Department of Electrical and Computer Engineering The Ohio State University1 Evaluation of Intersection Collision Warning System Using an Inter-vehicle Communication Simulator Atakan Doğan, Gökhan Korkmaz, Yiting Liu, Füsun Özgüner, Ümit Özgüner, Keith Redmill, Oscar Takeshita, K. Tokuda

Department of Electrical and Computer Engineering The Ohio State University2 Outline of Contents  Introduction  Vehicle Traffic Simulator  Shadowing Effect  The Wireless Simulator  Simulations  Conclusions

Department of Electrical and Computer Engineering The Ohio State University3 Outline of Contents  Introduction Background Information Problems Inter-vehicle Communication (IVC) Simulator  Vehicle Traffic Simulator  Shadowing Effect  The Wireless Simulator  Simulations  Conclusions

Department of Electrical and Computer Engineering The Ohio State University4 Background Information  Develop a simulator Study and solve the intersection collision problems  Based on OSU and OKI project  Incorporate Intelligent Transportation System Physical Layer MAC Layer

Department of Electrical and Computer Engineering The Ohio State University5 Problems Animation of Intersection warning system Intersection Collision Scenario

Department of Electrical and Computer Engineering The Ohio State University6 Problems (Other Scenarios) SV POV POV: Principle other Vehicle SV: Subject Vehicle

Department of Electrical and Computer Engineering The Ohio State University7 IVC Simulator  Components of Intersection Collision Warning System Local Map Database Intersection position, lanes, speed limit etc. Differential GPS Vehicle position Inter-vehicle Communication System

Department of Electrical and Computer Engineering The Ohio State University8 IVC Simulator Vehicle Traffic Simulator Trace files: Vehicle information Vehicle position Vehicle velocity Shadowing Wireless Simulator WS VTS  VTS and WS runs independently of each other  VTS is interfaced to WS through trace files Input Parameters: Vehicle density Vehicle throughput Road Information Shadowing

Department of Electrical and Computer Engineering The Ohio State University9 Outline of Contents  Introduction  Vehicle Traffic Simulator Vehicle Characteristic Input Scenario Input Intersection Collision Simulator 1. Vehicle Management 2. Traffic-Light Management Message Generator  The Wireless Simulator  Shadowing Effect  Simulations  Conclusions

Department of Electrical and Computer Engineering The Ohio State University10 VTS Block Diagram Vehicle Management Road Traffic Light Management Vehicle Characteristic Input Scenario Input Intersection Collision Simulator

Department of Electrical and Computer Engineering The Ohio State University11 Input Block  Vehicle Characteristic Input Vehicle Classification Vehicle Length, Width Vehicle Speed Vehicle Origin and Destination Vehicle Flow Rate  Scenario Input Collision Scenario Traffic Light Availability Intersection Collision Simulator Vehicle Characteristic Input Scenario Input

Department of Electrical and Computer Engineering The Ohio State University12 Simulation Setup Screen Scenario Input Traffic Flow Characteristic Input

Department of Electrical and Computer Engineering The Ohio State University13 Vehicle Management Turning Normal Driving Vehicle Following Vehicle Management Driver information: Its own speed Its own position data from DGPS Turning direction Other vehicles in Line-of-sight and the estimated distance and speed Status of traffic lights

Department of Electrical and Computer Engineering The Ohio State University14 Traffic Light Management Scenario Input Cycling Time Direction Status Cycling Time ( Two Phase): G=25sec; Y=5sec

Department of Electrical and Computer Engineering The Ohio State University15 Message Generator Initial data update Transmission intervals Retransmission attempts Send messages when vehicle crosses initial data update border Distance-based Transmissions 50 meters Vehicle Characteristics

Department of Electrical and Computer Engineering The Ohio State University16 Outline of Contents  Introduction  Vehicle Traffic Simulator  Shadowing Effect  The Wireless Simulator  Simulations  Conclusions

Department of Electrical and Computer Engineering The Ohio State University17 Shadowing TX RX Block TX RX Block Blocking area h d1d1 d2d2

Department of Electrical and Computer Engineering The Ohio State University18 Shadowing  Fresnel-Kirchoff diffraction parameter:  Using the Fresnel integral,

Department of Electrical and Computer Engineering The Ohio State University19 Shadowing (Adjacency Matrix)  ε = 0ε 12 ε 13 …… ε 21 0……… ε 31 …0…… …………… …………0 Note: ε ij diffraction gain (in dB) for receiver j from transmitter i. This is a symmetric matrix. Both negative and positive gains are possible.

Department of Electrical and Computer Engineering The Ohio State University20 Outline of Contents  Introduction  Vehicle Traffic Simulator  Shadowing Effect  The Wireless Simulator MAC Layer Physical Layer  Simulations  Conclusions

Department of Electrical and Computer Engineering The Ohio State University21 WS Process Structure  Main process: initialization, termination, VTS interface, etc.  Each process (except Main) implements MAC and PHY layers  All processes run in parallel in the simulated time Main Process 1 Process 2 Process 3 Process n n: no of vehicles MAC PHY MAC PHY MAC PHY MAC PHY

Department of Electrical and Computer Engineering The Ohio State University22 MAC Layers  CSMA/CA a, b, and a R/A are implemented RTS, CTS, and ACK packets are not implemented because Broadcast Application => More than one destination Short Data Packets Nodes wait DIFS amount of time before sending their packets If nodes sense the channel busy, they wait a random amount of time  DOLPHIN Non-persistent CSMA 5 retransmissions Vehicles transmit one packet in each slot slot length = 20 msec 5 retransmissions

Department of Electrical and Computer Engineering The Ohio State University23 PHY Layer  Path loss, shadowing, and fading: Modeled  Carrier sensing and capture: Modeled  Noise: Cumulative  Signal reception: SNR threshold based

Department of Electrical and Computer Engineering The Ohio State University24 Signal Power A packet will be received when the received signal power is larger than the threshold. The received signal power is computed as:

Department of Electrical and Computer Engineering The Ohio State University25 Fading  Gilbert-Elliot model: Good Bad Pgb Pbg Pge: bit error probability in Good state Pbe: bit error probability in Bad state 1-Pgb 1-Pbg

Department of Electrical and Computer Engineering The Ohio State University26 Outline of Contents  Introduction  Vehicle Traffic Simulator  Shadowing Effect  The Wireless Simulator  Simulations  Conclusions

Department of Electrical and Computer Engineering The Ohio State University27 Simulation time Wireless repeater Building location Truck Bus Motorcycle Car Intersection Type Traffic signal North – South Stop sign Last message Critical messages Last collision Transmitter Receiver Collision warning Motorcycle Simulation Results

Department of Electrical and Computer Engineering The Ohio State University28 Simulation Results  Performance metric for Wireless Communication For a packet to be treated as successful, it should be received by ALL receivers in the region. Even if one vehicle can not hear the transmission, this packet is treated as unsuccessful.

Department of Electrical and Computer Engineering The Ohio State University29 Simulation Results Dolphin at 0.5 Mbps a R/A, left turn (Similar Results for other Scenarios)

Department of Electrical and Computer Engineering The Ohio State University30 Outline of Contents  Introduction  Vehicle Traffic Simulator  Shadowing Effect  The Wireless Simulator  Simulations  Conclusions

Department of Electrical and Computer Engineering The Ohio State University31 Conclusions  Successfully incorporated two time-scales (C++) VTS: millisecond WS: microsecond  Simulator Simulate different intersection collision scenarios Simulate various road and traffic conditions 1. Traffic flow etc 2. Speed limit etc. Evaluate inter-vehicle communication  Warning System can be rely on inter-vehicle communication High packet success rate (DOLPHIN) Only short packet is needed for transmission

Department of Electrical and Computer Engineering The Ohio State University32 Conclusions  Distance-based packet transmission Improve medium utilization Reduce unnecessary packets Lower packet collision probability  Most packet losses due to physical layer  To reduce physical layer errors Lower data rates can be used  Number of Retransmissions have positive impact on packet successful rate

Department of Electrical and Computer Engineering The Ohio State University33 Recent Development  A Simulation Study of An Intersection Collision Warning System (ITST 2004) Wireless Communication (MAC, PHY)  Current Status: Drivers’ Model, Three-level Warning System Repeater, Buildings, Transmission Intervals  Demo for 11 th World Congress on ITS (2004) Vehicle and Traffic Simulator and Intersection Collision Warning System Performance of Wireless Intersection Collision Warning System