DOI: 10.4018/IJVTIS.2017070101 International Journal of Vehicular Telematics and Infotainment Systems Volume 1 • Issue 2 • July-December 2017  Copyright©2017,IGIGlobal.CopyingordistributinginprintorelectronicformswithoutwrittenpermissionofIGIGlobalisprohibited.  A Review of Congestion Control Schemes for Vehicular Ad-Hoc Network (VANET) Communication Samuel Ibukun Olotu, Federal University of Technology Akure, Akure, Nigeria Bolanle Adefowoke Ojokoh, Federal University of Technology Akure, Akure, Nigeria Olumide Sunday Adewale, Federal University of Technology Akure, Akure, Nigeria ABSTRACT Intelligent Transportation Systems (ITS) are built on top of self-organizing networks, known as VehicularAdhocNetworks(VANET).InVANET,eachvehicleequippedwithcommunicationdevices representsanodeandisallowedtosendandreceivesafetymessagesthroughwirelesscommunication channels. These messages are either periodic (beacons) or event-driven. Beacons are transmitted periodically while the event-driven messages are generated when an abnormal condition or an imminentdangerisdetected.Theevent-drivenmessagesshouldbedeliveredtoneighbouringnodes withhighreliabilityandlimittimeasasingledelayedorlostmessagecouldresultinlossoflives.In densenetwork,theperiodicmessagesbroadcastleadtobroadcaststorm/blindfloodingproblemin VANETs.Itisveryimportanttokeepthecommunicationchannelfreefromcongestioninorderto ensuretimelyandreliabledeliveryofevent-drivensafetymessages.Thisstudypresentsareviewof existingcongestioncontrolschemesforVANETswiththeaimofdiscussingthecontributionsand drawbacksofthealgorithms. KEywoRdS Beacon Messages, Dedicated Short Range Communication (DSRC), Event-Driven Messages, IEEE 802.11p., Intelligent Transport System (ITS), Wireless Access in Vehicular Environment (WAVE) INTRodUCTIoN Theprogressofthetransportationindustryisanessentialfactorinthedevelopmentofoursociety. Itsimplymakestherelationbetweendifferenteconomicbranchespossibleandefficient.However, the increase in the number of vehicles has also brought an increase in the number of accidents andhumanfatalities(Stanica,2011).AccordingtoWorldHealthOrganization(2013),roadtraffic accidentsleadtoabout1.24milliondeathsworldwide,and92%ofthemoccurinmiddle-income andlow-incomecountries.Thischallengehasledtothedevelopmentofnewtransportationsystems suchastheIntelligentTransportationSystem(ITS).IntelligentTransportationSystems(ITS)isthe integrationoftelecommunicationandinformationtechnologiestoimprovethesafetyandefficiencyin transportationsystems(Jarupan&Ekici,2011).OneofthepotentialarchitecturesforITSisvehicular adhocnetwork(VANET)(Bouk,Kim,Ahmed,&Kim,2015). AVANETisaself-organized,multi-purpose,serviceorientedcommunicationnetworkenabling vehicle-to-vehicleandvehicle-to-roadsideinfrastructurecommunicationforthepurposeofexchanging messagestoensureanefficientandcomfortabletrafficsystemonroads(Biswas,2012).InVANET, 1