XOR-Based Routing Protocols in Vehicular Ad Hoc Networks: How Well Do They Perform?

This paper presents a performance analysis of exclusive-or logical operator (XOR)-based flat routing protocols in high mobility conditions, considering a vehicular ad hoc network (VANET) formed in a highway scenario. The main advantage of XOR-based routing is related to their logarithmic requirement of information per node in order to perform traffic forwarding, providing the basis to achieve better scalability levels for the routing mechanism convergence. First, this paper describes a protocol that incorporates several adaptations of the existing XOR-based routing algorithms for wired networks, in order to cope with the network mobility. Then it is proposed an improved version of it, XORi, which modifies the protocol’s information gathering process to accommodate the specific dynamic nature of VANETs topology in highways. Finally, the performance of XOR-based protocols is compared with other topology-based and position-based routing protocols. Simulation results allow us to characterize the performance of this class of protocols through the comparison of the path availability, end-to-end path delay, average path length and path duration. When a moderate density of nodes is considered, simulations show that XOR-based algorithms achieve almost the same path availability rate as link state algorithms, such as OLSR, and for high density of nodes, XOR-based algorithms scale better in terms of delay when compared to source routing algorithms, such as DSR.