An Efficient Distance Estimation Method Based on Bluetooth Low Energy and Ultrasound
Suk-Un Yoon, Jongha Woo, JungYon Cho, Cheul-Ree Rahm · 2018
In this paper, we propose an efficient distance estimation method using Bluetooth Low Energy (BLE) and ultrasound which frequency range is higher than 20 kHz and not audible for human. Estimating distance from Received Signal Strength Indicator (RSSI) is not accurate because the propagation constants are varying depending on the environmental factors such as antenna orientation, transmission power, and hardware structure. Thus, it is important to determine appropriate propagation constants before estimating distance based on RSSI. On the proposed method, the propagation constants are estimated based on Time-Difference-of-Arrival (TDoA) between BLE and ultrasound propagations. With the determined propagation constants, the application can estimate the distance using BLE RSSI only, where we use a Low Pass Filter (LPF) to reduce the deviation of RSSI values. The proposed method evaluated with real products shows accurate distance estimation results.