NEW YORK — The national wireless carriers are laying the groundwork to expand data capacity, increase network efficiency and – depending on the network — potentially deliver peak data speeds exceeding 2Gbps from up to about 150Mbps today.
The groundwork consists of infrastructure capable of supporting LTE-Advanced technology, and some carriers – Verizon and Sprint – have already implemented elements of the technology. For their part, T-Mobile and AT&T have installed networks that are LTEA- ready so that key elements can be implemented in the future.
LTE-Advanced is a smorgasbord of more than a dozen different network enhancements that carriers can pick to increase capacity, efficiency and speed – or just keep up with growing data demand without slowing users’ download speeds.
Carriers, of course, are also deploying traditional LTE technology in new spectrum in the AWS (1.7/2.1GHz) and 700MHz bands to boost speed, capacity and efficiency.
Two of the more important LTE-Advanced elements include carrier aggregation and MIMO. Carrier aggregation combines two or more channels into awider channel that transmits data to compatible devices at faster speeds. Aggregated channels could cross over disparate bands such as 700MHz, 1.9GHz, 2.5GHz and AWS.
MIMO stands for multiple-input/multiple-output technology. Carriers are looking at base stations and mobile devices with up to eight transmitters and eight receivers (8T8R), each with their own antenna, per spectrum band.
Also in the LTE-A arsenal is heterogenous network (hetnet) technology, which lets carriers install small cells and coordinate their operation with larger macro cells.
“LTE Advanced is not just about speed,” a Verizon spokesperson noted. “It’s about getting the most out of the spectrum that our LTE service rides on and creating the extra capacity to stay ahead of customer demand for high-speed mobile bandwidth services.”
Here’s what the top four carriers say they are doing to implement LTE-A:
Sprint: The carrier is rolling out Sprint Spark triband LTE technology, which expands 4G LTE to all three of the carrier’s bands: 1.9GHz, 800MHz and 2.5GHz. “Sprint Spark will have many features of LTEAdvanced, including carrier aggregation and advanced antenna processing (8T8R MIMO),” a spokesperson said. “Sprint Spark will include carrier aggregation in the 2.5GHz spectrum band. We’re deploying TDD-LTE with a 1x20MHz channel initially, growing to 2x20MHz [two-channel carrier aggregation] in late 2014 and 3x20MHz in late 2015.”
Today Spark delivers peak speeds per sector of 60Mbps to capable devices, with the potential for speeds three times as fast by late next year, the spokesperson said. “With two-channel (2x20MHz) carrier aggregation, our sector capacity will be doubled, and with three-channel (3x20MHz) carrier aggregation, it will be tripled for both peak and average speeds,” she continued.
“With three-channel carrier aggregation, we expect to be able to achieve peak speeds as high as 1.3Gbps. And given our spectrum assets and expected technological improvements in multi-layer MIMO and multiple-channel carrier aggregation, it is technically feasible over time to deliver greater than 2Gbps speeds over the air.”
The carrier’s current Sprint Spark triband devices support MIMO in a two-antenna, two-transmitter configuration. As part of its LTE-A rollout, however, Sprint said it plans to deploy 8T8R MIMO.
On the device side, “we expect all of our postpaid smartphones this year to be triband LTE, and we expect to launch devices capable of two-carrier aggregation before the end of the year,” the spokesperson added.
Before offering Sprint Spark, available in 14 markets, the carrier achieved 25Mbps peak LTE speeds in its 1.9GHz band with average throughput of 6Mbps to 8Mbps. The carrier’s previous 4G technology, Mobile Wi-MAX in the 2.5GHz band, delivered peak speeds of 10Mbps with average throughout of 3Mbps to 6Mbps.
Verizon: The carrier is already deploying small cells to interact with its macro network to increase capacity, a spokesperson said. “Prepatory work is underway [to offer carrier aggregation] but is not yet being implemented,” he added. Carrier aggregation and heterogeneous networks “both enable us to stay ahead of demand and add capacity while meeting our brand promise of 4G LTE speeds of 5 to 12Mbps on the downlink and 2 to 5Mbps on the uplink,” he said.
When carrier aggregation is implemented, the spokesperson continued, it “will allow us to operate our 700MHz and AWS [1.7/2.1GHz] bands as well as any future spectrum as one asset.” That, in turn, “increases our ability to provide consistent performance along with increased capacity.”
In the meantime, the spokesperson said, Verizon’s deployment of AWS spectrum “is already enabling us to double and triple capacity in many markets around the country,” the spokesperson noted.
AT&T: The carrier said its network is LTE-Advanced- ready but declined to state when LTE-A features would be implemented. Two of its devices – the LG Flex and Unite Pro Mobile Hotspot – already support LTE Advanced elements and the Asus Padfone will support LTE Advanced when it is available.
The carrier declined to comment on which elements of LTE-A are supported by the devices, but carrier aggregation is a possibility given that the G Flex operates in the U.S. AWS and 700MHz bands. In addition, AT&T launched carrier aggregation in a handful of markets to combine data transmission over 700MHz bands with either its AWS band or 1.9GHz band.
T-Mobile: The carrier hasn’t announced a timetable for launching LTE-Advanced features, but “all of the T-Mobile LTE hardware in place is capable of supporting LTE-Advanced, so we can move to advanced features without needing to install new infrastructure,” a spokesperson said.
Meantime, T-Mobile is accelerating speeds by other means, in particular by expanding its LTE network and adding to its spectrum holdings. The carrier’s LTE network will expand to reach 250+ million people by the end of this year.
Currently, a spokesperson said, 10+10MHz LTE spectrum blocks now reaches 43 of the top 50 metro areas, and T-Mobile Wideband LTE (LTE with at least 15+15 MHz of spectrum) will expand this year as well. Wideband LTE, as T-Mobile has deployed it today, can provide theoretical peak speeds up to 150Mbps,” he said. Unlike some of T-Mobile’s peers, the spokesperson noted, “carrier aggregation is not a top concern today given our contiguous AWS-band spectrum position. We’re able to launch 20+20 MHz LTE without carrier aggregation.”
T-Mobile also expects to deploy LTE in 700MHz spectrum in 2014.