The IT Guy
Wireless Lab Interference Problems
Question:
We're experiencing interference to a wireless laptop system. We have 7 carts of wireless laptops in our 9-12 high school building. The laptops have wireless cards (Lucent or Orinoco) for the WL110 11Mbps Wireless LAN. We take the carts to various classrooms along with an Access Point and a network printer.
This system worked very well in the past years, but now there's interference with the wireless signals, which causes the students to become disconnected from the server and lose data.
We upgraded the operating systems on all of the laptops to XP and we added encryption. We also have done some remodeling in the building — new lighting, heating, and new wiring in some areas. We have tried different configurations, using more access points, using fewer access points, spacing out the points, trying static addresses, removing 2.4Gh cordless phones, having students log on just a few at a time, etc.
There are just too many variables for us to actually narrow it down to one factor to solve the problem. We do not plan to install access points throughout the building at this time, but to just bring the access points along with the carts into the classrooms.
The IT Guy says:
It sounds like it's time to have a professional come in and do a RF site survey to determine your potential interference sources. You are right about there being many variables: it is great when you can plug in an access point and "it just works," but the proliferation of devices operating in the 2.4 GHz band makes this more difficult than ever. As you likely already know, microwave ovens, nearby radio stations, and wireless telephones can all cause interference. For wireless phones, you may be able to switch the channel used to reduce interference. Other sources could include Bluetooth devices, however, so if you have Bluetooth networking active on computers in the area you could try turning those off or disabling Bluetooth. Try and position access points as high in a room as possible, on an upper floor if trying to cover a large area, and away from large metal objects like filing cabinets. By the way, an RF site survey is a great idea even BEFORE starting a wireless project.
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