Abstract
Cognitive radio (CR) is a promising technology that allows secondary users (SUs) to access licensed spectrum in an opportunistic way with limited interference to licensed users, i.e, primary users (PUs). To protect PU communications, spectrum sensing is often necessary for SUs to detect PU activities before doing SU transmission. Since PUs have a priority to use the licensed channels, SU transmission must be forced to terminate when PU reoccupation is detected. However, such SU’s forced termination would degrade the spectrum utilization and the system capacity significantly if it occurs frequently. In this thesis, we consider the SU’s forced termination probability as a quality-of-service (QoS) requirement and propose a dynamic spectrum access scheme with QoS provisioning for CR networks. Different from a previous related work under perfect spectrum sensing, this one considers imperfect spectrum sensing and throughput maximization. It is shown that there exists an optimal sensing time that can satisfy the QoS requirement and maximize the throughput performance simultaneously, where Newton’s method can be used to find a suboptimal solution. Simulation results demonstrate that the proposed dynamic spectrum access scheme with QoS provisioning under imperfect spectrum sensing achieves better throughput performance than the previous related one under perfect spectrum sensing.