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|a Cognitive Radio Networks (CRNs) provide a solution for the spectrum scarcity problem facing modern wireless communications. However, compared with the traditional networks, cognitive radio networks exhibit some distinct features, which result in necessity of further research in the resource allocation and scheduling that have been solved for the traditional networks. The basic concept of CRNs relies on utilizing the unused spectrum of a primary network, without interfering with the activity of primary users (PUs). Therefore, an effective scheduling algorithm is needed in order to manage the opportunistically available resources and provide the necessary Quality of Service (QoS) for different traffic classes for secondary users. In this work, we focus on link queue aware earliest deadline first scheduling in a single cell cognitive radio system. The purpose of this work is to investigate how CAQA-EDF algorithm satisfies the QoS for various secondary user traffic. A buffer selection criterion is introduced together with the channel availability to adjust the priority of different cognitive radio user traffic to be selected for service. Extensive simulations have been carried out and important performance metrics are investigated in the simulation, such as the system throughput, fairness and sevice delay time and are quantified by the impact of PU channel availability. Simulation result shows that all traffics are scheduled before missing their deadline, despite giving rtPS default scheduling, nrtPS and BE are served before their deadline. In terms of throughput, PU activity effect the overall throughput, the result shows that lower PU active period and high probability of detection with lower false alarm increases the throughput. Finally, fairness is achieved for all traffic and no starvation happened during packet transmission.
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