Distributed beamforming with close to optimal number of nodes for green wireless sensor networks

In wireless cognitive sensor networks the number of cognitive nodes for distributed beamforming should be large in order to reduce interference to primary users. The available optimal numbers of nodes selection schemes of distributed beamforming techniques do not address the cognitive radio scenarios and minimization of interference in the direction of primary users. In this paper a close to optimal number of nodes selection method for distributed beamforming in cognitive radio network is proposed. The issue of interference minimization brings non-optimality in the energy consumption of the network. Using the proposed method, this non-optimality is avoided by using a close to optimal number of nodes. Simulation results showed that it is possible to save as much as 83 % of the total required energy per transmission and thus enhance the greenness of the network.