Whose Problem is WLAN Interference?

Breakable Rules

This bandwidth is free for the taking, as long as you abide by FCC regulations. The ISM band, for example, includes restrictions on output power and requires the use of spread-spectrum modulation. The UNII bands impose complex restrictions that regulate EIRP (equivalent isotropic radiated power). The FCC even regulates whether standard antenna connectors can be used on unlicensed devices. Companies must get FCC certification for all unlicensed radio products.

Still, consumers have relatively little protection. For example, it's legal for a company to sell a 2.4-GHz cordless phone that renders wireless LANs inoperable. And there are no dispute-resolution procedures to protect you if you install an unlicensed wireless connection and someone down the street installs another system that causes interference. In fact, the FCC has little power to enforce the rules, and consequently, individuals and organizations routinely violate FCC rules by using amplifiers and high-gain antennas to blast their signals louder and farther.

Enterprises, service providers, small businesses and home users all love unlicensed systems because you can buy them Monday and have them operational Tuesday. Vendors that sell unlicensed gear say they can count on one hand the number of cases in which interference problems couldn't be solved. Maybe so, but what will we do when everyone shows up at the wireless party?

And the Answer Is...Industry experts propose two solutions. The first is simply to allocate more unlicensed bandwidth--after all, there's plenty of licensed spectrum that isn't being used. But look at the difficulties the U.S. government has faced in trying to come up with licensed frequency for 3G wireless systems and it'll be obvious that increasing the amount of unlicensed spectrum is no stroll in the park.

The second possible solution is self-regulation: no need to involve politicians and government technocrats when the industry can police itself. There's some merit to this argument because the industry has a vested interest in keeping things under control--the airwaves are a public good, but without regulation, all hell could break loose. Yet while technical solutions for many interference problems are indeed possible and a number have been implemented, you have to wonder whether a mere Band-Aid can stop the kind of bleeding the wireless industry may have in store.

And if the industry can't solve these problems, can the FCC? Frankly, I'm not optimistic. It makes perfect sense to question the logic of building mission-critical information services on top of unlicensed radios, especially in densely populated outdoor environments. If there's any good news, it's that wireless LANs are so compelling they may pay for themselves well before interference becomes a serious problem. Just remember you need a fallback plan if and when that time does come.