If you’re sitting with your laptop at an outside cafe, you’ll be happy with the service. But if you happen to be at home, you realize that service to the doorstep is not enough: you still need to buy equipment to bolster the signal and solve the “last mile plus 10 more yards” problem — that is, getting coverage indoors.

Wi-Fi signals do not bend, and you usually can’t get much of a useful bounce from them, either. Because Wi-Fi uses unlicensed bands of the radio spectrum, by law it must rely on low-power transmitters, which reduce its ability to penetrate walls. Travel-round-the-world shortwave, this ain’t.

Trying to cover a broad area with Wi-Fi radio transmitters set atop street lights brings to mind a fad of the 1880s: attempts to light an entire town with a handful of arc lights on high towers. But overeager city boosters around the country soon discovered that shadows obscured large portions of their cities, and the lighting was not as useful as had been expected. Municipal Wi-Fi on streetlamps, another experiment with top-down delivery, may run a similarly short-lived — and needlessly expensive — course.

WiMax, which will be a high-power version of the tower approach, comes in two flavors: mobile, which has not yet been certified, and fixed, which is theoretically well suited for residential deployment. Unfortunately, it’s pricey. Peter Bell, a research analyst at TeleGeography Research in Washington, said fixed WiMax would not be able to compete against cable and DSL service: “It makes more economic sense in semirural areas that have no broadband coverage.”

An intriguingly inexpensive alternative has appeared: a Wi-Fi network that is not top-down but rather ground-level, peer-to-peer. It relies not on $3,500 radio transmitters perched on street lamps by professional installers but instead on $50 boxes that serve, depending upon population density, more than one household and can be installed by anyone with the ease of plugging in a toaster.