Network Working Group A. Petrescu, Ed.
Internet-Draft CEA, LIST
Intended status: Informational J. Huang
Expires: March 24, 2016 Huawei Technologies
T. Ernst
Mines ParisTech
R. Buddenberg
" "
September 21, 2015
Cooperative Adaptive Cruise Control and Platooning at SDOs and Gap
Analysis
draft-petrescu-its-cacc-sdo-03.txt
Abstract
This document describes the use-cases of Cooperative Adaptive Cruise
Control, and Platooning, as defined by several Standards Development
Organizations such as ETSI, IEEE P1609, SAE, 3GPP, ISO and FirstNet.
C-ACC and Platooning involve concepts of direct vehicle-to-vehicle,
and device-to-device communications, which are developped at least by
3GPP and precursory by the METIS EU project. They are illustrated
very clearly in emergency settings such as FirstNet.
IP messages - instead of link-layer messages - are pertinent for
C-ACC and Platooning use-cases because applications for road safety
such as WAZE, iRezQ and Coyote (currently involving infrastructure)
are IP messages, and proved succesful in deployments. Applications
such as Sentinel are direct between vehicles but are not IP,
currently.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. ETSI ITS C-ACC and Platooning use-case and reqs . . . . . . . 4
4. IEEE P1609 perspective on communications for C-ACC and
Platooning . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. SAE perspective on C-ACC and Platooning . . . . . . . . . . . 5
6. 3GPP SDO and EU projects using LTE Device-to-Device concepts 5
6.1. 3GPP . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.2. METIS . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. ISO perspective on V2V . . . . . . . . . . . . . . . . . . . 7
8. FirstNet EMS use of LTE and IP in V2I2V . . . . . . 8
9. Internet apps: WAZE, iRezQ, Coyote, Sentinel . . . . . . . . 9
10. Gap Analysis . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Neighbor Discovery protocol . . . . . . . . . . . . . . 10
10.2. Mobile IP protocol . . . . . . . . . . . . . . . . . . . 10
10.3. AODV protocol . . . . . . . . . . . . . . . . . . . . . 11
11. Security Considerations . . . . . . . . . . . . . . . . . . . 11
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 11
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
14.1. Normative References . . . . . . . . . . . . . . . . . . 11
14.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
Cooperative Adaptive Cruise Control and Platooning are two use-cases
described recently at particular Standards Development Organizations.
C-ACC is understood as a formation of chains of automobiles following
each other at constant speed, in an automated manner. This is to
offer more comfort for human drivers on long journeys on straight
roads.
Simple 'cruise control' was the automation of speed maintenance at a
single automobile (increase torque if uphill, smoothly brake
downhill, such as to maintain constant speed). The term "Adaptive
Cruise Control" was used earlier in related ISO standards. The
concept of C-ACC aims at the same level of automation but in a
cooperative manner between several vehicles: while in CC mode, when a
vehicle in front slowly decelerates, this vehicle will also do, such
as to maintain distance, and relieve driver from taking control over.
Platooning is a concept related to larger vehicles following each
other. The goal in this case is more than just comfort - large gains
are expected in terms of gas consumption: when large vehicles can
follow each other at small distance the air-drag is much lower,
reducing gas consumption, tyre use, and more.
Both C-ACC and Platooning must rely on data packet exchanges between
vehicles (in addition to more immediate indices like signal echoes -
radars and cameras). These exchanges may happen in a direct manner
(direct vehicle to vehicle communications) or with assistance from a
fixed communication infrastructure (vehicle-to-infrastructure-to-
vehicle communications).
This document presents the C-ACC and Platooning use-cases as
described at ETSI, IEEE, SAE, ISO, 3GPP and more. These use-cases
are widely accepted as Vehicle-to-Vehicle applications.
In emergency settings the concepts of direct vehicle-to-vehicle
communications are of paramount importance. FirstNet, an overarching
example described later in this document, covers V2V, V2I and V2I2V
communication needs, together with strong security requirements.
In the market, several systems for vehicular communications have
demonstrated a number of benefits in the context of vehicle-to-
vehicle communications. The Sentinel system is used between vehicles
to warn each other about approach; the WAZE application on
smartphones created a community where users influence others about
the route choice; the iRezQ and Coyote applications communicate
between vehicles, via infrastructure, about route risks.
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In [I-D.petrescu-ipv6-over-80211p] the use of IPv6 over 802.11p is
described. This link layer is potentially used in direct vehicle-to-
vehicle communications. It is obviously not the only link layer
pertinent for V2V.
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 RFC 2119 [RFC2119].
C-ACC: Cooperative Adaptive Cruise Control.
V2V: Vehicle-to-Vehicle communications.
3. ETSI ITS C-ACC and Platooning use-case and reqs
ETSI Technical Committee Intelligent Transportation Systems (ETSI TC
ITS) is responsible for the development and maintenance of standards,
specifications and other reports on the implementation of V2V
communications in Cooperative ITS. Its scope extends from the
wireless access (excluding issues in radio frequency) to generic
services and corresponding applications. Security and tests
specifications are also covered. This responsibility is reflected in
the organization with five working groups that make up the committee.
Among them, WG1 is responsible of the facilities and applications
needs.
Under the EU Mandate M/453, TC ITS has developed a minimum set of
standards (Release 1) for systems interoperability during initial
deployment. The list of standards and specifications are provided in
the publicly available report ETSI TR 101 607. A second release of
the standards is being prepared. It should support more complex use
case, possible integration with other technologies as well as a more
elaborate consideration of access networks other than the ITS-G5
(European profile of IEEE 802.11p). The TC ITS WG1 is currently
working on two separate work items for pre-standardization studies on
C-ACC (DTR/ITS-00164) and Platooning (DTR/ITS-00156). The scope of
the target technical reports is to describe the relevant use cases
that could be enabled by Cooperative ITS, to survey the existing
related standards and to identify what new features and standards are
needed to support these use cases.
4. IEEE P1609 perspective on communications for C-ACC and Platooning
One perspective from IEEE P1609 is that Cooperative Adaptive Cruise
Control (CACC) represents an "application". An application is
typically software whose communication needs are situated at the
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upper layers of a communication stack - e.g. the Application Layer.
As such it is little relevant to IEEE P1609; P1609 is concerned more
with physical, data-link and network communication layers. On
another hand, a perspective well considered in IEEE P1609 is that
C-ACC and Platooning may be more relevant to the Society of
Automotive Engineers.
5. SAE perspective on C-ACC and Platooning
The Society of Automotive Engineers (SAE) concerns itself with data
exchanges and host system requirements for applications. The SAE
DSRC Technical Committee (DSRC: Dedicated Short-Range Communications)
is working on C-ACC within the Cooperative Vehicle Task Force. In
addition, the SAE On-Road Vehicle Automation Committee is working on
a use-case relevant to C-ACC (under development) towards realization
of a reference architecture.
The SAE DSRC TC activities are in cooperative agreement to ETSI ITS
WG1, as there are information exchanges between the two bodies.
6. 3GPP SDO and EU projects using LTE Device-to-Device concepts
6.1. 3GPP
Proximity Service (ProSe) allows a UE to discover and communicate
with other UEs that are in proximity directly or with the network
assistance. This may also be called as Device-to-Device (D2D)
communication. ProSe is intended for purposes such as public
security, network offloading, etc [GPP-TR-22-803].
The ProSe Communication path could use E-UTRAN or WLAN. In the case
of WLAN, only ProSe-assisted WLAN direct communication (i.e. when
ProSe assists with connection establishment management and service
continuity) is considered [GPP-TS-22-278].
The work on ProSe is initiated in 3GPP Release 12. Some enhancements
are being added in Release 13, e.g. Restricted ProSe Discovery.
Some use cases are identified in [GPP-TR-22-803], but most of which
are intended for common mobile users, e.g. walking people, not for
vehicles moving at high speed, for example the latency in ProSe
communication may be a problem for V2X.
Although ProSe does not support V2X communication before Release 14,
but it has some very good characteristics which makes it a good
candidate for V2X besides DSRC. ProSe communication does not have to
go through the EPC, which will significantly reduce the latency.
ProSe also support group and broadcast communication by means of a
common communication path established between the UEs.
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There are some efforts at 3GPP Release 14, trying to address V2X
communication. The efforts are proposed by experts in the industry,
and may be subject to change. These efforts include the following:
1. To address the V2X use cases in 3GPP. The use cases may have
been defined by other SDOs, e.g. ETSI ITS, 3GPP can reference to
them. Requirements for V2X communication should also be
considered, for example network delay, packet loss rate, etc.
[METIS-D1.1] already propose some requirements, but those are
intended for future mobile network, which may be too critical for
LTE.
2. To address V2X applications and messages. The messages may
include message defined in SAE J2735, ETSI Cooperative Awareness
Message (CAM) and ETSI Decentralized Environmental Notification
Message (DeNM). The messages defined by different SDOs might be
similar to each other.
3. Study of possibility to add enhancements to ProSe, and to make it
able to support and enhance DSRC.
4. Study of using existing LTE technologies for unicast/multicast/
broadcast communication.
The above are just some examples, not an exhaustive list.
[GPP-TR-22-885] studies many V2X services using LTE. These services
include V2V communication (e.g. Cooperative Adaptive Cruise Control,
Forwarding Collision Warning, etc), V2I/V2N communication (e.g. Road
Safety Services) and vehicle to pedestrian communication. The
services' pre-condition, service flow, post-condition, including some
network communication requirements, such as delay, messages frequency
and message size, are ayalyzed.
In [GPP-TR-22-885], Cooperative Adaptive Cruise Control (CACC) allows
a vehicle to join a group of CACC vehicles, and the benefits are to
improve road congestion and fuel efficiency. Member vehicles of CACC
group should periodically broadcast messages including the CACC group
information, such as speed and gap policies, etc. If a vehicle
outside the group wants to join, it should send a request to the
group. If a member of the CACC group accepts the request, it should
send a confirm message and provide necessary distance gap; and
members of the group will update their group information. When a
Member wants to leave the CACC group, it should broadcast a goodbye
message, and the driver assumes control of the vehicle.
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6.2. METIS
METIS is co-funded by the European Commission as an Integrated
Project under the Seventh Framework Programme for research and
development (FP7).
METIS defines test cases and requirements of "Traffic safety and
efficiency", as depicted in [METIS-D1.1], which is intended for 5G in
2020 but may also be applicable for LTE and beyond.
The use cases include:
1. Dangerous situation that can be avoided by means of V2V
communications.
2. Dangerous situation with vulnerable road users (i.e. pedestrians,
cyclists,...) that can be avoided by means of V2D communications.
"D" can denote any cellular device that the vulnerable road user
may carry (e.g. smart phone, tablet, sensor tag).
3. Assistance services that can improve traffic efficiency by means
of V2X communications, e.g. traffic sign recognition and green
light assistance.
4. Platooning (or road trains) in an autonomous manner to increase
traffic flows and reduce fuel consumption and emissions.
5. Highly automated vehicles.
To support the above use cases, METIS works out the corresponding
network requirements, such as E2E latency should be within 5ms,
required data rates for various scenarios, service ranges in
highway/rural/urban scenarios, etc.
7. ISO perspective on V2V
The International Standards Organization's Technical Committee 204
"Intelligent transport systems" (ISO TC204, in short) has specified a
communication architecture known as the "ITS station reference
communication architecture" [ISO-21217]. This communication
architecture covers all layers (access technologies, network,
transport, facilities and applications) of a typical communications
protocol stack. It is designed to accommodate communications between
ITS stations engaged in ITS services. ITS stations can be deployed
in vehicles of any type, roadside infrastructure (traffic lights,
variable message signs, toll road gantries, etc.), urban
infrastructure (parking gates, bus stops, etc.) nomadic devices
(smartphones, tablets) and control centers (traffic control center,
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emergency call centers, data centers and services centers). The ITS
stations can be distributed in several nodes (e.g. an in-vehicle
gateway and a set of hosts attached to the internal in-vehicle
network). The ITS station architecture is designed to support many
kinds of wired and wireless access technologies (vehicular WiFi
802.11p, urban WiFi 802.11b/g/n/ac/ad; cellular networks; satellite;
infra-red, LiFi, millimeter wave, etc.)
The ISO ITS station architecture can thus support both broadcast and
unicast types of communication, vehicle-to-infrastructure
communications (road infrastructure using e.g. WiFi, or cellular
infrastructure using e.g. 3G/4G) and, most notably, direct vehicle-
to-vehicle communications.
The architecture includes the possibility to communicate using IPv6
[ISO-21210] or non-IP (ISO FNTP, currently being harmonized with IEEE
WAVE).
The ISO TC204/WG14 (Work Group 14 "Vehicle/Roadway Warning and
Control Systems") is developing a draft of international standard for
C-ACC systems. The focus is on vehicular system control, rather than
on communication media. The potential work item is in an early stage
of development; it may describe performance requirements or
validation through test procedures. It is considered that "C-ACC" to
be an expansion to the existing ACC concepts which have been
previously described in the document ISO 15622 "Adaptive Cruise
Control Systems". The potential C-ACC work item may require the
specific involvement of Vehicle-to-Vehicle communications and other
types of communications (I2V and more), in addition to requiring
active sensing involving radars and camera systems.
8. FirstNet EMS use of LTE and IP in V2I2V
FirstNet is a corporation housed inside the US Department of
Commerce. It gets capitalization budget from, among other sources,
sale of spectrum by the US FCC. It gets operating budget from sale
of services to state emergency services entities.
The specific use-cases for FirstNet include vehicle-to-vehicle,
vehicle-to-infrastructure and vehicle-to-infrastructure-to-vehicle
communications using in certain cases LTE and IP:
1. Emergency communications to vehicles from government entities
conveying, for example: weather warnings, road conditions,
evacuation orders. The government entities might include PSAPs
or mobile vehicles such as police cruisers.
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2. Instrumented emergency services vehicles such as ambulances. An
example is the ability to telemeter casualty (patient) data from
sensors attached to the casualty to a hospital emergency room.
3. Emergency communications from vehicles' occupants to government
entities such as Public Safety Access Points (PSAPs, also known
as 911 operators in US).
The National Public Safety Telecommunications Council describes
FirstNet as an emergency communications system (largely viewed
through the prism of the familiar Land Mobile Radio systems most
emergency services use.) The cellular telephone industry views
FirstNet as supplementary to an existing commercial cellphone system
(e.g. reusing the same towers and backhaul). Perhaps a better view
of FirstNet is as an extension of the Internet to emergency services
vehicles (including foot-borne).
It is clear that FirstNet overlaps to a large extent to the concepts
that have been discussed in vehicle-to-vehicle communications for
other purposes.
FirstNet has not been clear about its communication technology
choices to date. But LTE has been discussed as the most likely layer
2 protocol. A segregated segment of spectrum in the 700MHz band has
been set aside by Congressional action for emergency services and
control of that spectrum has been passed to FirstNet. There appear
to be no new protocols, development of which is fostered by FirstNet.
Several Internet applications would need rework to handle high
availability, security and assured access needs of emergency
services.
9. Internet apps: WAZE, iRezQ, Coyote, Sentinel
Applications using the Internet have been developped in the
particular context of vehicular communications. These applications
are designed for parties situated in vehicles. Their profile is less
of client-server kind, but more of peer-to-peer kind (vehicle to
vehicle).
Some use vehicle-to-infrastructure-to-vehicle IP paths, whereas
others involve direct vehicle-to-vehicle paths (without
infrastructure).
These applications are described in more detail in draft-liu-its-
scenario-00.txt issued on March 9th, 2015, authored by Dapeng Liu.
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10. Gap Analysis
It is generally agreed that an entire IP network is embedded in an
automobile. The embedded network is formed by at least two (and
generally up to 5) distinct IP subnets. In each of the subnets
several IP-addressable computers are currently enabled with IP
stacks.
The realization of V2V communications can happen by connecting
together two such embedded networks, each carried by a distinct
vehicle. With a direct connection, an IP Router in one vehicle
connects to an IP Router in another vehicle nearby. The maximum
distance between two such vehicles is dictated by the link layer
technology (e.g., with IEEE 802.11p OCB mode the distance may be up
to 800 metres). On another hand, an indirect connection may involve
the use of a Road-Side Unit fixed along the road, or a longer IP path
through a cellular network. It is expected that the shortest
latencies to be obtained with the most straightforward (direct)
connections rather than through-fixed-RSU through-cellular.
When two vehicles are connected to each other in this way, an IP
subnet is formed between the egress interfaces of Router embedded in
vehicles. There are several ways in which the IP path can be
established across this 1-hop subnet.
10.1. Neighbor Discovery protocol
Routers exchange Router Advertisement messages. An RA message
contains prefixes announced to be valid on one link. On another
hand, the prefix announced by an RA can not be equal to the prefix of
a same router but of one of its other interfaces. And this
represents the gap of the ND protocol - it can not realize V2V
topologies.
10.2. Mobile IP protocol
There are two modes of operation of a V2V topology. With a link
technology like IEEE 802.11b it is possible that one vehicle attaches
to another vehicle in "Access Point" mode, or alternatively in "ad-
hoc" mode. In "Access Point" mode (or Client-Server), the first
vehicle allocates an address, and potentially a prefix, to the second
vehicle. This latter may then use the Mobile IP protocol to inform
the first vehicle about is in-car prefix (use a Binding Update
message as if the Access Point vehicle were a Correspondent Node).
The gap is in that currently the Mobile IP protocol is not fully
specified to send BUs in that way.
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10.3. AODV protocol
The AODV protocol is a routing protocol used to build and find IP
paths in a MANET network. However, this protocol does not take into
account default routes. Default routes are extensively used in
current networks carried in vehicles. The good administration of
these routes simplify to a large extent the routing in such networks.
This represents a gap.
11. Security Considerations
All government-to-vehicle and vehicle-to-government communications
require authenticity; there will be no exceptions.
Some, but not all, communications from government-to-vehicle and
vehicle-to-government require confidentiality (some of these
requirements, such as medical data, have the force of law, many have
custom or respect as the requirements base).
These requirements pertain to the content.
12. IANA Considerations
mandatory
13. Contributors
Jim Misener (Qualcomm, SAE DSRC TC Chair), Masanori Misumi (Mazda,
ISO TC204/WG14 Convenor), Michelle Wetterwald (FBConsulting, ETSI
active member).
14. References
14.1. 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>.
14.2. Informative References
[GPP-TR-22-803]
3GPP, "Feasibility study for Proximity Services (ProSe)",
June 2013.
[GPP-TR-22-885]
3GPP, "Study on LTE Support for V2X Services", April 2015.
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[GPP-TS-22-278]
3GPP, "Service requirements for the Evolved Packet System
(EPS)", December 2014.
[I-D.petrescu-ipv6-over-80211p]
Petrescu, A., Pfister, P., Benamar, N., and T.
Leinmueller, "Transmission of IPv6 Packets over IEEE
802.11p Networks", draft-petrescu-ipv6-over-80211p-02
(work in progress), June 2014.
[ISO-21210]
ISO, "21210: TC ITS - WG CALM - IPv6 Networking -
International Standard", 2014.
[ISO-21217]
ISO, "21217: TC ITS - WG CALM - Architecture -
International Standard", 2014.
[METIS-D1.1]
Fallgren, M. and B. Timus, "Scenarios, requirements and
KPIs for 5G mobile and wireless system", April 2013.
Appendix A. ChangeLog
The changes are listed in reverse chronological order, most recent
changes appearing at the top of the list.
From -01 to -02:
o Added perspectives on C-ACC and Platooning from ETSI, SAE, and
IEEE P1609. Updated the perspective from ISO.
o Added Gap Analysis: what are the gaps between what existing
protocols ND, Mobile IP and AODV can do and what is needed to
realize a C-ACC and Platooning use-case with a V2V topology?
From nil to draft-petrescu-its-cacc-sdo-00.xml:
o initial version
Authors' Addresses
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Alexandre Petrescu (editor)
CEA, LIST
CEA Saclay
Gif-sur-Yvette , Ile-de-France 91190
France
Phone: +33169089223
Email: Alexandre.Petrescu@cea.fr
James Huang
Huawei Technologies
Shenzhen
China
Email: james.huang@huawei.com
Thierry Ernst
Mines ParisTech
Paris 75006
France
Email: Thierry.Ernst@mines-paristech.fr
Rex Buddenberg
" "
US
Email: buddenbergr@gmail.com
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