Research On Routing Scheme Of Emergence Message In VANET

In situation of sharp increase of vehicles numbers, difficulty of road construction tomatch with the incensement, frequent of traffic accidents, how to make use of advancedscience and technology we already possess, in order to provide people with convenient,comfortable traffic environment becomes the main problem for researchers. The Intelligenttransportation system (ITS), mix together with computational technologies, wirelesscommunications and control technologies comes out under such circumstances. Trafficinformation transformation becomes a key for safety related service offered by ITS. Whatcan we do to ensure the vehicles on the road can be informed of the accident message assoon as possible to have enough time for reaction of the sudden situation is the focus of thispaper.For emergency message transmission, this paper proposes a protocol based on distanceand receiver-oriented.It supposed to transmit the emergency message to the whole VANETin a short period of time with little redundant messages. The main idea of it is using the wayof simple broadcast scheme to send the emergence message with little latency and usingforward transmission scheme based on distance to solve the problem of large amountresend of emergence message in a short time. Choosing of forward node is based on thedistance between node and accident node. The node farthest from the source node in relatedzone will be chosen to be forward node. The forward scheme isn’t started by sending node,but started by receiving node through comparing the distance between itself and send nodewith distances of its neighbors, which called receiver-oriented.Based on distance receiver-oriented routing, BDRO, has some character as follows:(1)Optional，which embodied in two aspects. One of them is the optional of receiving message.Only the nodes locate in danger area receiving message and others will drop the message.Danger area defined in the paper refers to the lanes in the rear area of the accident vehiclewhich has the same direction with it. The other one refers to the selection of forwardingnodes. Not all node receiving emergence messages have the right of forwarding. Only thenode selected through forwarding algorithm can forward the message that make themessage can transmit as far as possible and reduce the number of redundant message.(2)Passivity. Selection of forward nodes isn’t started by sending node. It calculated byreceiving nodes that aims at reducing complexity of sending emergence message which canmake the nodes locate in danger area receive emergency message as soon as possible inorder to help them have more time for reaction to realize safe driving.(3)forwarding nodebackup mechanism, that is, receiving node which are not selected as forwarding nodes still need to monitor the whole network to check whether the emergence message hastransmitted in VANETs successfully. After waiting for more than threshold time, the sameemergence message doesn’t be received again, which could means the forward nodeselected in early time doesn’t send the emergency message successfully. Other round offorward node selection will start to ensure the transmission of emergency message.In the end of this paper, simulate the new route BDRO using network simulation toolnamed as NS2.To compare with the simple flood broadcast route, BDRO performs better.