This paper studies energy-efficient coordinated beamforming in multi-cellmulti-user multigroup multicast multiple-input single-output systems. We aim atmaximizing the network energy efficiency by taking into account the fact thatsome of the radio frequency chains can be switched off in order to save power.We consider the antenna specific maximum power constraints to avoid non-lineardistortion in power amplifiers and user-specific quality of service (QoS)constraints to guarantee a certain QoS levels. We first introduce binaryantenna selection variables and use the perspective formulation to model therelation between them and the beamformers. Subsequently, we propose a newformulation which reduces the feasible set of the continuous relaxation,resulting in better performance compared to the original perspectiveformulation based problem. However, the resulting optimization problem is amixed-Boolean non-convex fractional program, which is difficult to solve. Wefollow the standard continuous relaxation of the binary antenna selectionvariables, and then reformulate the problem such that it is amendable tosuccessive convex approximation. Thereby, solving the continuous relaxationmostly results in near-binary solution. To recover the binary variables fromthe continuous relaxation, we switch off all the antennas for which thecontinuous values are smaller than a small threshold. Numerical resultsillustrate the superior convergence result and significant achievable gains interms of energy efficiency with the proposed algorithm.
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