Distance Estimation of Smart Device using Bluetooth

Abstract

Distance estimation identifies the distance between two machines in wireless network. The Received Signal Strength Indication (RSSI) of Bluetooth can be used to estimate distance between smart devices. The characteristic of Bluetooth RSSI value is different as environments. So, we have tested the relation between distance and Bluetooth RSSI value in several environments, such as indoor hall, meeting room, and ElectroMagnetic Compatibility (EMC) chamber environment. This paper shows the distance characteristic of Bluetooth RSSI from these experiment results. There are a lot of measurement errors at Bluetooth RSSI raw data. The minimum RSSI value is -88 dBm and the maximum RSSI value is -66 dBm at 11m of the indoor hall environment. The difference between maximum value and minimum value is 22 dBm. So, it is hard to estimate the distance using Bluetooth RSSI raw data. Therefore, we use the Low Pass Filter (LPF) for reducing the measurement errors. The minimum RSSI value is -80.6 dBm and the maximum RSSI value is -71 dBm in the same environment. The difference between maximum value and minimum value is just 8.4 dBm. The measurement error is significantly reduced. We compare the distance estimation between the Bluetooth RSSI raw data and LPF data at the EMC environment. This paper shows that the distance estimation is possible with small error rates using Bluetooth RSSI LPF data.