Research On Beaconless-based Routing Protocol And Vehicle Access Scheme In VANETs

With the development of the science, the wireless networks become widely used. Vehicular ad hoc network uses the wireless network in traffic field, and is the important part for developing intelligent transportation and smart city. For the issue of safety and non-safety applications in VANET, the reliable transmission of the data plays the key role, and it cannot do without the reliable routing and access protocol. Therefore, the issue of the reliable transmission in VANET draws great attention to car manufacturers, universities and research institutions, also it gains a certain achievement in last few years.As a branch of MANET, VANET not only has the popularity of MANET, also has its own characters. Its universality of VANET is embedded in no center, self-organization, selfmanagement and its multi-hop forwarding. The specialty of VANET is reflected in the node which is the fast moving vehicle and its trajectory is predictive, and it leads to the challenge of reliable transmission of the data. As we all know, the fast moving nodes cause the highly dynamic topology, also lead to the intermittent link which affects the performance of protocol severely. Therefore it is vital to design a high-performance protocol for the data transmission. The beaconless protocols use the contention of the nodes which receive the data to select the most suitable next hop, which can raise the reliability of network and also can reduce the overhead of network without using beacon message. Moreover, when multiple vehicles send the request message to the RSU, the rule that the RSU serves the requests affects the networks heavily, hence designing an access service scheme which is suit to the highly dynamic scenario is essential.Aiming to the challenge of reliable transmission of data in VANET, it proposes the beaconless routing protocol called SLBF. This protocol bases on the existing beaconless scheme with defining a self-adaptive forwarding zone and designing a comprehensive algorithm to calculate the waiting time in which takes the greedy, link quality and traffic load into account. Moreover, SLBF uses the retransmission scheme to raise the reliable transmission.With simulation in NS-2, we simulate the performance of SLBF and compare SLBF with GPSR and BLR, and the simulation results show that the SLBF gains progress in delivery ratio, delay and average hop.When multiple vehicles access to the RSU, the rule about the RSU serves the multiple requests affects the performance of the network. To deal with the issues mentioned above,we propose the access scheme which is based on content-integrity and content-significance.We use the certain condition to pre-judge the content whether it can be fully served in the content-integrity, combining with the content-significance we calculate the priorities about the requests, at last a simple resource allocation scheme is used to the future service. Moreover, this access scheme mentioned above can enhance the performance of network with the help of the V2 V communication.