AT&T Mobility (NYSE:T) has started using carrier aggregation technology in Chicago and other markets to boost LTE capacity and speeds on its network, but it will be a little while before many customers can take advantage of the upgraded network.
According to GigaOM, Kris Rinne, senior vice president of network technologies in AT&T Labs, confirmed the carrier is using the LTE Advanced technology in Chicago, but she declined to identify the other markets. Carrier aggregation allows carriers to meld together disparate bands of spectrum for wider channels, thus supporting faster download speeds and additional network capacity.
In the case of Chicago, AT&T is using carrier aggregation to transmit over both 700 MHz spectrum and 2100 MHz AWS spectrum. Combining the two bands will allow AT&T to produce a 15 MHz-wide downlink, increasing theoretical download speeds to around 110 Mbps, according to GigaOM. Rinne said that as AT&T adds more frequencies to it LTE network in new metro areas it will also start aggregating them.
AT&T has started to refarm its 1900 MHz PCS spectrum for LTE service in New York City, and has said it will also do so in Baltimore, Dallas, Philadelphia, New York, San Francisco and Washington, D.C., and other markets. Presumably those markets could be ripe for carrier aggregation.
Rinne has said AT&T will use LTE Advanced and carrier aggregation to increase the capacity of its network rather than increase the download speeds available to users. Speaking at FierceWireless' "The Road to LTE Advanced" luncheon at the recent Mobile World Congress trade show in Barcelona, Spain, Rinne said AT&T will first deploy carrier aggregation as it adds a second carrier to its existing LTE network. "We're not really changing the speed discussion," she said. "It's more about doing an efficient utilization of the spectrum."
Rinne said that users' peak speeds may increase, but AT&T is deploying the technology to ensure it can meet users' data demands as more customers start using LTE. She said the carrier's advertised data speeds likely won't change.
AT&T only has one device that can support carrier aggregation, its Unite hotspot, which it launched late last year. However, Samsung Electronics' Galaxy S5 smartphone can support carrier aggregation and will likely be able to do so on AT&T's network when the carrier launches it in the spring.
AT&T is not alone in pushing for carrier aggregation. Sprint (NYSE:S) has said it will use the technology as part of its Sprint Spark service, which combines LTE across the carrier's 800 MHz, 1900 MHz and 2.5 GHz spectrum. And Verizon Wireless (NYSE:VZ) has said it expects to use carrier aggregation to combine data transmissions over its AWS and 700 MHz spectrum to improve speeds and capacity.
T-Mobile US (NYSE:TMUS) CTO Neville Ray said at an investor conference this week that "LTE Advanced is just around the corner" and that while other carriers are very focused on using carrier aggregation, that tool will be less important for T-Mobile because of its contiguous spectrum position in the AWS band. Yet he said "other features" of LTE Advanced will "start to come to life" in 2015 and 2016.
- see this GigaOM article
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AT&T's Unite hotspot is the carrier's first device to offer carrier aggregation technology