AT&T advanced development of a standalone (SA) 5G network with what it claimed was the first data call in the US using two-channel carrier aggregation (2CA) in the uplink.

Jason Sikes, AVP for device architecture, stated in a blog AT&T conducted a laboratory trial using Nokia’s 5G AirScale portfolio with MediaTek’s 5G M80 test platform to combine its 850MHz and C-Band 3.45GHz spectrum.

Sikes noted the operator achieved a 100 per cent increase in uplink throughput by aggregating 850MHz of low-band spectrum with 40MHz of C-Band compared with using the low-band alone, and a 250 per cent boost using 100MHz of the latter spectrum.

During the trial, AT&T achieved data rates of more than 70Mb/s using the 40MHz of C-Band and in excess of 120Mb/s with 100MHz.

The test marked a technical achievement for the operator, but it remains to be seen if users will notice the slightly faster data rates.

“While carrier aggregation is like adding more traffic lanes in the highway, adding another vehicle to carry traffic is another way we are managing surging uplink demand,” Sikes noted.

“We are doing this via a two-layer uplink MIMO on TDD in our mid-band n77 (C-Band)”.

In addition to faster speeds, two-layer uplink MIMO also improves cell capacity and spectrum efficiency, Sikes wrote.

AT&T plans to combine all its spectrum bands to provide 5G new radio dual connectivity (NR-DC) in the coming months: Sikes explained data rates of 5.3Gb/s in the downlink and 670Mb/s up had been achieved in laboratory tests, tipping “stadiums, airports, and other high-density venues”, as beneficiaries.