Antenna Selection Based On Energy Efficiency In Massive MIMO Systems

With the large-scale commercialization of the fourth generation mobile communication technology(4G)and the approaching of 2020,the research and standardization of the fifth generation mobile communication technology(5G)are being carried out.Compared with the 4G network,the amount of communication services of the 5G network will increase explosively,and the energy consumption of the system will be more serious.Therefore,green communication is the inevitable requirement of the future development.In order to achieve green communication,the research and development of 5G network should give full consideration to green technology and green strategy.In the development of 5G,the Massive Multiple-Input Multiple-Output(Massive MIMO)system will become one of the key technologies of the future mobile communication.In general,the Massive MIMO system will install a large number of antennas at the base station(BS),which requires a radio frequency(RF)chain for each antenna.When the number of antennas is less,the power consumption of the RF chains is negligible compared to the transmission power,with the increase of the number of antennas,the corresponding RF chain is increased,at this time,the power consumption of the internal circuit of the system will not be overlooked or even greater than the transmission power,resulting in a sharp decline in the energy efficiency of the system,at the same time,the physical factors,complexity and cost of the RF chains(such as RF amplifiers,mixers,converter and DAC are relatively expensive)are also considered,which will become an unfavorable factor in the development of Massive MIMO system.Based on this problem,the antenna selection technology based on energy efficiency in Massive MIMO systems is proposed in this paper.By establishing a relatively accurate power model,the energy efficiency of the system is simulated and analyzed,the relationship between the number of antennas,the number of users and the energy efficiency of the system is found,and the spectral efficiency and bit error rate(BER)of the system are also considered.The number of RF chains required in the system is discussed when the number of RF chains in the base station is less than the number of antennas.On this basis,the a ntenna selection is carried out,the channel state information(CSI)of the base station antenna is obtained through the channel estimation,and then the CSI of the antennas are evaluated,finally,the antennas are selected according to the evaluation result,when the number of RF chains are less than the number of antennas on the base station,a number of better CSI antennas are selected,which requires switching between different antennas by the RF chains,reducing the power cost and cost of the internal circuit of the system,and realizing the tradeoff between the system energy efficiency and the spectral efficiency.The simulation experiments show that: although the BER of the antenna selection is higher than that of the non-selected antenna,the system energy efficiency is higher.In the case of equal spectral efficiency,the energy efficiency of the system can be improved by the antenna selection.When the system energy efficiency,spectral efficiency and the number of RF chains are equal,the performance of the antenna selection system is better than that of the non-selected antenna.