A Cognitive Differentiated Routing Protocol For Vehicular Ad Hoc Networks

Vehicular ad hoc networks (VANETs) are of great significance to ensure traffic safety, to improve the comfort of driving and the effectiveness of traffic. Though the existing technical standards dedicated for the inter-vehicle and vehicle-to-road side unit communication such as Dedicated Short Range Communications (DSRC) and IEEE802.lip are now well developed, due to the limited available spectrum resources, they are not enough to support the broad range of services envisioned in VANETs. Cognitive Radio (CR) is a new paradigm to intelligently use the frequency spectrum that enable nodes to opportunistically exploit unlicensed frequency spectrum for transmissions, which opens up a novel approach to effectively solve the scarcity of spectrum resources. This paper combines the cognitive radio and differentiated service with location routing to design a cognitive VANETs differentiated routing protocol, called CoDRP, and evaluated the performance of the protocol by extensive simulations.First, this paper investigates the main features and application of vehicular networks and cognitive radio networks, analyzes the classic routing protocols in vehicular ad hoc networks and cognitive networks and presents the problems and challenges for routing design. Then, in order to satisfy different requirements of quality of service (QoS) for the traffic with different priority, GPS-based routing has been combined with cognitive radio and differentiated services to design a Cognitive VANETs Differentiated Routing Protocol (CoDRP) for an urban environment. The protocol selects a weighted routing metric which jointly considers the available channel information and the position information, and uses the adaptive power control scheme to dynamically adjust the transmit power for the different types of traffic. It is helpful to ensure the higher priority traffic with larger range of candidate node set to provide differentiated services for different types of traffic. Finally, VanetMobiSim and OPNET have been jointly used to build a cognitive vehicular ad hoc networks simulation platform for the urban VANETs, and extensive simulations have been performed to evaluate CoDRP protocol. Simulation results show that, compared with the traditional location routing protocol, CoDRP has higher packet delivery ratio and less hops number of route.