WiFi Jedi.com

Surveys – you know, the kind where a telemarketer interrupts your dinner.  Or the kind where someone with a clipboard stops you in the mall.  That’s *not* what I am talking about here.  I want to speak briefly about wireless site surveys.

I performed an active site survey in a warehouse environment this morning. It reminded of the differences between active and passive site surveys.  Active site surveys are where real measurements are taken using actual product to determine the optimal number and location of wireless access points.  Passive site surveys (also referred to as predictive analysis) are computer generated model showing the “what-if” scenario given a CAD drawing with layers containing information about the construction materials for a given facility.

Here is as sample photo of a heat map generated by an active site survey:

Active Site Survey

Each of the red dots represents a data point of the measured signal strength and noise level at that particular spot.  Because active site surveys take measurements of live data, they are much more accurate than predictive analysis, which relies on computer modeling. Beyond being more accurate, active site surveys offer many advantages:

• On site personnel can conduct interference analysis, including from WiFi and non-WiFi (Microwaves Ovens, Cordless Phones, Bluetooth, etc.) sources
• On site personnel can conduct a rogue security sweep in conjunction with an active site survey – rogue access points, ad-hoc networks, and other security liabilities can be identified.  This security sweep can also ensure company devices comply with corporate policies, which is helpful for audits relating to SOX, PCI, GLBA, etc.
• On site personnel can also conduct performance analysis and/or troubleshooting.  Because active site surveys bring software to the “front lines”, engineers are better equipped to provide a diagnosis and recommendations

The main detractor to active site surveys are they require a decent amount of time from a knowledgeable professional.  This translates into the fact that they are more expensive than predictive analysis. <company plug> My employer, Xirrus, conducts free (no-obligation) active site surveys as a part of our sales process.  We offer a 100% performance gauruntee, which actually drives the need for an active survey.  We use the survey to generate our bill of materials.  Since we take real measurements using actual product, we are able to generate quotes and perform installations that we know will work – hence the garuntee.  </company plug> Which site survey method do you prefer?  Why?  Tell me about your experiences with active vs. passive surveys in the comments below!