Temperature compensated time synchronisation in wireless sensor networks

Time synchronisation is a fundamental service in many distributed systems such as wireless sensor networks. Non-uniform operating temperature among deployed nodes and dynamic variation of the temperature represent the major cause of clock drift in the nodes of a network. Presented is a low-overhead clock synchronisation for WSNs based on a new temperature compensation algorithm (TCA). The TCA is local and uses a temperature sensor to remove the effects of environmental temperature changes and to increase the time between synchronisation intervals. Using the TCA, the 32 KHz unit achieves an effective clock drift of less than 5 ppm over a wide range of operating temperatures (25 to 628C), a significant improvement with respect to the 55 ppm featured without temperature compensation.