Optimal Sleep/Wake Scheduling for Time-Synchronized Sensor Networks with QoS Guarantees

We study sleep/wake scheduling for low-duty cycle sensor networks. Our work is different from previous work in that we explicitly consider the effect of the synchronization error. We study a widely used synchronization scheme and show that the synchronization error is non-negligible, and using a conservative guard time is energy wasteful. Hence, we formulate an optimization problem to minimize the expected energy consumption, with the constraint that the message capture probability should be no less than a threshold. We find that the problem is non-convex, hence cannot be solved by conventional convex optimization techniques. By investigating the unique structure of the problem, we transform the problem into a convex equivalent, and solve it using an efficient search method. Simulations show that our scheme significantly outperforms schemes that do not intelligently consider the synchronization error. We also remove the assumption that the capture probability threshold is given, and study how to decide it to meet the quality of services (QoS) requirements of the application