# BLE Signal Reception and Localization Performance with Varying Receiver and Beacon Setups
## 3 BLE Signal Analysis
### Wall Gateways BLE Signal Segments  
For the wall gateways, variations in signal segment lengths were observed regardless of the BLE device position. Analysis of the signal characteristics over 3 min revealed distinct patterns. The average signal values consistently decreased across all BLE positions. Specifically, the front pocket, back pocket, and top pocket positions exhibited a consistent decrease in mean values, indicating that shorter signal segments were generally associated with lower signal strength. Additionally, the standard deviation increased with shorter segments, indicating greater variability in signal strength. Conversely, as the threshold for longer signal segments increased, the mean signal values gradually rose. This trend was consistent across all BLE positions, indicating that  
Figure 4: Layout of the signal measurement positions in the indoor area. longer signal segments generally corresponded to higher signal strength. The standard deviation decreased with longer segments, suggesting greater stability in signal strength. Certain positions failed to register measurements from specific receivers, particularly from GW 5, as shown in the Appendix A. In these cases, missing signal values were replaced with a standardized value of \(-90\). Figure 5 illustrates an example of segments between the 60% and 70% thresholds emitted by the shoulder beacon received from the wall gateways. The different colors represent the various positions where the RSSI is measured. And gray colors represent signal segments of lengths belonging to other length ranges. Table 1 presents data on the quantity of BLE signal segments and their standard deviation across different length ranges for shoulder positions. Analysis of BLE signal segments received by wall-mounted gateways reveals variations in the quantity of short and long segments across different body positions. The front pocket, back pocket, and top pocket positions show a higher signal number of short segments, indicating potential challenges in signal stability. In contrast, fewer long segments are observed in these positions. The wrist position exhibits the highest number of long signal segments. The shoulder position consistently shows a lower number of short signal segments, suggesting a higher signal reception effectiveness. The standard deviation of signal values across all segment lengths and BLE positions remains relatively consistent. Figure 6 shows the distribution of BLE signal segments received from the wall-mounted GW, and their quality across different body positions. The left subfigure depicts the quantity of signal segments within different length ranges (e.g., 0-10%, 10-20%, etc.) for each body position, including the front pocket, back pocket, top pocket, shoulder, and wrist. The right subfigure shows the standard deviation of signal quality (representing variability) within each segment length range for the same body positions. These visualizations highlight variations in signal across different body locations. Figure 5: Example of signal segments (dBm) by the shoulder beacon received from the wall-mounted gateways, illustrating the range between the 60% and 70% thresholds. The analysis of signals from wall-mounted gateways at various BLE positions reveals consistent signal strength patterns. Evaluation of minimum, maximum, and average signal values provides insights into BLE signal performance at different body positions. The wrist and back pocket positions show the highest maximum and average signal strengths in the indoor environment, suggesting that the proximity of the BLE device to the wall-mounted gateways affects signal strength. The characteristics of BLE signal performance are further illustrated in the violin plot shown in Figure 7. The plot displays the distribution of signal strengths (minimum, maximum, and average values) for each body position.