Antenna selection schemes for energy efficiency in distributed antenna systems

In this paper two schemes of distributed antenna selection, Pathloss-based Antenna Selection (P-AS) and Energy-efficient Antenna Selection (E-AS), are studied for the purpose of improving energy efficiency in Distributed Antenna Systems (DAS). Path loss information is exploited in P-AS, whilst the energy consumption of antenna nodes is taken into account in E-AS for the Pre-coding Matrix Index (PMI) selection and resource scheduling. The performance of the two algorithms is evaluated by means of numerical simulations based on two different DAS topology models of node layouts; a homogeneous topology model where distributed directional antennas are deployed at equidistant positions on the cell edges, and a heterogeneous topology model where omni-directional antennas are positioned at the cell centers. Simulation results show that both P-AS and E-AS outperform the Single Frequency Network (SFN) where all the transmission antennas transmit the same signal continuously in terms of energy efficiency. When compared to SFN, energy efficiency is improved by more than 50% for both schemes and for both homogeneous and heterogeneous layouts. In the case of the homogeneous topology model, P-AS scheme improves the energy efficiency by 54% at a rather low throughput loss of 7%, whilst E-AS improves energy efficiency considerably by nearly 70% without any loss of throughput.