Energy Efficient Downlink Transmission Schemes for Multi-Cell Massive Distributed Antenna Systems

Abstract

In this paper, downlink transmission schemes that are able to improve the energy efficiency of multi-cell massive distributed antenna systems (DAS) are investigated. We employ a power consumption model by considering the transmit power, the backhaul power, the uplink pilot transmit power and the circuit power, in contrast to existing works which focus on co-located antenna systems where the backhaul power is negligible. By applying random matrix theory and given the power consumption model, we derive the asymptotic energy efficiency achieved by two transmission schemes, first a full transmission scheme where all remote radio heads (RRHs) in a cell jointly transmit, and second single-RRH user association transmission scheme where each user is associated with only one RRH. A new algorithm to associate user with RRH is proposed based on the asymptotic energy efficiency. The proposed algorithm takes into consideration the power attached to antennas as well as the backhauling power of RRH. Simulations show that the proposed user association algorithm for DAS achieves higher energy efficiency than full transmission scheme and the baseline nearest RRH association scheme, especially when the number of antennas is large.