Protocol Design of Sensor Networks for Wireless Automation

Abstract: The recent development of control applications overWireless Sensor Networks (WSNs) imposes new approaches to the protocol design. These networks are characterized by the scarcity of energy supply and processing capabilities. Furthermore, existing protocol solutions are often based on the traditional OSI model, where communication layers are not optimized to support efficiently the reliability and latency requirements imposed by control applications. The critical aspects of wireless transmission have lead to a lack of protocols that are able to guarantee latency and quality of service under unreliable channel conditions. In this thesis, we design and implement a cross-layer protocol for WSNs in industrial automation, the Extended Randomized Protocol, which considers jointly physical layer aspects (as power control and duty cycling strategies), randomized MAC and routing. The protocol can be considered and extension of an already existing Randomized Protocol, and it is designed with the objective to maximize the network lifetime under the constraints of error rate and end-to-end delay in the packet delivery. As a relevant part of our activity, we have provided a complete test bed implementation of the protocol building a WSN with TinyOS and a large number of Moteiv’s Tmote Sky wireless sensors. An experimental campaign has been conducted in order to test the validity of the protocol solution we propose. Experimental results show that the protocol achieves the required successful packet reception rate and the latency constraints while minimizing the energy consumption. Despite the fact that improving solutions are necessary to take into account the problem of duplicated packets, our protocol solution seems to be a good candidate for WSN in industrial automation.