Distributed Beamforming with Nodes Selection for Cognitive Radio Networks
Xiaohua Lian, H. Nikookar, L.P. Ligthart · Journal of CONASENSE · 2014
In order to collaboratively forward the Cognitive Radio (CR) signal to the Distant CR (DCR) users, we have introduced the Distributed Beamforming (DB) technique CR networks.However we face a practical difficulty of the extreme narrow main beam in the pattern generated by the DB method, when applying it to CR networks.To solve this problem, we propose a novel Nodes Selection (NS) method based on studies of the differences in beam width of a broadside array and an end-fire array.The proposed NS method selects those CR nodes, which are able to form a full size end-fire array and a reduced size broadside array.It chooses CR nodes located in the "belt" area along the direction of the DCR user.Simulation results of the average beampattern of our NS method show that the main beams are successfully directed towards the DCR users and are enlarged for practical applications in CR networks.What is more, for a CR network with a large physical size, our NS method can widen the main beam while maintaining sufficiently low sidelobe levels for CR transmission.