FEEDBACK CLOSED-LOOP SCHEDULING DISCIPLINE FOR QOS GUARANTEE IN MOBILE APPLICATIONS

摘要

Multi-function and high-quality services are indispensable for providing responsive information services in a highly interactive e-learning system. This study proposed a problem-solving mechanism based on 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. A closed-loop architecture was developed by cascading the open-loop schedule, QoS probe, Proportional-Integral-Derivative (PID) controller and feedback mechanism. In this architecture, the relationship between Input and Output is defined using a Lagrange λ -calculus module. The module estimates the future QoS via the current scheduling, and the parameters in the controller are tuned according to the system status, to achieve dynamic scheduling. Simulation results with learning activities showed that the closed-loop schedule achieved better performance than existing disciplines in terms of service delay and system utilization.