Along with rivals NTT Docomo and KDDI, SoftBank is already testing 5G in Japan, with a view to kick-starting services by 2020. Before then, the carrier will test how well Honda's cars can communicate with one another over its 5G network. Starting in 2018, SoftBank will install 5G base stations at the auto-maker's Takasu Proving Ground closed test course in Hokkaido, Japan. The 6.8 km circular course serves as a stomping ground for Honda's smart cars, and soon they'll be talking over wireless networks while speeding around.

All the while, the two firms will be monitoring outcomes in order to develop the vehicles' on-board tech and antennas. In addition, the experiment will allow SoftBank to test its 5G signal in a rural setting -- thus far its trials have been mainly limited to urban locations.

The bigger picture may encompass SoftBank's ridesharing investments, which include Singapore's Grab (which also counts Honda as a backer), India's Ola, China's Didi, and now Uber. We know that Uber is also testing driverless cars in select states in the US. And, smarter cars operating over faster wireless networks will only improve these services and, in turn, line SoftBank's bursting pockets.