## 5 Experimental Results
### Retransmission Tests  
#### 5.5.1 Test Explanation  
These tests aimed to measure the percentage of frames that are successfully received on the first attempt and what percentage needed to be retransmitted. To accomplish this, 500 packets were transmitted with the acRequest flag set to 1. Each device reported the result of its respective MCPS_DATA_CONFIRM primitive, which allowed us to check if the packet was acknowledged. Packets were transmitted at 30-s intervals.  
The network used two types of network devices: \"End Devices\" and \"ECG.\" The first device transmitted a packet with a 100-Byte payload with information about temperature. The second device transmitted 160 samples of an ECG signal in four consecutively sent packets. Importantly, this transmission was performed in the FCAP region of the super frame structure.  
In the case of duty cycle (D) = 0.25 and BO = 9, presented in Table 9, the end devices acknowledged 54.26% of the packets received by end devices in the first attempt; however, for the ECG, it was only 38.88%. This behavior can be explained by the short duration of the active section of the super frame, which is approximately 491 ms, as well as the temporal restrictions of TinyOS event handling and task posting.  
ECG transmissions significantly improve when the duty cycle is set at 0.5. In fact, the efficiency increases to 60% in the first transmission. Importantly, however, the performance of the end device drops to 41.36%. It is possible that this is due to the priority given to processing the incoming data  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**BO = 7**} \\ \hline \multicolumn{3}{c}{**4 Nodes**} & \multicolumn{3}{c}{**6 Nodes**} \\ \hline
**SD/BO** & **Time (s)** & **SD/BO** & **Time(s)** \\ \hline
0.25 & 38.3346878 & 025 & 28.8846584 \\
0.5 & 48.6352684 & 0.5 & 42.6441296 \\
1 & 15.9716565 & 1 & 18.850547 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Average set-up time. BO = 7.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**BO = 7**} \\ \hline \multicolumn{3}{c}{**4 Nodes**} & \multicolumn{3}{c}{**6 Nodes**} \\ \hline
**SD/BO** & **Time (s)** & **SD/BO** & **Time (s)** \\ \hline
025 & 32.184823 & 0.25 & 17.8481252 \\
0.5 & 22.9810905 & 0.5 & 32.1651341 \\
1 & 15.9716565 & 1 & 3.10913004 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Standard deviation of the set-up time samples. BO = 7.  
over the received ECG frames, which can cause delays in the ACK reply and an acKTimeOut. When the duty cycle is 1, the percentage of successfully transmissions in the first attempt increases to around 50% for both types of devices.  
Table 10 shows the results of these tests for BO = 7. Table 10 shows a significant improvement in the performance of transmissions when D is 0.5 with a BO of 7, both in the case of end device and the ECG, with percentages of 57.70% and 67.57%, respectively. This performance even exceeds the configuration for the test results with a BO of 9. It is possible that with shorter beacon intervals the internal clocks of the nodes suffer shorter displacements, which improves their synchronization capacities with the beacons.