Understanding where and when users can experience 5G in South Korea

South Korea is the most advanced country for 5G adoption with 11.8m 5G subscriptions at the end of 2020 out of a population of 52m people (22.7%). The country’s three operators have deployed 166,250 5G base stations which is approximately 19% of the country’s 870,000 4G base stations.

Deploying a new network technology is expensive for mobile operators. With 5G, operators must upgrade base station sites with new 5G antennas and baseband computing and must upgrade the backhaul links that connect each site into the core network to support 5G’s much greater speed and capacity. Operators need to judge where to focus their 5G investments to maximize the experience for their users.

Traditional metrics for quantifying network coverage do not help operators to target investments on users’ needs because they measure the network itself and not their users’ experience of the network. They risk wasting network spend serving areas where few users visit.

These existing coverage scores are problematic because they are usually based on mathematical predictions rather than on real world measurements. They typically refer only to outdoor coverage — not indoors — because it is easiest to predict outdoor coverage and scores calculated that way give a higher and more impressive result. There are several coverage metrics which operators, regulators and media often quote:

  • Population coverage. In South Korea, operators exceeded 90% 5G population coverage in early 2020 but Korean users still considered the 5G experience problematic and the number of base stations is under one fifth of the 4G base stations deployed. Population coverage focuses on covering the locations where users live — according to census data — and not the locations where users visit as they move around, for example as users visit shops, go to school or to work, or go on holiday. It is the most commonly quoted coverage measure because it is easier for operators to achieve a very high percentage score with this measure than with others.

  • Geographic coverage. This metric represents the percentage of square kilometers a network reaches, but it takes no account of which locations users spend their time, and locations with no inhabitants have the same weighting as those where many people live or visit. Results are often very different to population coverage. For example at the end of 2020 South Korea’s three mobile operators achieved geographic coverage between 4.9% and 6%, much lower than for population coverage because of the concentration of the population in cities. A high score is harder to achieve than for population coverage, but reaching a score over 90% will mean extremely high investment levels to cover very rural — or wilderness — locations which do not require 5G and where an older mobile technology will be more than sufficient.  

  • Base station numbers. The number of sites where operators have placed mobile antennas may seem a perfect way to compare 4G and 5G networks. However, to reach the same effective coverage operators will need to have many more base station sites for higher frequencies than for lower spectrum bands due to the physics of radio signals. Unfortunately, 5G networks around the world use a very wide range of frequencies from low bands such as 600 MHz up to extremely high mmWave frequencies, so base station numbers alone cannot indicate mobile coverage.

Opensignal believes the most important criteria for understanding the mobile world is the experience of real mobile users. For this reason, we have developed two measures to quantify the extent of 5G mobile network technology to understand different parts of the user experience, both are based on actual user measurements: 

  • 5G Reach is the proportion of locations a 5G user visits that have a 5G signal. It uses real-world measurements for 5G users rather than estimations. Our smartphone users measure the presence of a 5G signal across locations. As long as a location has a 5G signal either outdoors or indoors it will count as reached by 5G. All locations that an individual user visits have the same weighting in the final 5G Reach score. In South Korea we see 5G Reach scores of 5.7 on a ten point scale. In other words, in over half of the locations where 5G users go, they are in a location where there is a 5G signal.

  • 5G Availability reflects the proportion of time that 5G users have an active 5G connection. 5G Availability tends to reflect most heavily the experience users have in the places they spend the most time such as at home or at work. While measurements are taken both outdoors and indoors, most users spend more time indoors at their home or place of work and so 5G Availability tends to be sensitive to indoor experience. In South Korea, we see user scores of approximately one quarter of time, significantly lower than for 5G Reach where users’ see 5G in over half of locations they visit. This difference is most likely because of the challenges of receiving a mid-band 5G signal indoors.

When we compare the geography coverage of each of South Korea’s operators we see LG U+ covers more square kilometers than does SK telecom or KT according to the Ministry of Science and ICT. We see a similar trend in the number of 5G base stations that LG U+ has deployed to date. But when we look at 5G Availability and 5G Reach we see that there is a statistical tie in users’ experience of each operator’s network. This means that the increased number of 5G base stations that LG U+ has deployed has not yet translated into more locations where most 5G users typically visit and experience 5G. These differences highlight that Opensignal’s 5G Reach and 5G Availability are not measures of network coverage and instead measure users’ experience of the 5G network. 

It’s clear from the many different potential ways to measure users’ experience and mobile networks that there is no single correct way to measure the extent of a mobile network. Opensignal’s two different measures — 5G Availability and 5G Reach — represent the network experience of users which is perhaps the most important criteria as users are the paying customers for every mobile network operator.