The radio frequency IC chips like the tuner front ends and RF baseband. This process technology is not nearly so easy to copy and implement as regular digital elements on regular substrates. It's pretty important for mobile handsets.

This is reflected in the way 5G is being rolled out in China. Mostly new sub-6GHz 5G NR modulation basestations are being put in. Millimeter band is not being attempted initially. This gets them 15-20% modulation gain in thoroughput over LTE in the same circumstances at most.

Gallium nitride technology is used for the higher frequencies in 5G chips. Currently only suppliers outside of China produce such chips.

From a business perspective, pushing 5G as fast as it is pushed now by China, does not make sense. Chinese network operators would not want to deploy 5G quite as fast as they are being forced to, but China’s government is imposing it.

So why impose it? There might be several reasons, e.g. to have a dominant position in setting industry standards, but one reason stands out: The complex 5G standard requires frequent software that make it harder to enforce security software reviews and anti-espionage measures.

Huawei had own Rf backends and frontends for around 10 years...