2-D DoA Anchor Suitable for Indoor Positioning Systems Based on Space and Frequency Diversity for Legacy WLAN

In this letter, we present an anchor node suitable for 2-D direction-of-arrival estimation in indoor environments. It is enabled by the space and frequency division multiple access concept, and it is exploited in a dual-band IEEE 802.11 network operating at both 2.45 and 5.2 GHz. The anchor is suited for position estimators that compare the real-time system received signal strength indicator with the expected signal levels, from any possible position and without any prior calibration stage, to estimate the actual position. An independent experimental validation demonstrates the system performance in a 2-D scenario with respect to several position estimators: within an area of 25 m2, a mean error of 37 cm is observed, while the 90th percentile of the cumulative error distribution is 52 cm.