Wi-Fi Interference:
Can't We All Just Get Along?

Friend or foe, it's important to get to know all of the fixed wireless operators playing in your WISPs space. Form a consortium, coordinate your buildouts, hire an attorney ... Learn how to share spectrum and grow your WISP by adhering to a WISP Code of Conduct.

by Michael R. Anderson PDQLink Chief Internet Officer [May 1, 2001]

The fast-paced and ever-evolving Fixed Wireless Internet service segment—specifically those providers operating in unlicensed 2.4GHz and 5.8GHz territories, could be heading for disaster. If WISP operators do not take the time to plan their wireless point-of-presence (WiPOP) carefully and diligently, your wireless broadband setup could bumped off the air and out of business.

In a recently published report by ISP-Planet, The ISP Market: Challenges and Strategies for the Future, nearly 75 percent of the service providers surveyed indicate they have plans to offer fixed wireless Internet services before the year is through—and most plan to operate in unlicensed 2.4GHz and 5.8GHz spectrum.

With WISPs popping up all over, frequencies carrying fixed wireless data are getting more crowded every day. Portable phones, cordless phones, microwaves, and Bluetooth devices can wreak havoc with your WISPs signals—everyone accepts these types of interference and plans around them.

But there will be times when other wireless operators might not willingly relinquish what they consider to be their sovereign right to operate over the same unlicensed airwaves as your WISP business. Remember, everyone has the same rightful access to utilize the same public airwaves. We can all get along, playing in unlicensed spectrum—to a certain point.

Coordination complex
The Federal Communications Commission says we must all accept interference as a part of doing business over public airwaves, but that does not mean we must accept harmful interference. Harmful interference is an obstruction of such magnitude that signals carrying other telecommunication services are disrupted. For example, let's say XYZ.com deployed a WISP system in August 2000. ABC.com came along in January 2001 and unleashed its wireless service offering in the same service area, over the same unlicensed spectrum.

Both WISPs have systems up and running and both experience some interference with each other's systems. But the two WISPs have managed to keep their networks running, cohabiting over the same airwaves without losing connections or customers. ABC.com decides to expand its service area and reach more users by adding a 500-miliwatt amplifier on one of its Omni antennae. ABC.com's amplifier knocks out XYZ.com's signals and causes a total backhaul loss—bringing down XYZ.com's entire network.

ABC.com knew—or should have known—that adding a powerful amplifier to its WiPOP could cause significant or harmful interference to XYZ.com and other wireless systems operating in the area. ABC.com made three fundamental errors:

ABC.com failed to engineer a sustainable WiPOP:
Rather than amplifying its signal strength, ABC.com should have considered building a second WiPOP or adding directional antennas to broaden its service area. The configuration ABC.com used exceeded EIRP (Effective Isotropically Radiated Power) limits, as set by the FCC. In effect, ABC.com built an illegal system.

ABC.com failed to accommodate other operators in the area:
ABC.com did not realize their poorly planned WiPOP would bring down an entire school district or the local county seat. They might have thought its rival provider in the area, XYZ.com, would have to deal with some new interference created by the setup, but who cares about them, right? Wrong answer!

ABC.com failed to coordinate and communicate its plan:
ABC.com should have called other operators in its shared service area to inform them of what they planned to deploy. Doing so establishes a notice of intent (NOI), so that others operating in the same spectrum can monitor the situation as ABC.com restarts its amplified setup.

Among friends
If your wireless Internet service operates among friends, then you should remain friendly with other wireless systems in your WISPs footprint. Here's a few ways to get started and make sure that everyone remains amicable:

• Say hello: Before deploying your WiPOP, send a letter of introduction to others wireless operators in your service area that play in the same spectrum as your WISP business. By taking the time to introduce yourself and your WISP to others, you might learn something interesting facts about the market. When we introduced our fixed wireless system, one firm we thought was a rival turned out to be our best partner. We discovered that they only deliver business class fixed wireless access in our shared service area, so they offered to refer residential inquiries our way.
• Join or establish a local wireless consortium: Get some local HAM operators involved with your WISP and set up a time to meet at your local library, government conference room, or tavern once a month. Elect officers and establish a mediator to resolve frequency disputes in the area. By opening up the lines of communication, you just might make it easier to keep your WISPs invisible lines of communication open for business.
• Phone list: Build a telephone directory for all the local wireless operators in your service area so everyone can call and talk to each other about upcoming tests and plans. There are no secrets here, forget about keeping a WiPOP hidden—the moment your WISP goes live, others will know. Once you flip the switch, anyone will be able to see your signals.

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