A Node Performance and Encountering Probability-Based Adaptive Routing for Delay Tolerant Networks

Delay Tolerant Networks (DTNs) are characterized by node mobility and partitioned network topology, extremely long delivery latency, etc. Consequently, the traditional ad-hoc routing algorithms cannot work well in DTNs. In order to provide effective communication services in DTNs, in this paper, we propose an adaptive routing based on Node Performance and Encountering Probability (NPEP). NPEP chronologically consists of two phases, the asymmetric distribution stage and the probability forwarding stage. In the asymmetric distribution stage, by considering node throughput, we define an absorbing metric to select a better node as the next relay node. We also define another node activeness metric to asymmetrically allocate copies to relay nodes. In the probability forwarding stage, we evaluate the encountering probability with the destination node in order to select a better next relay node to optimize delivery ratio. Extensive simulations have been conducted and the results show that NPEP outperforms Epidemic, FirstContact and NPSW in terms of delivery rate, average latency and average hop count in the Random Waypoint mobility model. Specifically, NPEP has less average hop count than other three algorithms, and the overhead ratio of NPEP is 45% and 43% less than that of Epidemic, FirstContact.