wifi-in-tsunami-1Wi-Fi is one of the great technological successes of our age. It gives fast, reliable data transmission by anyone for any purpose. No FCC license is needed. No single provider controls the technology. The equipment is inexpensive and available in a large, competitive marketplace. It almost always works.

Was it too good to last?

We explained a year ago that carriers want to move traffic off their expensive auctioned frequencies and onto the same free-of-cost, and unlicensed, frequencies that Wi-Fi uses. We kept you current on the process of setting standards for the various technologies the carriers want to use, to include LTE-U, LAA, and MulteFire – see here and here – including the controversial issue of whether LTE-U would interfere with Wi-Fi.

Interference to Wi-Fi? Isn’t that illegal? Prepare to be surprised. The convenience of Wi-Fi being unlicensed has a cost: no unlicensed technology has any legal protection from interference. (We’ll pass over a minor exception.) The FCC regulates the power and other properties of unlicensed equipment to make sure it doesn’t interfere with licensed services. The very smart people who invented the Wi-Fi standards, and who design other devices for the same bands (like Bluetooth), are careful about coexistence, which is why all this equipment usually works well together. But coexistence is not a factor in whether the FCC will certify a device for sale as being compliant with its rules.

The FCC has now issued its first certifications for LTE-U devices. (The first LAA devices, a tad less controversial as to their ability to co-exist, were approved months ago.) The announcement reiterates that coexistence with other unlicensed devices is not an FCC requirement. But it mentions that the new devices were successfully evaluated for coexistence under a test plan worked out by industry – in this case, LTE-U and Wi-Fi stakeholders under the auspices of the Wi-Fi Alliance. That last is the group responsible for making sure that Wi-Fi-branded devices all connect to each other properly.

The real test of coexistence between Wi-Fi and LTE-U begins now, in the millions of homes and offices that rely on both Wi-Fi and cell phones to stay connected.