Research On Low Overhead Vehicular Ad Hoc Network Routing Algorithm

Vehicular Ad hoc Networks (VANET) is an important application of "Internet of Things", as well as a branch of Mobile Ad hoc Networks (MANET). As the product of modern automobile industry technology and new wireless communication technology, it attracts both academia and automobile manufacturer all over the world. Routing protocol is a key research content of VANET technology. The enormous routing overhead consumption is a key issue of VANET routing protocol. Alleviating the network bandwidth consumption caused by routing packet is a hot research area focused by academia and industry circle. Heavy vehicle density causes too many routing packets, resulting in network congestion problem.Based on Mobile Ad hoc Network routing protocol AODV-ETX, a kind of low overhead(including routing overhead and beacon overhead) routing protocol for VANET is designed. To reduce routing overhead, two mechanisms are adopted. The first one is to control the number of route request packets, and the second one is to add local repair mechanism; to alleviate the beacon overhead, beacons should be better use of. To examine the performance of the algorithm, simulation tools related to Vehicular Ad hoc Networks are investigated. SUMO, one kind of traffic simulation software, and NS2, a network simulation tool, are combined to analyze the performance of the algorithm proposed in this paper. The main research content and contribution of this paper is as follows.First, flooding route request of on-demand routing protocol of Vehicular Ad hoc Networks consumes the network bandwidth severely. What’s more, it may cause network congestion and broadcast storming. Therefore, an AODV-ETX-based algorithm called Low Overhead Routing Scheme is proposed in Chapter 2. The number of route request flooded in the process of finding destination is controlled, because the on-demand routing is combined with geographical routing. In addition, the concept of zone flooding is adopted; a kind of local repair function is added, so the large consumption caused by re-establishing a new route is substituted by a small amount of packets caused by local repair; the zone flooding is applied, so the number of nodes irrelevant affected by flooding is less. Through simulation, the performance of the algorithm is analyzed. What is concluded is that, as to routing overhead, LORS is much less than AODV-ETX. In addition, as the vehicle density increases, the extent of the optimization also increases.Two, to improve the utilization of beacon packets in Vehicular Ad hoc Networks is also a crucial issue. It is apparent that a constant frequency of sending beacons is irrational. For nodes with low speed, it’s a waste of network resource. Whereas for nodes with high moving speed, the information update frequency is not enough. Thus a kind of mobility prediction-based and a kind of velocity prediction-based adaptive beacon transmission strategy are proposed in the first two sectors of Chapter 3. Through our simulation, a conclusion is found. The number of beacon packets can be reduced greatly by adopting proposed beacon packet transmission scheme, thus the routing overhead is alleviated. At the same time, an extended beacon packet transmission algorithm is proposed, resulting in the in-time location and velocity information update for nodes in the active route. As a result, the frequency of route request flooding is lessened, consequently the purpose of reducing routing overhead is achieved.The performance of the algorithms proposed in this paper is tested in the scenario created by integrated use of SUMO and NS2, which are a kind of traffic simulation and a kind of network simulation tool, respectively.An outcome gained by simulation is found that, routing overhead could be reduced with the help of LORS; Beacon overhead could be reduced with the facility of the proposed beacon packet transmission scheme.