Positioning in Synchronized Ultra Low-Power Wireless Sensor Networks

Wireless Sensor Networks (WSNs) consist of densely deployed, independent, and collaborating low cost sensor nodes. The nodes are highly resource-constrained in terms of energy, processing, and data storage capacity. Thus, the protocols used in WSNs must be highly energy-efficient. WSN communication protocols achieving the lowest power consumption minimize radio usage by accurately synchronizing transmissions and receptions with their neighbors. In this paper, we show how network signaling frames of state-of-the-art synchronized communication protocols for low-power WSNs supporting mobile nodes can be used for positioning. We derive mathematical models for node power consumption analysis. Both centralized and distributed positioning architectures are modeled. The models provide a tool for estimating what kind of network lifetimes can be expected when average positioned node speed, the amount of anchor nodes required by the location estimation algorithm, and the location refresh rate required by the application are known. The presented analysis results are based on two kinds of node hardware: with and without Received Signal Strength Indicator (RSSI). The results show that the positioning parameters and used hardware have significant impact on node power consumption and network lifetime. In the presented results, the network lifetime ranges from over 10 years to 2 months with different positioning requirements and hardware. keywords: Wireless, Low-Power, Sensor Networks c ⃝[2010] IEEE. Portions reprinted, with permission, from [Ville Kaseva, Timo D. Hämäläinen, and Marko Hännikäinen, Positioning in Resource-Constrained Ultra Low-Power Wireless Sensor Networks, Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS), October/2010]