LTE-U, WiFi Backers Wrangle With FCC Over Sharing Spectrum

By Wayne Rash  |  Posted 2015-12-13 Print this article Print
Wireless Spectrum

You can change carriers on your unlocked iPhone any time you want to and it will work on any of the available networks, except that AT&T has an LTE band that the others don't.

But despite the shared spectrum, the similarity ends there. WiFi Calling is a service that meets the technical recommendations of the WiFi Alliance, but LTE-U isn't. On the other hand, the LTE-U Forum is working on recommended standards, including non-interference standards that will encompass WiFi. The LTE-U Forum has responded to earlier claims by the interests supporting WiFi in a letter to the FCC, claiming deficiencies in their argument.

If the pros and cons of the WiFi versus LTE-U argument were based strictly on the law and on engineering realities, this would be a relatively easy argument to settle. Sadly, the parties involved, especially on the WiFi side, are spreading fear, uncertainty and doubt as thickly as they can, making claims about LTE-U that aren't true, pointing to fanciful scenarios and what-ifs that are pure speculation.

The reality is this. WiFi can use the 5GHz portion of the unlicensed spectrum, and many—but far from all—devices have 5GHz capability. But that portion of the spectrum is lightly used by WiFi even though it's available because it has relatively short range and poor structure penetration. It's important to the success of 802.11ac, but that high-speed version of WiFi only works over relatively short ranges.

It's the 5GHz band that LTE-U is aiming at. This band is far broader than the 2.4GHz band you're most familiar with. There's room for a significantly greater amount of use on 5GHz than on the lower frequencies.

Interference is very unlikely to occur because of the relatively short range and poor structure penetration, but also because both WiFi and LTE-U have the ability to sense other signals on any specific frequency and move elsewhere. If there is interference, it's the result of poor design.

Of course, there's no shortage of poor design in WiFi, just as poor design exists in most other consumer electronics from televisions to auto entertainment systems. So the question now becomes whether the FCC should intervene to protect the poor engineering practices of one user of the spectrum to the disadvantage of another.

I've seen this same contest with other services over the years, and the only time any service has had the upper hand is when it's the licensed user of spectrum that's also being used by unlicensed users.

When that happens, the unlicensed users must give way. But here, both sides of the argument are on equal footing, with the WiFi interests trying to invent a right that doesn't exist. The FCC should—and I think will—keep this in mind as it considers the question.



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