Reconfigurable MIMO systems 5 Reconfigurable intelligent surface 4 Wireless communication 4 Wireless communications 4 Array processing 3 Array signal processing 3 Antenna arrays 2 Channel estimation 2 Electromagnetic waves 2 MIMO communication 2 Metasurface 2 Mobile telecommunication systems 2 Multiple-input multiple-output communications 2 Network architecture 2 Sensors 2 Signal to noise ratio 2 Training 2 reconfigurable intelligent surface 2 Active/passive 1 Ambient backscatter communication 1 Ambients 1 Artificial intelligence 1 Backscattering 1 Battery powered devices 1 Bayes method 1 Bayes methods 1 Bayesian 1 Beam alignments 1 Beamforming 1