Distributed beamforming for Cognitive Radio

The goal of the Distributed beamforming (DB) method is to collaboratively forward the Cognitive Radio (CR) signal to the Distant CR (DCR) user. We propose a novel Nodes Selection (NS) method which is based on the differences in beam width of a broadside array and an end-fire array. In this scheme the CR nodes which are able to form a full size end-fire array and a reduced size broadside array are selected for forming the beam. The method chooses those CR nodes which are located in the “belt” area along the direction of the DCR user. Simulation results of the average beampattern of the method show that the main beams are successfully directed towards the DCR users and are enlarged for practical applications in CR networks. Furthermore, for a CR network with a large physical size, the proposed node selection method can widen the main beam while maintaining sufficiently low sidelobe levels for CR transmission.