## 3 Current WSNs Designed for Do nana
### eSAPIENS Network  
Until 2013, all of the sensor information was gathered from our networks in a classical manner, _i.e._, each deployed WSN had its own base station that collected sensor node information and sent it to the central server in Do nana, using open-middleware that allowed us to access the information through the internet. The developed middleware allows the representation of the information on a webpage and uses the data with other tools, such as data mining tools (Figure 21).  
However, this structure has some scalability problems in very large and widely extended networks. This scheme suffers from several problems: All of the information goes through a Base Station to a single server; the nodes cannot share information directly among the different networks, and therefore, it is not possible to access data directly from its sources (data can be accessed only through the central server).  
As an alternative to these classical WSN schemes using a central server to retrieve the information, some authors have proposed a new scheme, which is directly related to the Internet of Things (IoT) philosophy based on the use of IPv6 communications over WSNs [39; 40]. Because of the advantages that IPv6 communication schemes add to WSNs, in 2012, we started to migrate all of our networks to this communication scheme.  
Figure 20: Node of the SENDA network. (**a**) Exterior of the node; (**b**) Devices in the node.  
IPv6 implementations for WSNs (also called 6 LoWPAN communications [41, 42]) are focused on reducing the requirements of the Base Station as much as possible, _i.e._, using the base station only as a gateway between the two networks [43], without any intelligence. Because IP is a very common stack, almost any device can be easily used, even standard PCs (Figure 22).  
The use of IPv6 provides a common framework in which additional protocols can be added, and a basic interoperability is maintained between networks. The 6 LoWPAN implementation not only solves the retrieving information problem from the Base Station but also allows access to every node in the WSN from anywhere on the Internet [44]. Thanks to 6 LoWPAN, each node can be uniquely identified [45].  
Moreover, IPv6 allows us to add some common communication layers to the network, such as compressed addressing [46] or security layers [47, 48]. Using a correct control of the exchange messages, it is possible to increase the efficiency of IPv6 [49, 50], which is not initially designed for devices with this reduced data bandwidth.  
Figure 21: Example of data mining using real-time environmental information on Do �na.  
Figure 22: Example of data mining, using real-time environmental information on Do �na.  
Due to these 6 LowPAN advantages, since 2013, we have been working on interconnecting all of the ICARO networks using this technology, especially focusing on allowing an effective communication infrastructure that permits us to monitor globally distributed problems, such as migratory birds or global climate change.  
With this infrastructure, we have created a new meta-network called eSapiens, which covers all of the deployed WSNs of Do nana (Figure 23). Moreover, eSapiens allows us to use external WSNs or other services by using the Internet. With eSapiens, each node can communicate directly with other devices, using its individual IP direction.  
eSapiens is based on CoAP [51], a UDP protocol that is designed specifically for maintaining the low power consumption of WSNs. With eSapiens, each node stores its own information, allowing direct access to the information through the Internet, _i.e._, each node acts as a local server, drastically increasing the reliability of the network.