Sleep/Active Schedules as a tunable characteristic of a Wireless Sensor Network

Energy constraints restrict the operation of the nodes of a wireless sensor network (WSN). Due to its limited size the sensor node can operate for a limited time. The main approach that significantly improves its lifetime is the sleep/active cycles scheme that is implemented as part of the MAC layer protocol. The two main characteristics of this model are the duty cycle and the synchronization. Protocols such as S-MAC, T-MAC and D-MAC have been designed based on different configuration of these parameters. This paper tries to analyze the sleep/active scheme in a more abstract way, by measuring it as a tunable property of any WSN. The range of our measurements includes fully synchronized schemes as well as schemes with no scheduling between the nodes. Thus, by performing several simulation scenarios we extract interesting results regarding the connectivity of the network under different duty cycles and synchronization schedules. We verify that WSNs with increased nodes density operate satisfactory even with more loosely synchronized schemes, thus significantly reducing the complexity and overhead added on the MAC layer. We present a framework that can evaluate and quantify this claim. Using this model, the designer of a WSN can fine-tune the parameters depending on the current conditions. Finally we extend this framework to accept these parameters as inputs and provide an optimized configuration of the sleep/active schedule based on them