Universidad Politecnica de Madrid
The authors model a cognitive radio system as a Quasi-Birth-Death (QBD) process and determine its performance parameters. They also model the system at the quasi-stationary limiting regime. They show that this regime defines the asymptotic system behavior. The performance parameters of interest at this regime are independent of the service time distributions and can be determined by simple recursions. They propose and evaluate a new methodology to determine when the quasi-stationary approximation can be considered a good approximation of the actual system behavior. It requires low computational cost and does not require to solve the exact system.