On December 17 the FCC issued a Notice of Proposed Rulemaking for the 5.9 GHz spectrum band that would create new public spectrum that can be used for WiFi or other purposes. The 5.9 GHz spectrum band was previously assigned in 2013 to support DSRC (Dedicated Short Range Communications), a technology to communicate between cars, and between cars and infrastructure. The spectrum band covered by the order is 75 megahertz wide. The FCC suggests that the lower 45 megahertz be made available to anybody as new public spectrum. They’ve assigned the highest 20 megahertz for a newer smart car technology called C-V2X. The FCC tentatively kept the remaining bandwidth for the older DSRC technology, dependent upon the users of that technology convincing the agency that it’s viable – otherwise, it also converts to C-V2X usage.
DSRC technology has been around for twenty years. The goal of the technology is to allow cars to communicate with each other and to communicate with infrastructure like toll booths or traffic measuring sensors. One of the biggest benefits touted for DSRC is increased safety so that cars will know what’s going on around them, such as when a car ahead is braking suddenly.
For the new technology, the V2X stands for vehicle-to-everything. Earlier this year Ford broke from the rest of the industry and dropped research in DSRC communications in favor of C-V2X. Ford says they will introduce C-V2X into their whole fleet in 2022. Ford touts the technology as enabling cars to ‘see around corners’ due to the ability to gather data from other cars in the neighborhood. They believe the new technology will improve safety, reduce accidents, allow things like safely forming convoys of vehicles on open highways, and act as an important step towards autonomous cars. C-V2X uses the 3GPP standard and provides an easy interface between 5G and vehicles.
This decision was not without controversy. The Department of Transportation strenuously opposed the reduction of spectrum assigned for vehicle purposes. The DOT painted the picture of the spectrum providing a huge benefit for traffic safety in the future, while the FCC argued that the auto industry has done a poor job of developing applications to use the spectrum.
This is an NPRM, meaning that there will be a cycle of public comments before the FCC votes on the order. I think we can expect major filings by the transportation industry describing reasons why taking away most of this spectrum is a bad idea. On the day of the FCC vote, Elaine Chao, the Secretary of Transportation said that the FCC is valuing Netflix over public safety – so this could yet become an ugly fight.
Perhaps the biggest news from the announcement is the big slice of the spectrum that will be repositioned for public use – a decision praised by the WiFi Alliance. The FCC proposes to make this public spectrum that is open to everybody, not just specifically for WiFi. The order anticipates that 5G carriers might use the spectrum for cellular offload. If the cellular carriers heavily use the spectrum in urban areas, then the DOT might be right and this might be a giveaway of 5G spectrum without an auction.
There is no guarantee that the cellular carriers will heavily use the spectrum. Recall a few years ago there was the opportunity for the cellular carriers to dip into the existing WiFi spectrum using LTE-U to offload busy cellular networks. The carriers used LTE-U much less than anticipated by the WiFi industry, which had warned that cellular offload could overwhelm WiFi. It turns out the cellular carriers don’t like spectrum where they have to deal with unpredictable interference.
Even if the cellular carriers use the spectrum for cellular offload in urban areas, the new public block ought to be mostly empty in rural America. That will create an additional spectrum band to help boost point-to-multipoint radios.
Regardless of how the new spectrum might be used outdoors, it ought to provide a boost to indoor WiFi. The spectrum sits just a little higher than the current 5.4 GHz WiFi band and should significantly boost home WiFi speeds and volume capability. The new spectrum will provide an opportunity to reduce interference with existing WiFi networks by providing more channels for spread home use.
This particular docket shows why spectrum decisions at the FCC are so difficult. Every potential use for this mid-range spectrum creates significant public good. How do you weigh safer driving against better 5G or against better rural broadband?