  This paper aims to solve the energy efficiency (EE) maximization problem for
multicast services in a multiple-input single-output (MISO) distributed antenna
system (DAS). A novel iterative algorithm is proposed, which consists of
solving two subproblems iteratively: the power allocation problem and the beam
direction updating problem. The former subproblem can be equivalently
transformed into a one-dimension quasi-concave problem that is solved by the
golden search method. The latter problem can be efficiently solved by the
existing method. Simulation results show that the proposed algorithm achieves
significant EE performance gains over the existing rate maximization method. In
addition, when the backhaul power consumption is low, the EE performance of the
DAS is better than that of the centralized antenna system (CAS).
