Design of QoS Optimal Controller in Monitoring and Controlling System for Protected Environment based on Wireless Sensor Networks

In order to reduce the impact of inherent network time-varying delay, packet loss, network congestion and other phenomena on performance of the monitoring and controlling system for protected environment based on wireless sensor networks, the QoS optimal control strategy based on feedback control technology is proposed from the perspective of improving quality of service (QoS) over wireless networks. The basic idea of the proposed QoS optimal control strategy is to use deadline miss ratio as the evaluating index of the QoS and to adapt the sampling period of each sensor nodes by means of PID controller and optimal controller at run time such that the deadline miss ratio associated with the whole wireless sensor networks and the real-time data transmission from the sensor nodes to the actuator nodes is maintained at a pre-determined desired level, and the required QoS can be achieved. Preliminary experimentations indicate the rationality, effectiveness and practicability of the proposed QoS optimal control strategy.