Performance analysis is carried out in a near-field multiple-input multiple-output (MIMO) system for both discrete and continuous aperture antennas. The effective degrees of freedom (EDoF) is first derived. It is shown that near-field MIMO systems have a higher EDoF than free-space far-field ones. Additionally, the near-field EDoF further depends on the communication distance. Based on the derived EDoF, closed-form expressions of channel capacity with a fixed distance are obtained. As a further advance, with randomly deployed receivers, ergodic capacity is derived. Simulation results reveal that near-field MIMO has an enhanced multiplexing gain even under line-of-sight transmissions. In addition, the performance of discrete MIMO converges to that of continuous-aperture MIMO.
翻译:本文在近场多输入多输出(MIMO)系统中,分析了离散和连续孔径天线的性能。首先推导出了有效自由度(EDoF)。表明近场MIMO系统具有比自由空间远场系统更高的EDoF。此外,近场EDoF还取决于通信距离。基于推导出的EDoF,得出了通道容量的封闭式表达式,在距离固定的情况下进行Analysis。此外,通过随机部署接收器,推导出了遍历容量。模拟结果表明,即使在视距通信下,近场MIMO也具有增强的多路复用增益。此外,离散MIMO的性能趋于连续孔径MIMO的性能。