Unlicensed spectrum is not the “Wi-Fi band”: it's open for any person and any device to use, for any (legal) purpose, and it's open to a wide variety of technologies.
It's understandable, then, that some people are confused by the skepticism Public Knowledge and many others have with respect to LTE-U, a technology that would allow wireless carriers to offload some of their existing traffic to the unlicensed bands, using the same communications protocols they use on their licensed spectrum.
But unlicensed spectrum is not and never has been a free-for-all. There have always been power limits and certification requirements, designed not just to keep unlicensed users from interfering with licensed users, but to keep unlicensed users from interfering with each other. Unlicensed spectrum means that everyone can use it–but not that everyone can use it in any way they want.
Put another way, there is a huge difference between “you need to accept whatever interference comes your way” versus “people can mess with each other, block each other’s services, and blast each other out of the sky.”
This is not some ad hoc, “protect Wi-Fi” principle, but a bedrock of the Communications Act that has been in place for more than a century. The Radio Act of 1912 stated that “in all circumstances … all stations shall use the minimum amount of energy necessary to carry out any communication desired.” And the current Communications Act states that users of the radio spectrum “shall use the minimum amount of power necessary to carry out the communication desired” (47 U.S.C. § 324). A device that does not cooperate with other spectrum users–for example, by adopting a listen-before-talk protocol that can coexist with other users–is using more power than it needs to in order to carry out the underlying communication, especially when alternative technologies exist. Just as 47 U.S.C. § 333 of the Communications Act, which prohibits deliberately interfering with radio communications, applies to unlicensed spectrum and prohibits deliberate attempts to block Wi-Fi, section 324 applies to unlicensed just as much as it applies to any other “broadcaster.”
As technology progresses and the population of unlicensed devices changes, it makes sense to make sure that devices that are authorized to use unlicensed spectrum don't make other uses impossible or more difficult. With LTE-U, there are serious concerns that it does not share spectrum as efficiently with other users as do technologies that were initially designed for unlicensed use. And it's not even clear that LTE-U solves any real problems. There are other technologies that carriers can use to offload their traffic onto the unlicensed bands that do not raise the same interference concerns, and licensed carriers have other bands of spectrum to use that are not available to Wi-Fi devices. LTE-U solves business problems for some equipment vendors on their customers, but it's not a compelling technology otherwise.
It's a core part of the FCC's mission to make sure that different users of spectrum, including unlicensed spectrum, can coexist. The enhanced scrutiny of LTE-U is part of this.
Image credit: Flickr user Tsahi Levent-Levi
 Pub. L. No. 62-264, 37 Stat. 302, §4, Reg. 14 (1912)