A Study Of On-Demand Geographic Routing For VANET

One important feature of vehicular ad hoc network is high mobility of vehicular node, especially in highway scenarios. High mobility of vehicular node makes high dynamics of topologic structure for vehicular network, and finally leads to frequently disconnection of multi-hop route in ad hoc network. All of them bring big challenges to reliability of routing algorithm and quality of data transmission.In this paper, a position-based routing algorithm for VANET called on-demand geographic routing (ODGR) is proposed. ODGR uses two new mechanisms to make sure information about positions of the destination nodes and neighbors valid and veracity when choosing next hop route, and finally guarantee the reliability of routing algorithm. The two mechanisms are listed as follows: (1) ODGR uses two independent messages to realize update of position information about the destination. This way of update can deal with the situation of network disconnection and make sure consistency of position information recorded in various nodes. (2)Different from proactively setting up the neighbor table, ODGR uses the idea of on-demand to build the neighbor table. By this way of setting up the neighbor table, it is able to eliminate update burden and inveracity of information which is caused by node's high mobility.In this research, we compare the performance of AODV and ODGR using network simulator NS-2. A specialized node mobility model simulator called VanetMobiSim is used to produce realistic vehicular movement trace. The final results of the research prove that: on the highway, when node moves at max acceleration of 4.9m/s2 and at max speed of 50m/s, ODGR outperforms AODV about quality of data transmission.