It's not just the major US mobile operators that are interested in delivering 5G services to their subscribers; regional carriers are looking into the possibilities too.

Ericsson AB (Nasdaq: ERIC) said Tuesday morning that it is undertaking a second tranche of 5G tests with US Cellular , this time using 28GHz millimeter wave (mmWave) radios. The companies had previously tested 5G at 15GHz with a maximum speed of 9-Gbit/s, over a range of less than 1,000 feet. (See US Cellular Tests Fixed 5G With Ericsson ).

This time the pair say they are testing various "5G use cases" using 28GHz radios, the millimeter wave band frequency also being tested by AT&T Inc. (NYSE: T), T-Mobile US Inc. and Verizon Communications Inc. (NYSE: VZ). "The trials were conducted under a variety of real-world conditions, and they achieved peak throughput speed of 8.5 Gbps," Ericsson said in a statement.

The trials were held in rural and suburban areas of Madison, WI. Ericsson also claims that, with these trials, US Cellular is the "first carrier to trial 28GHz with radios at macro antenna height of 123 feet."

Even though the pace of 5G trials has seemed frenetic between 2016 and 2017, you can expect it to pick up into 2018, now that the first take on 3rd Generation Partnership Project (3GPP) 5G New Radio (NR) specification is nearly ready. (See Verizon Migrating From Homebrew 5G, Enlists Qualcomm for Trials.)

— Dan Jones, Mobile Editor, Light Reading