Adaptive Beaconing Schemes in VANETs: Hybrid Approach

KYUNGPOOKNATIONAL UNIVERSITY, Daegu, Korea.

MoNet Laboratorywww.monet.knu.ac.kr

Adaptive Beaconing Schemes in VANETs:Hybrid Approach

SYED HASSAN AHMED, SAFDAR HUSSAIN BOUK, AND DONGKYUN K IM

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Outline

• Introduction

• Beaconing

• Hybrid Beaconing Schemes Overview

• Comparison

• Conclusion and Future Work

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Introduction

Intelligent Transportation System (ITS)

◦ Need of today due to exponential growth in number of Vehicles around the globe.

◦ ITS = Applications + Technologies + Communication Infrastructure

◦ Provides:

◦ Mobility and traffic management,

◦ Driver and passengers’ Safety and Comfort,

◦ Travel efficiency Time and Energy Saving,

◦ Information availability on the go,

◦ etc.

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Introduction

Vehicular Ad hoc NETwork (VANET)

◦ One of the promising step towards the future ITS.

◦ Vehicles with communication capability.

◦ Vehicle to Vehicle (V2V) communication.

◦ Vehicle to Infrastructure (Road Side Unit) (V2I) Communication.

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Introduction

Vehicular Ad hoc NETwork (VANET)◦ Characteristics:

◦ Dynamic topology (High Mobility).

◦ Unpredictable network density.

◦ Delay bound communication.

◦ Intermittent connectivity and link lifetime.

◦ Safety and Non-Safety applications.

◦ Large data requirements.

◦ Delay constraints, etc.

◦ With/Without infrastructure support.

◦ Data ranges from short messages to large video contents

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Introduction

Vehicular Ad hoc NETwork (VANET) (Applications)

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Safety-related applications

• Assistance • Navigation

• Cooperative collision avoidance

• Lane-changing

• Information • Speed limit

• Work zone info

• Warning • Post-crash

• Obstacle

• Road condition warnings

Non Safety-related applications (Comfort-related)

• Weather information

• Instant messaging

• Online games

• Internet access

• Advertisements

Intersection Collision Warning

Work Zone Warning

Rollover WarningEmergency Vehicle Approaching Warning

Lane Change Warning

Co-operative Collision Warning



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Beaconingo Information sharing through short messages (Beacons) among vehicles,

called Beaconing.

o Freshness and Accuracy of information Frequency/Interval of Beacons.

o Proximity area of Network Awareness Transmission Power of Beacons.

Info

rmat

ion

Acc

ura

cy/F

resh

ne

ss

BeaconInterval SmallLarge

Beaconing Schemes for VANETs

Fixed Rate Adaptive

Rate / Frequency

Trans. (Tx) Power

Contention Window

Hybrid+

Network/Channel characteristics:• Node Density• Packet Drop Rate• Distance between neighbors• ….. etc.



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Hybrid Beaconing Schemes1. Joint Power and CW Size [D.B. Rawat et al.]

◦ Uses Enhanced Distributed Channel Access (EDCA) mechanism of 802.11e to control Transmission Power.

◦ Provides QoS by defining multiple Access Categories [ACs] at MAC.◦ First computes Range (R) using vehicular traffic

characteristics

◦ Map R in “Range vs Power” loop-up table.

◦ The CW size is adaptive adjusted with access priority

of the critical message, collision rate and 2.

D. B. Rawat et al., “Enhancing VANET Performance by Joint Adaptation of Transmission Power and Contention Window Size,” IEEE Transactions on Parallel

and Distributed Systems, vol.22, no.9, Sep. 2011, pp.1528–1535.

Length ofRoad Segment

Ratio of vehicle density:Actual No. of Vehicles Total No. of Vehicles

Traffic Flow Constant



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Hybrid Beaconing Schemes2. Power, CW, and Rate [D. Puthal et al.]

• Parameters: Data Rate, Neighborhood Density (N), Current Queue Level (QL), and Channel Usage (CU) Time.

• Congestion Level (CD)

• Transmission Power and Transmission Rate• Adoption is based on the measured CD.

D. Puthal et al., “Cross-layer architecture for congestion control in Vehicular Ad-hoc Networks,” International Conference on Connected Vehicles and Expo (ICCVE), 2013, Dec. 2013,pp.887–892.

No. of QueuesAccess Category (AC)Number

Arbitration Inter-Frame Space Number

TABLE I. ACCESS CATEGORIES WITH MIN., MAX. CW AND AIFSN

Congestion Level Value of CD CW Adaption

Full CD > 90 Block comm. for all ACs except AC3

High 70 < CD ≤ 90 CW of all ACs except AC3CW(ACi)=CW(ACi)*1.5Medium 30 < CD ≤ 70 CW(ACi)=min(CW(ACi),CW(ACi)MAX)

Ideal CD ≤ 30 All ACs CW(ACi)=CW(ACi)MIN



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Hybrid Beaconing Schemes3. Power and Rate [Tessa Tielert et al.]

o Parameters: Speed of Vehicle (v), Max. acceleration (a), Speed difference to its neighbors (), System Latency (ts), and Driver’s reaction time (tr). Packet Reception Probability (p) between successive lost packets, Channel Load (l), etc.

o Target Distance: (To optimize reception performance)

T. Tielert et al., “Joint power/rate congestion control optimizing packet reception in vehicle safety communications,” In Proceeding of the tenth ACM international workshop on Vehicular inter-networking, systems, and applications (VANET ’13), 25–28 June 2013, pp.51–60.

max

Congestion Control Start

Congestion Control Active

?

estimate l

l < l max

?

Pt < f (dt , lmax)

?

r < rmax

?

increase Pt

increase r

r > rmin

?

decrease Pt

decrease r

Yes

No

Yes

Yes

No

No

No

Yes

Yes

Congestion Control Stop

Case 1: when vehicle sends emergency

beacon message to its neighbors that are within the close proximity.

Case 2: when speed difference between vehicle and its neighbors is large.



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Comparison



o A comprehensive study of state of the art hybrid adaptive beaconing schemes proposed for VANETs.

o These schemes optimize the combination of beacon power, rate and/or CW.

o All schemes are contrasted using the following parameters:

o Classification

o Performance Criteria

o Control Parameters

o Control Method

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Conclusion



Thanks

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Education

Adaptive Beaconing Schemes in VANETs: Hybrid Approach