Upswitching is going to be a problem for any operator using NSA 5G, but South Koreans have been particularly vocal about it
South Korea’s claim that it launched the world’s first 5G network in April might be somewhat contested in the U.S. — with some arguing that because it was only available to select celebrities, it didn’t really count — but there is no doubt that the country has a massive lead over much of the rest of the world.
In August, data showed that only four months after local carriers commercially launched the technology, the number of 5G subscribers in South Korea hit the 2 million mark, and according to the GSM Association, South Korean 5G users accounted for 77% of the global population of 5G users by the end of June.
The three South Korean carries, SK telecom, KT and LG Uplus, launched limited 5G commercial services in December 2018. The simultaneous launch, which spanned limited areas in Seoul and some other major Korean cities, was part of an agreement with the ICT ministry to avoid excessive competition.
Earlier this summer, South Korea completed a tender process through which it awarded spectrum in both the 3.5 GHz and 28 GHz bands, making available a total of 280 megahertz in the 3.5 GHz spectrum band and 2,400 megahertz in the 28 GHz band.
SK Telecom, KT and LG Uplus had a 10-block cap per spectrum band, paying a total of 3.6183 trillion won ($3.3 billion) for the spectrum.
In April, SK Telecom rolled out its nation-wide 5G networks on 3.5 Ghz mid-band in data-traffic-concentrated areas, focusing on major cities and highly populated areas like universities, high-speed trains, highways and metropolitan subways with plans to expand that coverage to nationwide subways, national parks and festival sites as 2019 concludes.
The initial launch included a total of 34,000 5G base stations in 85 cities.
SK Telecom worked with Ericsson who has provided the telecom with different variants of mid-band Massive MIMO, and in the second half of 2019, began providing mmWave technology in hotspots to address extreme capacity needs.
In August, SK Telecom announced that it was the first mobile operator in the world to reach 1 million 5G subscribers, and managed do so just 140 days after launching the world’s first 5G smartphone in April. The operator aspires to end the year with more than 2 million 5g subscribers.
SK Telecom has also been aware of the increasing concern around data security as the level of connectivity skyrockets around the world, stating that its network has been secured by applying quantum cryptography technologies to eliminate the risk of hacking and eavesdropping.
South Korean mobile operator KT launched its 5G network in April with help from Ericsson, which provided 3GPP standards-based 5G New Radio (NR) hardware and software for KT’s 3.5 GHz non-standalone (NSA) network.
KT aims to have its 5G commercial offering available in 85 major cities nationwide by the end of 2019, covering the country’s key transportation routes, including two major highways, six airports, and the ground section of high-speed railways. The company plans to expand the coverage to subways, public offices and university hospitals.
Recently, KT connected a baseball stadium in Suwon, Gyeonggi Province, home to the KT Wiz baseball team, with its 5G network. “Media services for baseball are one of the few areas where mobile users can experience the advantages of 5G firsthand,” Hahn Woo-jae, a manager at KT Sports’ marketing team, explained July 31. ““From purchasing a ticket to food delivery, 5G technology is an integral part of KT Sports’ marketing schemes to attract baseball fans.”
There have also been rumors that KT is rolling out its 5G network services to large indoor spaces, which will require specialized hardware to enable network access. 5G networks struggle to penetrate walls due to the frequency of the radio waves used, and while this is a bigger issue for millimeter wave (mmWave) 5G networks, it is still a challenge faced by the mid-band spectrum that KT and its competitors in Korea use.
KT, however, has been working through this problem since last year, even before the launch of 5G, developing 5G-signal repeater hardware specifically geared for use in buildings.
In August, LG Uplus reported 540,000 5G subscribers on its 5G network, which includes around 50,000 5G base stations in Seoul and surrounding areas, as well as some metropolitan cities. The operator is aiming to deploy 80,000 base stations across South Korea and cover 90% of the population by the end of 2019.
Initially, the operator only designated Huawei’s 5G equipment for Seoul and the Gangwon Province, while intending to work with Samsung as its main supplier and Ericsson and Nokia as secondary suppliers for the remaining areas in the country. In May, however, KT announced it will also use 5G equipment from Samsung for the additional base stations installed in Seoul.
IHS Markit’s RootMetrics, ranked mobile operators based on their 5G networks, showed that South Korea has “incredible” 5G speeds compared to LG Uplus. Further, RootMetrics reported that that LG Uplus’ network delivered the fastest speeds and lowest latency.
“The results for LG Uplus were a step above those of KT and SK Telecom, but all operators provided significantly faster speeds on 5G compared to non-5G mode,” RootMetrics said. “LG Uplus […] had an impressive 5G median download speed of 426.4 Mbps.”
Where South Korea’s 5G falls short
While South Korea appears to be leaps and bounds ahead of the rest of the world in deploying 5G, the country has been experiencing some latency issues. The super-fast speeds reported by RootMetrics are accurate, just not when a connection is “upswitching,” or when a device first switches from LTE to 5G.
And, according to the RootMetrics report, this is a big deal. “The best end-user download latency experience could be delivered not necessarily by the operator that offers the best pure 5G performance,” report authors Suzantha Subramaniyan and Patrick Linder wrote, “but by the network that most efficiently handles upswitching.”
RootMetrics found that the need to upswitch from LTE to 5G raised KT’s initial 5G latency to 244 ms, from just 88ms in cases where it was not necessary.
Upswitching is going to be a problem for any operator whose network requires it, but South Koreans have been particularly vocal about their disappointment around latency.
A byproduct of rushing to deploy 5G – which South Korea certainly did in an effort to be the first – the need to upswitch is the result of wireless operators and equipment vendors deciding to implement non-standalone (NSA) 5G first, which requires the support of a 4G LTE network to perform certain functions like voice calling.
U.S. operators, Verizon and T-Mobile US have voiced plans to move to a standalone (SA) version of 5G in the coming years to rid themselves of the upswitching issue.
South Korean mobile customers still spend most of their time on LTE networks, even if they are 5G subscribers, according to the RootMetrics authors. This is because LTE is better for battery life, as well as performance of some functions. Further, users are often put onto an LTE network by default at the beginning of a session, meaning the user’s device almost always has to actively switch to 5G. “As long as upswitching is necessary,” explained the authors, “download latency will be affected at the beginning of that data task.”
Recently, KT applied CDRX technology on its 5G network, which puts devices on sleep mode periodically when there is no data transmission in order to conserve battery life. The operator reported that on average, battery life lasted 65% longer when the technology was applied.
Perhaps this is part of the operator’s plans to address the upswitching latency issues currently plaguing the country. If users spend less time switching back and forth between LTE and 5G, which they might do if battery life is less of a concern, this may reduce latency frustrations, which lie primarily at the moment of network upswitching.