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Overcoming wireless network interference in public venues

In public venues, unplanned personal hotspots can cause wireless network interference. Wireless expert, Lisa Phifer explains how to overcome this and maintain Wi-Fi coverage.

Our company holds a semi-annual show that moves around the country. At this show, we always connect back to our...

corporate network by secure tunnel over a convention center wireless network. At recent shows, wireless was slow and we were told it was due to wireless network interference from all of the other wireless users. I turned on my sniffer and noticed that almost all of the other devices were on channel 11. I have never heard of this problem, have you?

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Yes -- perhaps the most notorious example of wireless network interference came in June 2010, when competition from 570 portable and smartphone personal Wi-Fi hotspots ruined the iPhone 4 demo being given by Steve Jobs – watch for yourself on YouTube.

Competition from nearby access points (which Jobs called base stations) has only gotten worse since 2010. Current-generation Windows laptops and iPhones and Androids can all behave as virtual APs, letting users share that device’s 3G/4G Internet with Wi-Fi-only tablets, Kindles and other consumer electronics. These unplanned personal hotspots are wreaking havoc on permanently installed WLANs, especially in public venues such as convention centers and hotels and airports.

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As you noted, the vast majority of that competition occurs in the 2.4 GHz band, which includes channel 11. Not only are the lower-end consumer devices 2.4 GHz only, but that band has fewer channels for APs with automated channel selection to try to find less congested air. Enterprises can (and often should) try to avoid wireless network interference by moving to 5 GHz when possible. However, in a convention center, wireless network operators must try to serve the broadest number of devices – and that means 2.4 GHz.

Try asking the network operator at your next venue whether they have 5 GHz service available – if so, configure your own dual-band devices to use 5 GHz. In convention centers, the 5 GHz WLAN may even have a different SSID to help customers explicitly choose that more responsive network. The downside: 5 GHz signal strength often declines faster over distance, so check Wi-Fi coverage during your pre-show site visit to select a meeting room or booth with good 5 GHz coverage.

This was last published in May 2012

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