Power efficient massive MU-MIMO via antenna selection for constructive interference optimization

Low-complexity linear precoders are known to be asymptotically optimal in massive multi-input multi-output (MMIMO) systems. However, employing a very large set of antennas at the transmitter imposes an equally large number of radiofrequency (RF) chains. As a consequence, a MIMO approach for massive systems is prohibitive, as it leads to very high computational burdens and high hardware complexity at the transmitter. In this paper, a low complexity antenna selection (AS) scheme based on constructive interference is presented to reduce hardware complexity. We show that the proposed AS algorithm, combined with a simple matched filter (MF) precoder, outperforms more complex and computationally expensive AS techniques that involve channel inversion (CI) precoding. We derive the computational burdens of the proposed technique and analyze the benefits through the definition of a new power efficiency metric, that combines performances in terms of throughput with the circuit power required.