Adaptive Proportional–Integral Clock Synchronization in Wireless Sensor Networks

In this paper, we present a novel control-theoretic time synchronization algorithm, named PISync for synchronizing sensor nodes in wireless sensor networks (WSNs). The PISync algorithm is based on an adaptive proportional-integral controller. It applies a proportional feedback (P) and an integral feedback (I) on the local measured synchronization errors to compensate the differences between the clock offsets and the clock speeds. We present practical flooding-based and fully distributed protocol implementations of the PISync algorithm, and we provide theoretical analysis to highlight the benefits of this approach in terms of improved steady-state error and scalability as compared with existing synchronization algorithms. We show through theoretical analysis, real-world experiments, and simulations that PISync protocols have better or comparable performance over existing protocols in the WSN literature in terms of rate of convergence and steady-state error with the additional advantages of requiring minimal CPU overhead, memory allocation, and code footprint independent of network size and topology, and of employing blind communication.