Evaluation of Intersection Collision Warning System Using an Inter-vehicle Communication Simulator

1. Evaluation of Intersection Collision WarningSystem Using an Inter-vehicle CommunicationSimulator 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 University

2. Outline of Contents • Introduction • Vehicle Traffic Simulator • Shadowing Effect • The Wireless Simulator • Simulations • Conclusions Department of Electrical and Computer Engineering The Ohio State University

3. 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 University

4. 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 University

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

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

7. 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 University

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

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

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

11. 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 Scenario Input Vehicle Characteristic Input Intersection Collision Simulator Department of Electrical and Computer Engineering The Ohio State University

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

13. 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 Vehicle Management Turning Vehicle Following Normal Driving Department of Electrical and Computer Engineering The Ohio State University

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

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

16. Outline of Contents • Introduction • Vehicle Traffic Simulator • Shadowing Effect • The Wireless Simulator • Simulations • Conclusions Department of Electrical and Computer Engineering The Ohio State University

17. Shadowing RX h TX RX Block Block Blocking area TX d1 d2 Department of Electrical and Computer Engineering The Ohio State University

18. Shadowing • Fresnel-Kirchoff diffraction parameter: • Using the Fresnel integral, Department of Electrical and Computer Engineering The Ohio State University

19. Shadowing (Adjacency Matrix) • ε = • Note: • εij 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 University

20. 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 University

21. WS Process Structure Main Process n: no of vehicles Process 1 Process 2 Process 3 Process n MAC MAC MAC MAC PHY PHY PHY PHY • 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 Department of Electrical and Computer Engineering The Ohio State University

22. MAC Layers • 802.11 CSMA/CA • 802.11a, 802.11b, and 802.11a 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 University

23. 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 University

24. 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 University

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

26. Outline of Contents • Introduction • Vehicle Traffic Simulator • Shadowing Effect • The Wireless Simulator • Simulations • Conclusions Department of Electrical and Computer Engineering The Ohio State University

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

28. 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 University

29. Simulation Results 802.11 a R/A, left turn (Similar Results for other Scenarios) Dolphin at 0.5 Mbps Department of Electrical and Computer Engineering The Ohio State University

30. Outline of Contents • Introduction • Vehicle Traffic Simulator • Shadowing Effect • The Wireless Simulator • Simulations • Conclusions Department of Electrical and Computer Engineering The Ohio State University

31. Conclusions • Successfully incorporated two time-scales (C++) • VTS: millisecond • WS: microsecond • Simulator • Simulate different intersection collision scenarios • Simulate various road and traffic conditions • Traffic flow etc • 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 University

32. 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 University

33. 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 11th World Congress on ITS (2004) • Vehicle and Traffic Simulator and Intersection Collision Warning System • Performance of Wireless Intersection Collision Warning System Department of Electrical and Computer Engineering The Ohio State University