Research On Key Technologies Of Massive MIMO Antenna Selection

With the development of wireless communication technology and the popularity of mobile intelligent terminals,the traditional MIMO technology is difficult to support the growing demand for wireless data traffic.As an extension and evolution of the current MIMO technology,massive MIMO can fully exploit spatial dimension resources and provide a considerable diversity and multiplexing gain,increasing channel capacity and spectral efficiency obviously without increasing the transmission power and expanding the bandwidth.Traditional MIMO technology requires the same amount of radio frequency(RF)chains and the number of antennas is pretty large in massive MIMO systems,system cost and complexity will increase significantly if equal RF chains are installed in the conventional way.On the other hand,the increased RF links will lead to a growth in RF power consumption which is not conducive to the realization of energy-efficient green communications.Antenna selection technology can reduce the RF cost and system complexity without affecting the advantages of massive MIMO technology,and optimize the system's energy efficiency.Therefore,the antenna selection technology in massive MIMO is studied in this paper and the main contents are as follow:In this paper,the advantages and challenges of massive MIMO systems are introduced,and the necessity of antenna selection for massive MIMO systems is elucidated by the analysis of present antenna selection technology and the classical antenna selection algorithms.Aiming at the characteristics of massive MIMO,the corresponding solution is put forward under the maximization of channel capacity.Bidirectional search antenna selection algorithm can flexibly respond to different requirements of the number of selection antennas,and maintain a low computational complexity.Improved Maxvol antenna selection algorithm based on matrix volume can achieve the global optimization of fast antenna subset selection and improve the performance of the low signal to noise ratio.Proposed new low-complexity joint transmit/receive antenna selection algorithm can achieve the fast joint antenna selection with the same complexity of single-side antenna selection.The simulation results show the effectiveness of the proposed algorithms.The role of antenna selection technology in massive MIMO energy efficiency optimization is studied.Firstly,according to the characteristics of massive MIMO systems,the sum capacity expression of multi-user large-scale MIMO is deduced.The relationship between antenna selection and energy efficiency optimization of single-user massive MIMO systems is analyzed and then extended to multi-user scenarios,the energy efficiency model for multi-user MIMO antenna selection is established,and the relationship between energy efficiency and the number of selected antennas is discussed.The existence and uniqueness of the optimal number of antennas that maximize the energy efficiency of the system are proved by mathematical derivation,and on this basis an antenna selection algorithm is proposed based binary search.After the optimal number of antennas is determined,the energy efficiency optimization problem is transformed into capacity optimization problem.The simulation results show that antenna selection technique can improve the energy efficiency of MIMO system greatly,which is of great value for realizing green communication.