SK Telecom

In October 2000 the company became the second in the world to launch a 3G W-CDMA network, using B1 (2100 MHz). The network was upgraded to HSPA+ in July 2010.

4G LTE was launched July 2011 over B5 (850 MHz), using a 10 MHz channel width. National coverage was achieved by April 2012, and by May had begun carrier aggregation trials to combine B5 and a new B3 carrier. The dual carrier network was implemented July 2012 - the first in the world to use two LTE bands. Following the 3GPP Rel. 10 launch, the company commercially activated LTE-Advanced using 2C aggregation of B3+B5. Following an August 2013 auction, SK Telecom secured an additional 20 MHz of 1800 MHz spectrum and increased B3 width to 20 MHz. LTE-A peak data rates were subsequently extended to 225 Mbps.

Mid 2014 saw the company begin B1 (2100 MHz) LTE, and by December SK Telecom announced 3C aggregation of B1+B3+B5.

In June 2014 the company conducted the world's fastest LTE CA, achieving 3.8 Gbps using 9 TDD carriers and 1 FDD carrier. Further CA trials conducted in December 2015 saw 428 Mbps DL achieved using 3C TDD B41 (2500 MHz) with 256QAM modulation. 

SK Telecom launched LTE-Advanced Pro in June 2016, supporting peak data rates of 500 Mbps using 3C aggregation and 256QAM modulation. By end of 2016 B7 (2600 MHz) was implemented, taking data rates to 525 Mbps. 4X4 MIMO and 4C aggregation was later implemented in 2017, taking data rates over the 900 Mbps mark by adding a further non-contiguous B7 channel. In June 2017 the company announced the launch of 5C aggregation, with the network for the first time exceeding 1 Gbps peak DL rates.

SK deployed both LTE-M and LoRa networks, announcing their commercial activation in March and July 2016 respectively. LTE-M is implemented on the network's existing B3 and B5 carriers.

SK Telecom has conducted a number of 5G trials, beginning December 2016 in partnership with Ericsson and Qualcomm. The network trials have been conducted over n78 (3500 MHz) and n257 (28 GHz). Further trials were conducted in June and September 2017 with Nokia and Samsung. Infrastructure deployment began in December 2017, supporting data rates up to 20 Gbps. Working in partnership with Samsung, the company announced the completion of its first NR test bed call in October 2018.

SK Telecom officially launched its 5G network in April 2019, operating an initial 34,000 5G base stations across 85 cities nationwide. The company is understood to be using the 100 MHz of n78 (3500 MHz) spectrum it secured during June 2018 auctions.