AT&T today fired up its ultra-fast 4G LTE network in six new markets, including three in Puerto Rico.

AT&T today fired up its ultra-fast 4G LTE network in six new markets, including three in Puerto Rico.

The carrier introduced its 4G LTE service in Salt Lake City, Utah; Albuquerque, N.M.; and Reading, Penn. In Puerto Rico, the rollout includes Guayama, San German-Cabo Rojo, and Yauco. At this point, AT&T 4G LTE is now available in 109 markets, covering more than 150 million people.

AT&T has been making progress with its 4G LTE rollout. The carrier last month in Milwaukee, Wis., Denver, Colo., Louisville, Ky., Daytona Beach, Fla. and several smaller markets, including York, Pa., Annapolis, Md., Tacoma, Wash., and Provo, Utah.

Also last month, AT&T announced a three-year upgrade to its wireless and wired networks dubbed (VIP). As part of the plan, the service provider will spend $8 billion over the next three years beefing up its wireless network.

Project VIP will expand AT&T's 4G LTE network to cover 300 million people in the U.S. by the end of the 2014. The company also plans to buy more spectrum for a total of 118 MHz nationwide and push for the FCC to release more. AT&T also pledged to deploy small cell tech, macro cells, and more distributed antenna systems to boost the performance of its existing network.

When it comes to 4G LTE, rival carrier Verizon is leading the charge in the U.S., currently serving more than 440 cities. Meanwhile, Sprint is planning to bring its own 4G LTE network to more than 100 new cities over the coming months. T-Mobile expects to upgrade to 4G LTE in 2013.

Global 4G LTE subscribership is expected to skyrocket from 9 million last year to more than 560 million in 2016, according to a recent report from Parks Associates.

For more, see PCMag's test of the Fastest Mobile Networks 2012.