Performance Evaluation of Joint Admission and Eviction Controls of Secondary Users in Cognitive Radio Networks

In recent years, cognitive radio (CR) has been proposed to promote the efficient utilization of the spectrum by exploiting the spectrum holes. The fundamental issue in CR networks is the efficient utilization of radio resources. Call admission control (CAC), which controls the number of calls based on the available resources and bandwidth, is an important functionality to ensure the quality of service (QoS). Thus, in this paper, a new call admission and eviction control of secondary users (CAEC) is proposed. The proposed CAEC is a combination of three variant schemes. The main objective of this proposed scheme is to make admission and evictions decisions jointly in order to improve the spectrum utilization efficiency and ensure the QoS for secondary users (SUs) and to provide better balance between the required SU's QoS and primary users' protection. Performance evaluation of the proposed scheme with its variants is studied and compared with other two previous schemes, known as basic CAC (BCAC) and queue-based CAC (QCAC), in terms of the QoS requirements, such as useful utilization and loss probability. Results show that the proposed CAEC achieves higher admitted traffic for SUs than BCAC and QCAC. In addition, it ensures higher system utilization without degrading the primary users' performance.