Feedback Closed-Loop Scheduling Discipline for QoS Guarantee in Mobile Applications

Multi-functional and high-quality services are indispensable for providing responsive information services in a highly interactive elearning system. This work presents a problem-solving mechanism using closed-loop scheduling discipline to achieve QoS e-learning applications. In the closed-loop schedule, the feedback mechanism supports wireless mobile communications services with dynamic QoS requirements. This work presents a closed-loop architecture by cascading the open-loop schedule, the QoS probe, the Proportional-Integral-Derivative (PID) controller and the feedback mechanism. In this architecture, the relationship between input and output is defined using a Lagrange (lambda)-calculus module. The module estimates the future QoS according to the current scheduling, while the controller parameters are tuned according to the system status to achieve dynamic scheduling. Simulation results with e-learning activities demonstrate that the closed-loop schedule outperforms existing disciplines in terms of service delay and system utilization.