Abstract. Opportunistic Networks (ONs) are the newly emerging type of Delay Tolerant Network (DTN) systems that opportunistically exploit unpredicted contacts among nodes to share information. As with all DTN environments ONs experience frequent and large delays, and an end-to-end path may only exist for a brief and unpredictable time. In this paper, we employ optimal theory to propose a novel buffer management strategy named Optimal Buffer Scheduling Policy (OBSP) to optimize the sequence of message forwarding and message discarding. In OBSP, global optimization considering delivery ratio, transmission delay, and overhead is adopted to improve the overall performance of routing algorithms. The simulation results show that the OBSP is much better than the existing ones.

This paper analyzes the principle and performance of routing algorithm in intermittently connected sensor networks, and proposes an enhanced routing algorithm, which is named Transmission Probabilities Routing (TPR).TPR chooses the next-hop node to forward packets according to the forward-probability, which is calculated by contact-frequency and contact-duration. Simulation results indicate that TPR can obviously improve the performance of networks, compared to PROPHET and Epidemic.