5-carrier aggregation gives AT&T network edge – RootMetrics

AT&T delivered speed gains across 51 markets in the early part of 2020, with its wide-scale use of 5-component carrier aggregation and 4x4 MIMO giving it an edge over competition, according to RootMetrics.

RootMetrics temporarily suspended its network testing but in the meantime is publishing carrier-specific reports on 4G LTE and 5G performance in the first half of 2020.

AT&T’s speeds improved significantly in 51 out of 55 markets in RootMetrics' testing, outpacing every other carrier. Speed performance on AT&T’s network jumped more than 30 Mbps in four cities at the start of 2020, compared to the end of 2019.

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The biggest increase was seen in Ogden, Utah, where median download speeds spiked 37 Mbps from 38.2 Mbps in 2019 to 75.2 Mbps in early 2020.

Markets rounding out the top five for AT&T’s most improved speeds include Minneapolis, Cincinnati, Charleston, South Carolina, and Allentown, Pennsylvania.

In 37 of the 55 markets tested, speeds jumped at least 10 Mbps compared to 2019, and at least 15 Mbps in 22 markets.

“Considering that 15 Mbps is generally fast by itself, an increase of 15 Mbps from a speed that was already fast can profoundly change the end-user experience,” the report noted.

RootMetrics' tests done last year only connected to AT&T’s 4G LTE, while the 2020 results connected to the carrier’s low-band 5G where available.

In the latest test period, AT&T’s network recorded median download speeds above 50 Mbps in 23 markets, compared to just three markets in the second half of 2019. At the start of this year, only two cities registered speeds under 20 Mbps.

AT&T is moving forward with its low-band 5G rollouts, just this week expanding to 90 additional cities, but RootMetrics called out the carrier’s heavy investment over the last 18 months to enhance its already strong 4G LTE network.  

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“AT&T erected new cell sites in cities across the country, added more spectrum layers, and utilized 5-carrier aggregation (5CA) on a wide scale paired with 4x4 MIMO technology to maximize its vast spectrum holdings and provide faster speeds,” RootMetrics reported. “AT&T also reallocated some of the spectrum reserved for its FirstNet Public Safety network and began using it for general customers while still satisfying its commitments to first responders.”

AT&T is in a unique position to use five-component carrier aggregation (5CA), according to the testing company, a technology which requires and enables it to combine five separate channels for increased capacity.

“AT&T has an advantage over the competition as the only carrier that can utilize 5-carrier aggregation on a wide scale in the U.S.,” according the report. That compares to Sprint and T-Mobile’s use of 3-carrier aggregation, while Verizon uses 4-component carrier aggregation.

While 5-carrier aggregation is helping enhance AT&T's speeds over low-band spectrum, 8-component carrier aggregation (8CC) has been cited in work to hit record 5G speeds using millimeter wave spectrum.

In lab tests in February, Ericsson alongside Qualcomm, used 8CC to aggregate 800 MHz of millimeter wave spectrum and achieve a record 5G speed of 4.3 Gbps.

RELATED: Verizon works with Samsung, Qualcomm to achieve 4.2 Gbps on its 5G network

Verizon, meanwhile, worked with Samsung and Qualcomm earlier this year, using the technology to aggregate 800 MHz of 28 GHz mmWave spectrum and hit speeds of 4.2 Gbps on its live 5G network in Texas. Verizon SVP of Technology Planning Adam Koeppe said at the time that 8-channel carrier aggregation using mmWave would be widely available on the carrier’s network this year.

In terms of RootMetrics’ latest report, the company didn’t test AT&T’s 5G+ network, which was just recently opened up to consumers and leans on high-band millimeter wave instead of low-band spectrum.

Out of the 55 markets, AT&T’s low-band flavor of 5G still delivered strong results. That includes Philadelphia, which ranked the fastest with median 5G download speeds of 94.5 Mbps – though limited availability of just 1.6%.

“AT&T’s network investments have clearly paid dividends for its subscribers on both 5G and 4G LTE,” RootMetrics concluded. “As more and more 5G devices become available, consumers will find even faster speeds thanks not only to 5G, but also because some 5G-ready smartphones can take advantage of AT&T’s pairing of wide-scale 5CA with 4x4 MIMO.”