Equal-Phase Beamforming Architecture for RF-MIMO Antenna Systems
This paper considers a novel multiple-input multiple-output (MIMO) architecture, which combines the signals in the radio-frequency (RF) domain. Unlike previous approaches, the proposed architecture is exclusively based on the application of different gain factors to the transmitted/received signals, and therefore it avoids the need of including a controllable phase-shifter (or sign switch) for each transmit/receive antenna. From a baseband point of view, the transceiver design consists in obtaining the optimal equal phase transmit (EPT) and equal-phase combining (EPC) beamformers. Interestingly, this problem can be exactly solved in the case of rank-one channels, which can be exploited to construct an iterative algorithm for the general MIMO case. The proposed architecture is evaluated by means of Monte Carlo simulations, which show that the slight performance degradation with respect to previous approaches is justified by the significant reduction in the hardware cost and power consumption.
KeywordsRF-MIMO beamformer equal-phase MIMO beamforming semidefinite relaxation (SDR)
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