The core technical support for these upgrades is Massive MIMO (Massive Multiple-Input Multiple-Output) technology, which is also the most iconic technology of 5G antennas. Massive MIMO technology is based on the basic principle of MIMO technology, which uses multiple transmit antennas and multiple receive antennas to transmit and receive data simultaneously, thereby improving spectral efficiency and system capacity. Unlike traditional MIMO technology, Massive MIMO technology achieves a qualitative leap in the number of antenna elements, which brings two core advantages. On the one hand, it can realize spatial multiplexing, that is, the base station can transmit different data streams to multiple user equipment at the same time and in the same frequency band through different antenna beams, which greatly improves the utilization rate of the frequency spectrum and the system capacity. According to industry tests, compared with 4G 8T8R antennas, 5G 64T64R Massive MIMO antennas can increase the single-cell capacity by 5-10 times and the edge user rate by more than 3 times. On the other hand, it can realize beamforming, which is a key technology for 5G antennas to achieve precise signal control. Beamforming technology uses digital signal processing algorithms to adjust the phase and amplitude of the signals emitted by each antenna element, so that the electromagnetic waves emitted by multiple antenna elements superimpose and enhance each other in a specific direction, forming a directional signal beam, while weakening the signal in other directions. This "focused" transmission method not only improves the signal strength at the user end, extends the coverage distance of the signal, but also reduces the interference between adjacent cells and between different users, improving the reliability and stability of communication.
Beamforming technology used in 5G antennas can be divided into three types according to the implementation method: digital beamforming, analog beamforming, and hybrid beamforming. Digital beamforming is implemented at the baseband level, which can independently adjust the phase and amplitude of each transmit signal, and has the advantages of high flexibility and precise beam control. It can form multiple independent beams at the same time to serve multiple users, and can dynamically adjust the beam parameters according to the changes of the communication channel. However, its disadvantage is that it requires a separate radio frequency chain for each antenna element, which increases the cost and power consumption of the system, and is mainly used in low-frequency band (Sub-6GHz) Massive MIMO antennas with a small number of antenna elements. Analog beamforming is implemented at the radio frequency level, which uses a phase shifter to adjust the phase of the signal, and all antenna elements share a single radio frequency chain. It has the advantages of low cost and low power consumption, but the flexibility of beam control is poor, and it is mainly used in high-frequency band (millimeter wave) antennas with a large number of antenna elements. Hybrid beamforming combines the advantages of digital beamforming and analog beamforming, which uses a small number of digital radio frequency chains and a large number of analog phase shifters to achieve a balance between beam control flexibility, cost, and power consumption. It is currently the mainstream beamforming solution for 5G Massive MIMO antennas, especially in millimeter wave frequency bands.
