V2V Communication for Safety, Information and Entertainment J. Parikh General Motors R&D Nov. 14, 2006

Content Introduction and Background DSRC Wireless Communication Safety, Information and Entertainment Applications Technical Challenges Current and Future Research Work

Introduction

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).

Communication on Road…

Today’s Vehicles - Wireless Data Interfaces Terrestrial Broadcast Digital Radio Satellite A/V GPS DSRC PCS/ Cellular 802.11 WLAN Ad Hoc Networks 802.15.3 WPAN Bluetooth 802.11 802.15.3 Existing and proposed vehicle connectivity

Integrated Traffic Management Systems Central Control Center Transit Dynamic Signal Control En-Route Traffic Advisory and Assistance DSRC and Other Communications 911 and Other Call Center Trip Planning This slide shows but a few of the elements that may make up a complete traffic management systems. Key to all of these is a central control center with communications capabilities to all of the sensors, displays, and other control centers (such as police and fire) with which it must interact. Commercial Vehicle Operation Traveler Assistance VARIABLE MESSAGE SIGNS

DSRC – Wireless Communication

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.”

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 peer Based 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

Standards Program

5.9 GHz Channel Plan Shared Public Safety/Private Dedicated Public Safety Control Med Rng Service Short Rng Service Hi Av-Low Lat Intersections Power Limit 43 dBm 40 dBm Power Limit 33 dBm Power Limit 23 dBm Uplink Downlink Public Safety Veh-Veh Public Safety/ Private Public Safety/ Private Public Safety/ Private Public Safety/ Private Public Safety Intersections Control Channel Ch 172 Ch 174 Ch 176 Ch 178 Ch 180 Ch 182 Ch 184 5.925 5.825 5.830 5.835 5.840 5.845 5.850 5.855 5.860 5.865 5.870 5.875 5.880 5.885 5.890 5.895 5.900 5.905 5.910 5.915 5.920 Frequency (GHz) Canadian Special License Zones*

– DSRC Applications – Safety, Information & Entertainment

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.

Safety Application Areas

Example Traffic Scenario – Safety Application Incidence notification to OnStar Information relay to other vehicles for dynamic route guidance Exit Immediate spread of knowledge to surrounding vehicles within broadcast range

V2V/V2I Safety Application

Traffic Probe - Information Report GPS Time Speed Lon, Lat Heading GPS Vehicles report speed, position and heading Form small clusters of vehicles Aggregate data within cluster Transmit aggregated values

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…

Application Categories Applications Network Configurations V2V V2V + Ad-Hoc Ad-Hoc + Other wireless (Pervasive) Active Safety  Security X Productivity Convenience Entertainment

Technical Challenges

“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 OLSR CGSR STAR Hybrid ABR DSR TORA AODV RDMAR CBRP ZRP/GRID/LAR

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 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

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

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)

Research Work

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

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

Vehicle Networks: Unique Degrees of Freedom Protocol Operation Modes Time of Day: “Rush Hour – Set cluster size to 3-hops” Traffic Characteristic: “Highway Driving – Switch to Cluster-based Routing Mode” Traffic Database Update: “Traffic Probe: Congestion ahead – Routing Table Burst Update” Routing Metrics (a) Hop count (b) SNR (c) Signal Stability (d) Connectivity (e) Link load (f) Multiple Paths

Experimental Multi-hop Vehicular Network Test-bed 5.9 GHz DSRC Dedicated Short Range Communications Between vehicles GPS 1xRTT Cellular Data Network Differential GPS reference station beacons Mobile Nodes Internet Remote Monitoring of Experiment Vehicle-to-Vehicle Multi-hop Vehicle-to-Mobile Gateway Vehicle-to-Infrastructure

Vehicular Networking Application Categories Safety Alerts Sudden Braking Airbag deployment Skidding Traffic Congestion Probing Travel Time Dynamic Route Planning Road Condition Notification Interactive Applications Social Networking Multimedia Content Exchange Advertising

GeoRoute: Broadcast Scenarios Highway Driving City Driving Rural Driving Path with Intermediate points Static Source Routing Radial Broadcast Bounding Box Controlled Flooding

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.

Questions ???