Energy Efficient Multicast Beamforming in Ultra Dense Networks

Ultra Dense Networks (UDNs) are considered a key element to address the expected growing of communication capacity demand in an affordable and sustainable way, improving both spectral and energy efficiency. This paper focuses on the energy efficiency of a coordinated multicell multicast transmission in UDNs. In particular, a new iterative algorithm is proposed, whose goal is to maximize the energy efficiency of a single group multicast service. Toward this goal, the cells are activated opportunistically, only when needed, using suitable transmission power. Moreover, small cells use adaptive beamforming weights in order to increase the efficiency of the radiated power. The effectiveness of the proposed method is proven in terms of energy efficiency and in comparison with different benchmark solutions. Benefits and limits of network densification are evaluated.