T-Mobile wants to test dual-connectivity on the standard mobile 5G, in a non-standalone setting, with its vendors, as it prepares to launch 5G in the first half of next year.

Dual-connectivity is an important factor in the 3rd Generation Partnership Project (3GPP) 5G New Radio standard. The technology maintains a constant connection with the 4G LTE network, as well as 5G, if in coverage range.

"T-Mobile is working with equipment vendors to test 5G NR in non-standalone mode, which requires an LTE carrier to act as the anchor for Dual Connectivity with 5G NR," T-Mobile says in its application to the Federal Communications Commission (FCC) .

T-Mobile wants to test with its vendors in Las Vegas and Spokane, Wash., between November 1 and the end of the year. T-Mobile has so far announced infrastructure deals with Ericsson AB (Nasdaq: ERIC) and Nokia Corp. (NYSE: NOK). (See Nokia Reels In $3.5B 5G Deal With T-Mobile US and Ericsson Lands $3.5B 5G Deal With T-Mobile Weeks After Nokia Did Same.)

Non-standalone 5G NR uses LTE as a control plane for the 5G radio layer. In other words, 5G is the fast radio highway, while LTE functions as the stop and go lights controlling the traffic and making sure calls (or in actuality, data sessions) get on and off the highway smoothly.

What are the key technologies and processes that will underpin successful, full 5G deployments? Check out our 5G Big Picture Prime Reading report to find out.

All the major US carriers are using non-standalone 5G for initial next-gen deployments, as they race to place in the medals with 5G services.

Interestingly, T-Mobile is using its AWS spectrum to test NSA systems, not the 600MHz slated to be used for the actual deployment in 2019. We've asked T-Mobile about this, and we'll update the story if new details emerge.

— Dan Jones, Mobile Editor, Light Reading