"We expect to begin reaching peak theoretical speeds of up to 1 Gbit/s at some [LTE) cell sites in 2017," AT&T Inc. (NYSE: T) said in a statement that largely recapped its latest 5G announcements, but did add some small details on LTE-Advanced. (See AT&T Lays Out 5G Plans & More for 2017.)

AT&T is the latest carrier in the US to make claims for Gigabit LTE speeds in 2017. T-Mobile US Inc. CTO Neville Ray recently insisted the operator would beat its rivals to the 4.5G feature, in partnership with Nokia Corp. (NYSE: NOK), while Sprint CTO John Saw is expecting to "unveil some innovative work ... pushing 1 Gbit/s class speed boundaries" in 2017.

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LTE-Advanced Pro uses a lot of technology that will eventually end up in the 5G specification too, on both the network and device sides. This includes three- or four-carrier aggregation, which uses multiple radio channels bonded together to increase mobile speed and capacity. Other features include multiple input and output antenna arrays (MIMO), and a 256-quadrature amplitude modulation (QAM) signal modulation scheme -- how the data bits are sent over the air -- for boosting throughput on available mobile spectrum.

The good news is that will increase speed and capacity for all the 4G handsets on these updated networks somewhat. To get the maximum near-gigabit speeds, though, users will need new devices with the latest chips onboard. (See New Qualcomm Chip Promises 'Gigabit' 4G.)

Outside of the lab, these Gigabit LTE downloads are unlikely to be realized by actual users. Notice that operators tend to use a variant of "peak theoretical speeds" when talking about Gigabit LTE. Nonetheless, as network and device upgrades happen over the next couple of years, we are likely to see another noticeable upgrade in LTE performance, at least in the cities, where operators will spend on small cells and more to upgrade the network.

At the moment, however, we don't really know fast "Gigabit" LTE will be in real life.

— Dan Jones, Mobile Editor, Light Reading