| Multiple input multiple output technology is a key technology of mobile communication system.With the wide spread use of active antenna array,the two-dimensional MIMO channel model is extended to the three-dimensional MIMO channel which can simulate the actual environment more accuratly.3D MIMO technology can take full advantage of the vertical dimension of the degree of freedom,which can reduce the interference between the cell users furtherly.During the 3D MIMO downlink transmission process,the cell users will be disturbed by interference.In order to reduce the interference between the cell users furtherly to meet the demands of users for high data rates,people introduce the coordinated multi-point transmission / reception technology to solve the interference.The focus of the previous 3D MIMO technology research was to improve throughput and spectral efficiency of the system.However,there is less attention to energy efficiency.Therefore,the combination of 3D MIMO technology and energy efficiency optimization problem is also the key research of the future mobile communication.In this thesis,we take the 3D MIMO system downlink transmission scene as the research object and study the two following aspects:(1)An optimized downlink transmission scheme based on quantum baceteria forging algorithm in 3D MIMO system.In the process of 3D MIMO downlink transmission,the power allocated to the users,the downtitles of the beams and whether to introduce the joint transmission technology will affect the total throughput of the system and the spectral efficiency of the cell edge users.A downlink transmission optimization scheme is proposed in 3D MIMO downlink system in order to improve the total spectral efficiency of the system and the spectral efficiency of the cell edge users?The optimization problem is actually a nonconvex optimization problem,we use the the quantum bacteria foraging algorithm to get the optimal solution.Simulation results show that the proposed scheme has good perform for the total spectral efficiency of the system and the spectral efficiency of the cell edge users.(2)Energy efficient resource allocation algorithm based on vertical beamforming for 3D MIMO OFDMA downlink system.An algorithm is proposed for energy-efficient resource allocation scheme in 3D MIMO OFDMA downlink mobile communication system.The proposed algorithm is based on vertical beamforming technology to maximize energy efficiency and improve the energy efficiency of the system by adjusting the resource allocation,power allocation and the downtitles of the beam.According to the theory of fractional optimization,the complex fractional optimization problem can be converted into a more tractable integral optimization problem.The lagrangian operator is introduced to obtain the optimal value of energy efficiency by iteration.Simulation results show that the proposed algorithm not only has less interation number but also have good perform for energy efficiency. |
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