" (AACN). "ACN" is used in this document as a general term. ACN systems transmit some amount of data specific to the incident, referred to generally as "crash data" (the term is commonly used even though there might not have been a crash). While different systems transmit different amounts of crash data, standardized formats, structures, and mechanisms are needed to provide interoperability among systems and PSAPs.
As of the date of this document, currently deployed in-vehicle telematics systems are circuit-switched and lack a standards-based ability to convey crash data directly to the PSAP (generally relying on either a human advisor or an automated text-to-speech system to provide the PSAP call taker with some crash data orally, or in some cases via a proprietary mechanism). In most cases, the PSAP call taker needs to first realize that the call is related to a vehicle incident, and then listen to the data and transcribe it. Circuit-switched ACN systems are referred to here as CS-ACN.
The transition to next-generation calling in general, and for emergency calling in particular, provides an opportunity to vastly improve the scope, breadth, reliability and usefulness of crash data during an emergency by allowing a standardized set to be transmitted during call set-up; to be automatically processed by the PSAP and made available to the call taker in an integrated, automated way; as well as provide the ability for a PSAP call taker to request that a vehicle take certain actions, such as flashing lights or unlocking doors. In addition, vehicle manufacturers are provided an opportunity to take advantage of the same standardized mechanisms for data transmission and request processing for internal use if they wish (such as telemetry between the vehicle and a service center for both emergency and non-emergency uses, including location-based services, multi-media entertainment systems, remote door unlocking, remote diagnostics, and road-side assistance applications).
Next-generation ACN provides an opportunity for such calls to be recognized and processed as such during call set-up, and routed to an equipped PSAP where the vehicle data is available to assist the call taker in assessing and responding to the situation. Next-generation (IP-based) ACN systems are referred to here as NG-ACN.
An ACN call can be initiated by a vehicle occupant or automatically initiated by vehicle systems in the event of a serious incident. (The "A" in "ACN" does stand for "Automatic," but the term is broadly used to refer to the class of calls that are placed by an in-vehicle system (IVS) or Telematics Service Providers (TSP) and that carry incident-related data as well as voice.) Automatically triggered calls indicate a car crash or some other serious incident (e.g., a fire). Manually triggered calls include reports of observed crashes or serious hazards (such as impaired drivers or roadway debris).
The Association of Public-Safety Communications Officials (APCO) and the National Emergency Number Association (NENA) have jointly developed a standardized set of incident-related vehicle data for ACN use, called the Vehicle Emergency Data Set (VEDS) [VEDS]. Such data is often referred to as crash data although it is applicable in incidents other than crashes.
This document describes how the IETF mechanisms for IP-based emergency calls are used to provide the realization of next-generation ACN. Although this specification is designed with the requirements for North America ACN in mind (and both APCO and NENA are based in the U.S.), it is specified generically such that the technology can be re-used or extended to suit requirements in other regions.
This document reuses the technical aspects of next-generation pan-European eCall (a mandated and standardized system for emergency calls by in-vehicle systems within Europe), as described in [I-D.ietf-ecrit-ecall]. However, this document specifies use of a different set of vehicle (crash) data, specifically, the Vehicle Emergency Data Set (VEDS) rather than the eCall Minimum Set of Data (MSD). This document is an extension of [I-D.ietf-ecrit-ecall], with the differences being that this document makes the MSD data set optional and VEDS mandatory, and adds new attribute values to the metadata/control object defined in that document. This document also registers a new SIP INFO package (identical to that defined in [I-D.ietf-ecrit-ecall] with the addition of the VEDS MIME type).
This document registers the 'application/EmergencyCallData.VEDS+xml' MIME media type, registers the 'VEDS' entry in the Emergency Call Data Types registry, and registers a SIP INFO package to enable carrying this and related data in SIP INFO requests.
Section 6 introduces VEDS. Section 7 describes how VEDS data and metadata/control blocks are transported within NG-ACN calls. Section 8 describes how such calls are placed.
These mechanisms are used to place emergency calls that are identifiable as ACN calls and that carry standardized crash data in an interoperable way.
Calls by in-vehicle systems are placed using cellular networks, which might ignore location information sent by an originating device in an emergency call INVITE, instead substituting their own location information (often determined in cooperation with the originating device). Standardized crash data structures often include location as determined by the IVS. A benefit of this is that it allows the PSAP to see both the location as determined by the cellular network (often in cooperation with the originating device) and the location as determined by the IVS.
This specification inherits the ability to utilize test call functionality from Section 15 of [RFC6881].
This document is focused on how an ACN emergency call is setup and incident-related data (including vehicle, sensor, and location data) is transmitted to the PSAP using IETF specifications. For the direct model, this is the end-to-end description (between the vehicle and the PSAP). For the TSP model, this describes the call leg between the TSP and the PSAP, leaving the call leg between the vehicle and the TSP up to the entities involved (i.e., IVS and TSP vendors) who are then free to use the same mechanism as for the other leg or not.
Note that Europe has a mandated and standardized system for emergency calls by in-vehicle systems. This pan-European system is known as "eCall" and is the subject of a separate document, [I-D.ietf-ecrit-ecall], which this document builds on. Vehicles designed to operate in multiple regions might need to support eCall as well as NG-ACN as described here. A vehicle IVS might determine whether to use eCall or ACN by first determining the region or country in which it is located (e.g., from a GNSS location estimate and/or identity of or information from an MNO). If other regions adopt other data formats, a multi-region vehicle might need to support those as well. This document adopts the call set-up and other technical aspects of [I-D.ietf-ecrit-ecall], which uses [RFC7852]; this makes it straightforward to use a different data set while keeping other technical aspects unchanged. Hence, both NG-eCall and the NG-ACN mechanism described here are compatible, differing primarily in the specific data block that is sent (the eCall MSD in the case of NG-eCall, and the APCO/NENA VEDS used in this document), and some additions to the metadata/control data block. If other regions adopt their own vehicle data sets, this can be similarly accomodated without changing other technical aspects. Note that any additional data formats require a new SIP INFO package to permit transport within SIP INFO requests.
Legacy (circuit-switched) systems for placing emergency calls by in-vehicle systems generally have some ability to convey at least location and in some cases telematics data to the PSAP. Most such systems use one of three architectural models, which are described here as: "Telematics Service Provider" (TSP), "direct", and "paired". These three models are illustrated below.
In the TSP model, both emergency and non-emergency calls are placed to a Telematics Service Provider (TSP); a proprietary technique is used for data transfer (such as a proprietary in-band modem) between the TSP and the vehicle.
In an emergency, generally the TSP call taker bridges in the PSAP and communicates location, crash data (such as impact severity and trauma prediction), and other data (such as the vehicle description) to the PSAP call taker verbally (in some cases, a proprietary out-of-band interface is used). Since the TSP knows the location of the vehicle (from on-board GNSS and sensors), location-based routing is usually used to route to the appropriate PSAP. In some cases, the TSP is able to transmit location automatically, using similar techniques as for wireless calls. Typically, a three-way voice call is established between the vehicle, the TSP, and the PSAP, allowing communication between the PSAP call taker, the TSP call taker, and the vehicle occupants (who might be unconscious).
///----\\\ proprietary +------+ 911 trunk or POTS +------+ ||| IVS |||-------------->+ TSP +------------------->+ PSAP | \\\----/// crash data +------+ location via trunk +------+
Figure 1: Legacy TSP Model.
In the paired model, the IVS uses a local link (typically Bluetooth [Bluetooth]) with a previously-paired handset to establish an emergency call with the PSAP (by dialing a standard emergency number; 9-1-1 in North America), and then communicates location data to the PSAP via text-to-speech; crash data might or might not be conveyed also using text-to-speech. Some such systems use an automated voice prompt menu for the PSAP call taker (e.g., "this is an automatic emergency call from a vehicle; press 1 to open a voice path to the vehicle; press 2 to hear the location read out") to allow the call taker to request location data via text-to-speech.
+---+
///----\\\ | H | 911/etc voice call via handset +------+
||| IVS |||-->| S +----------------------------------->+ PSAP |
\\\----/// +---+ location via text-to-speech +------+
Figure 2: Legacy Paired Model
In the direct model, the IVS directly places an emergency call with the PSAP by dialing a standard emergency number (9-1-1 in North America). Such systems might communicate location data to the PSAP via text-to-speech; crash data might or might not be conveyed using text-to-speech. Some such systems use an automated voice prompt menu (e.g., "this is an automatic emergency call from a vehicle; press 1 to open a voice path to the vehicle; press 2 to hear the location read out") to allow the call taker to request location data via text-to-speech.
///----\\\ 911/etc voice call via IVS +------+ ||| IVS |||---------------------------------------->+ PSAP | \\\----/// location via text-to-speech +------+
Figure 3: Legacy Direct Model
Migration of emergency calls placed by in-vehicle systems to next-generation (all-IP) technology per this document provides a standardized mechanism to identify such calls and to convey crash data with the call setup, as well as enabling additional communications modalities and enhanced functionality. This allows ACN calls and crash data to be automatically processed by the PSAP and made available to the call taker in an integrated, automated way. Because the crash data is carried in the initial SIP INVITE (per [RFC7852]) the PSAP can present it to the call taker simultaneously with the appearance of the call. The PSAP can also process the data to take other actions (e.g., if multiple calls from the same location arrive when the PSAP is busy and a subset of them are NG-ACN calls, a PSAP might choose to store the information and reject the calls, since the IVS will receive confirmation that the information has been successfully received; a PSAP could also choose to include a message stating that it is aware of the incident and responders are on the way; a PSAP could call the vehicle back when a call taker is available).
The migration of origination devices and networks, PSAPs, emergency services networks, and other telephony environments to next-generation provides enhanced interoperability and functionality, especially for emergency calls carrying additional data such as vehicle crash data. (In the U.S., a network specifically for emergency responders is being developed. This network, FirstNet, will be next-generation from the start, enhancing the ability for data exchange between PSAPs and responders.)
NG-ACN calls can be recognized as originating from a vehicle, routed to a PSAP prepared both technically and operationally to handle such calls, and the vehicle-determined location and crash data made available to the call taker simultaneously with the call appearance. The PSAP can take advantage of enhanced functionality, including the ability to request the vehicle to take an action, such as sending an updated set of data, converying a message to the occupants, flashing lights, unlocking doors, etc.
Vehicle manufacturers using the TSP model can choose to take advantage of the same mechanism to carry telematics data and requests and responses between the vehicle and the TSP for both emergency and non-emergency calls as are used for the interface with the PSAP.
A next-generation IVS establishes a next-generation emergency call (see [RFC6443] and [RFC6881]), with an initial INVITE containing a Request-URI indicating an ACN type of emergency call and Call-Info header fields indicating that both vehicle crash and capabilities data are included; the IVS typically does not perform routing or location queries but relies on the carrier for this.
[I-D.ietf-ecrit-ecall] registers new service URN children within the "sos" subservice. These URNs request NG-ACN resources, and differentiate between manually and automatically triggered NG-ACN calls (which might be subject to different treatment depending on policy). The two service URNs registered in [I-D.ietf-ecrit-ecall] are "urn:service:sos.ecall.automatic" and "urn:service:sos.ecall.manual". The same service URNs are used for ACN as for eCall since in any region only one of these is supported, making a distinction unnecessary. (Further, PSAP equipment might support multiple data formats, allowing a PSAP to handle a vehicle that erroneously sent the wrong data object.)
Note that in North America, routing queries performed by clients outside of an ESInet typically treat all sub-services of "sos" identically to "sos" with no sub-service. However, the Request-URI header field retains the full sub-service; route and handling decisions within an ESInet or PSAP can take the sub-service into account. For example, in a region with multiple cooperating PSAPs, an NG-ACN call might be routed to a PSAP that is NG-ACN capable, or one that specializes in vehicle-related incidents.
Migration of the three architectural models to next-generation (all-IP) is described below.
In the TSP model, the IVS transmits crash and location data to the TSP either by re-using the mechanisms and data objects described in this document, or using a proprietary mechanism. In an emergency, the TSP bridges in the PSAP and the TSP transmits crash and other data to the PSAP using the mechanisms and data objects described in this document. There is a three-way call between the vehicle, the TSP, and the PSAP, allowing communication between the PSAP call taker, the TSP call taker, and the vehicle occupants (who might be unconscious). The TSP relays PSAP requests and vehicle responses.
proprietary
///----\\\ or standard +------+ standard +------+
||| IVS ||| ------------------->+ TSP +------------------->+ PSAP |
\\\----/// crash + other data +------+ crash + other data +------+
Figure 4: Next-Generation TSP Model
The vehicle manufacturer and the TSP can choose to use the same mechanisms and data objects on the left call leg in Figure 4 as on the right. (Note that the TSP model can be more difficult when the vehicle is in a different country than the TSP (e.g., a US resident driving in Canada) because of the additional complexity in choosing the correct PSAP based on vehicle location performed by a TSP in a different country.)
In the direct model, the IVS communicates crash data to the PSAP directly using the mechanisms and data objects described in this document.
///----\\\ NG emergency call +------+ ||| IVS |||----------------------------------------->+ PSAP | \\\----/// crash + other data +------+
Figure 5: Next-Generation Direct Model
In the paired model, the IVS uses a Bluetooth link to a previously-paired handset to establish an emergency call with the PSAP; it is unclear what facilities are or will be available for transmitting crash data through the Bluetooth link to the handset for inclusion in an NG emergency call. Hence, manufacturers that use the paired model for legacy calls might choose to adopt either the direct or TSP models for next-generation calls.
+---+
///----\\\ (undefined) | H | standard +------+
||| IVS |||------------------>| S +------------------->+ PSAP |
\\\----/// (undefined) +---+ crash + other data +------+
Figure 6: Next-Generation Paired Model
If the call is routed to a PSAP that is not capable of processing the vehicle data, the PSAP ignores (or does not receive) the vehicle data. This is detectable by the IVS or TSP when the status response to the INVITE (e.g., 200 OK) lacks a metadata/control structure acknowledging receipt of the data [I-D.ietf-ecrit-ecall]. The IVS or TSP then proceeds as it would for a CS-ACN call (e.g., verbal conveyance of data)
The Association of Public-Safety Communications Officials (APCO) and the National Emergency Number Association (NENA) have jointly developed a standardized set of incident-related vehicle data for ACN use, called the Vehicle Emergency Data Set (VEDS) [VEDS]. Such data is often referred to as crash data although it is applicable in incidents other than crashes.
VEDS provides a standard data set for the transmission, exchange, and interpretation of vehicle-related data. A standard data format allows the data to be generated by an IVS or TSP and interpreted by PSAPs, emergency responders, and medical facilities. It includes incident-related information such as airbag deployment, location and compass orientation of the vehicle, spatial orientation of the vehicle (e.g., upright, on its side or roof or a bumper), various sensor data that can indicate the potential severity of the crash and the likelihood of severe injuries to the vehicle occupants, etc. This data better informs the PSAP and emergency responders as to the type of response that might be needed. Some of this information has been included in U.S. government guidelines for field triage of injured patients [triage-2008] [triage-2011]. These guidelines are designed to help responders identify the potential existence of severe internal injuries and to make critical decisions about how and where a patient needs to be transported.
VEDS is an XML structure (see [VEDS]) transported in SIP using the 'application/EmergencyCallData.VEDS+xml' MIME media type.
If new data blocks are needed (e.g., in other regions or for enhanced data), the steps required during standardization are briefly summarized below:
[RFC7852] establishes a general mechanism for including blocks of data within a SIP emergency call. This document makes use of that mechanism. This document also registers a SIP INFO package (in Section 14.7) to enable NG-ACN related data blocks to be carried in SIP INFO requests (per [RFC6086], new SIP INFO method usages require the definition of a SIP INFO package).
The Vehicle Emergency Data Set (VEDS) is an XML structure defined by the Association of Public-Safety Communications Officials (APCO) and the National Emergency Number Association (NENA) [VEDS]. It is carried in a body part with MIME media type 'application/EmergencyCallData.VEDS+xml'.
An In-Vehicle System (IVS) transmits a VEDS data block (see [VEDS]) by including it as a body part of a SIP message per [RFC7852]. The body part is identified by its MIME media type ('application/emergencyCallData.VEDS+xml') in the Content-Type header field of the body part. The body part is assigned a unique identifier which is listed in a Content-ID header field in the body part. The SIP message is marked as containing the VEDS data by adding (or appending to) a Call-Info header field at the top level of the SIP message. This Call-Info header field contains a CID URL referencing the body part's unique identifier, and a 'purpose' parameter identifying the data as a VEDS data block per the Emergency Call Additional Data Types registry entry; the 'purpose' parameter's value is 'emergencyCallData.VEDS'. A VEDS data block is carried in a SIP INFO request by using the SIP INFO package defined in Section 14.7.
A PSAP or IVS transmits a metadata/control object (see [I-D.ietf-ecrit-ecall]) by including it in a SIP message as a MIME body part per [RFC7852]. The body part is identified by its MIME media type ('application/emergencyCallData.control+xml') in the Content-Type header field of the body part. The body part is assigned a unique identifier which is listed in a Content-ID header field in the body part. The SIP message is marked as containing the metadata/control block by adding (or appending to) a Call-Info header field at the top level of the SIP message. This Call-Info header field contains a CID URL referencing the body part's unique identifier, and a 'purpose' parameter identifying the data as a metadata/control block per the Emergency Call Additional Data Types registry entry; the 'purpose' parameter's value is 'emergencyCallData.control'. A metadata/control object is carried in a SIP INFO request by using the SIP INFO package defined in Section 14.7.
A body part containing a VEDS or metadata/control object has a Content-Disposition header field value containing "By-Reference" and is always enclosed in a multipart body part (even if it would otherwise be the only body part in the SIP message), since as of the date of this document, the use of Content-ID as a SIP header field is not defined (while it is defined for use as a MIME header field).
An In-Vehicle System (IVS) initiating an NG-ACN call includes in the initial INVITE a VEDS data block and a metadata/control object informing the PSAP of its capabilities. The VEDS and metadata/control body parts (and PIDF-LO) have a Content-Disposition header field with the value "By-Reference; handling=optional". Specifying handling=optional prevents the INVITE from being rejected if it is processed by a legacy element (e.g., a gateway between SIP and circuit-switched environments) that does not understand the VEDS or metadata/control (or PIDF-LO) objects. The PSAP creates a metadata/control object acknowledging receipt of the VEDS data and includes it in the SIP final response to the INVITE. The metadata/control object is not included in provisional (e.g., 180) responses.
If the IVS receives an acknowledgment for a VEDS data object with received=false, this indicates that the PSAP was unable to properly decode or process the VEDS. The IVS action is not defined (e.g., it might only log an error). Since the PSAP is able to request an updated VEDS during the call, if an initial VEDS is unsatisfactory in any way, the PSAP can choose to request another one.
A PSAP can request that the vehicle send an updated VEDS data block during a call. To do so, the PSAP creates a metadata/control object requesting VEDS data and includes it as a body part of a SIP INFO request sent within the dialog. The IVS then includes an updated VEDS data object as a body part of a SIP INFO request and sends it within the dialog. If the IVS is unable to send the VEDS, it instead sends a metadata/control object acknowledging the request with the 'success' parameter set to 'false' and a 'reason' parameter (and optionally a 'details' parameter) indicating why the request cannot be accomplished. Per [RFC6086], metadata/control objects and VEDS data are sent using the SIP INFO package defined in Section 14.7. In addition, to align with the way a VEDS or metadata/control block is transmitted in a SIP message other than a SIP INFO request, one or more Call-Info header fields are included in the SIP INFO request referencing the VEDS or metadata/control block. See Section 14.7 for more information on the use of SIP INFO requests within NG-ACN calls.
Any metadata/control object sent by a PSAP can request that the vehicle perform an action (such as sending a data block, flashing lights, providing a camera feed, etc.) The vehicle sends an acknowledgement for any request other than a successfully executed send-data action. Multiple requests with the same 'action' value MUST be sent in separate body parts (to avoid any ambiguity in the acknowledgement).
If the IVS is aware that VEDS data it sent previously has changed, it MAY send an unsolicited VEDS in any convenient SIP message, including a SIP INFO request during the call. The PSAP sends an acknowledgment for an unsolicited VEDS object (if the IVS sent the unsolicited VEDS in a SIP INFO request, the acknowledgment is sent in a new SP INFO request, otherwise it is sent in the reply to the SIP request containing the VEDS).
A next-generation In-Vehicle System (IVS) initiating an NG-ACN call sends a SIP INVITE request using one of the SOS sub-services "SOS.ecall.automatic" or "SOS.ecall.manual" in the Request-URI. This SIP INVITE request includes standard sets of both crash and capabilities data as described in Section 7.
Entities along the path between the vehicle and the PSAP are able to identify the call as an ACN call and handle it appropriately. The PSAP is able to identify the crash and capabilities data included in the SIP INVITE request by examining the Call-Info header fields for 'purpose' parameters whose values start with 'EmergencyCallData.' The PSAP is able to access the data it is capable of handling and is interested in by checking the 'purpose' parameter values.
This document extends [I-D.ietf-ecrit-ecall] by reusing the call set-up and other normative requirements with the exception that in this document, support for the eCall MSD is OPTIONAL and support for VEDS in REQUIRED. This document also adds new attribute values to the metadata/control object defined in [I-D.ietf-ecrit-ecall].
This document adds new attribute values to the metadata/control structure defined in [I-D.ietf-ecrit-ecall].
Mandatory Actions (the IVS and the PSAP MUST support):
The <ack> element indicates the object being acknowledged (i.e., a data object or a metadata/control block containing <request> elements), and reports success or failure.
The <capabilities> element has child <request> elements indicating the actions supported by the IVS.
The <request> element contains attributes to indicate the request and to supply any needed information, and MAY contain a <text> child element to contain the text for a dynamic message. The 'action' attribute is mandatory and indicates the specific action. [I-D.ietf-ecrit-ecall] established an IANA registry to contain the allowed values; this document adds new values to that registry in Table 2.
Per [I-D.ietf-ecrit-ecall], the PSAP sends a metadata/control block in response to the VEDS data sent by the IVS in SIP requests other than INFO (e.g., the INVITE). This metadata/control block is sent in the SIP response to the request (e.g., the INVITE response). When the PSAP needs to send a control block that is not an immediate response to a VEDS or other data sent by the IVS, the metadata/control block is transmitted from the PSAP to the IVS in a SIP INFO request within the established dialog. The IVS sends the requested data (e.g., the VEDS) or an acknowledgment (for requests other than to send data or to indicate an inability to send the requested data) in a new SIP INFO request. This mechanism flexibly allows the PSAP to send metadata/control data to the IVS and the IVS to respond. If a metadata/control block sent in a SIP response message requests the IVS to send a new VEDS or other data block, or to perform an action other than sending data, the IVS sends the requested data or an acknowledgment regarding the action in a SIP INFO request within the dialog.
The following new "action" values are defined:
Note that there is no 'request' action to play dynamic media (such as an audio message). The PSAP can send a SIP re-INVITE to establish a one-way media stream for this purpose.
<?xml version="1.0" encoding="UTF-8"?>
<EmergencyCallData.control
xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<request action="send-data" datatype="VEDS"/>
<request action="lamp" element-id="hazard"
requested-state="flash" persistence="PT1H"/>
<request action="msg-static" int-id="1"/>
<request action="msg-dynamic">
<text>Remain calm. Help is on the way.</text>
</request>
</EmergencyCallData.control>
Figure 7: Request Example
In [I-D.ietf-ecrit-ecall], the <ack> element is transmitted by the PSAP to acknowledge the MSD. Here, the <ack> element is also transmitted by the PSAP to acknowledge the VEDS data and by the IVS to acknowledge receipt of a <request> element that requested the IVS to perform an action other than transmitting a data object (e.g., a request to display a message would be acknowledged, but a request to transmit VEDS data would not result in a separate <ack> element being sent, since the data object itself serves as acknowledgment.) An <ack> element sent by an IVS references the unique ID of the metadata/control object containing the request(s) and indicates whether the request was successfully performed, and if not, optionally includes an explanation.
<?xml version="1.0" encoding="UTF-8"?>
<EmergencyCallData.control
xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<ack ref="1234567890@atlanta.example.com">
<actionResult action="msg-dynamic" success="true"/>
<actionResult action="lamp" success="false" reason="unable"
details="The requested lamp is inoperable"/>
</ack>
</EmergencyCallData.control>
Figure 8: Ack Example from IVS to PSAP
The <capabilities> element ([I-D.ietf-ecrit-ecall]) is transmitted by the IVS to indicate its capabilities to the PSAP.
The <capabilities> element contains a <request> child element per action supported by the vehicle. The vehicle MUST support sending the VEDS data object and so includes at a minimum a <request> child element with the 'action' attribute set to "send-data" and the 'supported-values' attribute containing all data blocks supported by the IVS, which MUST include 'VEDS'. All other actions are OPTIONAL.
If the "msg-static" action is supported, a <request> child element with the 'action' attribute set to "msg-static" is included, with the 'int-id' attribute set to the highest supported static message supported by the vehicle. A registry is created in Section 14.4 to map 'int-id' values to static text messages. By sending the highest supported static message number in its <capabilities> element, the vehicle indicates its support for all static messages in the registry up to and including that value.
If the "lamp" action is supported, a <request> child element with the 'action' attribute set to "lamp" is included, with the 'supported-values' attribute set to all supported lamp IDs. A registry is created in Section 14.5 to contain lamp ID values.
If the "enable-camera" action is supported, a <request> child element with the 'action' attribute set to "enable-camera" is included, with the 'supported-values' attribute set to all supported camera IDs. A registry is created in Section 14.6 to contain camera ID values.
<?xml version="1.0" encoding="UTF-8"?>
<EmergencyCallData.control
xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<capabilities>
<request action="send-data" supported-values="VEDS"/>
<request action="lamp"
supported-values="head;interior;fog-front;
fog-rear;brake;position-front;position-rear;
turn-left;turn-right;hazard"/>
<request action="msg-static" int-id="3"/>
<request action="msg-dynamic"/>
<request action="honk"/>
<request action="enable-camera"
supported-values="backup; interior"/>
<request action="door-lock"/>
</capabilities>
</EmergencyCallData.control>
Figure 9: Capabilities Example
An NG-ACN test call is a call that is recognized and treated to some extent as an NG-ACN call but not given emergency call treatment and not handled by a call taker. The specific handling of test NG-ACN calls is not itself standardized; the test call facility is intended to allow the IVS, user, or TSP to verify that an NG-ACN call can be successfully established with voice and/or other media communication. The IVS might also be able to verify that the crash data was successfully received.
This document builds on [I-D.ietf-ecrit-ecall], which inherits the ability to utilize test call functionality from Section 15 of [RFC6881]. A service URN starting with "test." indicates a test call. [I-D.ietf-ecrit-ecall] registered "urn:service:test.sos.ecall" for test calls.
MNOs, emergency authorities, ESInets, and PSAPs determine how to treat a vehicle call requesting the "test" service URN so that the desired functionality is tested, but this is outside the scope of this document. (One possibility is that MNOs route such calls as non-emergency calls to an ESInet, which routes them to a PSAP that supports NG-ACN calls; the PSAP accepts test calls, sends a crash data acknowledgment, and plays an audio clip (for example, saying that the call reached an appropriate PSAP and the vehicle data was successfully processed) in addition to supporting media loopback per [RFC6881]).
Note that since test calls are placed using "test" as the parent service URN and "sos" as a child, such calls are not treated as an emergency call and so some functionality might not apply (such as preemption or service availability for devices lacking service ("non-service-initialized" or "NSI" devices) if those are available for emergency calls).
Figure 10 shows an NG-ACN call routing. The mobile network operator (MNO) routes the call to an Emergency services IP Network (ESInet), as for any emergency call. The ESInet routes the call to an appropriate NG-ACN-capable PSAP (using location information and the fact that that it is an NG-ACN call). The call is processed by the Emergency Services Routing Proxy (ESRP), as the entry point to the ESInet. The ESRP routes the call to an appropriate NG-ACN-capable PSAP, where the call is received by a call taker. (In deployments where there is no ESInet, the MNO itself routes the call directly to an appropriate NG-ACN-capable PSAP.)
+---------------------------------------+
| |
+------------+ | +-------+ |
| | | | PSAP2 | |
| | | +-------+ |
| Originating| | |
| Mobile | | +------+ +-------+ |
Vehicle-->| Network |--+->| ESRP |---->| PSAP1 |--> Call-Taker |
| | | +------+ +-------+ |
| | | |
+------------+ | +-------+ |
| | PSAP3 | |
| +-------+ |
| |
| |
| |
| ESInet |
+---------------------------------------+
Figure 10: Example of Vehicle-Placed Emergency Call Message Flow
The example, shown in Figure 11, illustrates a SIP emergency call INVITE request with location information (a PIDF-LO), VEDS crash data (a VEDS data block), and capabilities data (a metadata/control block with extensions defined in this document) included in the SIP INVITE request message. The INVITE has a request URI containing the 'urn:service:sos.ecall.automatic' service URN.
The example VEDS data structure shows information about a crashed vehicle. The example communicates that the car is a model year 2015 Saab 9-5 (a car which does not exist). The front airbag deployed as a consequence of the crash. The 'VehicleBodyCategoryCode' indicates that the crashed vehicle is a passenger car (the code is set to '101') and that it is not a convertible (the 'ConvertibleIndicator' value is set to 'false').
The 'VehicleCrashPulse' element provides further information about the crash, namely that the force of impact based on the change in velocity over the duration of the crash pulse was 100 MPH. The principal direction of the force of the impact is set to '12' (which refers to 12 O'Clock, corresponding to a frontal collision). This value is described in the 'CrashPulsePrincipalDirectionOfForceValue' element.
The 'CrashPulseRolloverQuarterTurnsValue' indicates the number of quarter turns in concert with a rollover expressed as a number; in our case 1.
No roll bar was deployed, as indicated in 'VehicleRollbarDeployedIndicator' being set to 'false'.
Next, there is information indicating seatbelt and seat sensor data for individual seat positions in the vehicle. In our example, information from the driver seat is available (value '1' in the 'VehicleSeatLocationCategoryCode' element), that the seatbelt was monitored ('VehicleSeatbeltMonitoredIndicator' element), that the seatbelt was fastened ('VehicleSeatbeltFastenedIndicator' element) and the seat sensor determined that the seat was occupied ('VehicleSeatOccupiedIndicator' element).
Finally, information about the weight of the vehicle, which is 600 kilogram in our example.
In addition to the information about the vehicle, further indications are provided, namely the presence of fuel leakage ('FuelLeakingIndicator' element), an indication whether the vehicle was subjected to multiple impacts ('MultipleImpactsIndicator' element), the orientation of the vehicle at final rest ('VehicleFinalRestOrientationCategoryCode' element) and an indication that there are no parts of the vehicle on fire (the 'VehicleFireIndicator' element).
INVITE urn:service:sos.ecall.automatic SIP/2.0
To: urn:service:sos.ecall.automatic
From: <sip:+13145551111@example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
Geolocation: <cid:target123@example.com>
Geolocation-Routing: no
Call-Info: <cid:1234567890@atlanta.example.com>;
purpose=EmergencyCallData.VEDS
Call-Info: <cid:1234567892@atlanta.example.com>;
purpose=emergencyCallData.control
Accept: application/sdp, application/pidf+xml,
application/emergencyCallData.control+xml
Recv-Info: emergencyCallData.eCall
Allow: INVITE, ACK, PRACK, INFO, OPTIONS, CANCEL, REFER, BYE,
SUBSCRIBE, NOTIFY, UPDATE
CSeq: 31862 INVITE
Content-Type: multipart/mixed; boundary=boundary1
Content-Length: ...
--boundary1
Content-Type: application/sdp
...Session Description Protocol (SDP) goes here
--boundary1
Content-Type: application/pidf+xml
Content-ID: <target123@atlanta.example.com>
Content-Disposition: by-reference;handling=optional
<?xml version="1.0" encoding="UTF-8"?>
<presence
xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
xmlns:dyn="urn:ietf:params:xml:ns:pidf:geopriv10:dynamic"
xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
entity="sip:+13145551111@example.com">
<dm:device id="123">
<gp:geopriv>
<gp:location-info>
<gml:Point srsName="urn:ogc:def:crs:EPSG::4326">
<gml:pos>-34.407 150.883</gml:pos>
</gml:Point>
<dyn:Dynamic>
<dyn:heading>278</dyn:heading>
<dyn:direction><dyn:direction>
</dyn:Dynamic>
</gp:location-info>
<gp:usage-rules/>
<method>gps</method>
</gp:geopriv>
<timestamp>2012-04-5T10:18:29Z</timestamp>
<dm:deviceID>1M8GDM9A_KP042788</dm:deviceID>
</dm:device>
</presence>
--boundary1
Content-Type: application/EmergencyCallData.VEDS+xml
Content-ID: <1234567890@atlanta.example.com>
Content-Disposition: by-reference;handling=optional
<?xml version="1.0" encoding="UTF-8"?>
<AutomatedCrashNotification xmlns="http://www.veds.org/acn/1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<Crash>
<CrashVehicle>
<ItemMakeName xmlns="http://niem.gov/niem/niem-core/2.0">
Saab
</ItemMakeName>
<ItemModelName xmlns="http://niem.gov/niem/niem-core/2.0">
9-5
</ItemModelName>
<ItemModelYearDate
xmlns="http://niem.gov/niem/niem-core/2.0">
2015
</ItemModelYearDate>
<Airbag>
<AirbagCategoryCode>FRONT</AirbagCategoryCode>
<AirbagDeployedIndicator>true
</AirbagDeployedIndicator>
</Airbag>
<ConvertibleIndicator>false</ConvertibleIndicator>
<PowerSourceCategoryCode>MAIN</PowerSourceCategoryCode>
<VehicleBodyCategoryCode
xmlns="http://niem.gov/niem/domains/jxdm/4.1">
101
</VehicleBodyCategoryCode>
<VehicleCrashPulse>
<CrashPulseChangeInVelocityMeasure>
<MeasurePointValue
xmlns="http://niem.gov/niem/niem-core/2.0">
100
</MeasurePointValue>
<MeasureUnitText
xmlns="http://niem.gov/niem/niem-core/2.0">
MPH</MeasureUnitText>
</CrashPulseChangeInVelocityMeasure>
<CrashPulsePrincipalDirectionOfForceValue>12
</CrashPulsePrincipalDirectionOfForceValue>
<CrashPulseRolloverQuarterTurnsValue>1
</CrashPulseRolloverQuarterTurnsValue>
</VehicleCrashPulse>
<VehicleRollbarDeployedIndicator>false
</VehicleRollbarDeployedIndicator>
<VehicleSeat>
<VehicleSeatLocationCategoryCode>1
</VehicleSeatLocationCategoryCode>
<VehicleSeatOccupiedIndicator>true
</VehicleSeatOccupiedIndicator>
<VehicleSeatbeltFastenedIndicator>true
</VehicleSeatbeltFastenedIndicator>
<VehicleSeatbeltMonitoredIndicator>true
</VehicleSeatbeltMonitoredIndicator>
</VehicleSeat>
<VehicleUnladenWeightMeasure
xmlns="http://niem.gov/niem/niem-core/2.0">
<MeasurePointValue
xmlns="http://niem.gov/niem/niem-core/2.0">
600
</MeasurePointValue>
<MeasureUnitText
xmlns="http://niem.gov/niem/niem-core/2.0">
kilogram
</MeasureUnitText>
</VehicleUnladenWeightMeasure>
</CrashVehicle>
<FuelLeakingIndicator>true</FuelLeakingIndicator>
<MultipleImpactsIndicator>false</MultipleImpactsIndicator>
<SevereInjuryIndicator>true</SevereInjuryIndicator>
<VehicleFinalRestOrientationCategoryCode>Driver
</VehicleFinalRestOrientationCategoryCode>
<VehicleFireIndicator>false</VehicleFireIndicator>
</Crash>
</AutomatedCrashNotification>
--boundary1
Content-Type: application/emergencyCallData.control+xml
Content-ID: <1234567892@atlanta.example.com>
Content-Disposition: by-reference;handling=optional
<?xml version="1.0" encoding="UTF-8"?>
<EmergencyCallData.control
xmlns="urn:ietf:params:xml:ns:EmergencyCallData:control"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<capabilities>
<request action="send-data" supported-datatypes="VEDS"/>
<request action="lamp"
supported-values="head;interior;fog-front;fog-rear;
brake;position-front;position-rear;turn-left;
turn-right;hazard"/>
<request action="msg-static" int-id="3"/>
<request action="msg-dynamic"/>
<request action="honk"/>
<request action="enable-camera"
supported-values="backup;interior"/>
<request action="door-lock"/>
</capabilities>
</EmergencyCallData.control>
--boundary1--
Figure 11: SIP INVITE for a Vehicle-Initated Emergency Call
Since this document relies on [I-D.ietf-ecrit-ecall] and [RFC7852], the security considerations described there and in [RFC5069] apply here. Implementors are cautioned to read and understand the discussion in those documents.
As with emergency service systems where location data is supplied or determined with the assistance of an end host, there is the possibility that that location is incorrect, either intentially (e.g., in a denial of service attack against the emergency services infrastructure) or due to a malfunctioning device. The reader is referred to [RFC7378] for a discussion of some of these vulnerabilities.
In addition to the security considerations discussion specific to the metadata/control object in [I-D.ietf-ecrit-ecall], note that vehicles MAY decline to carry out any requested action (e.g., if the vehicle requires but is unable to verify the certificate used to sign the request). The vehicle MAY use any value in the reason registry to indicate why it did not take an action (e.g., the generic "unable" or the more specific "security-failure").
Since this document builds on [I-D.ietf-ecrit-ecall], which itself builds on [RFC7852], the data structures specified there, and the corresponding privacy considerations discussed there, apply here as well. The VEDS data structure contains optional elements that can carry identifying and personal information, both about the vehicle and about the owner, as well as location information, and so needs to be protected against unauthorized disclosure, as discussed in [RFC7852]. Local regulations may impose additional privacy protection requirements.
The additional functionality enabled by this document, such as access to vehicle camera streams, carries a burden of protection and so implementations need to be careful that access is only provided within the context of an emergency call or to an emergency services provider (e.g., by verifying that the request for camera access is signed by a certificate issued by an emergency services registrar).
This document registers the 'application/EmergencyCall.VEDS+xml' MIME media type, and adds "VEDS" to the Emergency Call Data Types registry. This document adds to and creates sub-registries in the "Emergency Call Metadata/Control Data" registry created in [I-D.ietf-ecrit-ecall]. This document registers a new SIP INFO package.
This specification requests the registration of a new MIME media type according to the procedures of RFC 6838 [RFC6838] and guidelines in RFC 7303 [RFC7303].
This specification requests IANA to add the 'VEDS' entry to the Emergency Call Data Types registry, with a reference to this document; the 'Data About' value is 'The Call'. The Emergency Call Data types registry was established by [RFC7852].
This document adds new values for the 'action' attribute of the <request> element in the "Emergency Call Action" registry created by [I-D.ietf-ecrit-ecall].
| Name | Description |
|---|---|
| msg-static | Section 9.1 of [TBD: THIS DOCUMENT] |
| msg-dynamic | Section 9.1 of [TBD: THIS DOCUMENT] |
| honk | Section 9.1 of [TBD: THIS DOCUMENT] |
| lamp | Section 9.1 of [TBD: THIS DOCUMENT] |
| enable-camera | Section 9.1 of [TBD: THIS DOCUMENT] |
| door-lock | Section 9.1 of [TBD: THIS DOCUMENT] |
This document creates a new sub-registry called "Emergency Call Static Message" in the "Emergency Call Metadata/Control Data" registry established by [I-D.ietf-ecrit-ecall]. Because all compliant vehicles are expected to support all static messages translated into all languages supported by the vehicle, it is important to limit the number of such messages. As defined in [RFC5226], this registry operates under "Specification Required" rules, which require a stable, public document and implies expert review of the publication. The expert should determine that the document has been published by an appropriate emergency services organization (e.g., NENA, EENA, APCO) or by the IETF with input from an emergency services organization, and that the proposed message is sufficiently distinguishable from other messages.
The contents of this registry are:
When new messages are added to the registry, the message text is determined by the registrant; IANA assigns the IDs. Each message is assigned a consecutive integer value as its ID. This allows an IVS to indicate by a single integer value that it supports all messages with that value or lower.
The initial set of values is listed in Table 3.
| ID | Message |
|---|---|
| 1 | Emergency services has received your information and location, but cannot speak with you right now. We will get help to you as soon as possible. |
This document creates a new sub-registry called "Emergency Call Vehicle Lamp ID" in the "Emergency Call Metadata/Control Data" registry established by [I-D.ietf-ecrit-ecall]. This new sub-registry uniquely identifies the names of automotive lamps (lights). As defined in [RFC5226], this registry operates under "Expert Review" rules. The expert should determine that the proposed lamp name is clearly understandable and is sufficiently distinguishable from other lamp names.
The contents of this registry are:
The initial set of values is listed in Table 4.
| Name | Description |
|---|---|
| head | The main lamps used to light the road ahead |
| interior | Interior lamp, often at the top center |
| fog-front | Front fog lamps |
| fog-rear | Rear fog lamps |
| brake | Brake indicator lamps |
| brake-center | Center High Mounted Stop Lamp |
| position-front | Front position/parking/standing lamps |
| position-rear | Rear position/parking/standing lamps |
| turn-left | Left turn/directional lamps |
| turn-right | Right turn/directional lamps |
| hazard | Hazard/four-way lamps |
This document creates a new sub-registry called "Emergency Call Vehicle Camera ID" in the "Emergency Call Metadata/Control Data" registry established by [I-D.ietf-ecrit-ecall]. This new sub-registry uniquely identifies automotive cameras. As defined in [RFC5226], this registry operates under "Expert Review" rules. The expert should determine that the proposed camera name is clearly understandable and is sufficiently distinguishable from other camera names.
The contents of this registry are:
The initial set of values is listed in Table 5.
| Name | Description |
|---|---|
| backup | Shows what is behind the vehicle, e.g., often used for driver display when the vehicle is in reverse. Also known as rearview, reverse, rear visibility, etc. |
| left-rear | Shows view to the left and behind (e.g., left side rear-view mirror or blind spot view) |
| right-rear | Shows view to the right and behind (e.g., right side rear-view mirror or blind spot view) |
| forward | Shows what is in front of the vehicle |
| rear-wide | Shows what is behind vehicle (e.g., used by rear-collision detection systems), separate from backup view |
| lane | Used by systems to identify road lane and/or monitor vehicle's position within lane |
| interior | Shows the interior (e.g., driver) |
| night-front | Night-vision view of what is in front of the vehicle |
| night-rear | Night-vision view of what is behind the vehicle |
| night-left | Night-vision view of what is to the left of the vehicle |
| night-right | Night-vision view of what is to the right of the vehicle |
This document registers the 'emergencyCallData.eCall.VEDS' SIP INFO package.
Both endpoints (the IVS and the PSAP equipment) include 'emergencyCallData.eCall.VEDS' in a Recv-Info header field per [RFC6086] to indicate ability to receive SIP INFO messages carrying data as described here.
Support for the 'emergencyCallData.eCall.VEDS' SIP INFO package indicates the ability to receive NG-ACN related body parts as specified in [TBD: THIS DOCUMENT].
A SIP INFO request message carrying data related to an emergency call as described in [TBD: THIS DOCUMENT] has an Info-Package header field set to 'emergencyCallData.eCall.VEDS' per [RFC6086].
The requirements of Section 10 of [RFC6086] are addressed in the following sections.
This section describes "what type of information is carried in Info requests associated with the Info Package, and for what types of applications and functionalities UAs can use the Info Package."
SIP INFO requests associated with the emergencyCallData.eCall.VEDS SIP INFO package carry data associated with emergency calls as defined in [TBD: THIS DOCUMENT]. The application is vehicle-initiated emergency calls established using SIP. The functionality is to carry vehicle data and metadata/control information between vehicles and PSAPs. Refer to [TBD: THIS DOCUMENT] for more information.
This section describes "why the Info Package mechanism, rather than some other mechanism, has been chosen for the specific use-case...."
The use of the SIP INFO method is based on an analysis of the requirements against the intent and effects of the INFO method versus other approaches (which included the SIP MESSAGE method, SIP OPTIONS method, SIP re-INVITE method, media plane transport, and non-SIP protocols). In particular, the transport of emergency call data blocks occurs within a SIP emergency dialog, per Section 7, and is normally carried in the initial INVITE request and its response; the use of the INFO method only occurs when emergency-call-related data needs to be sent mid-call. While the SIP MESSAGE method could be used, it is not tied to a SIP dialog as is the INFO method and thus might not be associated with the dialog. Both the SIP OPTIONS or re-INVITE methods could also be used, but is seen as less clean than the INFO method. The SIP SUBSCRIBE/NOTIFY method could be coerced into service, but the semantics are not a good fit, e.g., the subscribe/notify mechanism provides one-way communication consisting of (often multiple) notifications from notifier to subscriber indicating that certain events in notifier have occurred, whereas what's needed here is two-way communication of data related to the emergency dialog. Use of the media plane mechanisms was discounted because the number of messages needing to be exchanged in a dialog is normally zero or very few, and the size of the data is likewise very small. The overhead caused by user plane setup (e.g., to use MSRP as transport) would be disproportionately large.
Based on the analyses, the SIP INFO method was chosen to provide for mid-call data transport.
The SIP INFO package name is emergencyCallData.eCall.VEDS
None
None
The body of an emergencyCallData.eCall.VEDS SIP INFO package is a multipart body which MAY contain zero or one application/emergencyCallData.eCall.VEDS+xml (containing a VEDS data block) part, zero or more application/emergencyCallData.control+xml (containing a metadata/control object) parts, and zero or one application/emergencyCallData.eCall.MSD+per (containing an MSD) part. At least one VEDS, MSD, or metadata/control body part is expected; the behavior upon receiving a SIP INFO request with none is undefined.
The body parts are sent per [RFC6086], and in addition, to align with with how these body parts are sent in non-INFO messages, each associated body part is referenced by a Call-Info header field at the top level of the SIP message. The body part has a Content-Disposition header field set to "By-Reference".
A VEDS or metadata/control block is always enclosed in a multipart body part (even if it would otherwise be the only body part in the SIP message), since as of the date of this document, the use of Content-ID as a SIP header field is not defined (while it is defined for use as a MIME header field). The innermost multipart that contains only body parts associated with the SIP INFO package has a Content-Disposition value of Info-Package.
Service providers are not expected to add [RFC7852] Additional Data to SIP INFO requests.
See [TBD: THIS DOCUMENT] for more information.
Usage is limited to vehicle-initiated emergency calls as defined in [TBD: THIS DOCUMENT].
The SIP INFO request is used within an established emergency call dialog for the PSAP to request the IVS to send an updated data set, and for the IVS to send the requested data set. Because this is normally done only on manual request of the PSAP call taker (who suspects some aspect of the vehicle state has changed), the rate of SIP INFO requests associated with the emergencyCallData.eCall.VEDS SIP INFO package is normally quite low (most dialogs are likely to contain zero SIP INFO requests, while others can be expected to carry an occasional request).
The MIME media type registations for the data blocks that can be carried using this SIP INFO package contains a discussion of the security and/or privacy considerations specific to that data block. The "Security Considerations" and "Privacy Considerations" sections of [TBD: THIS DOCUMENT] discuss security and privacy considerations of the data carried in vehicle-initiated emergency calls as described in that document.
See [TBD: THIS DOCUMENT] for protocol details.
See [TBD: THIS DOCUMENT] for protocol examples.
We would like to thank Lena Chaponniere, Alissa Cooper, Stephen Edge, Christer Holmberg, Allison Mankin, and Dan Romascanu for their review and suggestions; Robert Sparks and Paul Kyzivat for their help with the SIP mechanisms; Michael Montag, Arnoud van Wijk, Ban Al-Bakri, Wes George, Gunnar Hellstrom, and Rex Buddenberg for their feedback; and Ulrich Dietz for his help with earlier versions of the original version of this document.
RFC Editor: Please remove this section prior to publication.