5G mobile communication systems 1 Active users 1 Antennas 1 Base station 1 Channel state information 1 Circuit power consumption 1 Complex networks 1 Computational complexity 1 Digital radio 1 Electric power utilization 1 Energy efficiency 1 Fading (radio) 1 Intercell interference 1 Iterative methods 1 Lagrange multipliers 1 Life cycle 1 Low complexity algorithm 1 Low-complexity algorithm 1 MIMO systems 1 Massive MIMO 1 Massive multiple-input- multiple-output system (MIMO) Maximum ratio transmission 1 Optimization problems 1 Pilot contamination 1 Power amplifiers 1 Radio frequency 1 Radio frequency amplifiers 1 Radio frequency chains 1 Radio interference 1 Transmit power allocation 1