“We cannot allow any other country to out-compete the United States in this powerful industry of the future,” Trump said. By next year, the US will “have more 5G spectrum than any other country in the world”, he said.

The problem, however, is that initial 5G networks in the US are to be built on what experts deem as less efficient, higher frequency millimetre wave (mmWave) spectrum, while countries in Europe and the Asia-Pacific are deploying their next-generation infrastructure on lower frequency radio bands in the so-called sub-6 gigahertz spectrum.

That difference may lead to interoperability issues with 5G devices and services in the US to those of the rest of the world. It would be akin to the world’s largest economy being on the Betamax video standard, while other markets are on VHS, according to The Washington Post.

While there is enormous free capacity in the higher frequency bands, the propagation of signals in these frequencies is very unstable and at normal power levels will be unable to penetrate walls or windows, according to a Bernstein Research 5G primer published in March.

The stakes are high for the US to put its mobile infrastructure expansion in order amid a race against China for 5G leadership. The strain in US-China relations – owing to heightened trade tensions, military showdowns and diplomatic rows – has intensified that competition.

It has also been complicated by the Trump administration’s pressure to get 5G equipment from Huawei Technologies banned in mobile networks around the world over alleged security concerns and after a US indictment that accuses the Chinese telecoms gear maker of financial fraud and violation of trade sanctions against Iran, among nearly two dozen charges.

In the absence of a local 5G systems champion, major US telecoms network operators, including AT&T, Verizon Communications and Sprint, have announced they will work with Finland’s Nokia, Ericsson of Sweden and South Korea’s Samsung Electronics as their 5G equipment suppliers.

The US has moved from third place in 2018 to tie China in first position this year in the latest study on the 5G commitments of countries by telecoms research firm Analysys Mason. It also ranked South Korea, which unveiled its initial roll-out of 5G mobile services early last month, as well as Japan and the UK among the top five in global 5G readiness.

Major US telecoms carriers AT&T and Verizon have already started rolling out their 5G mobile networks over mmWave. AT&T has launched in 19 cities, while Verizon has introduced 5G in two cities and plans to expand that number to 30 cities by the end of this year.

“In many other markets in the world, they are more cautious about using mmWave because they are not convinced it will have meaningful coverage and capacity to boost the network … It’s impossible to build nationwide coverage with mmWave spectrum,” said Bengt Nordstrom, chief executive of Swedish telecoms consulting firm Northstream.

“In a way, you can say that the US is a guinea pig for how useful mmWave spectrum will be.”

5G mobile networks are expected to provide from 20 to 100 times faster data rates than current 4G networks.

The technology can also support 1 million connected devices per square kilometre and up to 1 millisecond latency, representing the nearly instant time a packet of data takes to get from one point to another.

Those advances would enable the so-called internet of things to go mainstream as more devices – from fitness-tracking watches to internet-linked televisions and smart speakers at home – get connected for data to be collected and analysed.

5G infrastructure would also serve as the backbone for the industrial internet, supporting highly automated manufacturing, smart cities and autonomous driving.

“I think the US may be making a tactical error with [deploying 5G over mmWave] initially,” said Dean Bubley, director at independent US technology research firm Disruptive Analysis. “The rest of the world is going to find deployment easier with 5G on the [lower frequency] bands.”

The main reason why the US has restricted its 5G network development to mmWave is because many of the lower frequency bands relevant to 5G are off-limits, according to a paper released last month by the Defence Innovation Board, an independent federal advisory committee of the US Defence Department.

It said a large portion of those mobile airwaves are owned by the government, and extensively used by the Defence Department for secure communications.

“The question of spectrum allocation is at the heart of the 5G competition, for the spectrum band of choice … impacts nearly every other aspect of 5G development,” the paper said. “US carriers may continue to pursue mmWave, but it is impossible to lead in the 5G field without followers.”

To be sure, experts have also said that mmWave and sub-6GHz mobile airwaves can be used in a complementary manner, with the higher frequency bands used for large-capacity, localised functions such as in densely populated areas, while the mid- to low bands are used in areas which require wider coverage.

US carrier T-Mobile, for example, plans to combine its licensed low-frequency and mmWave bands with Sprint’s own lower frequency band for better coverage and capacity, according to Subramanian Venkatraman, a principal analyst at Arizona-based MTN Consulting.

Still, the US 5G infrastructure roll-out on different mobile airwaves from what the rest of the world is using would put it at a disadvantage as more next-generation networks are rolled out around the globe. Most 5G mobile services worldwide will roll out from 2020.

“As sub-6GHz becomes the global standard, it is likely that China, the current leader in the space will lead the charge,” the Defence Innovation Board said in its paper, highlighting security risks for operations by the Department of Defence overseas.

“Even if the US were to restrict use of Chinese equipment suppliers domestically, the US is not a big enough market in wireless to prevent China’s 5G suppliers from continuing to increase market share globally.”

The paper said the impact may range from a decline of vendors that would serve the US market to limited availability of competitive products, which would result in more expensive supply chains.

China, which has the world’s largest mobile market by subscriber and network size, realises that the advent of 5G is its chance to get out in front for the first time in the development of wireless communications technology, an area that has previously been dominated by the US and Europe.

5G has been identified in China’s 13th Five-Year Plan as a “new area of growth”, and Shenzhen-based Huawei is currently the front runner in the race to supply 5G gear to telecoms companies around the world.

The difference in mobile spectrum strategy in the US also means that the mmWave 5G systems are “much more complex and expensive [to build] than the sub-6GHz systems … which are a natural extension of traditional wireless technologies, such as 4G LTE”, said Guo Yongxin, a professor at the National University of Singapore’s department of electrical and computer engineering.

The main issue with mmWave is that the coverage area is smaller, which means additional antennae and other hardware are needed to get decent coverage, according to Nordstrom.

The only option for the US would be to have its Defence Department release or share its lower frequency mobile airwaves for commercial use, according to MTN Consulting’s Venkatraman.

“But with the major telecoms carriers already pursuing 5G development using mmWave, a switch could cause delays,” he said.

The UK government, for example, last year auctioned off lower frequency mobile airwaves to mobile network operators that were previously used by the Ministry of Defence.

Trump, however, has remained confident that the US can still get ahead of the pack in the 5G race.

“By the end of this year, the United States will have 92 5G deployments in markets nationwide. The next nearest country, South Korea, will have 48,” he said last month. “And we’re going to accelerate that pace greatly.”