The announcement that the Federal Communications Commission was prepared to approve unlicensed digital operations in slices of frequency spectrum occupied by television guard bands is being greeted eagerly by many, including Google and Microsoft.
Ultimately it will probably be a good idea, but it’s by no means clear that it will be the panacea to a national broadband solution that some hope it will be. In fact, there’s every possibility that the whole “White Space” excitement is badly overhyped and in the long run will likely to lead to more disappointment than broadband growth.
First, it helps to know exactly what this “white space” that everyone’s talking about really is. No doubt you have some idea that a television channel is a set of frequencies used by broadcasting stations for transmitting their signals. In the past, the FCC has always allocated a slice of spectrum between TV channels as a guard band. These were frequencies where nothing was allowed to operate so that television could be protected from interference from another broadcast station operating on an adjacent frequency.
The reason the stations needed this guard band was because television signals really consisted of two radio transmissions, one for the audio and one for the video. One signal was transmitted in analog using AM and the other using FM. The result was that these signals used a lot of bandwidth, and the amount of bandwidth could vary slightly depending on the nature of the signal. The guard bands kept things separate, and given the fairly primitive technology used by television receivers when these were set up, the television sets needed that space as much as the broadcasters did.
Since then, things have changed. Television in the United States is almost entirely digital, except for some low-power community stations. Television receivers have vastly improved technology with far greater precision, so guard bands are less necessary. The idea is to use those formerly empty bands for digital transmission that includes (but isn’t restricted to) high-speed broadband. This all sounds good, right?
The problem is that television broadcasters don’t want their signals interfered with any more than they ever did. While televisions stations produce an effective radiated power in the hundreds of thousands of watts in some cases, it’s not the transmitted signal they’re worried about. Because radio waves diminish greatly with distance, and because every white space data device includes its own little transmitter, the broadcasters are worried that somebody’s broadband Internet will interfere with their programming at sites where their signals are relatively weak.
White Space as a Badly Needed Broadband Solution
Adding to the complexity is the existence of licensed users in the frequencies being considered for white space use by the FCC. These users can include such things as wireless television cameras used by television stations and in sports stadiums, wireless microphones used in theaters and concert venues, and a number of other existing uses. Depending on where you are in the spectrum, such use is complicated. This is a very complex assignment process, as you can see from a look at the existing spectrum allocation plan.
Currently, the FCC is planning to require buffer zones around areas where such licensed users operate, which means that the white space use in Manhattan could have a big blank area around Broadway because of the number of wireless microphones used in the theaters. Imagine, if you will, the confusion that might be caused if you take your wireless Internet device into one of these buffer zones and in the process manage to take Lady Gaga off the air during a concert.
Adding to the difficulty of allocating chunks of spectrum to digital communications for broadband is the fact that at least some of the white space allocation is going to be location-specific. In addition to the Broadway problem mentioned above, those guard bands exist only in some areas. It’s not a stretch to find that the assigned frequencies are not nationwide, but instead are a collection of frequencies that every mobile device must find in order to work. How that might function remains a mystery.
And of course, this isn’t WiFi at all. It’s actually a data service operating at a much lower frequency than WiFi that has better range and building penetration characteristics than WiFi, but also greater exposure to interference. For users, it’ll seem like WiFi, but it’s not. In other words, it’s not a solution for iPhone overpopulation. Worse, these frequencies will be allocated for such purposes only in the United States. Everywhere else in the world, they’re being used for digital radio. So if you do have a mobile device, it’ll only work on those bands in the United States.
In some ways, the white space solution is a much better solution for fixed wireless than for mobile. It also seems that the FCC realizes this and is already questioning cable companies about the pricing plans for such frequencies.
Fortunately, even if it’s mostly fixed wireless, it’ll provide a badly needed solution for high-speed data access for underserved areas of the United States, especially rural areas, and in economically distressed areas that are bypassed by the cable companies. If that’s the only thing it accomplishes (and surely it won’t be), then it’s a good thing.