Time Synchronization and Calibration in Wireless Sensor Networks

In this chapter, we review time synchronization and calibration for wireless sensor networks. We will first consider time synchronization in Sections 1.1–1.6, before turning to calibration in Section 1.7. We will show that time synchronization can be considered as a calibration problem and many observations about time synchronization can be transferred to calibration. In Section 1.1, we discuss applications of synchronized time in sensor networks, present challenges of sensor networks, and discuss why traditional synchronization approaches fail to meet these challenges. Section 1.2 presents models of sensor nodes, of hardware clocks, and of communication. Section 1.3 gives an overview of the various classes of synchronization. In Section 1.4, we present common synchronization techniques. Section 1.5 examines current synchronization algorithms. Section 1.6 presents common techniques for evaluating synchronization algorithms and selected evaluation results.