# Routing Topologies of Wireless Sensor Networks for Health Monitoring of a Cultural Heritage Site
## 7 Conclusions  
This paper provides a performance evaluation of tree and mesh routing topologies of wireless sensor networks (WSNs) in San Juan Bautista church in Talamanca de Jarama (Madrid, Spain). To test which routing topology was better for this kind of application, the WSNs were first deployed on the upper floor of the CAEND institute in Arganda del Rey (Madrid, Spain) simulating the church deployment. Two parameters were selected to evaluate the performance of the routing topologies selected, the percentage of received messages and the lifetime of the network. To analyze in more detail which topology gave the best performance, other communication parameters were measured, such as the number of hops required for every message to reach the base station, the parent identifier for each message, and the RSSI values for each more. The tree topology used was the collection tree protocol and the mesh topology was the XMESH provided by MEMSIC (Andover, MA, USA). These topologies were selected because they are the most commonly used. Three different experiments were carried out to evaluate the selected routing topologies. Experiments 1 and 2 were conducted at the CAEND institute with high and low crowd intensity, respectively, while Experiment 3 was performed at the church deployment with occasional high crowd intensities during mass times. In this study, the following conclusions were obtained:  
* The CTP network performed better than the XMESH network in all experiments, meaning that fewer messages were lost. The main reason of this behavior is that the XMESH network tends to reconfigure itself faster than the CTP one, if there are communication problems, which were mainly due to the movement of people. This could be an advantage in some applications, but the reverse situation occurs if the location of the network is static, mainly because the time required to reconfigure the network can lead to message loss. When XMESH became more unstable, mainly due to high crowd intensity, the number of hops increased and message loss was associated with route changes. * The CTP network was more stable, i.e., there were fewer changes from one parent to another. * People presence affected the XMESH network more than the CTP one. Under quiet conditions (low people presence), during evenings and weekends, as well as in Experiment 2 performed during a holiday period, it was found that the behavior of both networks, in terms of network configuration, was very similar and the number of lost messages was reduced. In all experiments, it was found that, on average, the WSN using the CTP protocol depleted its energy faster than the WSN using the XMESH protocol. In both protocols, nodes closer to the base station handling more traffic lasted longer than the other nodes. Therefore, the number of transmissions does not affect the lifetime of the modes. The conclusions of this work are constrained to WSNs using the very common CTP and XMESH protocols, as representative of tree and mesh topologies, respectively. Future work using different protocols is needed to verify if our findings apply to tree and mesh topologies in general. This task is out of the scope of the present work, which is one of the first attempts to provide an experimental evaluation to test the performance of WSNs. **Acknowledgments:** The Spanish Ministry of Economy and Competitiveness supported this research under grant numbers BIA2009-14395-C04-01 and TEC2012-38402-C04-03. The present study was also funded under project CGL2010-19554. [PERSON] benefited from funding provided by the Spanish National Research Council (CSIC) through its Post-graduate Studies Council's post-doctoral specialisation programme (JAE-Doc). Researcher [PERSON]'s was supported by an International Programme for Recruiting Talent (PICATA) predoctoral fellowship awarded by the Moncola Campus of International Excellence (UPM-UCM, CSIC). [PERSON] benefited from a FPI grant BES-2010-038826 of the Ministry of Education, Culture and Sports.