By Jun-young Park WIRED Korea.

So much has happened to Korea’s wireless telecommunication industry since three mobile network carriers – SKT, KT and LG Uplus – started to stream data on their 5G networks on December 1 last year.

First of all, more than 4 million people have jumped ship from LTE to 5G, which is no small feat, given that the mobile network carriers started commercial 5G service just a short while ago, in April. They believe their combined number of subscribers will reach the 5 million mark by year-end.

To better serve their rapidly expanding subscriber base, they have launched and are planning to launch new 5G services empowered by cutting-edge technologies, such as virtual reality, augmented reality and artificial intelligence. Jumping on the bandwagon are companies providing entertainment, healthcare and gaming services, to name only a few.

One such example is an immersive music service provided by Genie Music, a KT subsidiary, which has recently come up with a “virtual album” featuring K-pop girl band Mamamoo.

Download the app and put on your headset, and you will be able to watch the entertainers sing and dance right in front of you. Their concert, streamed in 10K-resolution, virtual imagery, is so real that it looks as if you could touch the nonexistent entertainers.


5G taking root

All things considered, 5G service has started taking root in Korea. Indeed, foreign mobile carriers, including AT&T, China Telecom and Deutsche Telekom, have contacted their Korean counterparts to share experience while preparing for their own commercial services.

Still, many ask what the difference is between 5G and 4G, with no remarkable change being brought to the public’s attention. No one is commuting to work on a connected, self-driving car. No company is running an AI-empowered factory with unmanned assembly lines, either. Nor is there any hospital practicing telemedicine, or the use of a 5G platform in addressing the patient’s concerns and diagnosing his conditions remotely.

If any of these state-of-the-art service is to be launched, the mobile carriers will have to provide ultra-high speed, ultra-low latency and super-massive connectivity.

But speed, for one, is way behind. True, data is transmitted five times as fast on the 5G networks as on the 4G LTE networks. Still, the performance is woefully below the promised target of 20 times. Another problem is with connections, which are frequently disrupted, inviting a deluge of complaints from subscribers.

If SKT, KT and LG Uplus are to deliver on their promises for connected, autonomous vehicles, smart factories, smart cities and many others, they will have to make huge investments in opening additional networks on a new band of the radio frequency spectrum for data transmissions at ultra-high speeds.

This is comparable to spending a huge amount of money on a new multi-lane expressway designed to deal with an explosive number of fast-running vehicles. The expressway would need so many ramps for easier access by those vehicles.

In this regard, Choi Ki-young, minister of science and ICT, has recently demanded that the three Korean mobile carriers build additional 5G networks on the 28GHz band of the radio frequency spectrum as soon as possible.

But the mobile carriers are balking, saying that they cannot afford to launch multi-trillion-won projects soon after pouring tremendous amounts of money into their yet-to-be-completed projects of building 5G networks on the 3.5GHz band during the past couple of years.


More base stations are needed

To expand their 5G coverage, they need to install more base stations – fixed points of communication on carrier networks that have signal-receiving and transmitting antennae – in provincial capitals as well as in Seoul.

What’s all this fuss really about? If you are to understand what is at issue, you will have to understand some arcane terms, such as hertz, frequency and band. Hertz, also known as Hz, is a unit of radio frequency – with 1MHz and 1GHz frequencies denoting an electric current oscillating 1 million times and 1,000 million times per second, respectively.

What the science minister means is that the three carriers will have to start new 5G services on the 28GHz band, which actually spans from 26.5GHz to 28.9GHz, to address subscriber complaints and provide new game-changing services.

The available combined bandwidth for their services would amount to 2.4GHz on the 28GHz band (the bandwidth being the size of the band equal to the sum of the lowest frequency subtracted from the highest, 28.9GHz minus 26.5GHz), which is much wider than that on the 3.5GHz band – a mere 0.28GHz (3.7GHz minus 3.42GHz)

Data transmission would naturally be much faster on the 28GHz band than on the 3.5GHz band, given that the wider the bandwidth is, the speedier the transmission gets.

Providing services on the 28GHz has another advantage, with the science minister offering to make an additional 1.4GHz available if the carriers find the 2.4GHz bandwidth not wide enough. With the bandwidths adjacent to the 3.5 GHz already being used for other purposes, providing 5G services on that band has its limits. 

The problem is even worse, given the prediction by the Electronics and Telecommunications Research Institute saying that the 3.5 GHz band will be exploited to the fullest extent possible by 2023.


No other option

If so, it is a matter of time until the carriers start new 5G services on the 2.8GHz band. There is no other option.

But the downside is that 5G services on the 28GHz band would cost much more as they require far more base stations than on the 3.5GHz band. The reason is that a short wavelength (a high frequency) tends to be thrown back by an obstacle on its path, instead of being sent to the intended receiver, while a long wavelength (a low frequency) tends to bend around it.

But the Korean government is adamant in its demand for early 5G services on the 28GHz band. Oh Yong-su, director general for radio policy at the ministry, says the new policy on the use of the radio spectrum is designed to go beyond the smartphone services for general subscribers and create B2B markets for brand-new services combining advanced technologies.

The above is a combination of articles written by Jun-young Park, which was translated by Nam-hyun Choi, deputy editor in chief at WIRED Korea.