T-Mobile US touted its latest 5G test with Nokia as a milestone, claiming it was the first 3GPP standards-based trial to achieve a bi-directional data transmission over mmWave.

An operator representative told Mobile World Live the test used 28GHz spectrum, adding it “proved the transmission to be 3GPP-compliant in both the uplink and downlink directions.” CTO Neville Ray (pictured) broadcast the achievement on Twitter.

The test follows a trial by Verizon in February, which it said was the first standards-based over-the-air call.

T-Mobile previously said it plans to use 28GHz as part of its 5G network alongside low- and mid-band spectrum, to provide additional speed and capacity in urban areas. The operator revealed in February 5G construction work in the 600MHz, 28GHz and 39GHz bands will begin in 30 US cities this year, but the representative declined to disclose how many, or which, cities would get 28GHz.

Auction adjustments
Taking its 28GHz and 39GHz assets together, T-Mobile owns around 200MHz of mmWave spectrum covering urban areas across the US. But the operator will have a chance to purchase additional airwaves in November during the US Federal Communications Commission’s (FCC) planned auctions of 28GHz and 24GHz spectrum.

In a recent filing, T-Mobile encouraged the FCC to include 37GHz, 39GHz and 47GHz bands in the process. The operator said auctioning more bands at once would increase revenues and enable more efficient 5G deployments.

It added the FCC should space out the 28GHz and 24GHz auctions, which are currently expected to run back-to-back, by at least a few months “if for no other reason than to assess whether the current upfront payment and reserve price levels are too high for Auction 102 once the results of Auction 101 become known”.