(2011!09!06) Introduction to Vehicular Networks for Enhanced Safety Assistance

8/16/2019 (2011!09!06) Introduction to Vehicular Networks for Enhanced Safety Assistance

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n ro uc on o e cu ar e wor s or

Enhanced Safety Assistance

Sept. 06, 2011

Institute of Logistics IT

Pusan National University

Han-You Jeong

CONTENTS

• ot vat on

• Tutorial on Vehicular Networking


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Motivation

Impacts of Road Accident s

Megat rend of Saf et y Assist ance

MOTIVATION- Casualties of Road Accidents

Worldwide, 1.2 million people are killed in road crashes

and as high as 50 million are injured every year.

: How man eo le are killed in the Ira War?

A: 100 ~ 150 thousand casualties

from 2003 to 2006 (Source: Wikipedia)


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MOTIVATION- Global Injury Mortality

MOTIVATION- Regional Distribution


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MOTIVATION- Megatrend of Safety Assistance

Past Safety SolutionsPresent Safety

Solutions

Future Safety

Solutions

SeriousAccident

SlightAccident

MinorImpact

Road Accident

Minor

Vehicular

Communications

Impact

Dangerous

Warning Recovery

Needs enough time to perceive, decide, and react to road environments

MOTIVATION- Past Safety Solutions against Road Accidents

Safety Belt Airbag Child Car Seat

Past safety solutions mostly focus on the reduction of the casualties.


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MOTIVATION- Statistics of Road Accidents

Past safety solutions reduce the fatalities, not road accidents.

MOTIVATION- Present Safety Solutions against Road Accidents

60 ~ 200 m 5 ~ 10 m30 ~ 50 m

The present safety solutions focus on the avoidance of road accidents.


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MOTIVATION- VIAC Project (VisLab, Parma Univ., Italy)

Intercontinental Autonomous Driving (July 10th ~ Oct. 26th 2010)

MOTIVATION- MBC News (Jan. 26, 2011)


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Tutorial on Vehicular Networkin

Character ist i cs of Vehicular Netw orks

Vehicular Netw ork Appl icat ions

SAE J2735

IEEE 160 9. x

IEEE 802 .1 1p

TUTORIAL ON VEHICULAR NETWORKING- Overview of Vehicular Networks

• A vehicular network is an example of mobile ad-hoc

networks (MANETs)

– No Limitation in Power Consumption and Computation

• A vehicular network supports – Safety Applications. e.g., Collision Warning

– Non-Safety Applications, e.g., Navigation

– Infotainment Applications, e.g., Internet Access, LBS, etc.

• A message of a safety application is either a periodic or

an event-based broadcast message.


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TUTORIAL ON VEHICULAR NETWORKING- Characteristics: Location-based Message Delivery

• Location-based Message Delivery

Vehicle Collision

Region of Interest (ROI)

– Assume that a safety application informs all vehicles arriving at

the accident location within 5 min. – ROI of an Urban Road (54 Km/h): 4.5 Km

– ROI of a Highway (108 Km/h): 9 Km

– Needs a Multi-hop Message Delivery Mechanism

TUTORIAL ON VEHICULAR NETWORKING- Characteristics: Dynamic Network Connectivity

40 m/sec40 m/sec

• Dynamic Network Connectivity

40 m/sec

400 m

40 m/sec

ommun ca on

– e ransm ss on range s m, e connec on me e ween

two vehicles is about 10 sec, which is much shorter than Wi-Fi

connection time!!!

– Predictable Mobility


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TUTORIAL ON VEHICULAR NETWORKING- Characteristics: Wide-Range of Vehicle Density

• Wide-Range of Vehicle Density

– Intermittent Connectivit

Low Vehicle Density High Vehicle Density

–

Scale to Large Network• If the inter-car distance is 10 m on average at the intersection of highway with

four lanes for each direction, a vehicle can have 640 neighbor vehicles!!!

– Vehicle Density based on the Safe Distance

• Urban Road [Two Lanes per Direction, 60 Km/h (35 m)] : 95 (Vehicles/Km)

• Highway [Two Lanes per Direction, 100 Km/h (77 m)] : 48 (Vehicles/Km)

TUTORIAL ON VEHICULAR NETWORKING- Vehicular Network Architecture

Camera

Roadside Unit (RSU)Backhaul

V2I CommV2V Comm.

.

• Entities in Vehicular Networks

– n oar n t

• A communication device at each vehicle

– Roadside Unit (RSU)

• Connects a vehicular network to an infrastructure network

• Acts similar to a wireless LAN access point (AP)


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TUTORIAL ON VEHICULAR NETWORKING- Vehicular Network Apps: Visibility Warning/Assistant

V2V Comm.V2V Comm.

• xamp e o s y arn n ss s an

– Visibility Enhancement

– Blind-Spot Warning

– Emergency Electronic Brake Light (EEBL)

TUTORIAL ON VEHICULAR NETWORKING- Vehicular Network Apps: Intersection Safety

: Road Sensors

: Traffic Controller

: RSU

: WAVE/DSRC Link

• Example of Intersection Safety

– Sign/Signal Notification

– Sign/Signal Violation Warning

– Intersection Collision Warning


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TUTORIAL ON VEHICULAR NETWORKING- Protocol Architecture

• Protocol Architecture of Vehicular Networks

TUTORIAL ON VEHICULAR NETWORKING- SAE J2735 DSRC Message Set

• SAE J2735 standard defines standard message sets, dataframes, and data elements of vehicular a lications

– 15 Messages/72 Data Frames/146 Data Elements

• Message Types of SAE J2735

– Each data item is encoded in TLV(Type/Length/Value) format

– List of Messages

• A La Carte (ACM) /Basic Safety Message (BSM) /Common Safety Request(CSR)/ Emergency Vehicle Alert (EVA)/Intersection Collision Avoidance (ICA)/

Map Data (MAP)/NMEA Corrections (NMEA)/Probe Data Management

(PDM)/Probe Vehicle Data (PVD)/Roadside Alert (RSA)/RTCM Corrections

(RTCM)/Signal Phase and Timing Message (SPAT)/Signal Request Message(SRM)/Signal Status Message (SSM)/Traveler Information Message (TIM)


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TUTORIAL ON VEHICULAR NETWORKING- Basic Safety Message (BSM)

• A basic safety message (BSM) conveys Core State

– Also known as the Beacon Message

– Part I – Core State Information with 10 Hz transmission rate• Latitude/Longitude/PositionalAccuracy/TransmissionandSpeed/Heading …

– Part II – Optional Data Elements and Frames

• EventFlags/PathHistory/PathPrediction/RTCMPackage

– The total size of Part I message is 43 byte.

• e tota rame s ze s yte, nc u ng ea er ytes , ea er

(28 bytes), and PLCP Header (5 bytes).

TUTORIAL ON VEHICULAR NETWORKING- Message Dispatcher

• Message Dispatcher

– assimilates data elements from all the on-board applications and

constructs a single message in the Tx side.

– is responsible for separating and disseminating data elements to

all on-board applications in the Rx side.


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TUTORIAL ON VEHICULAR NETWORKING- IEEE 1609.x Standard Overview

• IEEE 1609.x Standards

– IEEE 1609.0 WAVE architecture

– IEEE 1609.1 WAVE resource management

– IEEE 1609.2 Security defines protocols for optional message

authentication and encryption

– IEEE 1609.3 WAVE Short Message Protocol (WSMP) defines asimple alternative to network and transport layer protocols

– IEEE 1609.4 Multi-Channel Operation defines how a given,

time, which is called a channel-switching protocol – IEEE 1609.11 Electronic Toll/Free Collection

TUTORIAL ON VEHICULAR NETWORKING- IEEE 1609.3 WAVE Short Message Format

• WAVE Short Message Protocol (WSMP)

– Defines a standard for directly sending many packets over the air

from the source to the destination

– IEEE 1609.3 defines the WAVE Short Messages (WSMs) and the

WAVE Service Advertisements (WSAs) packet formats – Both messages can be transmitted in all channels, whereas the IP

packets are not allowed on the CCH

Provider Service IDentifier


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TUTORIAL ON VEHICULAR NETWORKING- IEEE 1609.3 WAVE Service Advertisements (WSAs)

1 1Var.1

Provider Service Table WAVE Routing AdvertisementWAVE

version

Extension

fields

RepeatsTransmit Power Used

2D/3D Location

Channel InfoService Info

2 16 1 16 166

Routerlifetim

e

IpPrefixPrefixlength

Defaultgatewa

y

PrimaryDNS

Gateway MAC

address

Extension

fields

Var.

KEY

OptionalField

Lengths in octets

1

WAVEElemen

t ID

IP configuration info

Secondary DNS

KEY

Extension fields

Optional

Lengths in octets

4 1 1 1 1 1

Channel

Number

Adapt-able

DataRate

TxPwr_Level

May be

repeatedMay be

repeated

11

PSIDServicePriority

Channel

Number

Extension

fields

Var.

Extension

fields

Var.1

WAVEElemen

t ID

WAVEElemen

t ID

Info about available services Info about service channels

PSC

IPv6 Address

Service Port

Provider MAC AddressEDCA Parameter Set

TUTORIAL ON VEHICULAR NETWORKING- IEEE 1609.4 Multi-Channel Operation

• IEEE 1609.4 defines a mechanism by which a device with

one or more radios can effectively switch among DSRC CHs

– With the rendezvous channel CCH and time-division o eration

– All devices have access to a common time source, the universalcoordinated time (UTC), in a GPS signal

• The CCH is primarily used for the WAVE short messages(WSMs) and the WAVE service advertisements (WSAs)

Sync Interval = 100 msec

Start of every UTC second Start of every UTC second

CCH Interval

= 50 msecSCH Interval= 50 msec

Guard Interval = 4 msec


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TUTORIAL ON VEHICULAR NETWORKING- Characteristics of IEEE 802.11p

• Characteristics of IEEE 802.11p

IEEE 802.11 Wi-Fi Cellular Mobile WiMAX

Data rate 3-27Mbps 6-54Mbps < 2 Mbps 1-32 Mbps

Latency < 50ms Seconds Seconds ?

Range < 1 Km < 100m < 10 Km < 15 Km

Mobility > 100 Km/h < 5mph > 100 Km/h > 100 Km/h

NominalBandwidth

10MHz 20MHz < 3MHz < 10MHz

FrequencyBand

5.85-5.925GHz

(ITS-RS)

2.4GHz, 5 GH

z (ISM)

800MHz, 1.9GH

z 2.5 GHz

IEEE std. 802.11p 802.11 N/A 802.16e

TUTORIAL ON VEHICULAR NETWORKING- Amendments to the Connection Setup in WAVE/DSRC

• Nodes in vehicular networks are free to use the

infrastructure and independent BSS concepts in 802.11

–

– It takes at least 0.2 sec to setup a connection in 802.11 WLAN

• There is a strong desire in vehicular networks to define

lightweight rules for accessing the medium

– There is no connection setup before STAs exchange data frames

– The BSSID field of an OCB frame is set of 0xFFFFFF, which iscalled the wildcard value

– Does not use authentication, association, and a beacon frameto announce a BSS in the MAC sub-layer


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TUTORIAL ON VEHICULAR NETWORKING- Adaptive Modulation and Coding in WAVE/DSRC

• WAVE/DSRC will more commonly use the 10 MHz channel

– 8 μsec OFDM symbol leads to a data rate of 125 Kbps per symbol

– .

– Data rate options in a DSRC 10 MHz OFDM channel

Data Rate(Mbps)

Modulation Coding RateCoded bits per

subcarrierCoded bits perOFDM symbol

Data bits perOFDM symbol

3 BPSK 1/2 1 48 24

4.5 BPSK 3/4 1 48 36

6 QPSK 1/2 2 96 48

9 QPSK 3/4 2 96 72

12 16-QAM 1/2 4 192 96

18 16-QAM 3/4 4 192 144

24 16-QAM 2/3 6 288 192

27 64-QAM 3/4 6 288 216

TUTORIAL ON VEHICULAR NETWORKING- DSRC Spectrum in US

• US FCC allocates 75 MHz of spectrum for DSRC servicesfrom 5.850 GHz to 5.925 GHz

– Ch. 178 in the middle of DSRC s ectrum is the control channel(CCH) and the other six channels are service channels (SCHs)


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Documents

(2011!09!06) Introduction to Vehicular Networks for Enhanced Safety Assistance