Beamforming with efficient node selection techniques for green cognitive radio networks

Distributed Beamforming conserves power consumption of wireless sensor networks and extends communication range by focusing the transmit signal energy in the direction of the receiver. Significant saving of power consumption is obtained by only selecting the optimal number of nodes prior to beam forming which are necessary to form the communication link. A new node selection method based on clustering is proposed. Clustering Method aims at minimizing interference on PU by selecting the combination of nodes with destructive carrier phase. Simulation results showed that the side lobe level was reduced down to -19.7 dB in the direction of primary users. This side lobe level would require N = 95 nodes to be involved in the beamforming process according to asymptotic side lobe relationship 10 log _N¹. Using clustering node selection method, it was possible to accomplish the same side lobe reduction in the direction of primary users using only 21 nodes.