# BLE Signal Reception and Localization Performance with Varying Receiver and Beacon Setups
## 4 Overview of Indoor Localization Accuracy Based on the RBF Method
### Localization Errors from the Ceiling GW Combinations  
The results exhibit variability across different body positions and the number of gateways. Generally, as the number of gateways increases from 2 to 5, positioning errors tend to decrease, with the most significant reductions observed at positions such as the top pocket, shoulder, and wrist. For example, at the shoulder position, the error decreases from 0.78 m with 2 gateways to 0.57 m with 5 gateways, indicating that a higher number of gateways enhances accuracy in indoor localization. However, the influence of gateway count on positioning errors is body position-dependent. Notably, errors at the top pocket position display inconsistent patterns across various gateway configurations.  
Figure 13 illustrates the indoor localization errors resulting from the utilization of various combinations of ceiling gateways. And Table 4. illustrates the best indoor localization errors at the five BLE positions on the body and considers different combinations of ceiling-mounted receivers. Figure 14 illustrates the best localization errors found along with their respective ceiling GW combinations. It is evident that the choice of body position has a discernible impact on localization accuracy. The results indicate that the shoulder position consistently yields the lowest errors across all combinations of GWs. This suggests that the shoulder position is particularly advantageous for achieving precise indoor localization when utilizing BLE beacons. On the other hand, the front pocket and back pocket positions exhibit higher errors, indicating a comparatively less reliable localization performance in these locations. The top pocket and wrist positions fall in between, demonstrating varying degrees of accuracy.  
The analysis of localization data from ceiling-mounted and wall-mounted receivers indicated that ceiling-mounted gateways generally offer higher localization accuracy, particularly at the shoulder position across various configurations. Both configurations demonstrated varying error rates with an increasing number of gateways; however, ceiling-mounted configurations consistently showed greater improvements in accuracy as the number of gateways increased. Examination of error patterns across different body positions suggested that the choice between wall-mounted and ceiling-mounted configurations should be influenced by the specific use case and the predominant body positions involved. The highest localization accuracy was consistently observed at the shoulder position across configurations.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Errors in Meters** & **2 GWs** & **3 GWs** & **4 GWs** & **5 GWs** \\ \hline Back Pocket & 1.2611 & 1.2733 & 1.1074 & 1.1172 \\ \hline Front Pocket & 1.4596 & 1.2513 & 1.4576 & 1.603 \\ \hline Shoulder & 0.78158 & 0.82943 & 0.60427 & 0.57919 \\ \hline Top Pocket & 1.4833 & 0.95874 & 0.95055 & 1.2279 \\ \hline Wrist & 1.4098 & 1.0701 & 1.0156 & 0.74182 \\ \hline \hline \end{tabular}
\end{table}
Table 4: The best indoor localization errors in meters across five body positions and ceiling-mounted GW configurations. The results in red boxes are depicted in detail in Figure 14. Highlighted boxes indicate the best errors for each quantity of GWs.  
Figure 13: Indoor localization errors using all possible combinations of ceiling GWs.