# Routing Topologies of Wireless Sensor Networks for Health Monitoring of a Cultural Heritage Site
## 5 Results  
In this section, the results obtained with the WSNs during the three experiments are presented. The number of lost messages was compared with the lifetime of the network to analyze the network behavior for a particular scenario and to detect hardware failures. To prevent erroneous data due to the lack of battery power needed to compute the number of lost messages, only measurements up to 8400 min were considered. Figure 3 presents the percentages of received messages using the XMESH and CTP protocols in the three experiments for each note. The percentage of received messages using the XMESH protocol was always lower compared to the CTP protocol. In Experiment 1 the difference between the average percentages of received messages using both protocols was the largest, probably due to the high crowd intensity during the test. In Experiment 3 this difference was the smallest since there was direct line of sight between notes. The nodes closest to the base station (Motes 12 and 14) in Experiment 2 were the motes with the lowest number of lost messages using the XMESH protocol, but this tendency was not observed when the CTP protocol was used in the same experiment. The percentage of the relative lifetime of each note using the XMESH and the CTP protocols in the experiments is presented in Figure 4. The relative lifetime for each experiment means the lifetime of each note considering 100% the lifetime of the last note depleting its energy. The value of 100% corresponds to 13,384 min. On average the WSN using the CTP protocol depleted its energy faster than the WSN using the XMESH protocol in all experiments. Experiment 1 had the longest lifetime and Experiment 2 the shortest one. In Experiment 1 the results obtained using the XMESH  
Figure 3: Percentage of received messages using the XMESH and CTP protocols. protocol had more dispersion than using the CTP protocol, while the reverse situation was observed in Experiments 2 and 3. Figure 4 also shows that, in general, the motes located at longer distances from the base station stopped emitting before those closer to the base station. In Experiment 3, since there was direct line of sight, both WSNs worked well and were very stable, and almost all motes had a direct connection to the base station. Therefore, a more detailed study was developed specifically for Experiments 1 and 2 to understand why the CTP protocol performed better than the XMESH one. The number of hops, the parent identifiers of each message, and the total number of lost messages as a function of time, using the XMESH (Mote 11) and CTP (Mote 21) protocols during Experiment 1, is shown in Figure 5. This representation illustrates the differences between protocols for Motes in the same positions. It was found that fewer messages were lost using the CTP and the WSN was more stable, i.e., there were fewer changes from one parent to another. Once a parent was selected, it was kept for a longer time interval. Figure 6 presents the average number of hops made for a message to reach the base station and the average hopping distance reached by each mode (i.e., the distance divided by the average number  
Figure 4: Percentage of the relative lifetime of each mote using the XMESH and CTP protocols. Figure 5: Number of hops, parent identifiers of each message, and total number of lost messages as a function of time using the XMESH (Mote 11) and CTP (Mote 21) protocols in Experiment 1.  
of hops) using each protocol in Experiments 1 and 2. As expected, the nodes closer to the base station had on average the lowest number of hops for both protocols. In Experiment 1, the average number of hops was always lower (and, therefore, the average hopping distance was larger) for the CTP protocol than for the XMESH protocol, except for Note 12. In Experiment 2, the average number of hops was, in general, lower (and, therefore, the average hopping distance was larger) for the XMESH protocol than for the CTP protocol.