On-Off Analog Beamforming with Per-Antenna Power Constraint

Abstract

In this paper we propose a new analog beamforming structure by switching on or off each of multiple transmit antennas according to channel state information. The proposed analogue beamforming can significantly reduce the high cost, high power and bulky analogue phase-shifters which are employed in analog massive MIMO systems. On one hand, the high performance low cost commercial switch devices make our architecture easy to implement, saving both system cost and space. On the other hand, our on-off analog beamforming (OABF) can achieve good performance with low complexity algorithms. Specifically, we first propose two SNR-maximization algorithms, which determines the on-off state of each switch under per-antenna power constraint. After that, we theoretically prove our on-off analog beamforming scheme can achieve full system diversity gain and array gain with polynomial complexity. The simple structure of OABF makes the massive MIMO much easier to implement, at a cost of small constant rate loss.