Energy-efficient joint beamforming and antenna selection for multicast systems

The problem of energy-efficient joint beamforming and antenna selection for multicast systems is consider in this paper. Under the performance objective of maximizing the number of bits per joule of energy consumed, beamformer design, optimal transmit power and antenna selection is discussed respectively. The beamforming problem is converted to an equivalent form of the max-min problem and we propose a suboptimal solution with low complexity whose validity is verified by the numerical results. The existence and uniqueness of the optimal transmit power is proved. Then, a simple antenna selection scheme is presented. In the end, we combine the above algorithms into a joint beamforming and antenna selection algorithm. Simulation results show the performance gain of the proposed scheme. A great deal of energy can be saved at the expense of acceptable throughput loss especially with low number of users or short distance. In addition, antenna selection is necessary for energy-efficient design in multi-antenna systems through the performance comparison.