J. Parikh

V2V Communication for Safety, Information and

Entertainment

J. Parikh

General Motors R&D

Nov. 14, 2006

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Content

•Introduction and Background

•DSRC Wireless Communication

•Safety, Information and Entertainment Applications

•Technical Challenges

•Current and Future Research Work

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Introduction

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What are wireless systems?

•Wireless systems encompass those technologies that enable communications of voice or data without a direct-wired connection.

•These currently employ much of the electromagnetic spectrum from very low radio frequencies (tens of kHz) through visible light (1012 kHz).

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Communication on Road…

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Today’s Vehicles - Wireless Data Interfaces

Bluetooth802.11802.15.3

GPSDigitalRadio

SatelliteA/V

DSRC

Ad HocNetworks

PCS/Cellular

802.11WLAN

802.15.3WPAN

TerrestrialBroadcast

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Integrated Traffic Management Systems

Transit

Dynamic Signal Control

911 and Other Call

Center

Traveler AssistanceVARIABL

E MESSAGE SIGNS

Trip Planning

En-Route Traffic Advisory and Assistance

Commercial Vehicle Operation

Central Control Center

DSRC and Other Communications

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DSRC – Wireless Communication

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Dedicated Short Range Communication

“… a short to medium range (1000 meters) communications service that supports both public safety and private operations in vehicle-to-vehicle and vehicle-to-roadside communication environments by providing very high data transfer rates where minimizing latency in the communication link and isolating relatively small communication zones is important.”

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Don’t Confuse With Existing DSRC

915 MHz

• Range < 30 meters• Data rate = 0.5 mbps• Designed for ETC, but can be

used for other applications• Single unlicensed channel• Requires special (custom)

chip set & software• Vehicle to Infrastructure• Command-response

5.9 GHz

• Range to 1000 meters• Data rate 6 to 27 mbps• Designed for general internet

access, can be used for ETC• 7 licensed channels• Uses open off-the-shelf chip set

& software• V2V and V2I• Command-response & peer to

peerBased on IEEE 802.11a

• High speed impacts physical layer

• Very latency (<50ms) – MAC impact

• Random MAC addresses for privacy

• IPv6 for network layer• Support for in-car networks

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Standards Program

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5.9 GHz Channel Plan

Frequency (GHz)

5.8

50

5.8

55

5.8

60

5.8

65

5.8

70

5.8

75

5.8

80

5.8

85

5.8

90

5.8

95

5.9

00

5.9

05

5.9

10

5.9

15

5.9

20 5.9

25

5.8

25

5.8

30

5.8

35

5.8

40

5.8

45

Canadian Special License Zones*

Uplink

Downlink

Ch 172 Ch 174 Ch 176 Ch 180 Ch 184Ch 182Ch 178

Public Safety/ Private

Public Safety IntersectionsControl

Channel

PublicSafety/Private

PublicSafety/Private

IntersectionsControl Hi Av-Low LatDedicated Public Safety

Short Rng ServiceMed Rng ServiceShared Public Safety/Private

Public Safety/ Private

Public SafetyVeh-Veh

40 dBm

33 dBm

23 dBm

Power Limit

Power Limit

Power Limit

43 dBm

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– DSRC Applications – Safety, Information &

Entertainment

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Classes of Application

• Active Safety – Actively monitors the environment around the vehicle in order to warn

• Driver Assistance – Assists drivers in the operation of the vehicle either by relieving them of certain driving tasks or by providing them with useful information about the surrounding environment.

• Traffic Efficiency – Provides information to the managers of the roadway infrastructure to enable more efficient control and maintenance of the roadways.

• Infotainment/Commercial – Provides drivers with various types of communication services in order to improve driver productivity, entertainment, and convenience.

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Safety Application Areas

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Example Traffic Scenario – Safety Application

• Immediate spread of knowledge to surrounding vehicles within broadcast range

Exit

• Incidence notification to OnStar• Information relay to other vehicles for

dynamic route guidance

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V2V/V2I Safety Application

V-V messages

Avoiding rear-end collision

Avoiding lane change collision

Vehicle brakes hard Collision mitigation

Traffic signal

Avoiding intersection collision

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Traffic Probe - Information

Report GPS Time SpeedLon, LatHeading

GPS

Report GPS Time SpeedLon, LatHeading

Report GPS Time SpeedLon, LatHeading

Report GPS Time SpeedLon, LatHeading

Report GPS Time SpeedLon, LatHeading

Report GPS Time SpeedLon, LatHeading

Report GPS Time SpeedLon, LatHeading

•Form small clusters of vehicles

•Aggregate data within cluster

•Transmit aggregated values

Vehicles report speed, position and heading

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Roadcasting - Entertainment

A prototype system that allows anyone to have their own radio station, broadcasted among wirelessly capable cars (devices) of an ad-hoc wireless network. The system can become aware of individual preferences and is able to choose songs and podcasts that people want to hear, on their own devices and car stereos.

Visit http:roadcasting.org to learn more…

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Application Categories

Applications

Network Configurations

V2V V2V + Ad-Hoc

Ad-Hoc + Other wireless

(Pervasive)

Active Safety Security X X Productivity X Convenience X Entertainment X

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Technical Challenges

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“Ad hoc” Routing Protocols

• Proactive, Reactive, Hybrid Goal: Find a node given a logical address based

on a flat addressing hierarchy Method of Operation: Flooding Mechanism: Handshaking - Route request, route

reply, route maintenance and route erasure

Ad hoc Routing Protocols

Proactive/Table Driven Reactive/On-Demand

DSDV OLSRCGSR STAR

Hybrid

ABR DSR TORA AODV RDMAR CBRP

ZRP/GRID/LAR

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Ad hoc Routing Protocols – Quick Overview• AODV Ad hoc On-demand Distance Vector

Reactive Forwarding addresses stored in routers Lightweight and flexible

• DSR Dynamic Source Routing Reactive Packet header contains route Independent of router state

• OLSR Optimized Link State Routing Proactive Similar to link state routing with clusters Bounded routing overhead

• GRID Geographic Routing Protocol Controlled flooding based on geographic coordinates Requires location service

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OLSR: Reduced Flooding Through Hierarchy

24 retransmissions to diffuse a message up to 3 hops

Retransmission node

11 retransmission to diffuse a message up to 3 hops

Retransmission node

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Key Issues with Ad hoc Protocols

• Scalability – Flooding generates LOT of traffic• Optimizations have limited impact:

Use Route Caching (beware of stale routes) Use Node Hierarchy (longer setup duration)

• Link Oscillation – Channel variations cause pathological rerouting• Damp rerouting requests – when a “better” path is

available• Use Signal Stability Routing Metric• Route repair with controlled flooding – hop-count based

on previous route length • End-to-end Route Repair – Causes lot of overhead

• Use local repair• Link Quality – Shortest path often performs poorly

• Use combined routing metric (hop count, stability, load)

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Research Work

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Vehicle Networks: Unique Applications

• Safety Messages – Critical Broadcasts

• Low latency

• Send Locally

• Non-critical Traffic Updates• Send to targeted groups (location, speed,

neighborhood, id)

• Maintain connectivity map

• Telematics Applications• Provide QoS Support

• “Suspend & Resume” applications and routes

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Vehicle Networks: Unique Challenges

• Network Density - Large Dynamic Range Same protocol must work in bumper-to-bumper downtown

traffic and on interstates

• Mobility Patterns and Varying Vehicle Speeds Cars entering or exiting highways need complete route

updates and can possibly pollute new neighbors during transitions

Traffic moves in parallel and at different speeds – difficult to form clusters or handshake

• Heterogeneous Nodes Connectivity: Support DSRC and Cellular Positioning Capability: GPS and no-GPS Application Support: Full-function and Reduced-function

devices

• Information is Geographic Route and Direction Specific Need to map geographic routes to logical routes Getting direction info is not too reliable

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Vehicle Networks: Unique Degrees of Freedom

1. Protocol Operation Modes

1.Time of Day: “Rush Hour – Set cluster size to 3-hops”

2.Traffic Characteristic: “Highway Driving – Switch to Cluster-based Routing Mode”

3.Traffic Database Update: “Traffic Probe: Congestion ahead – Routing Table Burst Update”

2. Routing Metrics

(a) Hop count (b) SNR (c) Signal Stability

(d) Connectivity (e) Link load (f) Multiple Paths

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Experimental Multi-hop Vehicular Network Test-bed

GPS

Differential GPS reference station beacons

1. Vehicle-to-Vehicle Multi-hop2. Vehicle-to-Mobile Gateway3. Vehicle-to-Infrastructure

5.9 GHz DSRC Dedicated Short Range Communications Between vehicles

1xRTT Cellular Data Network

Internet

Remote Monitoring of Experiment

Mobile Nodes

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Vehicular Networking Application Categories

1. Safety Alerts

• Sudden Braking

• Airbag deployment

• Skidding

2. Traffic Congestion Probing

• Travel Time

• Dynamic Route Planning

• Road Condition Notification

3. Interactive Applications

• Social Networking

• Multimedia Content Exchange

• Advertising

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GeoRoute: Broadcast Scenarios

Highway Driving City Driving Rural Driving

• Path with Intermediate points• Static Source Routing

• Radial Broadcast • Bounding Box• Controlled Flooding

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Conclusion• Communicating vehicles and infrastructure will

bring cost effective, large scale gains in safety, traffic management and convenience.

• DSRC (IEEE 802.11p) is the enabling technology for making this vision into reality.

• Number of technical challenges remain, but can and will be solved with government, industry and academic research partners.

• VII (Vehicle Infrastructure Integration) will provide the necessary business and deployment framework over the next few years.

• There are many exciting opportunities for other industry participants to make contributions and to benefit from a DSRC/WAVE and VII deployment.

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Questions ???