AT&T has confirmed that it is currently in the process of deploying three-channel carrier aggregation across its LTE-Advanced (or LTE-A) network. In the detail, AT&T's spokesperson, Steven Schwadron, explained that AT&T is in the process of deploying three-channel carrier aggregation into "high-density, high-traffic areas," which implies that America's second largest carrier is rolling out this LTE-A technology in stages. According to their website, AT&T currently sells 27 "LTE-A capable" smartphones, which includes flagship smartphones from 2015 and 2016 such as the iPhone 6, iPhone 6S, LG G5, Samsung Galaxy S6 together with a number of pre-owned devices, including the HTC One M8, LG G3 and LG G2. AT&T's website does not currently differentiate between devices that are capable of either two-channel or three-channel carrier aggregation. In order for customers to benefit from three-channel carrier aggregation not only must they be in an area offering the service but they must also have a compatible device.
To explain three-channel carrier aggregation, this is a networking technique that combines spectrum at three different points in the frequency range in order to increase available bandwidth and so network performance. We've seen other carriers around the world increasing theoretical download speeds to 300 Mbps through combining three channels, although a more realistic real world download speed is considered to be around 200 Mbps taking into account network conditions and the load on the carrier at the time of use. Steven was unable to provide technical details as to the parts of the spectrum AT&T are combining for their three-channel carrier aggregation, nor the cities or indeed districts where the technology is available.
We've seen several other American carriers discussing their own use of high performance LTE-A technologies including three-channel carrier aggregation. Sprint have enabled 200 Mbps three-channel carrier aggregation in Chicago and Kansas City, where the fourth largest US carrier has combined three different channels of its capacious 2.5 GHz spectrum. Back in June, T-Mobile US announced they were testing the technology in Dallas and have since started offering the technology. Verizon Wireless has recently started marketing two-channel carrier aggregation and has upped this to three-channels where it has sufficient spectrum, plus they have been talking about other LTE-A technologies such as MIMO (multiple-input, multiple-output).