A reputation system to identify and isolate selfish nodes in Vehicular Delay-Tolerant Networks

Vehicular Delay-Tolerant Networks (VDTNs) were proposed as a solution to overcome some issues found in other vehicular technologies. VDTNs assume the bundle layer placement under the network layer. This vehicular architecture can be applied in sparse regions characterized by sparse connectivity, long propagation delays, high error rates, and short contact durations. Although some of the major issues were already solved and several improvements were already achieved, VDTNs still have several issues that should be overcome. One of these issues is related with nodes cooperation and nodes share their own resources to deliver packets from others. This can be a difficult task if selfish nodes affect the performance of cooperative nodes. To detect, identify, and avoid communications with selfish nodes, this paper proposes a reputation system with four different reputation mechanisms and studies their impact on the performance of the network. This reputation system is enforced on two different routing protocols (Spray-and-Wait and GeoSpray). Across all the experiments, it was shown that reputation mechanisms that punish aggressively selfish nodes contribute to an increase of the overall network performance by increase the number of delivery messages and decrease the message average delivery delay.