SK Telecom, South Korea’s largest mobile operator, said it will build more 1.8GHz base stations for LTE and LTE-Advanced rollout, so subscribers can get nationwide 150Mb/s (LTE) and 225Mb/s (LTE Advanced) coverage by the end of the year.

The operator said using a 20MHz chunk of spectrum at 1.8GHz will give it a competitive edge in deploying a nationwide LTE-Advanced network combining 20MHz (1.8GHz) and 10MHz (800MHz), which offers up to 225Mb/s.

Last November SK Telecom showcased download speeds of up to 225Mb/s using two-band carrier aggregation (CA), pooling together 20MHz in the 1.8GHz frequency band and 10MHz at 800MHz.

SK Telecom added it had gained approval to use 10MHz bandwidth in the 2.1GHz band for LTE. The company secured 30MHz bandwidth in the 2.1GHz band through a frequency auction in 2010.

With the newly-added 10 MHz LTE bandwidth in the 2.1GHz band, SK Telecom now has LTE bandwidth in three different frequency bands: 20MHz at 1.8GHz; 10MHz at 800MHz; and 10MHz at 2.1GHz.

SK Telecom says customers will be able to take advantage of three-band CA, capable of theoretical peak speeds up to 300Mb/s, once appropriate chipsets and devices have been developed.

The operator said it will begin building 2.1GHz base stations for LTE in Q2 2014, “making the network available for commercialisation as soon as the supporting handsets come to market”.

Until the three-band CA chipsets are developed, SK Telecom said it would use multi-carrier technology with 2.1GHz base stations to ease capacity strain on its existing LTE networks.

SK Telecom has plans to demonstrate its triple-band CA technology at this year’s Mobile World Congress, but will be going one step further by aggregating together three lots of 20MHz. This, says SK Telecom, will give top-line speeds of up to 450Mb/s on LTE-Advanced.

LG Uplus, South Korea’s third-largest mobile operator, also has three-band CA ambitions for LTE-Advanced.

According to the Yonhap news agency, LG Uplus plans to roll out three-band CA this year, combining 40MHz at 2.6GHz band, 20MHz at 800MHz, and 20MHz in 2.1GHz.

Korea Telecom, which runs South Korea’s second-largest mobile operator, also runs an LTE-Advanced network using two-band CA aggregation. The operator’s plans on three-band CA have yet to be announced.

According to GSMA Intelligence, South Korea is the world’s most advanced 4G market, with penetration as a percentage of total connections passing the 50 per cent mark in Q4 2013. This compares to around a quarter 4G-user penetration in Japan and the US.