Mutual Coupling Effect on Spectral Efficiency of 5G Massive MIMO Millimeter Wave Antenna Array

Abstract

The fifth generation (5G) wireless communication requires the massive multiple input multiple output (MIMO) technique. The massive MIMO antenna array of the millimeter wave (mm-wave) is recognized as a key enabler because of its high spectral efficiency. The higher the frequencies of the RF signal, the lower the distance it travels in free space caused by path loss, and it is more easily absorbed by obstacles, which are needed for high-gain transmitters. The advantage of the physical properties of higher New Radio (NR) frequencies is that 5G can utilize more spectrum, more antennas, and higher-order modulation schemes. The massive antennas and radio frequency chains improve the implementation of the cost of 5G wireless communication systems and result in an intense mutual coupling effect among antennas because of the limited space for deploying antennas. The upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Two antennas that receive diversity gain models, the mutual coupling matrix, and the spacing antenna distance are built and analyzed. The impacts and affections of the antenna spacing the number of antennas, the quality-of-service (QoS) statistical exponent, and the number of independent incident directions on the upper effective capacity of 5G multimedia massive MIMO communication systems are analyzed. It is shown that for MIMO systems with compact transmit antenna arrays, the mutual coupling seriously degrades system capacity to mitigate the capacity degradation. In case of improvement in the mutual coupling by 99%, the system performance is kept stationary and enhances system capacity. However, the improvement of the mutual coupling is still about 87.5% today, which means the mutual coupling should be considered in 5G massive MIMO networks.