Review: Wireless LAN Analysis Tools

Posted by Jameson Blandford and Daniel Renfroe on December 2, 2005

Spectrum Analysis Features Click to enlarge in another window

Site Survey Analysis Features Click to enlarge in another window

Most of these products don't fit neatly into one category or another; some protocol analyzers can also view wireless performance data, for instance. Likewise, some performance and security analyzers contain basic spectrum-analysis capabilities. Nonetheless, the groupings we've made let us draw relevant comparisons among the products.

We're not awarding an Editor's Choice because we don't want to limit our exploration of these tools to a single usage scenario. Rather, we want to focus on the many situations WLAN administrators are likely to face. We requested that for each device they submit, vendors supply us with associated usage scenarios, detailing the particular problem and how their product addresses it.

These products come with a variety of labels, but we divided them into the following categories: spectrum analyzers, wireless protocol analyzers, site survey analyzers and wireless performance and security analyzers.

We were surprised by the diversity of scenarios, which ranged from the specific (intermittent disconnection from the WLAN caused by an interfering Bluetooth device) to the broad (radio frequency analysis and troubleshooting). The scenarios and their solutions are discussed on a product-by-product basis.

The wireless RF signal is the most basic component of a WLAN. Unlike conventional wired infrastructures, where transmission takes place over a guarded and closed medium, wireless networks are an unpredictable no man's land with no guarantee of successful communication. The fact that 802.11-based wireless networks operate in an unlicensed spectrum alongside Bluetooth devices, microwave ovens and cordless phones opens the door to potential interference that ranges from annoying to showstopping. Although interference from adjacent wireless networks on the same or overlapping channels is relatively easy to identify and mitigate through channel and power configurations, noise from non-802.11 devices can be difficult to combat. For more background on the effects of some common sources of interference, check out "How To Block WLAN Interference".

Identifying and locating interference sources requires a good spectrum analyzer operating at 2.4 GHz for 802.11b/g and 5 GHz for 802.11a. This market, once dominated by conventional spectrum analyzer vendors like Agilent Technologies and Tektronics is now being supplemented by PC and Pocket PC products from BVS, Cognio, AirMagnet and WildPackets. Although spectrum analyzers have been used by professional WLAN installers for spectrum preplanning and verification, a growing number of IT departments have incorporated these tools into their bag of tricks.

WLAN Protocol Analysis Features Click to enlarge in another window

Because of the sporadic nature of many interferences, most enterprises are unaware when they experience a problem. Intermittent connection failures or unexplained dead spots often are written off as the temperamental nature of wireless networks but could be caused by a cordless phone down the hall, or a microwave in the break room. Even though most WLAN problems are not related to interference or other physical-layer issues, a spectrum analyzer is necessary on large networks, if only to rule out interference as the cause of a problem.

Site Survey Analysis Features Click to enlarge in another window