*3.1. Experiments Overview*

The experiments were conducted in two different indoor environments with a similar type of setup. The details of the hardware modules used for the experiments are discussed in Section 8.1. Four adults (two males and two females) with different heights, weights, and body shapes participated to allow us to collect data for the experiments. During each experiment, a participant wore a chest-mounted wearable device as shown in Figure 1a. Data were collected from six RNs installed in the ceiling, as shown in Figure 1b, and placed in the same direction 2.1 m, 5.1 m, 7.5 m, 9.9 m, 12.3 m, and 15.6 m away from the participant. There were both the LOS and NLOS communication scenarios between the participants and RNs. A participant collected the RSSI from each RN while standing and turning 360◦ towards the clockwise direction around the vertical axis. During data collection, a participant turned 15◦ in every 60 s and collected RSSI data with a frequency of 2 Hz that took 24 min for a complete rotation. The average of the collected RSSI was calculated for every angle position and stored in a database for further analysis. Each participant performed the experiment several times and at different time periods of a day for a month.

**Figure 1.** Experimental setup to measure user's body effect. (**a**) Wearable device attached to the chest of a user; (**b**) reference nodes attached beneath the ceiling (marked by circles).
