Adaptive wakeup scheduling based on power-law distributed contacts in delay tolerant networks

In mobile delay tolerant networks (DTNs), energy-efficient probing schemes are vital to prolong the limited battery life of mobile devices. Current solutions mainly focus on optimizing the probing interval during contacts by assuming the contact rate between devices are exponentially distributed. However, extensive experimental measurements have shown the contact rate follows a power law distribution, which indicates the current solutions not optimal while on the other hand dramatically increases the difficulty to analyze this problem. In this paper, we propose an adaptive wakeup schedule based on power-law distributed contacts. Our approach requires nodes stay asleep when a contact is unlikely to happen and wake up only when the possibility that it can successfully contact another node is relatively high. By predicting node contacts in the future, our approach significantly reduce energy consumption without degrading the performance of opportunistic networks. Extensive simulations with real-life human traces have demonstrated the outstanding performance of our approach, which are able to save 30 percent energy while keeping the same performance in most scenarios.