Collaborative Spectrum Sensing Optimisation Algorithms for Cognitive Radio Networks

The main challenge for a cognitive radio is to detect the existence of primary users reliably in order tominimise the interference to licensed communications. Hence, spectrum sensing is a most important requirementof a cognitive radio. However, due to the channel uncertainties, local observations are not reliable and collaborationamong users is required. Selection of fusion rule at a common receiver has a direct impact on the overall spectrumsensing performance. In this paper, optimisation of collaborative spectrum sensing in terms of optimum decisionfusion is studied for hard and soft decision combining. It is concluded that for optimum fusion, the fusion centremust incorporate signal-to-noise ratio values of cognitive users and the channel conditions. A genetic algorithm-based weighted optimisation strategy is presented for the case of soft decision combining. Numerical results showthat the proposed optimised collaborative spectrum sensing schemes give better spectrum sensing performance