An enhanced algorithm for 2D indoor localization on single anchor RSSI-based positioning systems

In this paper a cost-effective RSSI-based Range and Direction of Arrival (DoA) estimator using a single anchor node is proposed. Exploiting the Space Division Multiple Access enabled by a anchor node equipped with a switched beam front-end, the DoA of a nomadic node is estimated on the basis of maximum likelyhood approach driven by the expected power distribution. The distance is subsequently estimated on the basis of a robust inversion of the power-range relationship. Compared to conventional estimators, the proposed approach offers a precise DoA estimation as well as a adequate range estimation despite the simple implementation. The combination of the two information enables also the estimation of the absolute position with a very low-cost solution, suitable for Wireless Sensor Networks and for 802.11n/ac IEEE compliant networks. Experimental validations in an anechoic chamber confirm that the proposed method can provide a complete 2D localization with a mean error of 95cm and a sub-metric localization area coverage of about 60% within a typical home room area size (28m^2), without the needing of a multi-anchor system setup.