Wakeup scheduling for energy-efficient communication in opportunistic mobile networks

Opportunistic mobile networks consist of mobile devices which only communicate when they opportunistically contact each other. Periodic contact probing is required to facilitate opportunistic communication, but seriously reduces the limited battery life of mobile devices. Current research efforts on reducing energy consumption of contact probing are restricted to optimize the probing interval, but are insufficient for energy-efficient opportunistic communication. In this paper, we propose novel techniques to adaptively schedule wakeup periods of mobile nodes between their inter-contact times. A node stays asleep during inter-contact times when contact probing is unnecessary, and only wakes up when a contact with another node is likely to happen. Our approach probabilistically predicts node contacts in the future, and analytically balances between energy consumption for contact probing and performance of opportunistic communication. Extensive trace-driven simulations show that our approach significantly improves energy efficiency of opportunistic communication compared to existing schemes.