T-Mobile US is planning to add LTE-Advanced features to its new 4G network before the end of 2013.

"We'll begin rolling out LTE-Advanced features later this year," Dave Mayo, senior vice president of technology, strategy, finance and development at T-Mobile, said at Light Reading's Backhaul Strategies for Mobile Operators event in New York City on Tuesday.

Mayo didn't specifically reveal which LTE-Advanced features will arrive first on the T-Mobile network. After being late to the LTE party, T-Mobile was able to base its initial deployment -- launched this year -- on the 3GPP's Release 10 specification, which is the basis of LTE-Advanced. (See T-Mobile's 4G Advance: Where LTE Goes After Vegas.)

The key updates in LTE-Advanced include: "carrier aggregation" techniques that bond together two or more separate radio channels to get faster data speeds; two-by-two smart antenna arrays -- also known as 2x2 multiple input, multiple output (MIMO) -- for faster uplink and downlink; and relay nodes, low-power base stations that provide improved coverage and capacity at the cell edge. (See Why You Should Care About LTE-Advanced (Eventually).)

Carrier aggregation is likely to be a desirable initial update for T-Mobile as the operator is running both AWS (1700MHz/2100MHz) frequencies and 1900MHz spectrum.

Light Reading Mobile asked Mayo what percentage of antennas T-Mobile expects to upgrade to MIMO this year. "A few," Mayo replied, and then laughed.

Mayo says T-Mobile is currently focused on upgrading its macro network with LTE. "We're upgrading about 37,000 of our 52,000 cell sites," he confirmed. This will include tower-top electronics for about 3Db more of gain for a stronger 4G signal.

For Mayo, this means small cells are on the radar but will be used to add capacity as the major leg-work of upgrading the macro network gets done.

"Small cells are absolutely going to be required," he stated at the show. "We'll be leveraging small cells to a much greater degree."

— Dan Jones, Site Editor, Light Reading Mobile