Millimeter wave is becoming a buzzword in the 5G era. A few years ago, millimeter wave was only a minority technology in the laboratory stage. Today, millimeter wave has become a popular technology that global operators are researching and piloting.
According to the 3GPP agreement, 5G networks mainly use two frequency bands: 5G FR1 bands and FR2 bands. The frequency range of the FR1 frequency band is 450MHz~6GHz, also known as the Sub-6GHz frequency band. The frequency range of the FR2 frequency band is 24.25GHz~52.6GHz, usually called millimeter wave. If the low-frequency band is the basic coverage network of 5G, then millimeter wave is an important hot spot gap-filling technology for 5G. Millimeter wave and Sub-6GHz technology will complement each other to unleash the full potential of 5G.
Compared with Sub-6GHz, 5G millimeter wave technology has four major advantages: First, the millimeter wave spectrum resources are rich, and the user experience rate is higher; second, the millimeter wave communication delay in technical realization is smaller; third, the millimeter wave antenna is small and the equipment is lighter, easily achieving the quantification, and more convenient deployment; fourth, because of the mechanism of point-to-point communication, millimeter wave has higher positioning accuracy than Sub-6GHz.
Millimeter wave propagation is mainly based on line-of-sight propagation and non-line-of-sight propagation. However, millimeter waves have greater propagation loss and are easily blocked, which is an advantage and a disadvantage. The advantage is that it is easy to form isolation in the application and facilitate the control of the coverage, so as to realize different configurations between the coverage islands. For example, the camera monitoring area covered by the factory park can be configured as an uplink priority, while the software download in the factory can be configured as downlink priority. The disadvantage is that when serving 2C users, the coverage of the base station is small due to poor propagation and penetration. To achieve continuous coverage close to Sub-6GHz, more sites need to be deployed. Therefore, mmWave technology is only suitable for hotspot areas and Sub-6GHz joint networking use.