The energy cost of location information in wireless sensor networks

Based on a study of the optimal tracking error,we investigate the energy cost of obtaining location informationin emerging wireless sensor networks. Specifically, we study thecase of signal strength based positioning and tracking underthe assumption of log normal shadowing. We find that for nodedensities in which signal strength positioning is viable, an a prioridetermination of the path loss exponent of the shadowing model isenergy inefficient and unnecessary in terms of location accuracy.We also find that accuracy improvements in tracking obtainedby increasing the radio transmission range of the sensor nodesis energy inefficient in relation to accuracy improvements. Basedon our results we propose a simple location-update protocol thatdesigners of location-based network functionalities should deploy