Sprint (NYSE: S) executives said throughout 2014 that they planned to launch carrier aggregation technology on the company's 2.5 GHz TD-LTE service by the end of this year. However, the company now expects to miss that goal will instead launch the technology sometime in early 2015.

"We are in the final stages of testing and will begin deployment soon," Sprint said in a statement to FierceWireless. Sprint spokeswoman Kelly Schlageter said it is unlikely Sprint will make any kind of announcement about deploying carrier aggregation before 2015.

Sprint controls 120 MHz on average of 2.5 GHz spectrum licenses across 90 of the top 100 U.S. markets. Sprint has said it will use carrier aggregation on 2.5 GHz as a way to boost peak data speeds for customers using its tri-band LTE Spark service. Carrier aggregation, which is the most well-known and widely used technique of the LTE Advanced standard, bonds together disparate bands of spectrum to create wider channels and produce more capacity and faster speeds. Sprint aims to first deploy two-carrier carrier aggregation for its 2.5 GHz spectrum, melding together two 20 MHz channels.

John Saw, Sprint's chief network officer, told FierceWireless in March that the carrier planned to expand its Spark service to a two-carrier configuration toward the end of this year, though he acknowledged at the time that the launch could happen early next year.

However, during Sprint's second-quarter earnings conference call at the end of July, both former CEO Dan Hesse and Saw indicated Sprint was still targeting the carrier aggregation deployment by the end of 2014.

"The most powerful differentiator is fully utilizing the deep spectrum resources acquired with Clearwire via 3x carrier aggregation," Hesse said, according to a Seeking Alpha transcript of his remarks. "As previously announced, we expect 2x carrier aggregation capable devices with peak speeds in excess of 100 megabits per second once we turn up 2x in the network later this year, but even faster will be 3x carrier aggregation."

Saw added on same earnings call: "By the end of the year, we expect to have capabilities for two-channel career aggregation in 2.5 GHz spectrum band giving us added capacity and even the data speeds."

When Marcelo Claure took over from Hesse this summer, he said he would tweak Sprint's 2.5 GHz network buildout slightly in order to target high-use metropolitan areas first, rather than conduct a more wide-spread deployment.

Sprint has not said whether the carrier aggregation launch will be nationwide.

In its statement to FierceWireless, Sprint said that it expects peak speeds "beyond" 100 Mbps using two-carrier carrier aggregation, though the carrier declined to provide more specific expectations for real-world peak and average speeds. The carrier said it would be able to provide more accurate speed expectations after the technology is commercially deployed.

As it works to upgrade its network to two-carrier carrier aggregation, Sprint is also working to seed the market with devices capable of accessing the technology. "In November we launched two devices (a mobile broadband device--the ZTE Pocket Wi-Fi--and a smartphone--the Samsung [Galaxy] Note Edge) that support 2x20 carrier aggregation and customers with these devices will be able to enjoy the enhanced speeds once 2x CA is enabled on the network," the company said. "We are also anticipating other future devices to be released with CA capabilities in our device portfolio."

Hesse said that Sprint was working with chipset giant Qualcomm (NASDAQ:QCOM) to get devices that can support three-carrier carrier aggregation into the market in the first half of 2015. However, Sprint does not plan to turn on those capabilities in its network until late in 2015. That technology could enable peak data rates of 150 Mbps.

"Our development teams are currently working very closely with our vendors to enable 3x CA in the 2.5 GHz band," Sprint said. "As disclosed previously, we are targeting end of 2015 to have this capability tested, followed shortly by deployment."

Other U.S. carriers are also moving ahead with carrier aggregation plans. Verizon Wireless (NYSE: VZ) plans to launch carrier aggregation for its 700 MHz and AWS spectrum in 2015. AT&T Mobility (NYSE: T) has deployed carrier aggregation over both 700 MHz spectrum and 2100 MHz AWS spectrum, and T-Mobile US (NYSE:TMUS) is also planning to implement carrier aggregation, though it has not said when.

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