Energy-efficient resource allocation in SDMA systems with large numbers of base station antennas

In this paper, resource allocation for energy efficient communication in space division multiple access (SDMA) downlink networks with large numbers of transmit antennas is studied. The considered problem is modeled as a non-convex optimization problem which takes into account the circuit power consumption and a minimum required data rate. By exploiting the properties of fractional programming, the considered non-convex optimization problem in fractional form is transformed into an equivalent optimization problem in subtractive form, which enables the derivation of an efficient iterative resource allocation algorithm. The optimal power allocation solution for each iteration is derived based on a low complexity user selection policy for maximization of the energy efficiency of data transmission (bit/Joule delivered to the users). Simulation results illustrate that the proposed iterative resource allocation algorithm converges in a small number of iterations and unveil the trade-off between energy efficiency and the number of antennas.