5G technology debate, millimeter wave versus sub-6

The battle over 5G technology is essentially a battle over frequency bands. At present, the world uses two different bands to deploy 5G networks. The band between 30 and 300GHz is called millimeter wave. The other, which focuses on the 3ghZ-4ghz band, is called the sub-6.

Restricted by the physical characteristics of radio waves, the short wavelength and narrow beam characteristics of millimeter-wave can enhance signal resolution, transmission security and transmission speed, but the transmission distance is greatly reduced.

According to Google's 5G coverage test of the same number of base stations in the same area, the 5G network deployed with millimeter wave can cover 11.6% of the population at the rate of 100Mbps and 3.9% of the population at the rate of 1Gbps. The sub-6 band 5G network can cover 57.4 percent of the population at 100Mbps and 21.2 percent at 1Gbps.

It can be seen that the coverage of 5G networks operating under sub-6 is more than five times that of millimeter wave. The construction of millimeter-wave base stations, which would require about 13 million installations on power poles, would cost $400 billion to ensure 72% coverage at 100 megabits per second in the 28GHz band, and about 55% coverage at 1Gbps per second. Sub-6, on the other hand, only needs to install 5G base stations on the existing 4G base stations, greatly saving deployment costs.

From coverage to cost, sub-6 is superior to millimeter wave in the short term.

But the first reason is rich spectrum resources, carrier bandwidth can reach 400MHz/800MHz, wireless transmission rate can reach more than 10Gbps; Second, millimeter wave has a narrow beam, good directivity and high spatial resolution. Third, the size of millimeter wave components is small, compared with sub-6ghz equipment, easier to miniaturize; Fourth, the sub-carrier interval is large, the single SLOT period (120KHz) is 1/4 of the low-frequency sub-6ghz (30KHz), and the airport delay is reduced. In private network applications, the advantage of MMW is almost crushing Sub-6.

At present, the special network of vehicle-ground communication implemented by MMW communication in the rail transit industry can realize the transmission rate of 2.5Gbps at high speed and the transmission delay of 0.2ms, which has a very high promotion value of the special network.

For private networks, such as rail transit, public security monitoring and other scenarios can give full play to the technical advantages of millimeter wave to achieve the real 5G speed.