Alex Jinsung Choi
With Alex Jinsung Choi, executive vice president and head of SK Telecom's ICT R&D division
The South Korean mobile communications market is one of the world's most competitive and innovative. That keeps the pressure on SK Telecom, South Korea's largest mobile service provider, to find way to keep implementing cutting-edge technologies. So it was hardly surprising to see the operator recently sign deals with Ericsson (NASDAQ: ERIC) and Nokia (NYSE:NOK) to develop core technologies for next generation 5G networks. FierceWirelessTech Editor Tammy Parker recently conducted an email Q&A with Alex Jinsung Choi, executive vice president and head of SK Telecom's ICT R&D division, regarding the operator's roadmaps for LTE-Advanced and 5G. The following is an edited and condensed version of that Q&A.
FierceWirelessTech: In June 2013, SK Telecom rolled out the world's first LTE-A network with carrier aggregation (CA) with a commercial smartphone for use with the service. Were there any unforeseen challenges that arose in implementing this technology?
Choi: Now we provide stable LTE-Advanced service, but we had challenges when we were preparing commercialization of the LTE-Advanced network. As two different carriers of 1.8 GHz and 800 MHz have different [spectrum] characteristics, we had a challenge of matching the coverage of the different carriers to provide stable data transmission at twice faster speed. We were able to overcome the challenge by utilizing our own differentiated network planning/optimizing systems such as T-EoS (Total Engineering & Optimization System). Using the network simulator, we found the optimal parameters such as tilting angles of antennas and Tx power of base stations to apply them to base stations in advance.
FierceWirelessTech: Do all of the end-user devices currently sold for SK Telecom's network support carrier aggregation?
Choi: As of May 2014, 3.5 million users out of 15 million LTE customers are using CA-capable devices. We plan to introduce more CA-capable devices in the market this year. We were able to commercialize LTE-Advanced early by conducting interoperability tests and collaborating in terms of technology development for CA-capable devices based on close, strategic partnerships with major device/chipset makers as well as vendors. Also, SK Telecom is vitalizing the ICT ecosystem in terms of LTE technology and service development by, for example, providing a reference site with diverse field conditions to equipment manufacturers, handset/modem manufacturers and other third parties.
FierceWirelessTech: What is SK Telecom's timeline for three-carrier aggregation?
Choi: Tri-band carrier aggregation, technology that combines three carriers and then transmits the data simultaneously, should not affect quality of either new devices for tri-band CA or existing handsets using two-band CA. In fact, relevant technologies including load balancing among three carriers are more complex and difficult. We will do our utmost to commercially launch tri-band CA, once again, for the first in the world to enable our customers to enjoy the fastest LTE speed and top-quality service. Accordingly, tri-band CA will be commercialized by the year end, at the earliest, or in the beginning of next year as soon as the supporting handset is launched.
FierceWirelessTech: What other LTE-Advanced features has SK Telecom implemented so far? And what other LTE-A functions are planned for the near future?
Choi: Other LTE-Advanced technologies would include CoMP (coordinated multi-point) and eICIC (enhance inter-cell interference). CoMP improves wireless communications quality in a border area of cells through cooperation between base stations, and we applied downlink CoMP and uplink CoMP to our commercial network in early 2012 and in April 2014, respectively.
eICIC eases interference between micro cells and small cells to improve mobile quality. We internally demonstrated a system that maximized performance by combining eICIC and RPS (Reduced Power Subframe) in May 2013. TM9 (Transmission Mode 9) allows a move between cells without handover, preventing quality sacrifice caused during handover. This technology was successfully demonstrated in October 2013. We aim to complete technology development by the end of this year.
FDD-TDD CA combines multiple frequencies from different bands for better data speeds in an environment where different LTE technologies (FDD-LTE, TDD-LTE) are used together. SK Telecom, together with Nokia, demonstrated the technology at 3.8 Gbps speed at Mobile Asia Expo in June 2014.
FierceWirelessTech: SK Telecom was the first operator to publicly state it would test Nokia's Liquid Applications. Is SK Telecom using Liquid Applications commercially? If so, what services are being enabled by this technology?
Choi: With regard to Liquid Applications, SK Telecom and Nokia have worked together to develop technology for commercialization of managed services based on Edge Cloud platform. Given the features of Liquid Applications such as real-time data processing with low latency and distributed bulk data processing, we are considering the major service areas to include local advertising, augmented reality and contents transmission/cashing by base station and Smart Work. Such services are to be commercialized for specialized enterprise customers.
FierceWirelessTech: SK Telecom has deployed C-RAN, but I'm not sure how widely deployed it is. Is just mainly in city centers?
Choi: In an effort to improve mobile phone network operation efficiency and cost reduction, SK Telecom is establishing C-RAN. More than half of LTE network base stations, in particular, are C-RAN based, contributing to operational efficiency and cost reduction for network operation. Most base stations in high-traffic areas are C-RAN based, and application of C-RAN will gradually expand outside of cities as well.
FierceWirelessTech: The EU and South Korean governments have pledged to work together on 5G. Is SK Telecom conducting R&D in support of this effort?
Choi: As a follow-up of a joint declaration between Korea and EU for cooperation in the ICT field, 5G Forum of Korea and Europe's 5G-PPP signed a MOU on June 17. Under the MOU, the two will officially communicate, share information and discuss current issues on mutually-interested areas of 5G. 5G Forum, initiated by the Korean government, is a group of participants from industry and academia and SK Telecom is chairing the forum in its first term. Also, we are actively driving R&D in partnership with local/overseas manufacturers, public research institutes and universities and have recently signed a MOU with Nokia and Ericsson for cooperation for 5G technologies.
FierceWirelessTech: Many in the industry agree that 5G will need to have gigabit performance for fixed locations, low latency, support for small cells, etc. Does SK Telecom have any other expectations for 5G that might differ from what the rest of the industry is calling for?
Choi: In 5G, we believe network architecture change and service should be defined as well as speed and capacity discussed in 4G networks. The goals of SK Telecom in 5G network are summarized as hyper-connected infrastructure, enabling platform and innovative service.
Key indicators for hyper-connected infrastructure would be traffic capacity, the number of login users on mobile devices, decreased latency and energy consumption. And SK Telecom aims to improve these four major indicators by 1,000 times.
Also, by maximizing efficiency of the wireless network through virtualization of software-based network and E2E control and securing enabling platform that creates new value by converging information technology and communication technology, we will provide users with immersive customer experience and innovative service in 5G anytime and anywhere.
FierceWirelessTech: What else would you like to say about SK Telecom's future technology roadmap?
Choi: For LTE and LTE-Advanced technologies, we'll provide much faster data rate and stable data service through commercializing tri-band carrier aggregation, eICIC, and TM9. As for 5G, we plan to identify core technologies that hold high potential to become the next-generation network in four domains: namely, service and customer experience, network performance, new flat network architecture and operational excellence, and secure the core technologies according to mid- to long- term.
For service and customer experience, we plan to focus on providing services with lower latency and seamless connectivity, ultra high-quality contents and new user experience, and realize technologies for low battery consumption. For network performance, we aim to realize ultra high capacity, 1 Gbps edge data rate and massive traffic processing for IoT. For new flat architecture, we'll try to secure software-based flexibility and agility, high reliability and security, and cost and energy efficiency. For operational excellence, we'll focus on end-to-end quality of experience control, automatic optimization and recovery and intelligent traffic management.