Sensor nodes estimation for a greenhouse monitoring system using hierarchical wireless network

Abstract

The sensor nodes estimation for a greenhouse monitoring system using hierarchical wireless sensor network (WSN) is presented in this paper. The hierarchical wireless sensor network analyzed in this paper is composed by sensor nodes at the lowest level, the router nodes in the middle level to transmit data from sensor nodes to a controller named coordinator node. The coordinator node, in the highest level, is used to communicate with a central base, where all data received are analyzed. The total number of sensor nodes possible to accommodate in this hierarchical system is estimated for two different cases. In first case, considering the total number of addresses available for identification of the sensor and router nodes, an analytical expression is derived for calculation of number of sensor nodes the system can use. In second case, the number of sensor nodes is estimated considering that traffic of sensor nodes has a distribution and modeling the proposed hierarchical WSN as a network of queues. Two different models of network of queues are analyzed. In first model, the feedback traffic from coordinator for activation or deactivation of the actuator nodes is not taken into account, and in second model, the feedback traffic from coordinator is considered. The analysis showed that depending on the packet rates of sensor nodes, a very large monitoring system can be designed.