I recommend this article, for anyone who wants better to understand some basics of Internet transmission technology. Have you wondered the difference between DSL, cable modem service, fiber, and wireless? Dale Hatfield explains it all.
Based on these technological realities, he also makes an interesting policy argument in the last paragraph: while government policy is targeting the clearing of spectrum, it should also encourage increased build-out of fiber lines closer and closer to residential homes. This build-out is important for increasing capacity for wireline networks, but also for wireless networks, complimenting our spectrum policies.