Every year about this time, I write about wireless. I'm at the beach, and have to use the local wireless service. It works great at 6 AM, when no one else is up, but once all the other people in the neighborhood start logging on, the service gets slower and slower. Wireless is a shared medium, like cable modem service. A wireless access node with, for example, 20 megabits of bandwidth, shares that bandwidth among all users. So if you have 20 users on at the same time, each one effectively gets only about 1 megabit--or less, if one of those users is trying to download video or music.
Wireless and cable modem work moderately well today because fortunately, not everyone connected to a cable node or wireless access point is doing something at the same time. You are not using any bandwidth while you are reading a Web page or your email. The fly in the ointment is our ever increasing demand for video and multimedia, which use hundreds of times the bandwidth of email and Web pages. Trying to download a Netflix two hour movie over your cable modem or wireless connection may grab most of the available bandwidth, making everyone else's access, for a few minutes or even an hour, very, very slow.
All network architectures, even the "Internet," rely on sharing to some extent. But at the local level--neighborhoods and communities--shared bandwidth can be a challenge. As more of get connected, we will do more locally, and that means better networks, designed to minimize the effects of shared bandwidth. As always, we end up needing fiber as part of the solution.