Space and Time Localization in Wireless Sensor Networks

Wireless sensor networks (WSN) are an increasingly attractive means to bridge the gap between the physical and virtual world. WSNs are envisioned to be used to fulfill complex monitoring tasks. Space and time play a crucial role in wireless sensor networks, since sensor nodes are used to collaboratively monitor physical phenomena and their space-time properties. A number of techniques and distributed algorithms for location estimation and time synchronization have been developed specifically for sensor networks. There are many similarities in space and time domains. This affects the location estimation and time synchronization, ranging from applications and requirements to basic approaches and concrete algorithmic techniques. An improved approach for space and time localization in WSNs is given in this paper. The main aspect of the algorithm is the use of a mobile beacon for both localization and synchronization. A mobile beacon is a node that moves around the sensor's field and it is aware of its time and position, equipped with a Global Positioning System (GPS) receiver. The synchronization component uses the packets required by the positioning component to improve its performance. The positioning component benefits from the communication, required by the synchronization component to decrease errors. A set of experiments and simulations are presented to evaluate the performance of the algorithm in order to reduce communication and processing resources and save energy and network resources.