In May, Microsoft submitted a petition to the FCC calling for some specific changes that will improve the performance of white space spectrum used to provide rural broadband. Microsoft has now taken part in eleven white space trials and makes these recommendations based up on the real-life performance of the white space spectrum. Not included in this filing is Microsoft’s long-standing request for the FCC to allocate three channels of unlicensed white space spectrum in every rural market. The FCC has long favored creating just one channel of unlicensed white space spectrum per market – depending on what’s available.
A number of other parties have subsequently filed comments in support the Microsoft proposals including the Wireless Internet Service Providers Association (WISPA), Next Century Cities, New America’s Open Technology Institute, Tribal Digital Village and the Gigabit Libraries Network. One of the primary entities opposed to earlier Microsoft proposals is the National Association of Broadcasters (NAB), which worries about interference with TV stations from white space broadband. However, the group now says that it can support some of the new Microsoft proposals.
As a reminder, white space spectrum consists of the unused blocks of spectrum that are located between the frequencies assigned to television stations. Years ago, at the advent of broadcast television, the FCC provided wide buffers between channels to reflect the capability of the transmission technology at the time. Folks my age might remember back to the 1950s when neighboring TV stations would bleed into each other as ghost signals. As radio technology has improved the buffers are now larger than needed and are larger than buffers between other blocks of spectrum. White space spectrum is using those wide buffers.
Microsoft has proposed the following:
- They are asking for higher power limits for transmissions in cases where the spectrum sits two or more channels away from a TV station signal. Higher power means greater transmission distances from a given transmitter.
- They are asking for a small power increase for white space channels that sit next to an existing TV signal.
- They are asking for white space transmitters to be placed as high as 500 meters above ground (1,640 feet). In the US there are only 71 existing towers taller than 1,000 feet.
- Microsoft has shown that white space spectrum has a lot of promise for supporting agricultural IoT sensors. They are asking the FCC to change to white space rules to allow for narrowband transmission for this purpose.
- Microsoft is asking that the spectrum be allowed to support portable broadband devices used for applications like school buses, agricultural equipment and IoT for tracking livestock.
The last two requests highlight the complexity of FCC spectrum rules. Most people would probably assume that spectrum licenses allow for any possible use of spectrum. Instead, the FCC specifically defines how spectrum can be used and the rural white space spectrum is currently only allowed for use as a hot spot or for fixed point-to-point data using receiving antennas at a home or business. The FCC has to modify the rules to allow use for IoT for farms sensors, tractors and cows.
The various parties are asking the FCC to issue a Notice of Proposed Rulemaking to get comments on the Microsoft proposal. That’s when we’ll learn if any other major parties disagree with the Microsoft proposals. We already know that the cellular companies oppose providing multiple white space bands for anything other than cellular data, but these particular proposals are to allow the existing white space spectrum to operate more efficiently.