Research On Coordination And Scheduling Among Actuators In Wireless Sensor And Actuator

A typical Wireless Sensor Network (WSN) performs only one action: sensing the environment. The requirement for intelligent interaction with the environment has led to emergence of Wireless Sensor and Actuator Network (WSAN). WSAN is composed of sensors that have the ability of sensing the physical environment and actuators that have the ability to performing appropriate actions. With the presence of actuators, WSAN is heterogeneous, which brings about issues of real time, coordination and mobility that need to be addressed. From single actuator task and multiple actuators task, this thesis mainly studies coordination among actuators that only exists in WSAN. The main contents and contribution are as follows:First of all, we propose a new utility function. The new utility function considers not only the completion time, but also the actuator’s available energy. It can stop actuators that have little residue energy from performing actions. Thus, with delay requirement being satisfied, the new utility function can improve the system’s energy balance. By changing parameters in the function, WSAN can adapt to both delay restriction and energy consumption restriction scenes well.Secondly, localized auction method is brought in both single actuator task assignment and overlapping area task assignment. And it is considered that both single actuator task assignment and overlapping area task assignment should assign task to the unique actuator. Based on the new utility function, we can auction the task to the winner that has the minimal utility function. Simulation results demonstrate that performance of distributed method is superior to centralized method. Furthermore, based on localized auction method, the rate of correct task assignment in overlapping area is up to100%.Thirdly, we study a synchronous clock method (SC) that is sued to synchronize the ordered tasks in event dependency regions. Due to the transmission delay, tasks may be out of order when they are executed. SC method can improve the correct execution rate in dependency regions. compared with double confirmation (OBDC), SC method can further improve the correct rate of the execution. Simulation results demonstrate that SC method can efficiently improve the correct execution rate of the task.