Abstract
Vehicular ad hoc networks (VANETs) are envisioned as the future of intelligent transportation systems, which enable various kinds of applications aiming at improving road safety and transportation efficiency. Uni-cast routing is required for many of these applications. As VANET is expected to be massive in terms of number of nodes and amount of generated information, geographic routing protocols are considered the most suitable for such network owing to their scalability. Due to VANETs' extremely dynamic topology and variable channel condition, multiple metrics related to vehicles' mobility, link quality, and bandwidth availability need to be considered to make more informed and reliable routing decisions. However, some of these metrics might oppose each other. While the main forwarding strategy in geographic routing selects nodes closer to the destination to maximize distance progress, these nodes are most probably located at the border of the communication range where the probability of link breakage increases. Furthermore, the continuous selection of these nodes without considering their available bandwidth might result in higher packet delays and losses. This paper proposes a novel routing protocol based on fuzzy logic systems, which can help in coordinating and analyzing contradicting metrics. The proposed routing protocol combines multiple metrics considering vehicles' position, direction, link quality, and achievable throughput to select the most suitable next-hop for packet forwarding. Results from our simulation experiments of relatively dense urban environments show remarkable performance improvements in terms of packet delivery ratio, end-to-end delay, and total network throughput.