超大规模MIMO中包含球面波特征的最优传输方法研究

在超大规模多输入多输出(multiple input multiple output,MIMO)通信场景下，无线传输信道存在球面波特性，目前超大规模MIMO研究中多采用平面波模型，对球面波特征认识不足，忽略了其对系统传输设计的影响。针对此问题，基于球面波模型，利用统计信道状态信息，研究了多用户超大规模MIMO中的传输设计问题，分析了影响最优传输的关键特征参数，获得了包含球面波特征的最优发射策略的闭式表达式。研究结果表明，球面波模型下的最优发射策略与多用户所处位置有关，采用用户调度策略可以解决波束与用户间的误匹配问题。在此基础上，提出了一种基于贪婪思想的低复杂度多用户调度策略，仿真结果显示，所提传输策略能以较低复杂度达到近似最佳性能。

Study of optimal transmission methods with spherical wave characteristics in ultra-massive MIMO

In an ultra-massive multiple input multiple output (MIMO) communication scenario, a spherical wave feature exists in the wireless channel. However, most of the current ultra-massive MIMO studies use the plane wave model. These studies do not know enough about the spherical wave characteristics and neglect their impact on the system transmission design. In this paper, the optimal transmission design problem in multi-user ultra-massive MIMO is investigated based on the spherical wave model using statistical channel state information, and the key characteristic parameters affecting the optimal transmission are analyzed to obtain a closed-form expression for the optimal transmit strategy with the spherical wave characteristics. The results show that the optimal transmit strategy with the spherical wave characteristics is related to the location of multiple users. The user scheduling strategy is used to solve the mis-matching problem between the beam and users. Based on this, a low-complexity user scheduling strategy using the greedy idea is proposed. Simulation results show that the proposed transmission strategy can achieve the near-optimal performance with lower complexity.