From the view of the QPN model, events drive system operations and then result in energy consumption of sensor nodes.
Therefore, the key issue of the energy evaluation is to count the time variable [t.sub.s] and the frequency variable [c.sub.t], which can be obtained from the QPN model simulation
This QPN model is instantiated on the QPME emulator .
The two statistical parameters, the operation time ([t.sub.s]) in a state and the conversion number ([c.sub.t]) of a state transition, can be achieved through the simulation of the QPN model on the evaluation platform.
The energy results are obtained based on the QPN model simulation, shown in Table 6.
In WSN applications, the lifetime of WSN node is a key parameter for the protocol selection and topology deployment, which is predictable based on the QPN simulation and energy evaluation.
In order to evaluate this QPN model, we compare the simulation results with other evaluation approaches.
In , an energy model is developed to replace the original energy model in NS-2, which can be used to compare with this QPN model, given the same simulation environment defined in Table 8.
The result comparisons of energy consumption based on QPN and NS-2 are shown in Figures 11 and 12, illustrated as follows.
The physical measure is performed to verify the performance of QPN model.
Figure 14 shows the energy comparison between the QPN simulation and physical test.
At present, the "state-event-transition" formal descriptions for the energy behaviors of WSN nodes are defined, and the event-driven QPN model is proposed and instantiated on QPME.