In light of recent in-flight wireless service providers revealing plans to use the unlicensed 2.4 GHz band and given Microsoft's history with the 2.4 GHz band, it’s probably no wonder that Microsoft would want to test the impact of proposed new services on ground-based Wi-Fi.
In an application for Special Temporary Authority (STA) filed with the FCC this week, Microsoft explained that STA is required for airborne operation of a Wi-Fi router attached to the exterior of a general aviation aircraft. While the company recognizes that the commission has certified the equipment of one provider for such operations over a portion of the 2.4 GHz ISM band, "nevertheless, given that we are unclear regarding certain aspects of air-to-ground communications in the 2.4 GHz ISM band, we thought it best to request an STA."
Microsoft isn’t revealing much beyond that; the company didn't provide any more information in response to FierceWirelessTech's requests for further comment.
Microsoft's application with the FCC says the proposed testing would collect data “necessary to develop channel models for air-to-ground operations in the 2.4 GHz ISM band,” and the "testing will examine various techniques that might minimize the potential for the air-to-ground link to disrupt Wi-Fi communications on the ground in the area surrounding the ground station," adding that the aircraft will be manned and the maximum height of the antenna during transmission is 14,000 feet.
The service provider referenced in Microsoft's application wasn't named, but industry analyst Tim Farrar, president of TMF Associates, points to a Sept. 28 news release from SmartSky Networks in which it revealed that its patented SmartSky 4G radio system received FCC certification to use the unlicensed 2.4 GHz band, clearing the way for deployment of the SmartSky 4G air-to-ground network later this year, with nationwide service launching in mid-2017.
That announcement came right around the same day that in-flight wireless services provider Gogo said that it would be using the 2.4 GHz unlicensed spectrum to augment its next-generation air-to-ground (ATG) technology implementation.
“The question here is: Is Microsoft going to come up with something that makes this controversial” and requires the FCC to do a more detailed investigation, Farrar told FierceWirelessTech.
There are caveats that could be applied to these sorts of cases even though the technical details themselves comply with the rules as written, he said.
“That’s the same situation with LTE-U; it complies with the rules as written but that doesn’t mean that the FCC isn’t going to be careful it doesn’t cause any interference,” Farrar said.
This isn’t the first time Microsoft has sought permission to test the effect of other operations on the 2.4 GHz ISM band. Previously, it was granted permission to test terrestrial operations in the 2473-2483.5 MHz unlicensed band and the adjacent 2483.5-2500 MHz band, consistent with Globalstar’s proposal to operate a terrestrial low-power service (TLPS) on those frequencies nationwide. Microsoft has been a critic of Globalstar’s plans, citing the potential for interference (PDF) with millions of video game consumers.
In fact, Microsoft has demonstrated to the FCC that operating an Xbox 360S game console with a wireless controller in the presence of a TLPS signal resulted in a loss of connection between the controller and console, causing the need to re-establish connectivity by placing the controller close to the console before being able to resume game play.
Gogo has said it plans to use 60 MHz of unlicensed 2.4 GHz spectrum to connect airplanes to the Internet on the ground using a proprietary modem and new beam-forming antenna to produce peak network speeds of more than 100 Mbps. The technology would augment Gogo’s satellite technology, 2Ku, which also is being deployed and delivers a ground-like experience as well enabling streaming video.