Research On The Improved Power Allocation Algorithms In MIMO Systems

High-efficiency transmission and high-quality service are the primary objectives of the future mobile communication systems. For its high-speed and high spectral efficiency, Multiple-input Multiple-output(MIMO) technology has been highly valued by the mobile communication field. However, the fading of wireless channels is time-varying. In case the power allocation of the transmitters is unreasonable, the quality of the communication cannot be guaranteed while the channel is in a serious fading condition. Meanwhile, the energy of communication systems will also not be fully utilized. Therefore, the adoption of the power allocation technology in the transmitters has been of great significance to improve the quality of the communication systems, as well as the energy efficiency.Aiming to improve the transmission rate and the error performance of MIMO systems, a research for the power allocation algorithms is carried out in the thesis. Based on the research of classic power allocation algorithms, the power allocation algorithms for minimizing error rate and a linear power allocation algorithm with the beam-forming technique become the focus of analysis. Considering the limitations of the two algorithms, an improved power allocation algorithm is proposed combined with the characteristics of MIMO systems, which is an improvement and integration of the above two algorithms. The experimental results show that the channel capacity is maximized with the improved algorithm, which resulting in improving the overall performance of the system with meeting the error rate requirement of the users as much as possible according to the diversification of the channel state.With the miniaturization of the array antennas in MIMO systems, the signal preprocessing of the transmitters have been greatly affected by the mutual coupling among the antenna elements. In the thesis, receiving mutual impedance method is adopted for the compensation of the mutual coupling. Then the proposed improved power allocation algorithm is applied externally to the MIMO systems with compact array antennas. With MATLAB, the performance of power allocation algorithms in mutual coupling systems is analyzed. Then the simulation results show that, the anti-mutual coupling character of the improved power allocation algorithm is better than the classical algorithms. In addition, the channel capacity of MIMO systems is increased and the bit error rate is decreased by the compensation of mutual coupling, eventually leading to the overall system performance enhancement.