Channel capacity investigation of a linear massive MIMO system using spherical wave model in LOS scenarios

Massive multiple-input multiple-output (MIMO) is a key technology for the 5th generation (5G) of wireless communication systems. The traditional plane wave channel model (PWM) is often not suitable for the large antenna structure, and in certain cases should be replaced by the more accurate spherical wave model (SWM). By using the spherical wave characterization method, this paper investigates the channel capacity performance of a linear massive MIMO system in line-of-sight (LOS) scenarios. Two types of access settings, the point to point (PTP) system and multi-user (MU) system, are considered. In the PTP setting, a geometrical optimization is performed to obtain configurations that are able to generate a full rank channel matrix for a linear massive MIMO system, which yields full spatial diversity even in LOS scenarios. Compared with the approximate and commonly applied rank-1 PWM, this is very useful for fixed wireless access and radio relay systems requiring high throughput. For the MU case, we compare the eigenvalue distributions of the LOS channels using the plane wave and spherical wave characterization method, and sum rate results are obtained by Monte Carlo simulations. The results show that MU systems using the more realistic and accurate SWM can achieve a higher sum rate than results from the PWM. This is beneficial and informative when designing massive MIMO wireless networks.摘要摘要大规模多天线是未来第五代移动通信系统的关键技术之一,当天线尺寸较大时,传统的球面波信道模型并不适合用于准确的描述传播环境。本文使用更为准确的球面波信道模型,研究了直射场景下大规模线性多天线系统(点对点接入和多用户接入两种架构)的信道容量特征。在点对点接入架构中,本文提出了一种基于位置的系统优化方式,相对于平面波信道模型获得的信道秩为1的结果,该优化方式可以让多天线系统在直射场景下获得信道满秩,从而获得全部空间分集增益;在多用户接入架构下,本文比较了球面波和平面波信道模型下的信道的特征值分布特征,通过使用蒙特卡洛仿真方法研究了系统的信道和速率,仿真结果表明,使用球面波信道模型的信道和速率高于平面波信道模型的信道和速率。创新点本文使用更为准确的球面波信道模型,研究了直射场景下大规模线性多天线系统(点对点接入和多用户接入两种架构)的信道容量特征。在点对点接入架构中,本文提出了一种基于位置的系统优化方式,相对于平面波信道模型获得的信道秩为1的结果,该优化方式可以让多天线系统在直射场景下获得信道满秩,从而获得全部空间分集增益;在多用户接入架构下,本文比较了球面波和平面波信道模型下的信道的特征值分布特征,通过使用蒙特卡洛仿真方法研究了系统的信道和速率,仿真结果表明,使用球面波信道模型的信道和速率高于平面波信道模型的信道和速率。