High-precision synchronisation in Wireless Sensor Networks with no tuning in the field

Many Wireless Sensor Network (WSN) services rely on time synchronisation, and since WSN nodes frequently operate in varying ambient conditions, adequate compensation for thermally-induced clock drift is needed. Also, WSN software – including both applications and operating systems – has to run on heterogeneous hardware, which requires synchronisation solutions that can be deployed with no or minimal tuning in the field. In a previous paper we proposed a joint clock synchronisation and skew/drift compensation scheme entirely realised as a decentralised discrete-time LTI control system, achieving high precision and low-power operation, and compensating thermal drift without temperature measurements. Here, conversely, we concentrate on generality with respect to hardware, and tuning-free deployment. We show that such requirements practically rule out feedforward thermal compensation (which further backs up our previous proposal), devise a methodology to tackle the problem, and present an application demonstrated by experimental tests.