Hybrid Analog-Digital Processing System for Amplitude-Monopulse RSSI-Based MiMo WiFi Direction-of-Arrival Estimation

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 received signal strength indicator (RSSI) delivered by a 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 2.45 GHz 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 is distributed to localize the two-dimensional position of WiFi devices. This cost-effective hybrid solution can be applied to all WiFi standards and other Internet of Things narrowband radio protocols, such as Bluetooth Low Energy or Zigbee.