# Routing Topologies of Wireless Sensor Networks for Health Monitoring of a Cultural Heritage Site
## 6 Discussion  
In this section, a comparison between the performance of the XMESH and CTP protocols tested at the CAEND institute (Experiments 1 and 2) is presented. Two parameters, the percentage of received messages and the lifetime of the WSN, are proposed in this work to analyze which routing protocol is better in a particular deployment. According to the results reported in Figures 3 and 4, the percentage of received messages using the XMESH protocol was always lower than that using the CTP protocol. In general, the WSN using the CTP protocol depleted its energy faster. A more detailed analysis of the data was developed by us to understand why the WSN using the CTP protocol performed better, but depleted its energy faster, than the WSN using the XMESH protocol in both experiments. For that purpose, the communication parameters described above will be presented as a function of time during the experiment. For each more, the route followed by each message as a function of time is shown in Figures 9 and 10 using the XMESH and CTP protocols in Experiment 1, respectively. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**RSSI** & **Mode 20** & **Mode 21** & **Mode 22** & **Mode 23** & **Mode 24** & **Mode 25** & **Mode 26** & **Mode 27** \\ \hline \hline \multicolumn{1}{l}{Note 21} & 244 & X & 38 & 230 & 190 & 125 & 215 & 260 \\ \multicolumn{1}{l}{Note 22} & 182 & 138 & X & 265 & 169 & 195 & 248 & X \\ \multicolumn{1}{l}{Note 23} & \(\mathsf{X}\) & 230 & 265 & X & X & 76 & 35 & 220 \\ \multicolumn{1}{l}{Note 24} & 193 & 190 & 169 & X & X & 252 & X & X \\ \multicolumn{1}{l}{Note 25} & \(\mathsf{X}\) & 125 & 195 & 76 & 252 & X & 146 & 291 \\ \multicolumn{1}{l}{Note 26} & \(\mathsf{X}\) & 215 & 248 & 35 & X & 146 & X & 209 \\ \multicolumn{1}{l}{Note 27} & \(\mathsf{X}\) & 260 & X & 220 & X & 291 & 209 & X \\ \hline \end{tabular}
\end{table} 
Table 1: RSSI values of the WSN at the CAEND institute. Figure 9: Route distribution for each more using the XMESH protocol in Experiment 1. The black dot represents the more that created the message (source mode), a blue dot represents the parent of a more (the first parent), a red dot the parent of the parent (the second parent, i.e., a grandparent in human terms), a green dot the third parent, a cyan dot the fourth parent, a magenta dot the fifth parent, a yellow dot the sixth parent, and a black cross the seventh parent. It can be seen that the CTP network was more stable, i.e., there were fewer changes from one parent to another. Indeed, once a parent is selected it is kept for a longer time interval (which is visualized as a continuous line of the same color). Since this experiment starts on Monday morning, it can be observed that, during the weekend, the XMESH configuration was more stable than during working days, but compared with CTP the number of hops was generally larger. The lost messages (red color), number of hops made for a message to reach the base station (black color), and parent identifiers (blue color) as a function of time for each mode using the XMESH protocol, are shown in Figure 11. In the x-axis the time interval is presented as a day period, morning (m) from 7:00 to 15:00, afternoon (a) from 15:00 to 23:00, and night (n) from 23:00 to 7:00. The data considered in Figure 11 starts on Monday morning and lasts until Sunday morning. When a lost message occurs, a red cross is plotted with a value of \(-1\). This representation of the data serves to point out possible relationships between the lost messages and the change of the parent identifier or the number of hops required to reach the base station. It can be observed that, in many cases, a message loss using the XMESH protocol is associated with a route change. Note 12 had the lowest number of lost messages; it did not change its parent. With this representation, it can also be seen that, commonly, the received message losses occurred in the morning, probably due to the higher crowd intensity.