The 5G base station architecture includes BBU and AAU (4G is RRU + antenna). Among them, BBU (Base Band Unite) is responsible for centralized control and management of the entire base station system, completes uplink and downlink baseband processing functions, and provides physical interfaces with radio frequency units and transmission networks to complete information interaction. The AAU (Active Antenna Unit) / RRU (Remote Radio Unit) radio antenna communicates with the BBU through the baseband radio frequency interface to complete the conversion of the baseband signal and the radio frequency signal.
The 5G base station introduces Massive MIMO technology. The typical application is 64T64R. The typical power consumption of a single base station exceeds 3500W, while the 4G base station mainly uses 4T4R MIMO. The typical power consumption of a single base station is only about 1000W. As part of the electrical energy consumed by the device during operation will be converted into heat energy, the temperature in the integrated cabinet of the base station will continue to rise, so the heat dissipation requirements have increased significantly.
Judging from the composition of base station power consumption data, BBU power consumption is relatively stable, is related to the inserted board, and is not greatly affected by the service load. According to the operator's test data, the average power consumption of the 5G base station BBU is about 300W, which is about twice that of 4G. The increase in 5G power consumption mainly comes from the active antenna AAU. When the 5G service is no-load, 30% load and 100% load, the average power consumption of AAU is 633W, 762W and 1127W in turn; in the 4G era, the power consumption of RRU under the above three service loads is 222W, 259W and 290W respectively. Therefore, the power consumption of 5G AAU is about 3 times higher than that of 4G.
The current mainstream base station heat dissipation solution is: the front of the BBU is covered with fin heat sinks to cover the PCB, only the power supply part is exposed, the back is used metal heat sinks and heat pipes / soaking plates, and the interior uses thermal interface material (TIM). Due to the large increase in power consumption of AAU / RRU, in addition to using TIM materials to fill the gaps inside, it is also necessary to use a lighter weight and better heat dissipation die casting shell. The fin design, shell material and shell die casting process are all Put forward higher requirements. Semi-solid die-casting parts have the advantages of light weight and good heat dissipation performance, and the inflation plate has the advantages of high heat transfer efficiency and fast cooling speed. The heat sink combination of semi-solid die-casting parts and inflation plate is expected to greatly increase the heat dissipation value of 5G base stations.
In theory, the coverage density of 5G base stations (macro base stations) will be denser than 4G. The reason is that the 5G communication frequency band has increased, and the coverage of base stations has continued to shrink (the radius of cells has shrunk). To achieve the same coverage, the density of base stations will increase.
The total number of 4G base stations (macro base stations) in my country is about 4 million. Considering the operator's desire to improve capital efficiency, the actual number of stations built during the wide-area coverage of the initial 5G network construction may be maintained at about 4 million stations, but subsequent consideration of the traffic growth driven by new applications of new terminals and the construction of 5G base stations It is expected to continue to improve. From the perspective of construction progress, the Ministry of Industry and Information Technology said that 5G will be deployed in more than 40 cities in 2019, and it is expected to build 100,000 macro base stations. 2020-2022 will be the peak period for China's 5G construction. ~ 800,000.