Even if wireless from solar-powered space planes garner public attention, Google's interest in 5G radio technology actually extends well beyond "Moonshot" drone projects.

The company has recently posted jobs specifically looking for candidates with experience in millimeter wave (mmWave) radio among their skillsets. One of the jobs is for a network software engineer for the "Energy and Access" team, which is "responsible for defining and implementing projects that foster Google's broader goals of open, low-cost, fast and ubiquitous wired and wireless access to the Internet."

Separately, Google Fiber Inc. is advertising for an RF engineer. The winning candidate will help design microwave and mmWave circuits and systems at 5GHz to 100GHz, the ad says.

For more on 5G, visit the dedicated 5G section here on Light Reading.

So what is mmWave radio and why is Google interested?

Millimeter wave radio resides in the 30GHz to 300GHz bands, much higher frequencies than used in the cellular wireless systems deployed today. The benefits are that there is a lot of free spectrum up there -- 9GHz in the 60GHz band alone -- and high data speeds are possible at short ranges. To eke more range out of mmWave equipment, however, it needs to be twinned with the latest multiple antenna technology and can even then still struggle to attain good indoor coverage. (See 60GHz: A Frequency to Watch.)

Google has made no real secret of its interest in 5G either. In June 2014, it bought Alpental Technologies, a startup that was working with 60GHz radio at the time. The search giant has continued to add 5G-related staff since then. (See Google Buys Alpental for Potential 5G Future and Google Searching for 5G Wireless Engineer.)

The two mmWave jobs being advertised now fulfill two very different roles. The Google Fiber job suggests that the company might be looking at the feasibility of hybrid fiber and wireless systems, with super-high speed wireless links providing backhaul.

The Network Software Engineer might be more far-reaching since that team in Google is looking for creative ways to bring low-cost Internet to more people round the world. This may seem to be altruistic goal for Google, but it also makes plain business sense for the company: The more eyeballs on the Net, the more web adds it gets to serve up, helping to drive up revenue. (See Google's Internet Balloon Project Takes Flight.)

As Google has got deeper into wireless over the last years, it also makes sense, for a company with pockets as deep as Google's are, to be at the cutting edge of mobile development. 5G work gets Google new patents and a seat at the table with others developing the new standard. (See Spectrum 2025: Google's Pragmatic Road to 5G.)

Future radio technologies aren't the only point of new mobile interest for Google either. The company is also involved in promoting the use of 3.5GHz spectrum for wireless use in the US, and has its own mobile virtual carrier -- "Project Fi" -- now operational. (See 3.5GHz Startup Gets $22M for Small Cells and Google's WiFi-First Mobile Service 'Fi' Is Here.)

The Guardian also reports that Google has been experimenting with using 28GHz radio links for its solar drones, now called "SkyBender," which would connect to the ground from a low-earth orbit. Using 28GHz centimeter radio links in space will be an even more daunting challenge than using mmWave radio in terrestrial basestations, with the paper reporting that Google could use phased array antennas with directable beams. The research, however, could have other uses for Google, as 28GHz is expected to be an important band for land-based 5G networks.

At this stage it is impossible to quantify what Google's focus on 5G-related technologies will actually result in. So far, it has largely preferred to partner with existing carriers rather than go it alone with wide-range mobile networks. All the work on mmWave and 5G, however, does indicate that Google will have more influence on the birth of 5G than it ever could have had with the creation of 4G.

— Dan Jones, Mobile Editor, Light Reading