The Data Distribution Strategy Of Improving Interactive Efficiency In VANETs

As a special mobile ad hoc network(MANET),vehicular ad hoc networks(VANETs)enables data communication between vehicles and vehicles,vehicles and roadside infrastructure,so that it can provide a variety of services,such as crash,accident warning,traffic information prediction,entertainment content download to drivers and passengers.As we all know,all the applications that provide these services are inseparable from the reliable and efficient data distribution technology,so how to achieve effective data distribution in VANETs is an important research point.In addition,in order to give users a better travel experience,the requests and transmissions of non-security entertainment information have become inevitable.In order to ensure the correct transmission of the message,the importance of confirming the response strategy is obvious.However,some inherent features of VANETs,such as fast topology change,frequent interruption of communication links between nodes,node density changes at any time,has brought great challenges for the above services.In order to solve these problems,so that the vehicle nodes in VANETs can complete the data interaction efficiently,this paper studies the following two aspects:First,this paper presents a data distribution method based on nodes' travel direction which named SAMD(Slot Assignment scheme based on vehicles' Moving Direction).First,we dynamically divide the set of left and right time slots according to the change of node density,so that the nodes can acquire time slots according to their own moving direction,thus increasing the probability of nodes successfully accessing the channel,and aiming at efficient data distribution.Secondly,the protocol also combines CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance)and TDMA(Time Division Multiple Access)to reserve the slots in a combination of competition and reservation,so that it can reduce the impact of latency on protocol performance and ensuring that the business can be distributed in real time.Simulation results show that the protocol reduces the probability of node collisions and increases the packet delivery rate.Second,this paper presents a group acknowledgement strategy for non-security entertainment messages in VANETs.This policy is used to acknowledge multiple packets sent simultaneously by multiple nodes.Compared with the traditional acknowledgment strategy,it not only guarantees the reliability of data distribution,but also reduces the transmission of ACK frames,so as to ensure the successful transmission of the actual data and increase the data throughput in the effective time.By comparing with the traditional immediate confirmation strategy and the no-ack strategy,the gack strategy we propose reduces the end-to-end delay of data transmission to a certain extent,increases the packet delivery rate,and improves the network throughput.