The use of wireless devices is increasing in the enterprise. If you have a wireless network, soon your users will demand the same performance they expect from your wired network. To ensure the performance of your wireless network, it's a good idea to measure your wireless network's strength throughout your desired range. Doing so allows you to position your access points at appropriate places, upgrade antenna or other technology, deploy repeaters, and take other measures to get your desired throughput to the level required.
Many of the tools you can purchase are software that you load onto your computer. Those tools use your computer's network card as their detection device. In general these types of tools aren't as accurate as buying a hardware device that detects a wireless signal. When you purchase software you detect the protocol that your network card supports; certain hardware devices are able to detect multiple protocol. The truth is that rarely do you need to know the absolute strength of a wireless signal. Your interest is in whether you can connect in the first place, and how one location differs relatively from another location. So for most people software tools like NetStumbler, although a little difficult to master, are popular and widely used.
A good place to start is to create a scale diagram of your network's physical location. You should show walls and other obstructions, position your wireless network devices on the drawing, and begin to survey the reception at appropriately selected location. You will probably find that the type of antennas you use affects your transmission profile. An omni-directional antenna casts a circular wireless shadow. Other antenna types like dipoles will cast a barbell shaped transmission shadow.
For locations with multiple access points you will also find that by having those access points maintain different channels you can create overleap and a large supported area. So your testing should determine not only the strength of the signal, but the location, channel, and security used at each point. You'll want to document the following parameters:
- Your access point(s) physical address and logical address (e.g. MAC and IP)
- The specific connection of an access point to your network wiring
- The hardware configuration and level or firmware revision
- Client wireless card network and MAC addresses
Among the commonly used tools are: the AirMagnet handheld and Duo a/b laptop system; AirSnort; Fluke Networks Waverunner; Berkeley Varitronics Systems Yellow Jacket, Grasshopper, Locust, Beetle, and Hornet; NAI Sniffer; NetStumbler; and Wild Packets AiroPeek.
You may also want to read Fluke Networks white paper Wireless Site Survey Guide that is found on the SearchNetworking.com site.
Barrie Sosinsky is president of consulting company Sosinsky and Associates (Medfield MA). He has written extensively on a variety of computer topics. His company specializes in custom software (database and Web related), training and technical documentation.