Large scale carrier aggregation for the win: Entner

The Super Bowl is not only the pinnacle of the American Football season, but it is also the show case event for every wireless carrier.

Every year, the carriers set aside tens of millions of dollars to improve their wireless networks for the big game. The newest and best gets installed so that attendees and regular citizens alike get a superior experience. One of the challenges that mobile operators have to overcome in order to provide faster speeds is how to best utilize the spectrum they have.

The spectrum portfolio of each carrier ranges from low band 600 MHz and 700 MHz through 2.5 and 3.5 GHz mid band all the way to high band millimeter wave at 39 GHz. How carriers utilize disparate spectrum bands with different propagation and capacity characteristics often is an important factor in the speed and capacity available to consumers.

One of the tools that is often employed to increase speed by leveraging network resources is carrier aggregation (CA). CA allows for an increase in speed by bonding slivers of spectrum together into a single channel. "Wider" channels often translate to faster speeds: the maximum amount of spectrum that LTE can have in a channel is 20 MHz and 5G is 100 MHz.

Global Wireless Solutions (GWS) conducted network testing during the 2021 Super Bowl in Tampa and provided some additional insights that typically don’t get mentioned with other tests. GWS found that AT&T used 8 channel CA using 800 MHz of its high band 39 MHz spectrum, Verizon used 6 channel CA using 600 MHz in high band 28 GHz, and T-Mobile 4 channel CA using 400 MHz in 39 GHz plus 80 MHz in the mid band 2.5 GHz.

The availability using the 28 and 39 GHz band was almost the same for every carrier at 73% to 77%, which isn’t surprising considering the relatively small area covered. T-Mobile’s 2.5 GHz coverage added another 20% of coverage. Considering more spectrum means more speed, it comes as no surprise that AT&T was the fastest with peak speeds of 1.7 Gbps, Verizon with 1.5 Gbps and T-Mobile with 1.1 Gbps.

The GWS tests show that it is not only important to have a lot of spectrum. It is even more important to have the tools to use it. Not only does the network have to be ready for it, but also the device needs components that can manage the complexity of transmitting and receiving on banded CA channels.

Most flagship devices are using the Qualcomm Snapdragon X55 modem. Devices using this modem, like the Samsung Note 20 that the GWS engineers used for the tests, can utilize 8 channel CA in the mmWave band (> 6 GHz) with 2x2 MIMO and 200 MHz 4x4 MIMO below 6 GHz with 7x20 MHz channel CA for LTE. This means that when T-Mobile uses all its on average 130 MHz 2.5 GHz spectrum, current flagship devices will be ready. When Verizon and T-Mobile are ready to follow AT&T’s lead with 8 channel CA, the devices will also be able to support that.

The Qualcomm X60 modem that’s in newer devices like the Samsung Galaxy S21 can aggregate spectrum below and above 6 GHz. This allows them to combine the better coverage characteristics of sub-6 GHz spectrum with the massive spectrum bands and therefore speeds that are available above 6 GHz. The X60 modem also works with the upcoming C-Band networks that will probably become available in 2022. Future devices will include Qualcomm’s X65 modem, which combines CA technology with 3GPP Release 16 specifications for unlicensed spectrum to reach peak speeds of up to 10Gbps assuming that network and spectrum resources are available.

In the end, consumers win when mobile operators bring all their assets to bear utilizing the latest technologies. AT&T used greater carrier aggregation technology compared to the other operators and provided the fastest speeds taking advantage of the technical possibilities provided by the device and component manufacturers.

The United States has now allocated more spectrum in total to 5G than any other country. With the CBRS, C-Band and 3.45-3.55 GHz auctions we are closing the mid-band gap. We need every ecosphere provider to push the boundaries of 5G further to realize the visions of 5G that have been promised to the consumer.

Roger Entner is the founder and analyst at Recon Analytics. He received an honorary doctor of science degree from Heriot-Watt University. Recon Analytics specializes in fact-based research and the analysis of disparate data sources to provide unprecedented insights into the world of telecommunications. Follow Roger on Twitter @rogerentner and catch him on The Week with Roger podcast.

"Industry Voices" are opinion columns written by outside contributors—often industry experts or analysts—who are invited to the conversation by Fierce staff. They do not represent the opinions of Fierce.