The cellular bands are nearly filled, new spectrum is hard to come by, and modulation techniques already use existing spectrum about as efficiently as possible. What’s left to do? A recent report [PDF] of the U.S. President’s Council of Advisors on Science and Technology concludes that we must move to smaller and smaller cells. As the cell size shrinks, system capacity becomes virtually limitless.
I imagine a world filled with wireless picocells. But wait—don’t we already have something approaching that with the spread of Wi-Fi hot spots? I consider the one I’m using right now, as I write this column in a coffee shop. The shop’s little cell—where is it? behind the counter?—covers my fellow dozen customers. There’s another cell next door, and next door to that, and so on, all the way down the street. In fact, when I drive through this little community, I’m never out of range of a Wi-Fi hot spot.
The website WiGLE.net lists about 100 million sites that have been discovered by contributors. When I zoom in on the map of hot spot locations, I see that in my little town there is a dense concentration of sites along all the main roads, and I know that the unmapped side roads are also dense with sites. Even my own house, so far from any road that a laptop in a passing car can’t receive my home network’s signal, shows up on Google Maps. Indeed, Google knows exactly where I am when I use my iPad at home. Just how does it do this?
Google says it uses crowd-sourced Wi-Fi hot spot data to triangulate the location of networks. I assume that it locates me by combining information from networks reported by several neighbors before it reaches a known street location. However Google does it, I’m impressed, and it says something to me about the density of Wi-Fi coverage and geographic usability of this data.
In spite of this density of coverage, when I walk out of this café, I will have to rely on my cellphone and the services of my cellular provider. Needless to say, this is expensive—in terms of both network resources and my provider’s monthly bill—especially in comparison with the free coverage inside the café. But almost all those other networks outside this door are closed to me. WiGLE.net reports that only about 17 percent of the sites it lists are unencrypted and that this percentage has constantly decreased with time. I’m reminded of the old saying “Water, water everywhere, but not a drop to drink.” The picocells are everywhere; I just can’t use them.
I have this imaginary scenario where I convince everyone in my town to open up their Wi-Fi networks. We’d all use Skype for telephony, get rid of our cellphones, and get cheap, prepaid cellphones for travel and emergencies. Of course, there would be worries about privacy with open networks, although it could be maintained with encryption and other safeguards while leaving the network access open. Indeed, Apple’s Wi-Fi routers —and many others—allow for the creation of a separate “guest” network.
I wonder how this scenario would evolve. Maybe open networks would spread throughout the country and the cellular providers would lose a lot of business. Investment in the cellular infrastructure might disappear. Wi-Fi locations might get overloaded and experience interference problems. Even today some experts are predicting the imminent collapse of Wi-Fi, but maybe, as with the old predictions of the collapse of the Internet, it will continue to thrive. In any event, what role it plays remains to be seen. Right now Wi-Fi is considered an adjunct to the cellular network, but it’s conceivable that this paradigm could be reversed.
This article originally appeared in print as “Whither Wireless?”