Aerial localization of an RF source in NLOS condition

In this paper a particle filter approach to the localization of an RF source, such as a cell phone in a search and rescue mission, with unknown power and None Line Of Sight (NLOS) condition has been introduced. Two basic methods based on the Received Strength Signal Indicator (RSSI) and Angle of Arrival (AOA) using particle filters have been implemented. Two new approaches have been proposed to benefit from both RSSI and AOA methods. In the first approach the transmit power of the source has been estimated to improve the localization method. To reduce the number of particles while maintaining good accuracy, a differential method is proposed which combines the advantages of both RSSI and AOA methods, while keeping the number of particles low and keeping the accuracy acceptable. The methods have been implemented in simulation, and the results prove the efficiency of the proposed methods. The results show that even a low resolution AOA sensor can reduce NLOS propagation effects on RSSI based approaches. Furthermore, the proposed hybrid approaches did not add significant computational load to the localization process, making it suitable for real time applications.