Evaluation of Intersection Collision Warning System Using an Inter-vehicle Communication Simulator
description
Transcript of Evaluation of Intersection Collision Warning System Using an Inter-vehicle Communication Simulator
Department of Electrical and Computer Engineering
The Ohio State University 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
ProblemsAnimation of Intersection
warning system
Intersection Collision Scenario
Department of Electrical and Computer Engineering The Ohio State University 6
Problems (Other Scenarios)
SV
SV
SV
SV
POV
POV
POVPOV
POV: Principle other Vehicle
SV: Subject Vehicle
Department of Electrical and Computer Engineering The Ohio State University 7
IVC Simulator
Components of Intersection Collision Warning System
• Local Map DatabaseIntersection position, lanes, speed limit etc.
• Differential GPSVehicle position
• Inter-vehicle Communication System
Department of Electrical and Computer Engineering The Ohio State University 8
IVC Simulator
Vehicle Traffic Simulator
Trace files:• Vehicle information
• Vehicle position•Vehicle velocity
•Shadowing
WirelessSimulator
WSVTS
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 University 9
Outline of Contents Introduction Vehicle Traffic Simulator
• Vehicle Characteristic Input• Scenario Input• Intersection Collision Simulator
1. Vehicle Management2. Traffic-Light Management
• Message Generator The Wireless Simulator Shadowing Effect Simulations Conclusions
Department of Electrical and Computer Engineering The Ohio State University 10
VTS Block Diagram
VehicleManagement
Road
Traffic LightManagement
Vehicle Characteristic
Input
Scenario Input
Intersection Collision Simulator
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
Intersection
Collision
Simulator
Vehicle Characteristic
Input
Scenario Input
Department of Electrical and Computer Engineering The Ohio State University 12
Simulation Setup Screen
Scenario Input
Traffic Flow Characteristic Input
Department of Electrical and Computer Engineering The Ohio State University 13
Vehicle Management
Turning
NormalDriving
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 University 14
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 University 15
Message Generator
Initialdataupdate
Transmissionintervals
Retransmissionattempts
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 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
TX RX
Block
TX
RX
Block
Blocking area
h
d1 d2
Department of Electrical and Computer Engineering The Ohio State University 18
Shadowing Fresnel-Kirchoff diffraction parameter:
21
21
dd
)d2(dh
Using the Fresnel integral,
4.2),5/20log(0.22
4.21,)1.038.0(1184.020log(0.4
10),20log(0.5e
01),0.6220log(0.5
1,0
ψ(dBm)2
0.95
Department of Electrical and Computer Engineering The Ohio State University 19
Shadowing (Adjacency Matrix)
ε = 0 ε12 ε13 … …
ε21 0 … … …
ε31 … 0 … …
… … … … …
… … … … 0Note:• 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 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: initialization, termination, VTS interface, etc.
Each process (except Main) implements MAC and PHY layers
All processes run in parallel in the simulated time
MainProcess
Process 1
Process 2
Process 3
Process n
n: no of vehicles
MACPHY
MACPHY
MACPHY
MACPHY
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 PowerA packet will be received when the received signal power is larger than the threshold.The received signal power is computed as:
ψ(dBm)PL(dBm)(dBm)P(dBm)P tr
er transmittat thepower signal :(dBm)t
P
losspath :PL(dBm)
receiver at thepower signal :(dBm)r
P
shadowing :ψ(dBm)
Department of Electrical and Computer Engineering The Ohio State University 25
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 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 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
ReceiverCollision warning
Motorcycle
Simulation Results
Department of Electrical and Computer Engineering The Ohio State University 28
Simulation Results
Performance metric for Wireless Communication
packetsdtransmitteofnumberTotal
packetsdtransmittelySuccessfulRateSuccessPacket
____
____
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
Dolphin at 0.5 Mbps
10.9900.997Right angle
10.9930.996Left turn
light
10.9920.996Right turn
10.9830.995Left turn
MaximumMinimumMeanScenario
Packet Success Rate
10.9900.997Right angle
10.9930.996Left turn
light
10.9920.996Right turn
10.9830.995Left turn
MaximumMinimumMeanScenario
Packet Success Rate
802.11 a R/A, left turn(Similar Results for other Scenarios)
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
1. Traffic flow etc2. 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