Estimating Soil Moisture with COTS Hardware using BLE’s Angle-of-Arrival Feature

Measuring soil moisture for agriculture is currently a hot research topic. Wireless sensor networks, that transmit readings from moisture sensors are a main contender for this task. However, sensors used in these networks often suffer from corrosion. Here, we propose a more scalable solution, using Commercial Off-The-Shelf (COTS) Bluetooth Low Energy (BLE) beacons with no additional sensor. Because of the variety of their application areas, they are available at smaller unit costs. In comparison to many moisture sensors, they can be fully encapsulated in a case for protection against corrosion. Similar solutions have been proposed using Received Signal Strength Indicator (RSSI) readings of the sensor nodes. We propose to instead use the Angle-of-Arrival (AoA), model the influence of different error sources, and calculate the expected measurement accuracy.