## 3 Experimental Results
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Statistical Operator**} & \multicolumn{6}{c}{**Node**} \\ \cline{2-7}  & \#2 & \#3 & \#4 & \#5 & \#6 & \#7 \\ \hline Average & \(-\)64.4467 & \(-\)59.7705 & \(-\)79.2746 & \(-\)61.7483 & \(-\)57.8385 & \(-\)51.3382 \\ Std. Deviation & 2.1496 & 0.8942 & 1.5119 & 1.3928 & 0.7642 & 0.6049 \\ Maximum & \(-\)52 & \(-\)55 & \(-\)73 & \(-\)55 & \(-\)53 & \(-\)49 \\ Minimum & \(-\)88 & \(-\)80 & \(-\)94 & \(-\)80 & \(-\)68 & \(-\)60 \\ Mode & \(-\)64 & \(-\)60 & \(-\)79 & \(-\)62 & \(-\)58 & \(-\)51 \\ Median & \(-\)64 & \(-\)60 & \(-\)79 & \(-\)62 & \(-\)58 & \(-\)51 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: RSSI statistics for the indoor scenario. Figure 20: RSSI values (measured in dB) for each node. device (-95 dB) and node #4 has a reduced PER (0.42%). Mode and median values are -79 dB, which is sufficient to ensure the proper operation of the network. Once radio signal level as well as quality (in terms of signal to noise as well as Packet Error Ratio levels) has been obtained, the battery consumption of the WSN will be analyzed. For such purpose we distinguish between the number of iterations initiated by the network, the number of iterations correctly completed by each node and the number of iterations successfully completed by the network. Figure 22 (left) depicts the average battery consumption in microvolts according to such criteria. Figure 22 (right) shows the battery consumption (in millivolts) after 50,000 iterations. Note that nodes with a note that the nodes with fewer losses are those which have a greater number of transmissions. Although by the definition of the communication protocol node #1 does not receive messages from any of its neighbors, in fact, its radio interface receives messages and therefore, energy consumption occurs. The battery consumption of the nodes after 50,000 iterations is close to 100 mV. Also note that all nodes do not perform the same number of transmissions, since, as they advance along the chain, fewer messages are transmitted. Although it must be remembered that only 2806 messages are lost. Figure 23 depicts, in more depth, the battery consumption of each node. Figure 21: RSSI diagram. In order to validate the estimations given by the radio channel 3D Ray Launching code, simulation and measurements results have been correlated comparing RSSI values with 3D Ray Launching results previously obtained, as shown in Table 4. In this case the value has been obtained in the radio link established from the preceding WSN nodes, e.g., when first was emitting, the RSSI value received in the second node was obtained and when second was emitting the value was acquired from third, _etc._  
A mean error of 1.4 dB has been obtained in this comparison, validating the use of the 3D Ray Launching tool in order to adequately locate the proposed nodes of a WSN under design phases. Figure 23: Battery voltage by node and experiment, and final battery voltage after 50,000 iterations (large figure). Figure 22: Battery consumption according to the number of iterations initiated, completed by node and completed by the system (**left**), and battery consumption (in millivolts) after 50,000 iterations initiated (**right**).