## 2 Problem Formulation and Application Environments  
Let us suppose an environment where a great variety of sensors must be scattered to take measurements from the environment or the same type of sensor but with different types of profiles. Let us suppose that the whole area is divided into zones and each zone has one or several types of sensors (humidity, temperature, wind, movement, _etc._) organized by a central node as a cluster. Let us also suppose that exclusive networks with the same type of sensors (network of temperature sensors, network of wind sensors, network of humidity sensors, _etc._) are needed. An example could be the use of clusters of different sensors for each tree in a forest. So, there will be as many networks as types of sensors. It could be also used to create virtual wireless sensor networks (the same concept as Virtual Local Area Networks in wired networks). Some examples given to explain the form of that exclusive network between nodes from different clusters are the following:  
* They could have a different transceiver to connect to other cluster nodes but the same transceiver to connect to the cluster head node. * They could use a different wireless protocol to connect to other cluster nodes but the same transceiver to connect to the cluster head node. * They could be using different types of technology to connect to other cluster nodes but the same transceiver to connect to the cluster head node. * They could be transmitting different types of data that is not understandable by other types of nodes, only by the same type of node and the cluster head node. * They could have different types of profiles. * They could be different types of devices. Moreover, there are some statements that must be added:  
* When a new sensor joins the architecture, it will belong to the zone of its nearest central cluster sensor. * Due to processing consumption issues, the number of connections to the central cluster sensor should be limited, so when it reaches the maximum number of connections, the new sensor has to create a new cluster. * Sensors will have connections only with the same type of sensors of neighboring groups in a predefined distance or coverage area, but not with nodes from other groups that are not neighbors. * For energy saving purposes, when there are several sensors from other clusters in the sensor's coverage area, the one with higher capacity (which depends on the energy between other parameters that will be presented later) will be chosen as a neighbor. * The network formed by sensors of the same type will have its own routing protocol algorithm. Taking into account the aforementioned premises, several application environments can be found. Some of them are the following:  
* It could be used in any kind of system where an event or alarm is based on what is happening in a specific zone, but conditioned to the events that are happening in neighboring zones. One example is a group-based system to measure the environmental impact of a place (forest, marine reef, _etc._). It could be better measured if the measurements are taken from the plants and from the trees in that place with different type of sensors. Each kind of measurement could be taken from different groups of sensors, but those groups of sensors have to be connected with the same type of sensors in order to estimate the whole environmental impact. * It could be used in body area sensor networks. The devices used to sense the body could be several types of sensor (pulse sensors, skin sensors, sweat sensors, _etc._). A sensor may need to be connected with the same type of sensors of other zones of the body to form their specialized network in order to check the measurements of a specific parameter. * It could be used to build networks of sensors with the same profile that come from different communities (each community will be a cluster).