As a matter of fact, many environmental control devices are employed in the greenhouse to control a fixed area. Therefore, it is necessary to divide the zone into multiple sub-zones. This idea was adopted by Kim et al. (2008), who separated the control area according to the soil’s electrical conductivity in their outdoor irrigation WSN system. In our work, we divided the whole greenhouse into six sub-zones according to the control range of the drop irrigation (showed in Figure 7 below). In the process of network deployment, we randomly deployed 60 nodes into those sub-zones, with a cluster head and nine sensor
nodes in each sub-zone.Moreover, the network protocol and its performance compared with the LEACH (low energy adaptive clustering hierarchy; Heinzelman et al., 2000) protocol will be elaborated on in the section that introduces the specific design.