A novel and simple technique for Direction of Arrival (DoA) estimation in 802.11 Wi-Fi networks is proposed. It is based on the use of a dual-port frequency-beam scanning antenna, which is connected to single MIMO access point. By simply performing a channel hopping scheme and acquiring Received Signal Strength Information (RSSI) from each channel, the DoA can be estimated in a wide Field of View of 180° with a mean angular error of 5°. Due to its simplicity, a single commodity Wi-Fi AP can be used without the need of Channel State Information (CSI), or complex electronically reconfigurable or mechanically revolving antennas.

We investigate the use of a single leaky wave antenna (LWA) for amplitude-monopulse direction finding when compared to the more conventional use of two tilted antennas. Thanks to the inherent bidirectional feeding and scanning behavior of LWAs, it is demonstrated a more compact and planar design while offering similar functionality in the far field. The frequency beam squinting effect suffered by the LWA, and its capability to create frequency-scanned monopulse patterns, are also analyzed; moreover, its smaller size mitigates the near-field effects, thus reporting a superior localization performance in the proximity of the antenna. This is experimentally demonstrated with prototypes designed in the 2.4 GHz ISM band, which are subsequently applied for direction finding of mobile devices connected to a Wi-Fi network.

The purpose of this work is to implement a novel active radar system for single access point two-dimensional localization system based on 802.11 wireless local-area networks (WLAN). The active radar employes the 802.11 Fine Time Measurement (FTM) Round Trip Time (RTT) as specified in the 2016 update of WIFI Standard to calculate the ranging distance and acquires two channels of Received Signal Strength Indicator (RSSI) to estimate the azimuthal angle. In this way, real-time two-dimensional localization of Wi-Fi RTT-compatible mobile Internet of Things devices is demonstrated using a single access point operating in the 2.4GHz band. The experimental results performed in anechoic chamber and in a real environment point up a mean positioning error below one meter within a Field of View (FoV) of 60° and distances up to 14 meters, with an acquisition time below 0.5 seconds.

A novel two-dimensional indoor location system for IoT devices employing a single Wi-Fi Access Point is presented. The x, y position is estimated with a combination of Directionof-Arrival (DoA) and Time-of-Flight (ToF) algorithms. The azimuthal DoA is estimated using a modified MUSIC technique, which requires the acquisition of the Received Signal Strength Indicator (RSSI) using different Wi-Fi frequency channels in the 2.4 GHz band, together with a dual-port frequency-scanning antenna (FSA). This allows a wide Field-of-View (FoV) of 180: for the DoA. To estimate the ranging distance, an algorithm based in the 802.11mc Fine Time Measurement (FTM) protocol is employed to consider the effects of the channel hopping. Therefore, the proposed system does not rely on Channel State Information (CSI) or complex IQ information, which is not available in commercial Wi-Fi APs. The proposed system has been fully implemented with a commercial Wi-Fi AP and tested in a practical scenario, proving a root-mean-square error (RMSE) when estimating the localization of mobile devices of only 1.43m, in a wide area of 12 m x 12 m.

We present a cost-effective hybrid analog digital system to estimate the Direction of Arrival (DoA) of WiFi signals. The processing in the analog domain is based on simple well-known RADAR amplitude monopulse antenna techniques. Then, using the RSSI (Received Signal Strength Indicator) delivered by commercial MiMo WiFi cards, the DoA is estimated using the so-called digital monopulse function. Due to the hybrid analog digital architecture, the digital processing is extremely simple, so that DoA estimation is performed without using IQ data from specific hardware. The simplicity and robustness of the proposed hybrid analog digital MiMo architecture is demonstrated for the ISM 2.45GHz WiFi band. Also, the limitations with respect to multipath effects are studied in detail. As a proof of concept, an array of two MiMo WiFi DoA monopulse readers are distributed to localize the two-dimensional position of WiFi devices. This cost-effective hybrid solution can be applied to all WiFi standards and other IoT narrowband radio protocols, such us Bluetooth Low Energy or Zigbee.