SK Telecom, the nation’s No. 1 mobile carrier, said Tuesday that it has developed the world’s first femtocell designed to support the fourth-generation Long Term Evolution network service.

A femtocell, or a small cellular base station, allows service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable.

With the company’s latest innovation, SK Telecom said that its LTE users will be offered high-speed data service even while indoors and in basement areas within the coming months.

The company plans to build up a nationwide LTE network in 84 cities by April and to improve service quality by installing LTE femtocells first in crowded downtown areas.

The number of SK’s LTE customers surpassed the 500,000 mark on Dec. 14 since its launch in July.

“SK Telecom has already extended its LTE service coverage by installing more than one million gap fillers. The installment of LTE femtocells would further improve service quality,” a SK telecom official said.

By Lee Ji-yoon (jylee@heraldcorp.com)