A hybrid geographic-DTN routing protocol based on fuzzy logic in vehicular ad hoc networks

Position-based routing algorithms were proposed to overcome the poor efficiency of traditional routing protocols in vehicular ad hoc networks (VANETs); however, while selecting the next hop to send data packets in greedy mode, these algorithms encounter the so-called local maximum problem. The main objectives of this paper are: (1) improving the greedy routing efficiency and (2) reducing the chance of selecting an absurd node for routing. In fact, the proposed method in this paper is aimed at detecting the absurdity of each node before sending the packets to it. That is, sending packets to an absurd node will be avoided; accordingly, the packet will not be trapped in a local maximum. By applying fuzzy logic and parameters such as the number of neighbors, neighboring vehicles’ speed, their direction, and distance from a destination in the proposed method, a chance value is calculated for each neighbor node. Then, the node having the highest chance value among the neighbors is selected for greedy forwarding. In case the greedy forwarding fails, the proposed algorithm will switch to the perimeter forwarding mode for delivering packets to the destination. However, in case the perimeter forwarding also fails, DTN capability is used in the proposed method for delivering packets to the destination. The simulation results of the proposed method indicated that, due to using fuzzy logic and parameters such as nodes’ direction and speed and applying DTN forwarding approach, it was able to better improve packet delivery ratio and end-to-end delay when compared with GPSR, GPSR-DTN, and LSGO routing protocols.