The key reason why China's 5G technology leads the world is that 5G is a mobile communication system mainly based on TDD. TDD is actually not dominant in the 3 and 4G era, but this situation has been completely changed in the 5G era, and the mainstream 5G frequency bands are TDD. The main reason why 5G will focus on the TDD frequency band is that the high performance of 5G requires too much wireless spectrum resources. 5G has higher system performance requirements and faster download speeds that can accommodate users.

But to achieve such system performance, the most critical point is that 5G uses a larger bandwidth wireless spectrum. For Sub-6G, it can support a single carrier frequency of 100Mhz, and it can support a maximum of 400Mhz in the millimeter wave frequency band. The wireless spectrum resources are limited and non-renewable resources, and in addition to China, they need to be auctioned, and the cost is very high.

FDD requires paired radio frequencies, which is hard to find and too costly for operators to deploy. Moreover, as far as wireless components are concerned, it is very difficult to design a duplexer to achieve a large bandwidth and a small protective band. In addition, in order to achieve high-speed performance, one of the most critical technologies introduced in 5G is Massive MIMO, which is obviously more friendly to TDD. But to achieve such system performance, the most critical point isthat 5G uses a larger bandwidth wireless spectrum. For Sub-6G, it can support a single carrier frequency of 100Mhz, and it can support a maximum of 400Mhz in the millimeter wave frequency band. The wireless spectrum resources are limited and non-renewable resources, and in addition to China, they need to be auctioned, and the cost is very high. FDD requires paired radio frequencies, which is hard to find and too costly

for operators to deploy. Moreover, as far as wireless components are concerned, it is very difficult to design a duplexer toachieve a large bandwidth and a small protective band. In addition, in order to achieve high-speed performance, one of the most critical technologies introduced in 5G is Massive MIMO, which is obviously more friendly to TDD.