Antenna Pattern Optimization for a RSSI-based Direction of Arrival Localization System

In the area of wildlife research a gaining topic is the use of wireless sensor networks to track animals for studying their social behavior [1]. Depending on the tracked species, there are extreme requirements on weight, costs or energy consumption for the transmitter mounted on the animal. For a low cost localization system the received signal strength can be used to estimate the distance. In addition, using multiple directional antennas, a direction of arrival estimation is possible. Using sensor data fusion of multiple receivers a tracking of the animal is possible. In this paper the optimization of an antenna pattern for the direction of arrival estimation based on the received signal strength in such sensor networks is shown. For this purpose, quality parameters are defined and theoretical limits such as the Cramer Rao Lower bound are compared to the simulation results. It is shown that the proposed quality parameters allow an antenna pattern optimization. The optimized antenna patterns show lower localization errors in the trajectory simulation. These results are key enablers for developing a low cost received signal strength based localization system for tracking the flying trajectory of bats.