Multiple input multiple output technology refers to the use of multiple transmitting antennas and receiving antennas at the transmitting end and receiving end respectively so that signals are transmitted and received through multiple antennas at the transmitting end and the receiving end, thereby improving communication quality. Multiple input multiple output can make full use of space resources and realize multiple transmission and reception through multiple antennas. Without increasing the spectrum resources and antenna transmission power, the system channel capacity can be doubled, showing obvious advantages. The multiple input multiple output is widely used in fourth-generation mobile communications.
Massive multiple input multiple output technology is relatively mature in the application of the fifth-generation mobile communication technology. 5G can use low-frequency bands below 6GHz, but low-frequency band resources are limited, and 5G has a large demand for bandwidth, so most 5G networks will be deployed in high-frequency bands, that is, millimeter wave bands.
Increasing the number of transmitting antennas and receiving antennas means designing a multi-antenna array. This is the basis of massive multiple input multiple output technology. with the massive multiple input multiple output technology, there are multiple antennas on the base station side, and the phase of each antenna's signal is automatically adjusted through beamforming to form an effective superposition of electromagnetic wave at the receiving end, and produces a stronger signal gain to deal with loss so as to improve the strength of the received signal. The radiation pattern of the antenna array is adaptively adjusted according to a specific scene, beamforming can intelligently gather energy to the target, and construct a special transmission channel according to the number of targets.
The larger the number of antennas and the scale are, the more obvious the beamforming effect will be. The antenna array expands from one-dimensional to two-dimensional, and beamforming has developed into an all-rounder, which can simultaneously control the shape of the antenna pattern in the horizontal and vertical directions, and evolve into 3D beamforming, which directs the signal to the target user more accurately, and can move with the target to ensure signal stability.
Through a large-scale antenna array, more antennas are aggregated and combined at the transmitting end and the receiving end. 3D beamforming guides each signal to the best path of the terminal receiver, increasing signal strength and reducing interference. In practical applications, it is found that the 5G in pursue of high-speed mobile data rates and large channel capacity with massive multiple input multiple output works well and can achieve better performance.