The actual definition of 5G is likely to remain nebulous for a while, but that isn't stopping Verizon from announcing today at Mobile World Congress that it's already begun testing the tech for its next-generation networks, following through on a 2015 promise to carry out trials this year. Earlier this month AT&T said it will start 5G trials in 2016 after casting doubt on Verizon's previous announcement.

Verizon is collaborating on the tests with Ericsson, Intel, Nokia, Samsung, and Qualcomm as part of its own 5G Technology Forum. Samsung and Ericsson are also showing off their own 5G demonstrations at MWC. "Our field technical trials are proving that 5G is here and ready to be commercialized, and we've constructed several test beds that represent real-world environments," Verizon SVP Ed Chan says in a statement.

The specifications for what constitutes 5G are yet to be agreed on — and even 4G could be a murky term years after the LTE rollout — but Verizon promises "multiple gigabits per second speeds and single-millisecond latency" that will "deliver the benefits of fiber to wireless." The company says it will expand testing over the next few months, moving to "pre-commercial form factors and testing" later in the year with a view to commercialization in 2017.