| Rfc | 8148 |
|---|
| Title | Next-Generation Vehicle-Initiated Emergency Calls |
|---|
| Author | R. Gellens, B.
Rosen, H. Tschofenig |
|---|
| Date | May 2017 |
|---|
| Format: | TXT, HTML |
|---|
| Status: | PROPOSED STANDARD |
|---|
|
Internet Engineering Task Force (IETF) R. Gellens
Request for Comments: 8148 Core Technology Consulting
Category: Standards Track B. Rosen
ISSN: 2070-1721 NeuStar, Inc.
H. Tschofenig
Individual
May 2017
Next-Generation Vehicle-Initiated Emergency Calls
Abstract
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
Data Type for the vehicle, sensor, and location data (often referred
to as "crash data" even though there is not necessarily a crash) and
an INFO package to enable carrying this and related data in SIP INFO
requests. An external specification for the data format, contents,
and structure is 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 (IVSs) 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 it adds attribute values to the metadata/control
object to permit greater functionality. This document registers a
new 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.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8148.
Copyright Notice
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Document Scope . . . . . . . . . . . . . . . . . . . . . . . 8
4. Overview of Legacy Deployment Models . . . . . . . . . . . . 8
5. Migration to Next Generation . . . . . . . . . . . . . . . . 10
6. Vehicle Data . . . . . . . . . . . . . . . . . . . . . . . . 13
7. Data Transport . . . . . . . . . . . . . . . . . . . . . . . 14
8. Call Setup . . . . . . . . . . . . . . . . . . . . . . . . . 16
9. New Metadata/Control Values . . . . . . . . . . . . . . . . . 17
9.1. New Values for the "action" Attribute . . . . . . . . . . 18
9.2. Example <request> Element . . . . . . . . . . . . . . . . 19
9.3. The <ack> Element . . . . . . . . . . . . . . . . . . . . 19
9.4. The <capabilities> Element . . . . . . . . . . . . . . . 20
10. Test Calls . . . . . . . . . . . . . . . . . . . . . . . . . 21
11. Example Call Initiation . . . . . . . . . . . . . . . . . . . 22
12. Security Considerations . . . . . . . . . . . . . . . . . . . 27
13. Privacy Considerations . . . . . . . . . . . . . . . . . . . 28
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
14.1. MIME Media Type Registration for
application/EmergencyCall.VEDS+xml . . . . . . . . . . . 28
14.2. Registration of the "VEDS" Entry in the Emergency Call
Data Types Registry . . . . . . . . . . . . . . . . . . 30
14.3. New Action Values . . . . . . . . . . . . . . . . . . . 30
14.4. Emergency Call Static Messages Registry . . . . . . . . 31
14.5. Emergency Call Vehicle Lamp IDs Registry . . . . . . . . 32
14.6. Emergency Call Vehicle Camera IDs Registry . . . . . . . 33
14.7. The EmergencyCallData.VEDS INFO Package . . . . . . . . 35
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 38
15.1. Normative References . . . . . . . . . . . . . . . . . . 38
15.2. Informative references . . . . . . . . . . . . . . . . . 39
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction
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 that, 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 minimize
degradation by vehicle glass coatings, interference from other
vehicle systems, etc. Thus, the Public Safety Answering Point (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.).
A common term for such systems is Automatic Crash Notification (ACN)
or Advanced Automatic Crash Notification (AACN). Sometimes the word
"Collision" is used instead of "Crash." In this document, "ACN" is
used 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 emergency calling provides an
opportunity to vastly improve the scope, breadth, reliability, and
usefulness of crash data by transmitting a standardized set during
call setup; the data can be processed by the PSAP in an integrated,
automated way and made available to the call taker at call
presentation. It also provides the ability for the 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, multimedia entertainment systems, remote door unlocking,
remote diagnostics, and roadside assistance applications).
Next-generation ACN provides an opportunity for such calls to be
recognized and processed as such during call setup, 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 by Telematics Service Providers (TSPs) 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),
requests for medical assistance, etc.
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 reused 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
[RFC8147]. However, this document specifies use of a different set
of vehicle (crash) data, specifically, VEDS rather than the eCall
Minimum Set of Data (MSD). This document is an extension of
[RFC8147], with the differences being that this document makes the
MSD data set optional and VEDS mandatory, and it adds new attribute
values to the metadata/control object defined in that document. This
document also registers a new INFO package (identical to that defined
in [RFC8147] with the addition of the VEDS MIME type).
This document registers the application/EmergencyCallData.VEDS+xml
MIME media type, the VEDS Emergency Call Data Type, and the
EmergencyCallData.VEDS 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 (although often determined in cooperation with the
originating device). Standardized crash data structures typically
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 and the location as determined by the IVS.
This specification inherits the ability to utilize test call
functionality from Section 15 of [RFC6881].
2. Terminology
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 reuses terminology defined in Section 3 of [RFC5012].
Additionally, we use the following abbreviations:
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: 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
either an IVS or a TSP, to avoid repetitively writing "IVS or TSP",
the term "IVS" is used to represent either an IVS or a TSP when
discussing signaling behavior (e.g., sending VEDS data, sending a SIP
INVITE request, receiving a SIP INFO request, etc.).
3. Document Scope
This document is focused on how an ACN emergency call is set up 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 free to use the same mechanism for both legs, 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, [RFC8147], 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 setup and other technical aspects of [RFC8147], which uses
[RFC7852]; this makes it straightforward to use a different data set
while keeping other technical aspects unchanged. Hence, both next-
generation eCall (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 VEDS 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 accommodated without changing other technical aspects.
Note that any additional data formats require a new INFO package to
permit transport within SIP INFO requests.
4. Overview of Legacy Deployment Models
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: "TSP", "direct", and "paired". These three models are
illustrated below.
In the TSP model, both emergency and routine TSP service calls are
placed to a TSP; a proprietary technique (e.g., a proprietary in-band
modem) is used for data transfer between the TSP and the vehicle.
In an emergency, typically a TSP agent verifies the emergency,
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 orally (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. A three-way voice call is
generally established between the vehicle, the TSP, and the PSAP,
allowing communication between the PSAP call taker, the TSP agent,
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.
///----\\\ +----+ 911/etc. voice call via handset +------+
||| IVS |||-->| HS |----------------------------------->| PSAP |
\\\----/// +----+ location via text-to-speech +------+
(Note: "HS" is handset.)
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
5. Migration to Next Generation
The 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, and 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 technology 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 such during call set-up; they can
be routed to a PSAP that is prepared both technically and
operationally to handle such calls, and the vehicle-determined
location and crash data can be processed automatically by the PSAP
and made available to the call taker simultaneously with the call
appearance. Enhanced functionality includes the ability for the PSAP
call taker to request the vehicle to take an action, such as sending
an updated set of data, conveying 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.
An IVS establishes a next-generation emergency call (see [RFC6443]
and [RFC6881]) with an initial INVITE containing a Request-URI
indicating an ACN 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 (relying on the MNO for this).
[RFC8147] 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 [RFC8147] 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 reusing the mechanisms and data objects described in
this document or by 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 agent, 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 local 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 link to the handset for inclusion in an NG emergency call
and receiving additional data items from the response. Hence,
manufacturers that use the paired model for legacy calls might choose
to adopt either the direct or TSP model for next-generation calls.
///----\\\ (undefined) +----+ standard +------+
||| IVS |||----------------->| HS |--------------------->| PSAP |
\\\----/// (undefined) +----+ crash + other data +------+
Figure 6: Next-Generation Paired Model
Regardless of model, if the call is routed to a PSAP that is not
NG-ACN capable, 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 [RFC8147]. The IVS or TSP then
proceeds as it would for a CS-ACN call (e.g., oral conveyance of
data).
6. Vehicle Data
APCO and 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 a side, roof, or bumper), 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:
o A set of data is standardized by a Standards Development
Organization (SDO) or appropriate organization.
o A MIME media type for the crash data set is registered with IANA
* If the data is specifically for use in emergency calling, the
MIME media type is normally under the application type with a
subtype starting with EmergencyCallData.
* If the data format is XML, then by convention the name has a
suffix of "+xml".
o The item is registered in the "Emergency Call Data Types"
registry, as defined in Section 11.1.9 of [RFC7852].
* For emergency-call-specific formats, the registered name is the
root of the MIME media type (not including the
EmergencyCallData prefix and any suffix such as "+xml") as
described in Section 4.1 of [RFC7852].
o A new INFO package is registered that permits carrying the new
media type, the metadata/control object (defined in [RFC8147]),
and for compatibility, the MSD and VEDS objects, in SIP INFO
requests.
7. Data Transport
[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 an 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 an INFO package).
VEDS is an XML structure defined by APCO and NENA [VEDS]. It is
carried in a body part with MIME media type application/
EmergencyCallData.VEDS+xml.
An 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 that 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 Content Identifier (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 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 INFO package defined in Section 14.7.
A PSAP or IVS transmits a metadata/control object (see [RFC8147]) 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 that 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 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 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).
An 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
Presence Information Data Format Location Object (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 for any
reason, it instead sends a metadata/control object containing an
<ack> element acknowledging the request and containing an
<actionResult> element 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 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 IVS sends an
acknowledgment for any request other than a successfully executed
send-data action. Multiple requests with the same "action:" value
MUST be sent in separate metadata/control body parts (to avoid any
ambiguity in the acknowledgment). For each metadata/control block
received containing one or more <request> elements (except for
successfully executed send-data requests), the IVS sends a metadata/
control object containing an <ack> element acknowledging the received
metadata/control block, containing an <actionResult> element per
<request> element.
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 SIP INFO
request; otherwise, it is sent in the reply to the SIP request
containing the VEDS.
8. Call Setup
An 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 [RFC8147] by reusing the call setup and other
normative requirements with the exception that in this document,
support for the eCall MSD is OPTIONAL and support for VEDS is
REQUIRED. This document also adds new attribute values to the
metadata/control object defined in [RFC8147].
9. New Metadata/Control Values
This document adds new attribute values to the metadata/control
structure defined in [RFC8147].
In addition to the base usage from the PSAP to the IVS to acknowledge
receipt of crash data, the <ack> element is also contained in a
metadata/control block sent by the IVS to the PSAP. This is used by
the IVS to acknowledge receipt of a request by the PSAP and indicate
if the request was carried out when that request would not otherwise
be acknowledged (if the PSAP requests the vehicle to send data and
the vehicle does so, the data serves as a success acknowledgment);
see Section 8 for details.
The <capabilities> element is used in a metadata/control block sent
from the IVS to the PSAP (e.g., in the initial INVITE) to inform the
PSAP of the vehicle capabilities. Child elements contain all actions
and data types supported by the vehicle and all available lamps
(lights) and cameras.
New request values are added to the <request> element to enable the
PSAP to request the vehicle to perform additional actions.
Mandatory Actions (the IVS and the PSAP MUST support):
o Transmit data object (VEDS MUST be supported; MSD MAY be
supported)
Optional Actions (the IVS and the PSAP MAY support):
o Display and/or play static (pre-defined) message
o Display and/or speak dynamic text (text supplied in action)
o Flash or turn on or off a lamp (light)
o Honk horn
o Lock or unlock doors
o Enable a camera
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 (including data types, lamps (lights), and cameras)
supported by the IVS.
The <request> element contains attributes to indicate the request and
to supply any needed information, and it MAY contain a <text> child
element to contain the text for a dynamic message. The "action"
attribute is mandatory and indicates the specific action. [RFC8147]
established an IANA registry to contain the allowed values; this
document adds new values to that registry in Table 1.
9.1. New Values for the "action" Attribute
The following new "action" values are defined:
msg-static: displays or plays a pre-defined message (translated as
appropriate for the language of the vehicle's interface). A
registry is created in Section 14.4 for messages and their IDs.
Vehicles include the highest registered message in their
<capabilities> element to indicate support for all messages up to
and including the indicated value. A registry of message
identification values is defined in Section 14.4. There is only
one static message initially defined (listed in Table 2). 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. Therefore, this
registry operates under "Specification Required" rules as defined
in [RFC5226], which requires a stable, public document and implies
expert review of the publication.
msg-dynamic: displays or speaks (via text-to-speech) a message
contained in a child <text> element within the request.
honk: sounds the horn.
lamp: flashes a lamp (light) or turns it on or off. The lamp is
identified by a lamp ID token contained in an "element-id"
attribute of the request. The desired state of the lamp is either
"on", "off", or "flash" as indicated in a "requested-state"
attribute. The duration of the lamp's requested state is
specified in a "persistence" attribute. A registry of lamp
identification values is defined in Section 14.5. The initial
values (listed in Table 3) are head, interior, fog-front,
fog-rear, brake, brake-center, position-front, position-rear,
turn-left, turn-right, and hazard.
enable-camera: adds a one-way media stream (established via SIP
re-INVITE sent by the vehicle) to enable the PSAP call taker to
view a feed from a camera. A registry of camera identification
values is defined in Section 14.6. The initial values (listed in
Table 4) are backup, left-rear, right-rear, forward, rear-wide,
lane, interior, night-front, night-rear, night-left, and night-
right.
door-lock: locks or unlocks all door locks. A "requested-state"
attribute contains either "locked" or "unlocked" to indicate if
the doors are to be locked or unlocked.
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.
9.2. Example <request> Element
<?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
9.3. The <ack> Element
The <ack> element is transmitted by the PSAP to acknowledge
unsolicited data sent by the IVS and transmitted by the IVS to
acknowledge receipt of a <request> element other than a successfully
performed "send-data" request (e.g., a request to display a message
to the vehicle occupants is acknowledged, but a request to transmit
VEDS data is not, since the transmitted VEDS serves as
acknowledgment). An <ack> element sent by an IVS references the
unique ID of the metadata/control object containing the request(s),
and for each request being acknowledged, it indicates whether the
request was successfully performed, and if not, it indicates why not.
9.3.1. Examples of the <ack> Element
<?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: Example <ack> from IVS to PSAP
9.4. The <capabilities> Element
The <capabilities> element [RFC8147] 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.
9.4.1. Example <capabilities> Element
<?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
10. Test Calls
An NG-ACN test call is a call that is recognized and treated to some
extent as an NG-ACN call but is not given emergency call treatment
nor handled by a PSAP call taker. The specific handling of test
NG-ACN calls is outside the scope of this document; typically, the
test call facility allows 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 [RFC8147], which inherits the ability to
utilize test call functionality from Section 15 of [RFC6881]. A
service URN starting with "test." indicates a test call. Per
[RFC8147], "urn:service:test.sos.ecall" is used for test NG-ACN
calls.
MNOs, emergency authorities, ESInets, and PSAPs handle 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, so some functionality might not apply (such as
preemption or availability for devices lacking service
("non-service-initialized" (NSI) devices) if those are available for
emergency calls).
11. Example Call Initiation
Figure 10 shows an NG-ACN call initiation. The vehicle initiates an
NG-ACN call using an MNO. The MNO routes the call to an 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 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 handled 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 Call Initiation
Figure 11 illustrates an example SIP emergency call INVITE request as
generated by the IVS. It includes a PIDF-LO with vehicle-determined
location information, a VEDS block with crash data, and a metadata/
control block with capabilities data. The INVITE has a request URI
containing the urn:service:sos.ecall.automatic service URN. For
brevity, the example VEDS block does not show VEDS location
information, although this is generally present.
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 that 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 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 seat belt 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) showing that the seat belt
was monitored (<VehicleSeatbeltMonitoredIndicator> element), the seat
belt was fastened (<VehicleSeatbeltFastenedIndicator> element), and
the seat sensor determined that the seat was occupied
(<VehicleSeatOccupiedIndicator> element).
The weight of the vehicle when empty is listed as 600 kilograms in
our example.
The <SevereInjuryIndicator> element is set to "true", indicating a
likelihood that a vehicle occupant has suffered a severe injury
requiring immediate trauma care.
Additional information is provided, including 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 no parts of the vehicle are currently detected as
being 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-Initiated Emergency Call
12. Security Considerations
Since this document relies on [RFC8147] and [RFC7852], the security
considerations described in those specifications apply here. The
security considerations of [RFC5069] apply as well. Implementors are
cautioned to read and understand the discussion in those documents.
In emergency service systems where location data is supplied or
determined with the assistance of an end host, it is possible that
the location is incorrect, either intentionally (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 [RFC8147], 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"). Because some actions carry more
potential risk than others (e.g., unlocking a door versus flashing
lights), vehicle policy MAY decline to carry out some requests in
some circumstances (e.g., decline a request to unlock doors, send an
updated VEDS, or enable a camera received in a vehicle-terminated
call while carrying out such requests received in a vehicle-initiated
emergency call).
13. Privacy Considerations
Since this document builds on [RFC8147], 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, so it 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, 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).
14. IANA Considerations
This document registers the application/EmergencyCallData.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 [RFC8147].
In addition, this document registers a new INFO package.
14.1. MIME Media Type Registration for application/
EmergencyCall.VEDS+xml
IANA has registered a new MIME media type according to the procedures
of [RFC6838] and guidelines in [RFC7303].
MIME media type name: application
MIME subtype name: EmergencyCallData.VEDS+xml
Mandatory parameters: none
Optional parameters: charset
Indicates the character encoding of enclosed XML.
Encoding considerations:
Uses XML, which can employ 8-bit characters, depending on the
character encoding used. See Section 3.2 of RFC 7303
[RFC7303].
Security considerations:
This media type is designed to carry vehicle crash data
during an emergency call.
This data can contain personal information including vehicle
VIN, location, direction, etc. Appropriate precautions need
to be taken to limit unauthorized access, inappropriate
disclosure to third parties, and eavesdropping of this
information. Please refer to Sections 9 and 10 of [RFC7852]
for more information.
When this media type is contained in a signed or encrypted
body part, the enclosing multipart (e.g., multipart/signed
or multipart/encrypted) has the same Content-ID as the data
part. This allows an entity to identify and access the data
blocks it is interested in without having to dive deeply
into the message structure or decrypt parts it is not
interested in. (The "purpose" parameter in a Call-Info
header field identifies the data, and the CID URL points to
the data block in the body, which has a matching Content-ID
body part header field.)
Interoperability considerations: None
Published specification: [VEDS]
Applications which use this media type: Emergency Services
Additional information: None
Magic Number: None
File Extension: .xml
Macintosh file type code: TEXT
Persons and email addresses for further information:
Randall Gellens, rg+ietf@randy.pensive.org;
Hannes Tschofenig, Hannes.Tschofenig@gmx.net
Intended usage: LIMITED USE
Author:
This specification is a work item of the IETF ECRIT working
group, with mailing list address <ecrit@ietf.org>.
Change controller: The IESG <ietf@ietf.org>
14.2. Registration of the "VEDS" Entry in the Emergency Call Data Types
Registry
IANA has added "VEDS" 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].
14.3. New Action Values
This document adds new values for the "action" attribute of the
<request> element in the "Emergency Call Action" registry created by
[RFC8147].
+---------------+-------------------------+
| Name | Description |
+---------------+-------------------------+
| msg-static | Section 9.1 of RFC 8148 |
| | |
| msg-dynamic | Section 9.1 of RFC 8148 |
| | |
| honk | Section 9.1 of RFC 8148 |
| | |
| lamp | Section 9.1 of RFC 8148 |
| | |
| enable-camera | Section 9.1 of RFC 8148 |
| | |
| door-lock | Section 9.1 of RFC 8148 |
+---------------+-------------------------+
Table 1: Emergency Call Action Registry New Values
14.4. Emergency Call Static Messages Registry
This document creates a new sub-registry called "Emergency Call
Static Messages" in the "Emergency Call Metadata/Control Data"
registry established by [RFC8147]. Because 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", which requires 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, or 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:
ID: An integer identifier to be used in the "int-id" attribute of a
metadata/control <request> element.
Message: The text of the message. Messages are listed in the
registry in English; vehicles are expected to implement
translations into languages supported by the vehicle.
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 value 0 is reserved; usable messages
start with 1.
The initial set of values is listed in Table 2.
+----+--------------------------------------------------------------+
| ID | Message |
+----+--------------------------------------------------------------+
| 0 | Reserved |
| | |
| 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. |
+----+--------------------------------------------------------------+
Table 2: Emergency Call Static Messages Registry Initial Values
14.5. Emergency Call Vehicle Lamp IDs Registry
This document creates a new sub-registry called "Emergency Call
Vehicle Lamp IDs" in the "Emergency Call Metadata/Control Data"
registry established by [RFC8147]. 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:
Name: The identifier to be used in the "element-id" attribute of a
metadata/control <request> element.
Description: A description of the lamp (light).
The initial set of values is listed in Table 3.
+----------------+---------------------------------------------+
| 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 |
+----------------+---------------------------------------------+
Table 3: Emergency Call Lamp ID Registry Initial Values
14.6. Emergency Call Vehicle Camera IDs Registry
This document creates a new sub-registry called "Emergency Call
Vehicle Camera IDs" in the "Emergency Call Metadata/Control Data"
registry established by [RFC8147]. 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:
Name: The identifier to be used in the "element-id" attribute of a
control <request> element.
Description: A description of the camera.
The initial set of values is listed in Table 4.
+-------------+-----------------------------------------------------+
| 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 |
| | rearview mirror or blind spot view) |
| | |
| right-rear | Shows view to the right and behind (e.g., right- |
| | side rearview mirror or blind spot view) |
| | |
| forward | Shows what is in front of the vehicle |
| | |
| rear-wide | Shows what is behind the vehicle (e.g., used by |
| | rear-collision detection systems), separate from |
| | backup view |
| | |
| lane | Used by systems to identify road lane and/or |
| | monitor the 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 |
+-------------+-----------------------------------------------------+
Table 4: Emergency Call Vehicle Camera IDs Registry Initial Values
14.7. The EmergencyCallData.VEDS INFO Package
This document registers the EmergencyCallData.VEDS INFO package in
the "Info Packages Registry".
Both endpoints (the IVS and the PSAP equipment) include
"EmergencyCallData.VEDS" in a Recv-Info header field per [RFC6086] to
indicate the ability to receive SIP INFO messages carrying data as
described here.
Support for the EmergencyCallData.VEDS INFO package indicates the
ability to receive NG-ACN-related body parts as specified in this
document.
A SIP INFO request message carrying data related to an emergency call
as described in this document has an Info-Package header field set to
"EmergencyCallData.VEDS" per [RFC6086].
The requirements of Section 10 of [RFC6086] are addressed in the
following sections.
14.7.1. Overall Description
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 User Agents (UAs) can use the INFO
package.
SIP INFO requests associated with the EmergencyCallData.VEDS INFO
package carry data associated with emergency calls as defined in 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.
14.7.2. Applicability
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 they are 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 the notifier have occurred, whereas
what's needed here is two-way communication of data related to the
emergency dialog. Use of 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 the
Message Session Relay Protocol (MSRP) as transport) would be
disproportionately large.
Based on the analyses, the SIP INFO method was chosen to provide for
mid-call data transport.
14.7.3. INFO Package Name
The INFO package name is EmergencyCallData.VEDS.
14.7.4. INFO Package Parameters
None
14.7.5. SIP Option-Tags
None
14.7.6. INFO Request Body Parts
The body of an EmergencyCallData.VEDS INFO package is a multipart
body containing zero or one application/EmergencyCallData.VEDS+xml
parts (containing a VEDS data block), zero or more application/
EmergencyCallData.Control+xml (containing a metadata/control object)
parts, and zero or one application/EmergencyCallData.eCall.MSD parts
(containing an MSD). 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]; in addition, to align 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, metadata/control block, or MSD is always enclosed in a
multipart body part (even if it would otherwise be the only body part
in the SIP message). The outermost multipart that contains only body
parts associated with the INFO package has a Content-Disposition
value of "Info-Package".
Service providers in the call path are not expected to add Additional
Data [RFC7852] to SIP INFO requests (as they would to an initial
INVITE request).
14.7.7. INFO Package Usage Restrictions
Usage is limited to vehicle-initiated emergency calls as defined in
this document.
14.7.8. Rate of INFO Requests
The SIP INFO request is used within an established emergency call
dialog to send requests, updated data, or an acknowledgment. Because
requests are normally sent only on manual action of the PSAP call
taker (who suspects some aspect of the vehicle state has changed) and
updated data is sent only when an aspect of previously sent data has
changed, the rate of SIP INFO requests associated with the
EmergencyCallData.VEDS 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).
14.7.9. INFO Package Security Considerations
The MIME media type registrations for the data blocks that can be
carried using this INFO package contains a discussion of the security
and/or privacy considerations specific to that data block. See
Sections 12 and 13 for information on the security and privacy
considerations of the data carried in vehicle-initiated emergency
calls.
14.7.10. Implementation Details
See Sections 7 and 8 for protocol details.
14.7.11. Examples
See Section 11 for protocol examples.
15. References
15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC6086] Holmberg, C., Burger, E., and H. Kaplan, "Session
Initiation Protocol (SIP) INFO Method and Package
Framework", RFC 6086, DOI 10.17487/RFC6086, January 2011,
<http://www.rfc-editor.org/info/rfc6086>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>.
[RFC6881] Rosen, B. and J. Polk, "Best Current Practice for
Communications Services in Support of Emergency Calling",
BCP 181, RFC 6881, DOI 10.17487/RFC6881, March 2013,
<http://www.rfc-editor.org/info/rfc6881>.
[RFC7303] Thompson, H. and C. Lilley, "XML Media Types", RFC 7303,
DOI 10.17487/RFC7303, July 2014,
<http://www.rfc-editor.org/info/rfc7303>.
[RFC7852] Gellens, R., Rosen, B., Tschofenig, H., Marshall, R., and
J. Winterbottom, "Additional Data Related to an Emergency
Call", RFC 7852, DOI 10.17487/RFC7852, July 2016,
<http://www.rfc-editor.org/info/rfc7852>.
[RFC8147] Gellens, R. and H. Tschofenig, "Next-Generation Pan-
European eCall", RFC 8147, DOI 10.17487/RFC8147, May 2017,
<http://www.rfc-editor.org/info/rfc8147>.
[VEDS] APCO International, "Vehicular Emergency Data Set (VEDS)",
Version 3.0, Prepared by the Advanced Automatic Crash
Notification (AACN) Joint APCO/NENA Data Standardization
Working Group, February 2012, <https://www.apcointl.org/
resources/telematics/aacn-and-veds.html>.
15.2. Informative references
[Bluetooth]
Bluetooth Special Interest Group (SIG), "Bluetooth
Specifications", <https://www.bluetooth.com/
specifications>.
[RFC5012] Schulzrinne, H. and R. Marshall, Ed., "Requirements for
Emergency Context Resolution with Internet Technologies",
RFC 5012, DOI 10.17487/RFC5012, January 2008,
<http://www.rfc-editor.org/info/rfc5012>.
[RFC5069] Taylor, T., Ed., Tschofenig, H., Schulzrinne, H., and M.
Shanmugam, "Security Threats and Requirements for
Emergency Call Marking and Mapping", RFC 5069,
DOI 10.17487/RFC5069, January 2008,
<http://www.rfc-editor.org/info/rfc5069>.
[RFC6443] Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,
"Framework for Emergency Calling Using Internet
Multimedia", RFC 6443, DOI 10.17487/RFC6443, December
2011, <http://www.rfc-editor.org/info/rfc6443>.
[RFC7378] Tschofenig, H., Schulzrinne, H., and B. Aboba, Ed.,
"Trustworthy Location", RFC 7378, DOI 10.17487/RFC7378,
December 2014, <http://www.rfc-editor.org/info/rfc7378>.
[triage-2008]
National Center for Injury Prevention and Control,
"Recommendations from the Expert Panel: Advanced Automatic
Collision Notification and Triage of the Injured Patient",
Centers for Disease Control and Prevention, 2008,
<https://stacks.cdc.gov/view/cdc/5304/>.
[triage-2011]
National Center for Injury Prevention and Control,
"Guidelines for Field Triage of Injured Patients:
Recommendations of the National Expert Panel on Field
Triage", Centers for Disease Control and Prevention,
January 2012, <https://www.cdc.gov/mmwr/preview/mmwrhtml/
rr6101a1.htm>.
Acknowledgments
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 preliminary draft versions of the
original document that later evolved into this document.
Authors' Addresses
Randall Gellens
Core Technology Consulting
Email: rg+ietf@coretechnologyconsulting.com
URI: http://www.coretechnologyconsulting.com
Brian Rosen
NeuStar, Inc.
470 Conrad Dr
Mars, PA 16046
United States of America
Email: br@brianrosen.net
Hannes Tschofenig
Individual
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at