Target Localization in Wireless Sensor Networks Based on Received Signal Strength

Abstract

We consider the problem of localizing a target taking the help of a set of anchor beacon nodes. A small number of beacon nodes are deployed at known locations in the area. The target can detect a beacon provided it happens to lie within the beacon's transmission range. Thus, the target obtains a measurement vector containing the readings of the beacons: '1' corresponding to a beacon if it is able to detect the target, and '0' if the beacon is not able to detect the target. The goal is twofold: to determine the location of the target based on the binary measurement vector at the target; and to study the behaviour of the localization uncertainty as a function of the beacon transmission range (sensing radius) and the number of beacons deployed. Beacon transmission range means signal strength of the beacon to transmit and receive the signals which is called as Received Signal Strength (RSS). To localize the target, we propose a grid-mapping based approach, where the readings corresponding to locations on a grid overlaid on the region of interest are used to localize the target. To study the behaviour of the localization uncertainty as a function of the sensing radius and number of beacons, extensive simulations and numerical experiments are carried out. The results provide insights into the importance of optimally setting the sensing radius and the improvement obtainable with increasing number of beacons. KEYWORDS Target Localization, uncertainty, Grid mapping based approach, Received Signal Strength (RSS)