Range-free Localization Algorithms with Mobile Anchors at Different Altitudes: A Comparative Study

In this work, we compare the performance of range-free localization algorithms either radius-based or radius-free that use a mobile anchor (rover or drone). All the compared algorithms are based on the so called heard/not-heard method. Despite its simplicity, the localization accuracy of the heard/not-heard method heavily depends on the radius of the antennas. Usually the only information available for the antenna is the average radius issued by the manufacturer's technical datasheet. Thinking that the knowledge of the actual average radius can be of help for the localization, we observe in a real test-bed, at different altitudes, the antenna radiation pattern of the DM1001 antennas used in the commercial MDEK1001 kit from DecaWave. We simulate the localization algorithms using the average antenna radius tested during the experiments on the field and using the radius provided by the manufacturer's technical datasheet. In practice, however, the more precise information about the radius does not reduce the localization error. It only reduces the number of unlocalized devices. We conclude that the knowledge of the exact antenna pattern is the essential requirement for any range-free localization algorithm. However, since increasing the altitude the antenna radius becomes smaller and less dispersed, smaller errors occur localizing with a drone than with a rover.