Ericsson has a 5G phone, and it weighs 150kg

For U.S. readers, that's about 330 pounds: Great for an NFL defensive lineman, not so much for a handset.

"We are running around with a big bus with a very big mobile phone on it," said Erik Dahlman, a senior expert in radio access technologies at Ericsson, which is testing potential 5G technologies near Stockholm. It's also experimenting with the technology in Japan and other countries.

The phone is so big because it's full of new, experimental components that haven't been miniaturized yet. It also has a large battery, because bigger parts use more energy. Turning that into a handset that fits in your pocket is a job for later. The 5G base stations in the test, by the way, are normal-sized, Dahlman said.

Last week, Ericsson announced that some people in Stockholm and in Tallinn, Estonia, would get 5G services starting in 2018 through Swedish carrier TeliaSonera. This won't be a full-scale network or even official 5G (that's coming in 2020), but it could help TeliaSonera develop services that are only possible with the new technology. They could include remote-control surgery and quick messages between cars to make driving safer.

5G will make regular cell service as much as 100 times faster, according to some proponents. It's also being tuned for new uses like the Internet of Things. This means a lot of new technologies are going into it, including much higher frequencies than 4G networks use.

Carriers around the world are already vying for firsts in 5G. SK Telecom says it will have 5G up and running at the 2018 Winter Olympics in South Korea, and Verizon plans trials this year and wants to be the first U.S. carrier with a 5G network.

TeliaSonera was on the cutting edge of 4G, too. In 2009, it became the first carrier to roll out commercial LTE service, also with Ericsson's help. Getting to that point took a lot of research, development -- and hauling power -- too.

"Our first 4G trial mobile was even bigger," Dahlman said.