How Can You Avoid RF Interference In Wi-Fi Deployments?
Last week, I talked about how to deploy a Wi-Fi network that actually works. I mentioned that the key is to avoid RF interference. This week, I want to discuss how to avoid it. First, I want to give you a “cheat sheet” on some basics of Wi-Fi.
Wi-Fi Quick Reference Guide:
- Wi-Fi is a broadband connection that runs on two different bands:
- 2.4GHz, with three non-overlapping channels in the U.S.
- 5GHz with roughly 7x the available bandwidth of 2.4 (including DFS)
- Most RF devices—microwaves, for example—run on the 2.4GHz band; interference can be an issue
- Any Wi-Fi networking gear that you buy should be approved by the Wi-Fi Alliance to ensure interoperability
- Test devices in the area in which they will be deployed; do not buy off the datasheet!
When it comes to avoiding RF interference, ensure that any vendor you are considering has a predictive analysis feature. This feature allows you to input your building or campus layout, deploy imaginary access points, and visualize any potential interference issues. This analysis will also help you to determine how many access points you really require, and to easily justify that expense by showing a graphical layout.
If at all possible, do a live site survey. It is compelling to believe some vendors who tell you that predictive analysis is sufficient to ensure a good Wi-Fi deployment, but, once again, remember that predictive analysis is theoretical. A full-blown site survey features a trained professional walking your site pre-deployment and looking at what is really going on in the radio frequency (RF) spectrum. You may easily get a surprise—your smartboard is transmitting, as are your new door locks. The microwave in the break room is leaking through the wall. And you may also have other Wi-Fi devices running; it’s not uncommon to discover pre-existing Wi-Fi gear or even products installed before any of the 802.11 standards were officially ratified hiding in older buildings! While a complete site survey could be unattainable, there are many interim steps, some of which you can run yourself, which will help you to see the real picture from an RF point of view.
Keep your pre-deployment results and retest after deployment. These records will put you far ahead of the game if/when you need to troubleshoot.
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