Taking stock of Verizon, AT&T, T-Mobile US and Sprint deployments of gigabit LTE
The combined features that deliver gigabit LTE were enhanced and adopted by standards-setting body 3GPP in October 2015 with the group’s Release 13. The primary building blocks of gigabit LTE are:
- 4X4 multiple-input, multiple-output (MIMO), which uses four antenna ports at the transmitter and receiver to multiply the capacity of an RF link. With compatible user equipment, 4X4 MIMO can transmit four simultaneous delivering faster mobile data speeds.
- Carrier aggregation effectively joins together non-contiguous bits of radio spectrum, both licensed and unlicensed, into a wider channel. Compatible with both TDD and FDD LTE networks, intra- and inter-band carrier aggregation in combinations of up to five component carriers of up to a 20 megahertz channel width.
- 256 quadature amplitude modulation (QAM) manipulates phase and amplitude of waveform to allow a higher bit rate per megahertz. The higher the order of modulation, the more bits per modulation symbol are transmitted.
In August 2017, Verizon conducted a “commercial network deployment” using Ericsson’s LAA-compatible Radio 2205 and a test device using Qualcomm’s Snapdragon 835 mobile platform and X16 modem. That collaborative work yielded a downlink throughput of 953 Mbps and prompted the carrier to begin deployment of LAA radios at small cell sites around the country. On the spectrum side, Verizon aggregated three unlicensed 5 GHz channels with one 20 megahertz channel of AWS spectrum.
“You’re going to see these pop up all across the country,” VP of Network Support Mike Haberman said at the time, adding that some sites will receive an upgrade not only to LAA but also to 4X4 MIMO. Further building on the network efficiency and user benefits of 4X4 MIMO, Verizon and Ericsson have been trialing massive MIMO, which further multiplies the number of antenna elements on either side of a radio link.
In January, Nicola Palmer, Verizon chief network engineer and head of wireless networks, said, “Massive MIMO is a critical component of our 4G LTE advancements and will play an important role in 5G technology that will result in single digit latency and scalability in the billions of connections.” Those tests involved a mobile test device using Qualcomm’s X20 LTE modem, which is part of the Snapdragon 845 platform, announced in December. Commercial smartphones that support massive MIMO and incorporate the 845 are expected in the first half of 2018 with potential debuts at Mobile World Congress.
Based on a tally provided by Verizon in November, the carrier has fully deployed carrier aggregation in near 2,000 markets and has 4X4 MIMO and 256 QAM available in more than 560 markets. All three technologies are providing gigabit LTE to users with compatible devices in 560 markets.
AT&T launched its gigabit LTE offering, branded as 5G Evolution, in Austin, Texas, in April 2017. Company CEO Randall Stephenson, when the deployment was announced, said Austin-area users with compatible devices had “the potential for 500 or 600 [Mbps].” Since that initial launch, AT&T has made its 5G Evolution service available in 23 metro areas including Atlanta, Boston, New York, Chicago, San Francisco and Houston with plans to grow that footprint to “hundreds of additional metro areas.”
At Mobile World Congress Americas in September, AT&T worked with Qualcomm and Ericsson to demonstrate how 4X4 MIMO, 256 QAM, carrier aggregation and LAA can deliver high-quality, 3D virtual reality video, as well as a download speed comparison between the Samsung Galaxy Note 8 and a Cat 12 LTE device that doesn’t support aggregation of unlicensed spectrum.
Noting “successful live LAA field trials,” AT&T Vice President, Ran and Device Design, Gordon Mansfield said, “This enhanced connectivity allows us to increase download speeds, expand network capacity and improve spectral efficiency in our network. People are consuming data at a rapidly increasing rate, and LAA will allow our consumers to do things like stream their favorite content on the go and experience virtual reality at faster speeds.” Building on those field trials and the demonstration, in November AT&T began commercial deployment of LAA in select areas of downtown Indianapolis, Indiana.
At a joint event hosted by T-Mobile US and Qualcomm, the carrier said in November that it has carrier aggregation, 256 QAM and 4X4 MIMO live in 430 markets, and at least one of the three technologies underpinning gigabit LTE present in an additional 490 markets. The “Un-carrier” also released plans to use LAA small cells to further boost network capacity. T-Mobile US Chief Technology Officer Neville Ray said, Gigabit class LTE technology is part of the secret sauce behind our success–and why others are struggling under the weight of unlimited–and we’re only continuing to advance with LAA on the horizon.”
Mark McDiramid, T-Mobile US vice president of network engineering, explained late last year that the operator would likely reach an installed base of 5,000 small cells by the end of 2017, and has 25,000 additional small cells contracted, “most of which will be done” in 2018, with LAA-compatible small cells turned up in the first quarter of 2018.
“These small cells are maybe a few 100 yards to maybe a quarter mile [apart]at most,” McDiramid said. “But when you take 40 [megahertz]of licensed spectrum and 60 [megahertz]of unlicensed spectrum…the capability and the capacity that you put in that small cell is quite dramatic. That’s one of the ways we’re going to deliver gigabit.”
In a March 2017 demonstration at Smoothie King stadium in New Orleans, Louisiana, Sprint claimed a domestic first gigabit LTE deployment on a commercial network using the Snapdragon 835 and X16 modem. In December, Sprint Chief Technology Officer John Saw said three channel carrier aggregation is already available in 100 markets; related to carrier aggregation, Sprint relies fully on its 2.5 GHz licensed spectrum portfolio rather than incorporating aggregation of unlicensed spectrum.
Massive MIMO was a major focus on Sprint throughout 2017. The carrier worked with Samsung to test the technology in Suwon, South Korea, and Sprint said it has been able to increase channel capacity by at least 300% and boost cell edge performance by 200%. Commercial roll outs will of massive MIMO will come in 2018. In June Saw said, “The performance that we’re seeing is very encouraging: peak speeds of more than 300 Mbps just one 20 megahertz channel. To get that sort of performance using a more traditional 8 transmit, 8 receive base station that we have deployed today, you need to do three channel carrier aggregation. But with massive MIMO simply on just one channel, were able to reach peak speeds of 300 Mbps and when we do three carrier aggregation on top of this massive MIMO antenna we should be going past teh gigabit per second capability.”
“The performance that we’re seeing is very encouraging: peak speeds of more than 300 megabits per second just using one 20 megahertz channel,” said Sprint CTO John Saw. “To get that sort of performance using a more traditional 8 transmit, 8 receive base station that we have deployed today, you need to do three channel carrier aggregation. But with massive MIMO simply on just one channel, we were able to reach peak speeds of more than 300 megabits per second and when we do three carrier aggregation on top of this massive MIMO antenna we should be going past the gigabit per second capability.”
In an end-of-year blog post, Saw said 2018 would bring “256 QAM and 4X4 MIMO nationwide for great spectral efficiency and faster data speeds. These critical ingredients will join three-channel carrier aggregation (using 60 megahertz of 2.5 GHz), already available today in more than 100 top markets, to form the Sprint receipt for gigabit class LTE service.” Massive MIMO is positioned as “a key enabler for 5G everywhere and our 2018 deployment will allow us to support both LTE and 5G NR modes simultaneously.”
For a deep dive into gigabit LTE, register for our upcoming webinar featuring insights from Rehbehn, as well as industry leaders from Qualcomm, Viavi and Anokiwave.