Aggregation Based Spectrum Allocation in Cognitive Radio Networks

In cognitive radio networks, the available vacant frequency bands, referred to as spectrum holes, are usually discontinuous. Hence, it is hard to exploit these vacant frequency bands since the bandwidth of single one may not be able to meet the wide bandwidth requirement of secondary users (SUs). Spectrum aggregation (SA) enables SUs to access several discontinuous spectrum holes simultaneously to satisfy the wide bandwidth requirement of SUs, which greatly improves the utilization of spectrum resources. In this paper, we firstly propose an aggregation based spectrum allocation scheme based on Knapsack Problems by considering both hardware constraints and different bandwidth requirement of SUs. Then, a novel spectrum allocation algorithm called Aggregation Spectrum Allocation Algorithm (ASAA) is given. ASAA is evaluated in terms of the total bandwidth SUs can access and the spectrum utilization efficiency. Numerical results show that the proposed algorithm can achieve better performances compared to the existing algorithms.