The FCC this week released the details of its "White Spaces" decision, authorizing the use of both fixed and mobile unlicensed devices within the television spectrum. In theory, these devices are supposed to be able to sense the existence of television signals so that they can operate on other frequencies and avoid creating interference. However, as an extra safety measure, the FCC has also required that these devices connect at least once a day with a database of all other protected users of the television spectrum and, by used of geo-location technology, determine what other users are in the area where the "TVBD" (television band device) is being used and operate on frequencies which protect those other users. Our firm has prepared a memo outlining the full decision. The Davis Wright Tremaine memo can be found here. When one reviews the full text of the FCC decision, it becomes pretty clear that we should not look for such devices anytime soon.
While the Commission’s order actually discussed in some detail the question of whether these devices should be permitted to operate before the end of the digital television conversion in February 2009, given the issues that still need to be resolved, this discussion really appears to be an academic one. First, devices that meet all of the FCC requirements have to be designed and built, and type-accepted by the FCC labs. In a recent article by Shelly Palmer in his well regarded blog on television issues, he suggests that many engineers are convinced that these devices simply will not work. When one reviews the FCC requirements, one can see why that might be the case.
First, the devices must be designed so that they can determine where they are operating, sense other users of the spectrum, and access the database of other users of the spectrum. That database has not yet been created, and the FCC has said that it will, by subsequent public notice, solicit private companies to create the database (or databases, as multiple companies may be authorized to maintain competing databases). The database will list not only full power television stations, but also low power TV stations and TV translators. And, while in most cases the TVBDs will be required to protect the full-power TV stations only to their protected contour, there will be added protections for stations outside of their protected contours in the path between the TV station and either LPTV or translator stations which pick up these stations off of the air, or cable television system headends which pick up TV station signals. Thus, the location of cable headends and that of LPTV and TV translators, and the signal paths between them and the stations that they pick up, must all be computed. In addition, there are Land Mobile radio services that operate in the television band, which will also have to be protected, and entered into the database. Wireless microphones that operate in the TV band will also be predicted, and sites that regularly use those microphones (e.g. theaters, stadiums, churches) will be eligible for registration in the database. Even sites that only use those microphones for special events can register for the length of the event. All of these items will need to be entered into a database that will be accessible by the devices – a project that will obviously take time.
In addition, the devices will not be able to operate in areas near the Canadian and Mexican borders, nor in areas near the "quiet zones" around radio astronomy installations. The TVBDs will have to be able to determine their locations so, for the most part, they will need outdoor antennas to receive the satellite signals to determine their locations. Fixed location TVBDs, which can operate at higher power than mobile devices, will also have to register with the FCC so that, if they create interference, they can be located.
With all of these requirements, it will be quite a design feat for engineers to accommodate all of the FCC requirements. In addition, the FCC will have to complete the regulatory requirements of authorizing the databases. So don’t look for these services to provide broadband access (or any other service) until all of these requirements are met. And, of course, there still may be legal hurdles to overcome should opponents of the devices appeal the FCC decision. So stay tuned…